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During the blood coagulation cascade, coagulation factor VIII (FVIII) is activated by thrombin to form activated factor VIII (FVIIIa). FVIIIa associates with platelet surfaces at the site of vascular damage to form an intrinsic tenase complex with activated factor IX. A working model for FVIII membrane binding involves the association of positively charged FVIII residues with negatively charged lipid headgroups and the burial of hydrophobic residues into the membrane interior. Currently, the atomic details of the FVIII lipid binding interactions and membrane orientation are lacking. This study reports residue-specific FVIII C domain interactions with 1,2-dioleoyl- sn -glycero-3-phosphocholine (DOPC) and 1,2-dioleoyl- sn -glycero-3-phospho-l-serine (DOPS) in atomistic detail. Contact maps between residues in the C domains with different lipid moieties support prior structural data describing how the C domains associate with membranes through electrostatic and hydrophobic interactions. Solvent-accessible surface area analysis quantified the extent to which residues in the C1 and C2 domains bury into the membrane. Calculations of the potential energy between the C domains and DOPC and DOPS revealed an FVIII membrane-binding orientation that agrees with previous experimental data. This study expands our knowledge of the structural basis of FVIII membrane association, which may be critical for the development of next-generation FVIII replacement constructs with improved activity.

Hemophilia A (HA) is caused by mutations in coagulation factor VIII (FVIII). Genome editing in conjunction with patient-derived induced pluripotent stem cells (iPSCs) is a promising cell therapy strategy, as it replaces dysfunctional proteins resulting from genetic mutations with normal proteins. However, the low expression level and short half-life of FVIII still remain significant limiting factors in the efficacy of these approaches in HA. Here, we constructed a functionally enhanced FVIII variant, F309S/E1984V-mutated B domain-deleted (BDD)-FVIII (FE-FVIII), with increased activity and stability. We inserted FE-FVIII with a human elongation factor-1 alpha (EF1α) promoter into the AAVS1 locus of HA patient-derived iPSCs via CRISPR/Cas9 (D10A) nickase to ensure expression in any cell type. FE-FVIII was expressed not only in undifferentiated FE-FVIII-inserted (FE-KI) iPSCs but also in endothelial cells (ECs) differentiated from them in vitro. Compared with mice transplanted with wild-type BDD-FVIII-containing ECs, immunocompetent HA mice intravenously transplanted with FE-KI ECs presented a 2.12-fold increase in FVIII activity in the blood and an approximately 20% greater survival rate after hemorrhagic tail injury. For sustained efficacy, FE-KI ECs were subcutaneously transplanted into immunodeficient HA mice, resulting in amelioration of the hemophilia phenotype for more than 3 months. This strategy can improve FVIII function and may provide a universal therapeutic approach for treating HA., Competing Interests: Competing interests: The authors declare no competing interests., (© 2025. The Author(s).)

Background: Following proteolytic activation, activated blood coagulation factor (F)VIII (FVIIIa) binds to activated platelet membranes, forming the intrinsic tenase complex with activated FIX (FIXa). Previous studies have identified the C1 and C2 domains as the membrane binding domains of FVIII through conserved arginine residues. A membrane binding model for the FVIII C domains proposes that surface-exposed hydrophobic and positively charged residues at each C domain interact with the membrane, yet a comprehensive thermodynamic and structural description of this interaction is lacking., Objectives: To determine residues of interaction, thermodynamics, and membrane binding preference for FVIII membrane association., Methods: The binding of FVIII constructs to lipid nanodiscs was characterized by nuclear magnetic resonance, isothermal titration calorimetry, bio-layer interferometry, and X-ray crystallography., Results: The thermodynamics of FVIII membrane binding indicated that the C1 domain associates through an enthalpically driven process while the C2 domain is entropically driven. Alanine mutations to surface-exposed hydrophobic residues in the C2 domain revealed differential effects on membrane binding, highlighting important determinants at the residue level. The structure of a C2 double mutant, L2251A/L2252A, demonstrated that its decreased affinity is likely due to decreasing the surface area hydrophobicity. Nuclear magnetic resonance studies with the C2 domain identified residues of interaction with soluble O-phospho-L-serine as well as lipid nanodiscs. Lastly, increasing phosphatidylethanolamine and decreasing phosphatidylserine content decreased overall FVIII affinity for membrane surfaces., Conclusion: This study provides further insight into the molecular basis for how FVIII interacts with platelets to form the intrinsic tenase complex., Competing Interests: Declaration of competing interests There are no competing interests to disclose., (Copyright © 2024 International Society on Thrombosis and Haemostasis. Published by Elsevier Inc. All rights reserved.)

Hemophilia A (HA) is associated with FVIII coagulation insufficiency or inactivity leading to excessive bleeding. Elevated FVIII, on the contrary, is associated with thrombophilia, thrombosis, myocardial infarctions, and stroke. Active FVIII (aFVIII) uses its C2 domain to bind to blood cells' membranes, consequently carrying out its coagulative function. We developed a reliable flow cytometry (FC) method for FVIII detection that can be utilized for assessing surface-bound FVIII on leukocytes in different coagulation/clinical states; we analyzed 49 pediatric subjects, encompassing patients with HA, other coagulopathies, venous thrombosis, and normal coagulation. Interestingly, the total leukocyte surface FVIII showed a declining trend across thrombosis, normal, and hypo-coagulation states. As expected, the leukocytes of HA patients displayed significantly lower levels of cellular-surface FVIII in comparison to patients with thrombosis. However, no significant correlation was observed between circulating levels of FVIII in plasma and the levels of FVIII bound to leukocytes, indicating that the differences in FVIII surface binding are not directly proportional to the availability of FVIII in the circulation and suggesting a specific binding mechanism governing the interaction between FVIII and leukocytes. Intriguingly, when analyzing the distinct blood subpopulations, we observed that surface FVIII levels were significantly elevated in classical monocytes of thrombosis patients compared to HA patients, healthy controls, and patients with other coagulopathies. Our study highlights the reliability of our FC platform in assessing FVIII abundance on leukocytes' membranes across coagulation states. Monocytes, particularly in cases of thrombosis, exhibit active binding of FVIII on their surface, suggesting a potential role in the pathophysiology of thrombosis that requires further investigation.

Background:  Bypassing agents are used for breakthrough bleedings in patients with hemophilia A with inhibitor (PwHAwI) receiving emicizumab prophylaxis. Previous study demonstrated a weak binding affinity between emicizumab and factor (F)X ( K d ; 1.85 μM), and that this value was much greater than the plasma FX concentration (∼130 nM). We speculated that increased FX levels could enhance coagulation potential in emicizumab-treated patients with hemophilia A (PwHA). To investigate the relationship between FX concentrations and emicizumab-driven coagulation., Methods:  Plasma FX (up to 1,040 nM) and emicizumab (50 µg/mL) were added to FVIII-deficient plasmas, and plasma-derived FX (520 nM) or recombinant (r)FVIIa (2.2 µg/mL) was added to plasmas from three emicizumab-treated PwHAwI. The adjusted maximum coagulation velocity (Ad|min1|) by clot waveform analysis and peak thrombin (PeakTh) by thrombin generation assay in them were evaluated. Emicizumab (3.0 mg/kg), human (h)FIX (100 IU/kg), and various doses of hFX (100-500 IU/kg) were intravenously administered to HA mice. Clotting time/clot formation time (CT/CFT) were assessed using rotational thromboelastometry, and blood loss was estimated by a tail-clip assay., Results:  The addition of FX to FVIII-deficient plasma with emicizumab increased Ad|min1| and PeakTh. The coagulation parameters in emicizumab-treated PwHAwI spiked with additional FX remained within the normal range as well as the additional rFVIIa. In animal models, hFX injection shortened the CT and CT + CFT. The shorter CT and CT + CFT, and the lower blood loss were evident after 200 or 500 IU/kg hFX administration, and those indices were comparable to those in wild-type mice., Conclusion:  Supplementation with FX may improve emicizumab-driven hemostasis in PwHA., Competing Interests: K.S. has no disclosure of conflict of interest. Y.N. has received a grant from Takeda Pharmaceutical Co. E.T. and H.N. are employees of KM Biologics Co., Ltd. K.N. has received grants, personal fees, and nonfinancial support from Chugai Pharmaceutical Co., Ltd.; personal fees from F. Hoffmann-La Roche Ltd.; grants and personal fees from Sysmex Co., SEKISUI Medical, Takeda Pharmaceutical Co., Sanofi S. A., CSL Behring Co., KM Biologics Co., Novo Nordisk A/S, Bayer AG, Fujimoto Seiyaku, Pfizer Inc.; and is an inventor of patents relating to emicizumab., (Thieme. All rights reserved.)

Bone infarction describes bone marrow necrosis that occurs within a long bone's metaphysis or diaphysis. Multiple causative factors lead to ischaemia and subsequent necrosis of bone marrow. The role of hypercoagulability in bone ischaemia is a well-established phenomenon. Orthopaedic specialists play a crucial role in managing affected individuals due to their risk of developing malignancy. We had a case of a man in his late 20s with multifocal osteonecrosis. He was evaluated for hypercoagulability and was found to have mild hyperhomocysteinaemia. He also had an elevated level of factor VIII activity. He was managed conservatively and showed good improvement on vitamin supplementation for hyperhomocysteinaemia. As malignant transformation of the infarction can occur, orthopaedic surgeons need to be aware of this and keep such patients under regular follow-up., Competing Interests: Competing interests: None declared., (© BMJ Publishing Group Limited 2024. No commercial re-use. See rights and permissions. Published by BMJ.)

Combined deficiency of coagulation factor V (FV) and factor VIII (FVIII) is a rare bleeding disease caused by variants in either lectin mannose binding 1 (LMAN1) or multiple coagulation factor deficiency 2 (MCFD2) gene. Reducing the level of FVIII by inhibiting the LMAN1-MCFD2 complex may become a new anticoagulant approach. We aimed to find a new therapeutic option for anticoagulation by RNA interference (RNAi) targeting LMAN1 and MCFD2. siRNA sequences with cross-homology between mice and humans were designed based on LMAN1 or MCFD2 transcripts in NCBI and were screened with the Dual-Luciferase reporter assay. The optimal siRNAs were chemically modified and conjugated with three N-acetylgalactosamine molecules (GalNAc-siRNA), promoting their targeted delivery to the liver. The expression of LMAN1 and MCFD2 in cell lines or mice was examined by RT-qPCR and western blotting. For the mice administered with siRNA, we assessed their coagulation function by measuring APTT and the activity of FVIII factor. After administration, siRNAs GalNAc-LMAN1 and GalNAc-MCFD2 demonstrated effective and persistent LMAN1 and MCFD2 inhibition. 7 days after injection of 3mg/kg GalNAc-LMAN1, the LMAN1 mRNA levels reduced to 19.97% ± 3.78%. MCFD2 mRNA levels reduced to 32.22% ± 13.14% with injection of 3mg/kg GalNAc-MCFD2. After repeated administration, APTT was prolonged and the FVIII activity was remarkably decreased. The tail bleeding test of mice showed that the amount of bleeding in the treated group did not significantly increase compared with the control group. Our study confirms that therapy with RNAi targeting LMAN1-MCFD2 complex is effective and can be considered a viable option for anticoagulation drugs. However, the benefits and potential risk of bleeding in thrombophilic mice model needs to be evaluated., Competing Interests: Declarations. Conflict of interest: The authors declare no competing interests., (© 2024. The Author(s).)

Background: The global burden of major depressive disorder (MDD) is rising, with current diagnostic methods hindered by significant subjectivity and low inter-rater reliability. Several studies have implied underlying link between coagulation-related proteins, such as kininogen (KNG) and coagulation factor VIII (FVIII), and depressive symptoms, offering new insights into the exploration of depression biomarkers. This study aims to elucidate the roles of KNG and FVIII in depression, potentially providing a foundational basis for biomarker research in this field., Methods: A three-part experiment was conducted: (1) we measured serum levels of KNG and FVIII in the chronic unpredictable mild stress (CUMS) model; (2) KNG adeno-associated-virus overexpression (KNG-AAV-OE) model was constructed to further investigate the roles of KNG and FVIII. Meanwhile, quantity PCR, western blotting and immunofluorescence staining detected the KNG-FVIII pathway. (3) Peripheral blood samples were gathered from healthy control (HC, N = 21), as well as first-episode drug-naive patients with MDD (FEDN-MDD, N = 21), to further confirm the association between KNG, FVIII and depression., Results: Firstly, serum KNG and FVIII levels were significantly elevated in the CUMS model. Then, the rats exhibited pronounced depressive-like behaviors in the KNG-AAV-OE model, with corresponding increases in serum KNG and FVIII. Lastly, clinical data showed increased KNG and FVIII levels in FEDN-MDD compared to HC. Furthermore, KNG and FVIII levels exhibited a strong positive correlation with the scores of the 24-item Hamilton Depression Scale and the 14-item Hamilton Anxiety Scale., Conclusion: To sum up, this study highlights critical roles of serum KNG and FVIII in depression and the KNG-AAV-OE may lead the augment of FVIII in serum. Consequently, our research may offer new evidence and foundation for depression biomarkers research in the future., Competing Interests: Declaration of Competing Interest The authors declare that they have no competing interests., (Copyright © 2025 Elsevier B.V. All rights reserved.)

Abstract: von Willebrand factor (VWF) is a multimeric protein consisting of covalently linked monomers, which share an identical domain architecture. Although involved in processes such as inflammation, angiogenesis, and cancer metastasis, VWF is mostly known for its role in hemostasis, by acting as a chaperone protein for coagulation factor VIII (FVIII) and by contributing to the recruitment of platelets during thrombus formation. To serve its role in hemostasis, VWF needs to bind a variety of ligands, including FVIII, platelet-receptor glycoprotein Ib-α, VWF-cleaving protease ADAMTS13, subendothelial collagen, and integrin α-IIb/β-3. Importantly, interactions are differently regulated for each of these ligands. How are these binding events accomplished and coordinated? The basic structures of the domains that constitute the VWF protein are found in hundreds of other proteins of prokaryotic and eukaryotic organisms. However, the determination of the 3-dimensional structures of these domains within the VWF context and especially in complex with its ligands reveals that exclusive, VWF-specific structural adaptations have been incorporated in its domains. They provide an explanation of how VWF binds its ligands in a synchronized and timely fashion. In this review, we have focused on the domains that interact with the main ligands of VWF and discuss how elucidating the 3-dimensional structures of these domains has contributed to our understanding of how VWF function is controlled. We further detail how mutations in these domains that are associated with von Willebrand disease modulate the interaction between VWF and its ligands., (© 2024 American Society of Hematology. Published by Elsevier Inc. All rights are reserved, including those for text and data mining, AI training, and similar technologies.)

Abstract: Coagulation factor VIII (FVIII) is essential for hemostasis. After activation, it combines with activated FIX (FIXa) on anionic membranes to form the intrinsic Xase enzyme complex, responsible for activating FX in the rate-limiting step of sustained coagulation. Hemophilia A (HA) and hemophilia B are due to inherited deficiencies in the activity of FVIII and FIX, respectively. Treatment of HA over the last decade has benefited from an improved understanding of FVIII biology, including its secretion pathway, its interaction with von Willebrand factor in circulation, the biochemical nature of its FIXa cofactor activity, the regulation of activated FVIII by inactivation pathways, and its surprising immunogenicity. This has facilitated biotechnology innovations with first-in-class examples of several new therapeutic modalities recently receiving regulatory approval for HA, including FVIII-mimetic bispecific antibodies and recombinant adeno-associated viral (rAAV) vector-based gene therapy. Biological insights into FVIII also guide the development and use of gain-of-function FVIII variants aimed at addressing the limitations of first-generation rAAV vectors for HA. Several gain-of-function FVIII variants designed to have improved secretion are currently incorporated in second-generation rAAV vectors and have recently entered clinical trials. Continued mutually reinforcing advancements in the understanding of FVIII biology and treatments for HA are necessary to achieve the ultimate goal of hemophilia therapy: normalizing hemostasis and optimizing well-being with minimal treatment burden for all patients worldwide., (© 2024 American Society of Hematology. Published by Elsevier Inc. All rights are reserved, including those for text and data mining, AI training, and similar technologies.)

Haemophilia is associated with reduced bone mass and mineral density. Due to the rarity of the disease and the heterogeneity among the studies, the pathogenesis of bone loss is still under investigation. We studied the effects of coagulation factors on bone cells and characterized in a pilot study the osteoclastogenic potential of patients' osteoclast precursors. To evaluate the effect of coagulation factors on osteoclasts, we treated Healthy Donor-Peripheral Blood Mononuclear Cells (HD-PBMC) with Factor VIII (FVIII), von Willebrand Factor (VWF), FVIII/VWF complex, activated Factor IX (FIXa), activated Factor X (FXa) and Thrombin (THB). FVIII, VWF, FVIII/VWF, FXa and THB treatments reduced osteoclast differentiation of HD-PBMC and VWF affected also bone resorption. Interestingly, PBMC isolated from patients with moderate/severe haemophilia showed an increased osteoclastogenic potential due to the alteration of osteoclast precursors. Moreover, increased expression of genes involved in osteoclast differentiation/activity was revealed in osteoclasts of an adult patient with moderate haemophilia. Control osteoblasts treated with the coagulation factors showed that FVIII and VWF reduced ALP positivity; the opposite effect was observed following THB treatment. Moreover, FVIII, VWF and FVIII/VWF reduced mineralization ability. These results could be important to understand how coagulation factors deficiency influences bone remodeling activity in haemophilia., (© 2024. The Author(s).)

Extracellular vesicles (EVs) are a heterogeneous collection of particles that play a crucial role in cell-to-cell communication, primarily due to their ability to transport molecules, such as proteins. Thus, profiling EV-associated proteins offers insight into their biological effects. EVs can be isolated from various biological fluids, including donor blood components such as cryoprecipitate and fresh frozen plasma (FFP). In this study, we conducted a proteomic analysis of five single donor units of cryoprecipitate, FFP, and EVs derived from these blood components using a quantitative mass spectrometry approach. EVs were successfully isolated from both cryoprecipitate and FFP based on community guidelines. We identified and quantified approximately 360 proteins across all sample groups. Principal component analysis and heatmaps revealed that both cryoprecipitate and FFP are similar. Similarly, EVs derived from cryoprecipitate and FFP are comparable. However, they differ between the originating fluids and their derived EVs. Using the R-package MS-DAP, differentially expressed proteins (DEPs) were identified. The DEPs for all comparisons, when submitted for gene enrichment analysis, are involved in the complement and coagulation pathways. The protein profile generated from this study will have important clinical implications in increasing our knowledge of the proteins that are associated with EVs derived from blood components.

It is common practice in laboratories to store biological samples in ultra-low temperature (ULT) freezers. There is growing interest in raising the temperature of ULT freezers in order to save energy and reduce expenses, as energy conservation becomes increasingly important and sustainable laboratory practices gain popularity. In our laboratory, plasma samples are stored for three months for diagnostic purposes. We therefore took the opportunity to investigate the effect of two different storage temperatures (-70 °C vs -80 °C), on activated partial thromboplastin time (APTT), factor VIII (FVIII), international normalized ratio (INR) and factor VII (FVII) measurements on paired plasma samples collected from 26 individuals after three months of storage. Automated coagulation analysers CS-5100 and ACL TOP were used to perform the tests. We found no consistent difference between the two storage temperatures for any of the four coagulation parameters (all p -values > 0.05). We conclude that the temperature of ULT freezers used to store plasma samples for APTT, FVIII, INR, and FVII measurements can be safely increased from -80 to -70 °C without affecting the stability of the samples.

COVID-19's long-lasting and complex impacts have become a global concern, with diverse clinical outcomes. This study evaluated 226 participants to understand the clinical spectrum of COVID-19/Long COVID (LC), exploring how disease severity correlates with sociodemographic factors and biomarkers. Determinants related to COVID-19 severity included age (P < 0.001), lower education (P < 0.001), ethnicity (P = 0.003), overweight (P < 0.001), MTHFR gene rs1801133 (P = 0.035), cardiovascular diseases (P = 0.002), diabetes mellitus (DM) (P = 0.006), Factor VIII (FVIII) (P = 0.046), von Willebrand factor (VWF) (P = 0.002), and dimer D (DD) (P < 0.001). Six months later, in a portion of the monitored participants, a significant reduction in FVIII (P < 0.001), VWF (P = 0.002), and DD (P < 0.001) levels was observed, with only DD returning to normal values. Different systemic sequelae were identified, with higher incidences of joint pain and myalgia in participants with a clinical history of DM, chronic lung disease (CLD) and sustained high interleukin 6 values in the convalescent phase. CLD, COVID-19 severity and high DD levels increased the risk of developing dyspnea and palpitations. Women were more likely to develop lower limb phlebitis long-term, while sustained elevated FVIII in the convalescent phase was associated with an increased risk of swelling. Regular physical activity had a protective effect against swelling. This study highlights factors contributing to COVID-19 severity/LC, emphasizing endothelial cell activation as a potential mechanism., (© 2024. The Author(s).)

The bleeding disorder hemophilia A (HemA) requires systemic functional factor VIII protein infusions on prophylactic schedules. Recently, chemically modified mRNAs have emerged as promising protein replacement therapies to reduce repeated infusions and improve safety profiles. However, the influence of base modifications on mRNA translation kinetics to specific cell types remains unexplored. In this study, towards developing mRNA therapeutics for haemophilia A, we synthesized chemically modified mRNAs with commercially available base modifications of adenine, guanine, uridine, and cytidine, and evaluated in vitro transcription yield and translation kinetics in hepatic cell lines using reporter eGFP mRNA. Our findings demonstrated that mRNA with N 1 -methyl pseudouridine (m 1 Ψ) showed a 5-12-fold increase in translation efficiency in both hepatic and endothelial cell lines. As a proof of concept for developing mRNA therapy for HemA, where FVIII is deficient, we developed a m 1 Ψ modified functional FVIII mRNA with our liver-targeting lipid nanoparticle (Gal-LNP) system. We evaluated its delivery efficiencies in both hepatic cell lines and the HemA mouse model. The m 1 Ψ-FVIII mRNA showed high therapeutic efficacy up to 15 days in vivo in the HemA mouse model. Gal-LNPs were found to be safe for systemic administration. Our study reveals that incorporating m 1 Ψ base modifications on mRNAs could improve therapeutic efficacy in liver- and endothelial-based therapeutics. Optimized mRNA synthesis for superior expression kinetics in hepatic cells and its delivery with liver-targeted nanoparticles may emerge as protein replacement therapies for monogenic liver disorders.

Background: To date, there is an ongoing debate regarding the ability to predict PVT development using markers of FVIII or FVIII/PC ratio. This study presents evidence-based medical findings on the influence of FVIII activity levels and FVIII/PC values in the formation of PVT in cirrhosis., Methods: The search for original studies on risk factors for portal vein thrombosis (PVT) associated with cirrhosis was conducted, which primarily focused on comparing circulating FVIII activity levels or FVIII/PC ratio in cirrhotic patients with and without PVT. The quality of evidence from each study was assessed using the Newcastle-Ottawa Scale., Results: The meta-analysis included a total of 10 original studies. In total, 2250 cirrhotic patients were included, with 414 having PVT and 1836 without PVT. The pooled analysis using a random-effects model showed no significant difference in standardized mean difference (SMD) for FVIII activity levels in cirrhotic patients with or without PVT (SMD = 0.12, 95% CI=-0.46 to 0.70, P = 0.68), but there was significant heterogeneity (I 2  = 95.52%, P = 0.00). Meta-regression analysis indicated that differences in mean FVIII activity levels in the PVT group, the number of cases in the non-PVT group, and the study design methods partially contributed to the heterogeneity (P < 0.05). However, compared to the non-PVT group, the PVT group had higher FVIII/PC ratio with a statistically significant difference (SMD = 0.39, 95% CI: 0.15 to 0.63, P = 0.00), and there was no significant heterogeneity (I 2  = 28.62%)., Conclusion: In conclusion, the FVIII/PC ratio not only reflects the severity of liver disease, but also can be used as one of the predictors of PVT development., (© 2024. The Author(s).)

Background: Transfusion-related acute lung injury (TRALI) remains a major contributor to transfusion-associated mortality. While the pathogenesis of TRALI remains unclear, there is evidence of a role for blood components. We therefore investigated the potential effects of fresh frozen plasma (FFP), cryoprecipitate, and extracellular vesicles (EVs) derived from these blood components, on the viability of human lung microvascular endothelial cells (HLMVECs) in vitro., Methods: EVs were isolated from FFP and cryoprecipitate using size-exclusion chromatography and characterized by nanoparticle tracking analysis, western blotting, and transmission electron microscopy. The potential effects of these blood components and their EVs on HLMVEC viability (determined by trypan blue exclusion) were examined in the presence and absence of neutrophils, either with or without prior treatment of HLMVECs with LPS., Results: EVs isolated from FFP and cryoprecipitate displayed morphological and biochemical properties conforming to latest international criteria. While FFP, cryoprecipitate, and EVs derived from FFP, each reduced HLMVEC viability, no effect was observed for EVs derived from cryoprecipitate., Conclusion: Our findings demonstrate clear differences in the effects of FFP, cryoprecipitate, and their respective EVs on HLMVEC viability in vitro. Examination of the mechanisms underlying these differences may lead to an improved understanding of the factors that promote development of TRALI., (© 2024 The Author(s). Transfusion published by Wiley Periodicals LLC on behalf of AABB.)

Background: Inhibition of tissue factor pathway inhibitor (TFPI) is an emerging therapeutic strategy for treatment of hemophilia. Concizumab is a monoclonal antibody that binds TFPI and blocks its inhibition of factor (F)Xa thereby extending the initiation of coagulation and compensating for lack of FVIII or FIX., Objectives: The objective of this in vitro study was to evaluate how concizumab affects clot formation in hemophilia A under flow., Methods: Blood was collected from normal controls or people with hemophilia A. An anti-FVIII antibody was added to normal controls to simulate hemophilia A with inhibitory antibodies to FVIII. Whole blood and recombinant activated FVII (rFVIIa, 25 nM) or concizumab (200, 1000, and 4000 ng/mL) were perfused at 100 s -1 over a surface micropatterned with tissue factor (TF) and collagen-related peptide. Platelet and fibrin(ogen) accumulation were measured by confocal microscopy. Static thrombin generation in plasma was measured in response to rFVIIa and concizumab., Results: Concizumab (1000 and 4000 ng/mL) and rFVIIa both rescued (93%-101%) total platelet accumulation, but only partially rescued (53%-63%) fibrin(ogen) incorporation to normal control levels in simulated hemophilia A. Results using congenital hemophilia A blood confirmed effects of rFVIIa and concizumab. While these 2 agents had similar effect on clot formation under flow, concizumab enhanced thrombin generation in plasma under static conditions to a greater extent than rFVIIa., Conclusion: TFPI inhibition by concizumab enhanced activation and aggregation of platelets and fibrin clot formation in hemophilia A to levels comparable with that of rFVIIa., Competing Interests: Declaration of competing interests There are no competing interests to disclose., (Copyright © 2024 International Society on Thrombosis and Haemostasis. Published by Elsevier Inc. All rights reserved.)

Background: Hemophilia A arises from dysfunctional or deficient coagulation factor (F)VIII and leads to inefficient fibrin clot formation and uncontrolled bleeding events. The development of antibody inhibitors is a clinical complication in hemophilia A patients receiving FVIII replacement therapy. LE2E9 is an anti-C1 domain inhibitor previously isolated from a mild/moderate hemophilia A patient and disrupts FVIII interactions with von Willebrand factor and FIXa, though the intermolecular contacts that underpin LE2E9-mediated FVIII neutralization are undefined., Objectives: To determine the structure of the complex between FVIII and LE2E9 and characterize its mechanism of inhibition., Methods: FVIII was bound to the antigen binding fragment (Fab) of NB2E9, a recombinant construct of LE2E9, and its structure was determined by cryogenic electron microscopy., Results: This report communicates the 3.46 Å structure of FVIII bound to NB2E9, with its epitope comprising FVIII residues S2040 to Y2043, K2065 to W2070, and R2150 to H2155. Structural analysis reveals that the LE2E9 epitope overlaps with portions of the epitope for 2A9, a murine-derived inhibitor, suggesting that these residues represent a shared antigenic region on the C1 domain between FVIII -/- mice and hemophilia A patients. Furthermore, the FVIII:NB2E9 structure elucidates the orientation of the LE2E9 glycan, illustrating how the glycan sterically blocks interactions between the FVIII C1 domain and the von Willebrand factor D' domain. A putative model of the FVIIIa:FIXa complex suggests potential clashing between the NB2E9 glycan and FIXa light chain., Conclusion: These results describe an antigenic "hotspot" on the FVIII C1 domain and provide a structural basis for engineering FVIII replacement therapeutics with reduced antigenicity., Competing Interests: Declaration of competing interests P.L. is listed as an inventor on a patent application describing ET3i and on patents owned by Emory University claiming compositions of matter that include modified FVIII proteins with reduced reactivity with anti-FVIII antibodies. C.B.D. and P.L. are cofounders of Expression Therapeutics and own equity in the company. Expression Therapeutics owns the intellectual property associated with ET3i. The terms of this arrangement have been reviewed and approved by Emory University in accordance with its conflict-of-interest policies. The remaining authors have no competing interests to disclose., (Copyright © 2024 International Society on Thrombosis and Haemostasis. All rights reserved.)

Objective: To investigate the association between periodontitis and cardiometabolic and haemostatic parameters., Materials and Methods: Between 2014 and 2019, 54 individuals needing full mouth extraction, and 50 control individuals, were recruited for a combined cross-sectional (individuals versus controls) and longitudinal (individuals before and after extraction) study. Periodontitis severity was measured using the periodontal inflamed surface area (PISA). Blood was drawn to measure the haemostatic (Factor VIII, von Willebrand factor [VWF], endogenous thrombin potential, d-dimer, clot lysis time) and cardiovascular risk (C-reactive protein [CRP], lipid profile) parameters, prior to and 12 weeks post-extraction. The results were analysed group-wise., Results: The mean VWF and CRP levels were higher and the high-density lipoprotein levels were lower in the individuals prior to extraction compared to the controls. The VWF was significantly correlated with the PISA (a 21% unit increase in VWF per 1000 mm 2 increase in PISA, 95%CI: 6-36%, p = 0.01). The other analyses were comparable between the individuals and controls, and did not change in the individuals after the extraction., Conclusion: VWF levels are associated with periodontitis severity; they do not improve after full-mouth extraction. Severe periodontitis in control individuals does not induce substantial changes in their haemostatic or inflammatory systems., Clinical Relevance: Treatment of periodontitis has been shown to improve the cardiometabolic blood profile of patients with established cardiometabolic disease. However, whether periodontitis treatment improves cardiometabolic and haemostatic profiles in people without cardiometabolic disease is uncertain., (© 2024. The Author(s).)

Durable factor VIII expression that normalizes hemostasis is an unrealized goal of hemophilia A adeno-associated virus-mediated gene therapy. Trials with initially normal factor VIII activity observed unexplained year-over-year declines in expression while others reported low-level, stable expression inadequate to restore normal hemostasis. Here we demonstrate that male mice recapitulate expression-level-dependent loss of factor VIII levels due to declines in vector copy number. We show that an enhanced function factor VIII variant (factor VIII-R336Q/R562Q), resistant to activated protein C-mediated inactivation, normalizes hemostasis at below-normal expression without evidence of prothrombotic risk in male hemophilia A mice. These data support that factor VIII-R336Q/R562Q may restore normal factor VIII function at low levels of expression to permit durability using low vector doses to minimize dose-dependent adeno-associated virus toxicities. This work informs the mechanism of factor VIII durability after gene transfer and supports that factor VIII-R336Q/R562Q may safely overcome current hemophilia A gene therapy limitations., (© 2024. The Author(s).)

Abstract: A2 domain dissociation in activated factor VIII (FVIIIa) results in reduced activity. Previous studies demonstrated that some FVIII mutants (D519V/E665V and K1813A) with delayed A2 dissociation enhanced coagulation potential. We speculated, therefore, that FVIII encompassing a combination of these mutations might further enhance coagulant activity. The aim was to assess the D519V/E665V/K1813A-FVIII mutation as a gain of function. The FVIII mutants, D519V/E665V/K1813A, D519V/E665V, and K1813A were expressed in a baby hamster kidney cell system, and global coagulation potential of these mutants was compared with wild-type (WT) FVIII in vitro and in hemophilia A mice in vivo. Kinetic analyses indicated that the apparent Kd for FIXa on the tenase assembly with D519V/E665V and D519V/E665V/K1813A mutants were lower, and that the generated FXa for D519V/E665V/K1813A was significantly greater than WT-FVIII. WT-FVIII activity after thrombin activation increased by ∼12-fold within 5 minutes, and returned to initial levels within 30 minutes. In contrast, The FVIII-related activity of D519V/E665V/K1813A increased further with time after thrombin activation, and showed an ∼25-fold increase at 2 hours. The A2 dissociation rate of D519V/E665V/K1813A was ∼50-fold slower than the WT in a 1-stage clotting assay. Thrombin generation assays demonstrated that D519V/E665V/K1813A (0.125 nM) exhibited coagulation potential comparable with that of the WT (1 nM). In animal studies, rotational thromboelastometry and tail-clip assays showed that the coagulation potential of D519V/E665V/K1813A (0.25 μg/kg) was equal to that of the WT (2 μg/kg). FVIII-D519V/E665V/K1813A mutant could provide an approximately eightfold increase in hemostatic function of WT-FVIII because of increased FVIIIa stability and the association between FVIIIa and FIXa., (© 2024 by The American Society of Hematology. Licensed under Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0), permitting only noncommercial, nonderivative use with attribution. All other rights reserved.)

Objective: Degenerative aortic stenosis and coronary artery disease are considered to be the most prevalent cardiovascular diseases in industrialized countries. This study aims to determine the change over time in von Willebrand factor antigen, von Willebrand factor activity, and factor VIII and where there is a correlation with total post-operative drainage., Methods: The single-center retrospective study included 203 consecutive patients (64.5% male), undergoing coronary artery bypass surgery between March 1, 2019 and June 30, 2020 at the University Clinical Center of Serbia in the Clinic for Cardiac Surgery in Belgrade, Serbia. All patients 18 years or older who presented with isolated, hemodynamically significant aortic stenosis were included. The control group consisted of patients who presented with only coronary artery disease., Results: Between patients with only coronary artery disease and patients with coronary artery diseases and aortic stenosis, there was a statistically significant difference between pre-op and 1-month post-op fibrinogen, factor VIII, von Willebrand factor antigen, and von Willebrand factor (p < 0.001), post-op drainage, with overall lower drainage in coronary artery disease patients, and consistent increase in von Willebrand factor antigen, von Willebrand factor activity, and Factor VIII post-operatively in patients with coronary artery diseases and aortic stenosis., Conclusion: This study has shown that there is a correlation between von Willebrand factor antigen, von Willebrand factor activity and total drainage to the level of statistical significance in aortic stenosis patients and in the overall study population., (© 2024. The Author(s), under exclusive licence to The Japanese Association for Thoracic Surgery.)

Background: Replacement and nonreplacement therapies effectively control bleeding in hemophilia A (HA) but imply lifelong interventions. Authorized gene addition therapy could provide a cure but still poses questions on durability. FVIIIgene correction would definitively restore factor (F)VIII production, as shown in animal models through nuclease-mediated homologous recombination (HR). However, low efficiency and potential off-target double-strand break still limit HR translatability., Objectives: To correct common model single point mutations leading to severe HA through the recently developed double-strand break/HR-independent base editing (BE) and prime editing (PE) approaches., Methods: Screening for efficacy of BE/PE systems in HEK293T cells transiently expressing FVIII variants and validation at DNA (sequencing) and protein (enzyme-linked immunosorbent assay; activated partial thromboplastin time) level in stable clones. Evaluation of rescue in engineered blood outgrowth endothelial cells by lentiviral-mediated delivery of BE., Results: Transient assays identified the best-performing BE/PE systems for each variant, with the highest rescue of FVIII expression (up to 25% of wild-type recombinant FVIII) for the p.R2166∗ and p.R2228Q mutations. In stable clones, we demonstrated that the mutation reversion on DNA (∼24%) was consistent with the rescue of FVIII secretion and activity of 20% to 30%. The lentiviral-mediated delivery of the selected BE systems was attempted in engineered blood outgrowth endothelial cells harboring the p.R2166∗ and p.R2228Q variants, which led to an appreciable and dose-dependent rescue of secreted functional FVIII., Conclusion: Overall data provide the first proof-of-concept for effective BE/PE-mediated correction of HA-causing mutations, which encourage studies in mouse models to develop a personalized cure for large cohorts of patients through a single intervention., Competing Interests: Declaration of competing interests There are no competing interests to disclose., (Copyright © 2024 The Authors. Published by Elsevier Inc. All rights reserved.)

Background: Von Willebrand Disease (VWD) is the most common inherited bleeding disorder. VWD is characterized by an abnormal quantity or quality of von Willebrand Factor (VWF). Anemia is often found at presentation for a bleeding disorder evaluation due to chronic blood loss., Objectives/hypothesis: We hypothesized that anemia is associated with elevations in both VWF and factor VIII (FVIII) over baseline. We also hypothesized that obesity would be associated with increased levels of VWF., Methods: We conducted a single-center review of the electronic health record for patients that had proximal von Willebrand profiles and Hb data., Results: We identified 4552 unique subjects with VWF studies and a CBC within 24 h. We found that decreasing hemoglobin inversely correlated with VWF antigen, VWF ristocetin cofactor activity, and FVIII activity. We also found that obesity and Black race were independently associated with increased VWF antigen, activity, and FVIII activity. Hb, race, and body mass index (BMI) continued to be determinants of VWF and FVIII levels in multivariable analysis., Conclusion: Our study demonstrates that anemia, race, and BMI were found to be associated with elevation of VWF antigen, VWF activity, and FVIII levels. As many individuals with anemia present for evaluation for a bleeding disorder, these variables need to be considered., Key Points: - Anemia was found to be associated with elevation of VWF antigen, VWF activity and FVIII levels. - Testing von Willebrand factor at times of anemia may mask a diagnosis of von Willebrand Disease., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024. Published by Elsevier Ltd.)

Background: Understanding the recovery of post-COVID-19 organ dysfunction is essential. We evaluated coagulation 6 months post-COVID-19, examining its recovery and association with lung function., Methods: Patients treated for COVID-19 at intensive care units between 3/2020 and 1/2021 were analyzed for complete blood count (CBC) and coagulation biomarkers (prothrombin time activity (%) (PT%), activated partial thromboplastin time (APTT), fibrinogen, coagulation factor VIII (FVIII), antithrombin (AT), and D-dimer) during the 6 months post-hospitalization. Results were compared with acute phase values and correlated with pulmonary function tests (PFT), including forced vital capacity (FVC) and hemoglobin-corrected diffusing capacity percentage of predicted (DLCOc%), recorded 6 months post-hospitalization. We examined the association between coagulation biomarkers and DLCOc% using linear regression with age, sex, and invasive mechanical ventilation (IMV) duration, and FVIII (correlated with DLCOc%) as covariates., Results: Most CBCs and coagulation biomarkers had median values within the normal range. However, only 21% (15/70) of patients achieved full normalization of all biomarkers. Compared to acute COVID-19, hemoglobin, PT%, and AT increased, while leukocytes, fibrinogen, FVIII, and D-dimer decreased. Despite decreased levels, FVIII remained elevated in 46% (31/68), leukocytes in 26% (18/70), and D-dimer in 27% (18/67) at 6 months. A weak negative correlation (r = -0.37, p = .036) was found between DLCOc% and FVIII. Multivariable analysis revealed a weak, independent association between DLCOc% and FVIII. Excluding patients with anticoagulation therapy, FVIII no longer correlated with DLCOc%, while AT showed a moderate correlation with DLCOc%., Conclusion: Only a few patients had normal CBC and coagulation biomarker values 6 months after critical COVID-19. A weak negative correlation between DLCOc% and FVIII suggests that deranged coagulation activity may be associated with reduced diffusing capacity., (© 2024 The Authors. Acta Anaesthesiologica Scandinavica published by John Wiley & Sons Ltd on behalf of Acta Anaesthesiologica Scandinavica Foundation.)

Background: Nearly half of all Americans have hypertension, and Black adults experience a disproportionate burden. Hypercoagulability may relate to hypertension risk, and higher levels of factor VIII increase thrombosis risk. Black adults have higher factor VIII and more hypertension than other groups. Whether higher factor VIII associates with incident hypertension is unknown., Methods: The Biomarkers as Mediators of Racial Disparities in Risk Factors (BioMedioR) study measured certain biomarkers in a sex-race stratified sample of 4,400 REGARDS participants who attended both visits. We included BioMedioR participants, excluding those with prevalent hypertension, missing factor VIII level, or covariates of interest. Modified Poisson regression estimated risk ratios (RR) for incident hypertension by higher log-transformed factor VIII level per SD (SD of log-transformed factor VIII, 0.33). Weighting was applied to take advantage of REGARDS sampling design., Results: Among the 1,814 participants included (55% female, 24% Black race), the median follow-up was 9.5 years and 35% (2,146/6,138) developed hypertension. Black participants had a higher median (IQR) factor VIII level (105.6%; 87.1%-126.9%) than White participants (95.6%; 79.8%-115.9%; P < 0.001). The age- and sex-adjusted Black-White hypertension RR was 1.45 (95% CI 1.28, 1.63). Higher factor VIII was not associated with more hypertension (final model RR 1.01; 95% CI 0.94, 1.07)., Conclusions: In a prospective study of Black and White adults without prevalent hypertension, factor VIII was not associated with greater hypertension risk., (© The Author(s) 2024. Published by Oxford University Press on behalf of American Journal of Hypertension, Ltd. All rights reserved. For commercial re-use, please contact reprints@oup.com for reprints and translation rights for reprints. All other permissions can be obtained through our RightsLink service via the Permissions link on the article page on our site—for further information please contact journals.permissions@oup.com.)

Background: von Willebrand disease (VWD) is the most common inherited bleeding disorder, characterized by either partial or complete von Willebrand factor (VWF) deficiency or by the occurrence of VWF proteoforms of altered functionality. The gene encoding VWF is highly polymorphic, giving rise to a variety of proteoforms with varying plasma concentrations and clinical significance., Objectives: To address this complexity, we translated genomic variation in VWF to corresponding VWF proteoforms circulating in blood., Methods: VWF was characterized in VWD patients (n = 64) participating in the Willebrand in the Netherlands study by conventional laboratory testing, DNA sequencing and complementary discovery, and targeted mass spectrometry-based plasma proteomic strategies., Results: Unbiased plasma profiling combined with immune enrichment of VWF verified VWF and its binding partner factor VIII as key determinants of VWD and revealed a remarkable heterogeneity in VWF amino acid sequence coverage among patients. Subsequent VWF proteotyping enabled identification of both polymorphisms (eg, p.Thr789Ala, p.Gln852Arg, and p.Thr1381Ala), as well as pathogenic variants (n = 16) along with their corresponding canonical sequences. Targeted proteomics using stable isotope-labeled peptides confirmed unbiased proteotyping for 5 selected variants and suggested differential proteoform quantities in plasma. The variant-to-wild-type peptide ratio was determined in 6 type 2B patients heterozygous for p.Arg1306Trp, confirming the relatively low proteoform concentration of the pathogenic variant. The elevated VWF propeptide/VWF ratio indicated increased clearance of specific VWF proteoforms., Conclusion: This study highlights how VWF proteotyping from plasma could be the first step to bridge the gap between genotyping and functional testing in VWD., Competing Interests: Declaration of competing interests There are no competing interests to disclose., (Copyright © 2024 The Author(s). Published by Elsevier Inc. All rights reserved.)

Introduction: Hereditary thrombotic thrombocytopenic purpura (hTTP) is caused by deficiency of plasma ADAMTS13 activity, resulting from ADAMTS13 mutations. ADAMTS13 cleaves ultra large von Willebrand factor (VWF), thus reducing its multimer sizes. Hereditary deficiency of plasma ADAMTS13 activity leads to the formation of excessive platelet-VWF aggregates in small arterioles and capillaries, resulting in hTTP., Areas Covered: PubMed search from 1956 to 2024 using thrombotic thrombocytopenic purpura and therapy identified 3,675 articles. Only the articles relevant to the topic were selected for discussion, which focuses on pathophysiology, clinical presentations, and mechanisms of action of emerging therapeutics for hTTP. Current therapies include infusion of plasma, or coagulation factor VIII, or recombinant ADAMTS13. Emerging therapies include anti-VWF A1 aptamers or nanobody and gene therapies with adeno-associated viral vector or self-inactivated lentiviral vector or a sleeping beauty transposon system for a long-term expression of a functional ADAMTS13 enzyme., Expert Opinion: Frequent plasma infusion remains to be the standard of care in most parts of the world, while recombinant ADAMTS13 has become the treatment of choice for hTTP in some of the Western countries. The success of gene therapies in preclinical models may hold a promise for future development of these novel approaches for a cure of hTTP.

The aim of this study is to characterize zebrafish coagulation cofactors fviii and fv mutant fish and assess if they phenocopy classical hemophilia A and factor V deficiency in humans. The embryos from fviii and fv zebrafish heterozygote mutants generated by ENU mutagenesis were purchased from the ZIRC repository. They were reared to adulthood and genotyped. The heterozygote male and female were crossed to get homozygote, heterozygote, and wild-type fish. Functional kinetic coagulation assays and bleeding assays were performed on normal and mutant adult fish, and venous laser injury assays were performed on the larvae. The DNA from fviii and fv mutants were sequenced to confirm if they have a premature stop codon in exon 19, and in exon 2, respectively, and in both mutants, the amino acid glutamine is replaced with a stop codon. Homozygous and heterozygous 5 days post fertilization (dpf) larvae for fviii and fv deficient mutants exhibited prolonged time to occlusion after venous laser injury compared to wild-type controls. The homozygous and heterozygous fviii adult mutants showed modest bleeding and delayed fibrin formation in the kinetic partial thromboplastin time (kPTT) assay with their plasma. fv homozygous larvae had poor survival beyond 12 dpf. However, heterozygous fv mutants exhibited heavy bleeding and prolonged fibrin formation in the kPTT and kPT assay compared with wild-type siblings. Our characterization showed fviii and fv mutants from ZIRC phenocopied to a considerable extent classical hemophilia A and factor V deficiency in humans, respectively. These models should be useful in studying and developing novel drugs that reverse the phenotype and in generating suppressor mutations to identify novel factors that compensate for these deficiencies., (Copyright © 2024 Wolters Kluwer Health, Inc. All rights reserved.)

Recombinant factor VIII (rFVIII), rFVIIIFc and emicizumab are established treatment options in the management of hemophilia A. Each has its unique mode of action, which can influence thrombin generation kinetics and therefore also the kinetics of thrombin substrates. Such differences may potentially result in clots with different structural and physical properties. A starting observation of incomplete wound closure in a patient on emicizumab prophylaxis led us to employ a relevant mouse model in which we noticed that emicizumab-induced clots appeared less stable compared to FVIII-induced clots. We therefore analyzed fibrin formation in vitro and in vivo. In vitro fibrin formation was faster and more abundant in the presence of emicizumab than in the presence of rFVIII/rFVIIIFc. Furthermore, the time-interval between the initiation of fibrin formation and factor XIII activation was twice as long for emicizumab than as for rFVIII/rFVIIIFc. Scanning electron microscopy and immunofluorescent spinning-disk confocal microscopy of in vivo-generated clots confirmed increased fibrin formation in the presence of emicizumab. Unexpectedly, we also detected a different morphology between rFVIII/rFVIIIFcand emicizumab-induced clots. Contrary to the regular fibrin mesh obtained with rFVIII/rFVIIIFc, fibrin fibers appeared to be fused into large patches upon emicizumab treatment. Moreover, fewer red blood cells were detected in regions in which these fibrin patches were present. The presence of highly dense fibrin structures associated with a diffuse fiber structure in emicizumab-induced clots was also observed when using super-resolution imaging. We hypothesize that the modified kinetics of thrombin, fibrin and factor XIIIa generation contribute to differences in structural and physical properties between clots formed in the presence of FVIII or emicizumab.

Haemophilic arthropathy (HA), a common comorbidity in haemophilic patients leads to joint pain, deformity and reduced quality of life. We have recently demonstrated that a long non-coding RNA, Neat1 as a primary regulator of matrix metalloproteinase (MMP) 3 and MMP13 activity, and its induction in the target joint has a deteriorating effect on articular cartilage. In the present study, we administered an Adeno-associated virus (AAV) 5 vector carrying an short hairpin (sh)RNA to Neat1 via intra-articular injection alone or in conjunction with systemic administration of a capsid-modified AAV8 (K31Q) vector carrying F8 gene (F8-BDD-V3) to study its impact on HA. AAV8K31Q-F8 vector administration at low dose, led to an increase in FVIII activity (16%-28%) in treated mice. We further observed a significant knockdown of Neat1 (~40 fold vs. untreated injured joint, p = 0.005) in joint tissue of treated mice and a downregulation of chondrodegenerative enzymes, MMP3, MMP13 and the inflammatory mediator- cPLA2, in mice receiving combination therapy. These data demonstrate that AAV mediated Neat1 knockdown in combination with F8 gene augmentation can potentially impact mediators of haemophilic joint disease., (© 2024 The Author(s). Journal of Cellular and Molecular Medicine published by Foundation for Cellular and Molecular Medicine and John Wiley & Sons Ltd.)

Lentiviral vectors (LV) are efficient vehicles for in vivo gene delivery to the liver. LV integration into the chromatin of target cells ensures their transmission upon proliferation, thus allowing potentially life-long gene therapy following a single administration, even to young individuals. The glycoprotein of the vesicular stomatitis virus (VSV.G) is widely used to pseudotype LV, as it confers broad tropism and high stability. The baculovirus-derived GP64 envelope protein has been proposed as an alternative for in vivo liver-directed gene therapy. Here, we perform a detailed comparison of VSV.G- and GP64-pseudotyped LV in vitro and in vivo. We report that VSV.G-LV transduced hepatocytes better than GP64-LV, however the latter showed improved transduction of liver sinusoidal endothelial cells (LSEC). Combining GP64-pseudotyping with the high surface content of the phagocytosis inhibitor CD47 further enhanced LSEC transduction. Coagulation factor VIII (FVIII), the gene mutated in hemophilia A, is naturally expressed by LSEC, thus we exploited GP64-LV to deliver a FVIII transgene under the control of the endogenous FVIII promoter and achieved therapeutic amounts of FVIII and correction of hemophilia A mice., (© 2024. The Author(s).)

Abstract: Coagulation factor VIII (FVIII) and its carrier protein von Willebrand factor (VWF) are critical to coagulation and platelet aggregation. We leveraged whole-genome sequence data from the Trans-Omics for Precision Medicine (TOPMed) program along with TOPMed-based imputation of genotypes in additional samples to identify genetic associations with circulating FVIII and VWF levels in a single-variant meta-analysis, including up to 45 289 participants. Gene-based aggregate tests were implemented in TOPMed. We identified 3 candidate causal genes and tested their functional effect on FVIII release from human liver endothelial cells (HLECs) and VWF release from human umbilical vein endothelial cells. Mendelian randomization was also performed to provide evidence for causal associations of FVIII and VWF with thrombotic outcomes. We identified associations (P < 5 × 10-9) at 7 new loci for FVIII (ST3GAL4, CLEC4M, B3GNT2, ASGR1, F12, KNG1, and TREM1/NCR2) and 1 for VWF (B3GNT2). VWF, ABO, and STAB2 were associated with FVIII and VWF in gene-based analyses. Multiphenotype analysis of FVIII and VWF identified another 3 new loci, including PDIA3. Silencing of B3GNT2 and the previously reported CD36 gene decreased release of FVIII by HLECs, whereas silencing of B3GNT2, CD36, and PDIA3 decreased release of VWF by HVECs. Mendelian randomization supports causal association of higher FVIII and VWF with increased risk of thrombotic outcomes. Seven new loci were identified for FVIII and 1 for VWF, with evidence supporting causal associations of FVIII and VWF with thrombotic outcomes. B3GNT2, CD36, and PDIA3 modulate the release of FVIII and/or VWF in vitro.

Adeno-associated virus gene therapy has been the subject of intensive investigation for monogenic disease gene addition therapy for more than 25 years, yet few therapies have been approved by regulatory agencies. Most have not progressed beyond phase 1/2 due to toxicity, lack of efficacy, or both. The liver is a natural target for adeno-associated virus since most serotypes have a high degree of tropism for hepatocytes due to cell surface receptors for the virus and the unique liver sinusoidal geometry facilitating high volumes of blood contact with hepatocyte cell surfaces. Recessive monogenic diseases such as hemophilia represent promising targets since the defective proteins are often synthesized in the liver and secreted into the circulation, making them easy to measure, and many do not require precise regulation. Yet, despite initiation of many disease-specific clinical trials, therapeutic windows are often nonexistent, resulting in excess toxicity and insufficient efficacy. Iterative progress built on these attempts is best illustrated by hemophilia, with the first regulatory approvals for factor IX and factor VIII gene therapies eventually achieved 25 years after the first gene therapy studies in humans. Although successful gene transfer may result in the production of sufficient transgenic protein to modify the disease, many emerging questions on durability, predictability, reliability, and variability of response have not been answered. The underlying biology accounting for these heterogeneous responses and the interplay between host and virus is the subject of intense investigation and the subject of this review., Competing Interests: Declaration of competing interests G.F.P. is a consultant to ASC Therapeutics, BioMarin, Pfizer, Regeneron, and Spark Therapeutics and is on the scientific advisory boards of Be Bio, Frontera, and Metagenomi. S.F. and B.R.L. are employees and stockholders of BioMarin Pharmaceutical Inc. R.K. is serving on scientific advisory boards of BioMarin and Pfizer and has received research funding from Bayer., (Copyright © 2023 The Authors. Published by Elsevier Inc. All rights reserved.)

Background and Aims: Blood disorders, such as sickle cell disease, and other clinical conditions are often accompanied by intravascular hemolytic events along with the development of severe coagulopathies. Hemolysis, in turn, leads to the accumulation of Fe(II/III)-protoporphyrin IX (heme) in the intravascular compartment, which can trigger a variety of proinflammatory and prothrombotic reactions. As such, heme binding to the blood coagulation proteins factor VIII (FVIII), fibrinogen, and activated protein C with functional consequences has been demonstrated earlier., Methods: We herein present an in-depth characterization of the FVIII-heme interaction at the molecular level and its (patho-)physiological relevance through the application of biochemical, biophysical, structural biology, bioinformatic, and diagnostic tools., Results: FVIII has a great heme-binding capacity with seven heme molecules associating with the protein. The respective binding sites were identified by investigating heme binding to FVIII-derived peptides in combination with molecular docking and dynamic simulation studies of the complex as well as cryo-electron microscopy, revealing three high-affinity and four moderate heme-binding motifs (HBMs). Furthermore, the relevance of the FVIII-heme complex formation was characterized in physiologically relevant assay systems, revealing a ~ 50 % inhibition of the FVIII cofactor activity even in the protein-rich environment of blood plasma., Conclusion: Our study provides not only novel molecular insights into the FVIII-heme interaction and its physiological relevance, but also strongly suggests the reduction of the intrinsic pathway and the accentuation of the final clotting step (by, for example, fibrinogen crosslinking) in hemolytic conditions as well as a future perspective in the context of FVIII substitution therapy of hemorrhagic events in hemophilia A patients., Competing Interests: Declaration of competing interest The authors declare no competing financial interests., (Copyright © 2024 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Background: The recruitment of activated factor VIII (FVIII) at the surface of activated platelets is a key step toward the burst of thrombin and fibrin generation during thrombus formation at the site of vascular injury. It involves binding to phosphatidylserine and, possibly, to fibrin-bound α IIb β 3 . Seminal work had shown the binding of FVIII to resting platelets, yet without a clear understanding of a putative physiological relevance., Objectives: To characterize the effects of FVIII-platelet interaction and its potential modulation of platelet function., Methods: FVIII was incubated with washed platelets. The effects on platelet activation (spontaneously or triggered by collagen and thrombin) were studied by flow cytometry and light transmission aggregometry. We explored the involvement of downstream pathways by studying phosphorylation profiles (Western blot). The FVIII-glycoprotein (GP) VI interaction was investigated by ELISA, confocal microscopy, and proximity ligation assay., Results: FVIII bound to the surface of resting and activated platelets in a dose-dependent manner. FVIII at supraphysiological concentrations did not induce platelet activation but rather specifically inhibited collagen-induced platelet aggregation and altered glycoprotein VI (GPVI)-dependent phosphorylation. FVIII, freed of its chaperone protein von Willebrand factor (VWF), interacted in close proximity with GPVI at the platelet surface., Conclusion: We showed that VWF-free FVIII binding to, or close to, GPVI modulates platelet activation in vitro. This may represent an uncharacterized negative feedback loop to control overt platelet activation. Whether locally activated FVIII concentrations achieved during platelet accumulation and thrombus formation at the site of vascular injury in vivo are compatible with such a function remains to be determined., Competing Interests: Declaration of competing interests The authors declare no competing financial interests., (Copyright © 2024 The Authors. Published by Elsevier Inc. All rights reserved.)

The ability to target the native production site of factor VIII (FVIII)-liver sinusoidal endothelial cells (LSECs)-can improve the outcome of hemophilia A (HA) gene therapy. By testing a matrix of ultrasound-mediated gene delivery (UMGD) parameters for delivering a GFP plasmid into the livers of HA mice, we were able to define specific conditions for targeted gene delivery to different cell types in the liver. Subsequently, two conditions were selected for experiments to treat HA mice via UMGD of an endothelial-specific human FVIII plasmid: low energy (LE; 50 W/cm 2 , 150 μs pulse duration) to predominantly target endothelial cells or high energy (HE; 110 W/cm 2 , 150 μs pulse duration) to predominantly target hepatocytes. Both groups of UMGD-treated mice achieved persistent FVIII activity levels of ∼10% over 84 days post treatment; however, half of the HE-treated mice developed low-titer inhibitors while none of the LE mice did. Plasma transaminase levels and histological liver examinations revealed minimal transient liver damage that was lower in the LE group than in the HE group. These results indicate that UMGD can safely target LSECs with a lower-energy condition to achieve persistent FVIII gene expression, demonstrating that this novel technology is highly promising for therapeutic correction of HA., Competing Interests: Declaration of interests The authors declare no competing interests., (Copyright © 2024 The American Society of Gene and Cell Therapy. Published by Elsevier Inc. All rights reserved.)

Tolerance to self-proteins involves multiple mechanisms, including conventional CD4 + T-cell (Tconv) deletion in the thymus and the recruitment of natural regulatory T cells (nTregs). The significant incidence of autoantibodies specific for the blood coagulation factor VIII (FVIII) in healthy donors illustrates that tolerance to self-proteins is not always complete. In contrast to FVIII-specific Tconvs, FVIII-specific nTregs have never been revealed and characterized. To determine the frequency of FVIII-specific Tregs in human peripheral blood, we assessed the specificity of in vitro expanded Tregs by the membrane expression of the CD137 activation marker. Amplified Tregs maintain high levels of FOXP3 expression and exhibit almost complete demethylation of the FOXP3 Treg-specific demethylated region. The cells retained FOXP3 expression after long-term culture in vitro, strongly suggesting that FVIII-specific Tregs are derived from the thymus. From eleven healthy donors, we estimated the frequencies of FVIII-specific Tregs at 0.17 cells per million, which is about 10-fold lower than the frequency of FVIII-specific CD4 + T cells we previously published. Our results shed light on the mechanisms of FVIII tolerance by a renewed approach that could be extended to other self- or non-self-antigens., (© 2024 The Authors. European Journal of Immunology published by Wiley‐VCH GmbH.)

Recently developed multi-specific antibody formats enable new therapeutic concepts. Conveniently, formats with an Fc domain allow purification in well-established mAb platform processes. However, due to the structural complexity of the formats, the assembled molecules may be sensitive to extreme pH commonly used for viral inactivation. An alternative to low pH incubation for virus inactivation is the use of a mixture of tri-n-butyl phosphate (TnBP, solvent) and Polysorbate 80 (PS80, detergent). While TnBP is toxic, this combination has a long history of use in the manufacturing of human plasma-derived products that are sensitive to low or high pH incubation. Data are provided demonstrating that the solvent/detergent (S/D) treatment using TnBP and PS80 can be successfully used for pH-sensitive, multi-specific antibody formats in the clarified cell culture fluid (CCCF). A different placement of the S/D within the purification process, namely during the capture by Protein A (PA), has been evaluated. This alternative placement allows effective viral inactivation by S/D while preserving the viral reduction and viral inactivation achieved through the PA step itself, enabling the cumulation of these effects. Furthermore, the process alternative simplifies the liquid handling by reducing the added volumes of the required S/D liquids, thus reducing the amount of toxic TnBP to a minimum. Data are shown demonstrating a complete removal of TnBP and PS80 in the process., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper. All authors were employees of Ichnos Sciences during the time of this work., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Background: One-third of patients with severe hemophilia A develop neutralizing antibodies to the factor VIII (FVIII) protein in response to intravenous replacement therapy. Patients may also generate natural, nonneutralizing antibodies to FVIII before FVIII exposure. These patients are at increased risk of developing neutralizing antibodies to FVIII. However, natural anti-FVIII antibodies are also present in healthy human donors., Objectives: To further characterize the natural antihuman (h) FVIII antibody repertoire in mice and humans., Methods: An in-house ELISA was developed using a purified polyclonal immunoglobulin (Ig) standard to quantify anti-hFVIII Ig in cell culture supernatant or plasma from mice (wild-type and FVIII -/- ) and adult human donors., Results: All naïve wild-type and FVIII -/- mice, as well as healthy human donors, possess natural anti-hFVIII antibodies. Mice only have natural anti-hFVIII IgM, which is present in germ-free mice, suggesting that they are germline encoded. Although murine marginal zone B cells (MZBs) contribute 44% to all circulating natural IgM, they contribute disproportionately to the anti-hFVIII IgM repertoire (82%). This naturally occurring murine MZB-derived IgM is not B-domain specific and is reduced by intravenously administered hFVIII, suggesting that it may form immune complexes immediately upon hFVIII administration. Natural anti-hFVIII antibodies of IgG, IgM, and IgA isotypes can be detected in adult human donors. There were increased levels of B-domain-favoring anti-hFVIII IgG in 14% of healthy donors, which were markedly different from the rest of the "low-titer" population., Conclusions: There is a preponderance of natural anti-hFVIII antibodies in both mice and healthy adult human donors., Competing Interests: Declaration of competing interests There are no competing interests to disclose., (Copyright © 2023 International Society on Thrombosis and Haemostasis. Published by Elsevier Inc. All rights reserved.)

Blood platelets have unique storage and delivery capabilities. Platelets play fundamental roles in hemostasis, inflammatory reactions, and immune responses. Beyond their functions, platelets have been used as a target for gene therapy. Platelet-targeted gene therapy aims to deliver a sustained expression of neo-protein in vivo by genetically modifying the target cells, resulting in a cure for the disease. Even though there has been substantial progress in the field of gene therapy, the potential development of immune responses to transgene products or vectors remains a significant concern. Of note, multiple preclinical studies using platelet-specific lentiviral gene delivery to hematopoietic stem cells in hemophilia have demonstrated promising results with therapeutic levels of neo-protein that rescue the hemorrhagic bleeding phenotype and induce antigen-specific immune tolerance. Further studies using ovalbumin as a surrogate protein for platelet gene therapy have shown robust antigen-specific immune tolerance induced via peripheral clonal deletions of antigen-specific CD4- and CD8-T effector cells and induction of antigen-specific regulatory T (Treg) cells. This review discusses platelet-targeted gene therapy, focusing on immune tolerance induction., Competing Interests: Declaration of competing interests Competing financial interests: QS have applied for a US Patent Application (serial no. PCT/US2023/068251) entitled ‘‘Immune tolerance induction for autoimmune diseases through platelet targeted gene therapy’’. The remaining authors declare no competing financial interests., (Copyright © 2023 International Society on Thrombosis and Haemostasis. Published by Elsevier Inc. All rights reserved.)

Abstract: von Willebrand disease (vWD) is an inherited bleeding disorder that is characterized by a quantitative or qualitative deficiency of the von Willebrand factor (vWF). Type 3 is the most severe form of vWD with a near-complete absence of vWF and a significantly increased risk of excessive bleeding and hematoma during a surgical procedure. To date, no data on surgical and hemostatic management of a type 3 vWD patient undergoing body-contouring surgery has been published. We report the case of a 47-year-old woman with type 3 vWD requiring medically indicated abdominoplasty after massive weight loss due to bariatric surgery. The case was successfully managed with individualized bodyweight-adapted substitution of recombinant vWF vonicog alfa and tranexamic acid under close monitoring of vWF and factor VIII activity. For further risk stratification, we propose the multidisciplinary treatment of patients with severe vWF undergoing elective plastic surgery in specialized centers providing around-the-clock laboratory testing and access to a blood bank. In addition, strict hemostasis during surgery and early postoperative mobilization with fitted compression garments are recommended to further reduce the risk of bleeding and thromboembolic complications., Competing Interests: Conflicts of interest and sources of funding: none declared., (Copyright © 2023 Wolters Kluwer Health, Inc. All rights reserved.)

Background: The effect of factor VIII (FVIII) or emicizumab on thrombin generation is usually assessed in assays using synthetic phospholipids. Here, we assessed thrombin generation at the surface of human arterial cells (aortic endothelial cells [hAECs] and aortic vascular smooth muscle cells [hVSMCs])., Objectives: To explore the capacity of hAECs (resting or stimulated) and hVSMCs to support thrombin generation by FVIII or emicizumab., Methods: Primary hVSMCs and hAECs were analyzed for tissue factor (TF)-activity and antigen, phosphatidylserine (PS)-exposure, tissue factor pathway inhibitor (TFPI)-content and thrombomodulin expression. Cells were incubated with FVIII-deficient plasma spiked with FVIII, emicizumab, activated prothrombin complex concentrate (APCC) or combinations thereof., Results: TF activity and PS-exposure were present on both hVSMCs and hAECs. In contrast, thrombomodulin and TFPI were expressed on hAECs, while virtually lacking on hVSMCs, confirming the procoagulant nature of hVSMCs. Tumor necrosis factor α-mediated stimulation of hAECs increased not only TF antigen, TF activity, and PS-exposure but also TFPI and thrombomodulin expression. As expected, FVIII and emicizumab promoted thrombin generation on nonstimulated hAECs and hVSMCs, with more thrombin being generated on hVSMCs. Unexpectedly, FVIII and emicizumab increased thrombin generation to a lesser extent on stimulated hAECs compared with nonstimulated hAECs. Finally, adding emicizumab to FVIII did not further increase thrombin generation, whereas the addition of emicizumab to APCC resulted in exaggerated thrombin generation., Conclusion: Tumor necrosis factor stimulation of hAECs increases both pro- and anticoagulant activity. Unexpectedly, the increased anticoagulant activity is sufficient to limit both FVIII- and emicizumab-induced thrombin generation. This protective effect disappears when emicizumab is combined with APCC., Competing Interests: Declaration of competing interests P.J.L. receives research funding to the institute from Hoffman-Laroche Ltd, Institut Roche, Pfizer, Sanofi, and Sobi. The other authors declare no conflict of interest., (Copyright © 2023 International Society on Thrombosis and Haemostasis. Published by Elsevier Inc. All rights reserved.)

Remarkably, it has been 40 years since the isolation of the 2 genes involved in hemophilia A (HA) and hemophilia B (HB), encoding clotting factor (F) VIII (FVIII) and FIX, respectively. Over the years, these advances led to the development of purified recombinant protein factors that are free of contaminating viruses from human pooled plasma for hemophilia treatments, reducing the morbidity and mortality previously associated with human plasma-derived clotting factors. These discoveries also paved the way for modified factors that have increased plasma half-lives. Importantly, more recent advances have led to the development and Food and Drug Administration approval of a hepatocyte-targeted, adeno-associated viral vector-mediated gene transfer approach for HA and HB. However, major concerns regarding the durability and safety of HA gene therapy remain to be resolved. Compared with FIX, FVIII is a much larger protein that is prone to misfolding and aggregation in the endoplasmic reticulum and is poorly secreted by the mammalian cells. Due to the constraint of the packaging capacity of adeno-associated viral vector, B-domain deleted FVIII rather than the full-length protein is used for HA gene therapy. Like full-length FVIII, B-domain deleted FVIII misfolds and is inefficiently secreted. Its expression in hepatocytes activates the cellular unfolded protein response, which is deleterious for hepatocyte function and survival and has the potential to drive hepatocellular carcinoma. This review is focused on our current understanding of factors limiting FVIII secretion and the potential pathophysiological consequences upon expression in hepatocytes., Competing Interests: Declaration of competing interests R.J.K. is a consultant for Miltenil Biotech. R.W.H. is serving on the scientific advisory boards and committees of Regeneron Pharmaceuticals, Pfizer, BioMarin, Spark Therapeutics, and Prevail Therapeutics and has received grant support from Hoffman-La Roche. Z.C. has no conflict of interest to disclose., (Copyright © 2023 International Society on Thrombosis and Haemostasis. Published by Elsevier Inc. All rights reserved.)