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The presence of both endothelial cells (ECs) and mural cells are central to the proper function of blood vessels in health and pathological changes in diseases including diabetes. Although iPSCs-derived vascular organoids (VOs) provide an appealing in vitro disease model and platform for drug screening, whether these organoids recapitulate human disease remains debatable. Here, we show human diabetic (DB)-VOs represent impaired vascular function including enhanced ROS activity, with higher mitochondrial content and activity, increased pro-inflammatory cytokines, and less regenerative potential in vivo. Using single-cell RNA sequencing, we identify all specialized types of vascular cells (artery, capillary, vein, lymphatic and tip cells, as well as pericytes and vSMCs) within vascular organoids, while demonstrating the dichotomy landscape of ECs and mural cells. Furthermore, we reveal basal heterogeneity within vascular organoids and demonstrate differences between diabetic and non-diabetic VOs. Of note, a subpopulation of ECs significantly enrich for ROS and oxidative phosphorylation hallmarks in DB-VOs, may represent early signs of aberrant angiogenesis in diabetes. This study helps to identify key biomarkers for diabetic disease progression and find signalling molecules amenable to drug intervention.

Implantable drug delivery systems are an interesting alternative to conventional drug delivery systems to achieve local or systemic drug delivery. In this work, we investigated the potential of fused-deposition modelling to prepare reservoir-type implantable devices for sustained drug delivery. An antibiotic was chosen as a model molecule to evaluate the potential of this type of technology to prepare implants on-demand to provide prophylactic antimicrobial treatment after surgery. The first step was to prepare and characterize biodegradable rate-controlling porous membranes based on poly(lactic acid) (PLA) and poly(caprolactone) (PCL). These membranes were prepared using a solvent casting method. The resulting materials contained different PLA/PCL ratios. Cylindrical implants were 3D-printed vertically on top of the membranes. Tetracycline (TC) was loaded inside the implants and drug release was evaluated. The results suggested that membranes containing a PLA/PCL ratio of 50/50 provided drug release over periods of up to 25 days. On the other hand, membranes containing lower PCL content did not show a porous structure and accordingly the drug could not permeate to the same extent. The influence of different parameters on drug release was evaluated. It was established that film thickness, drug content and implant size are critical parameters as they have a direct influence on drug release kinetics. In all cases the implants were capable of providing drug release for at least 25 days. The antimicrobial properties of the implants were evaluated against E. coli and S. aureus. The resulting implants showed antimicrobial properties at day 0 and even after 21 days against both type of microorganisms. Finally, the biocompatibility of the implants was evaluated using endothelial cells. Cells exposed to implants were compared with a control group. There were no differences between both groups in terms of cell proliferation and morphology.

Diabetic endotheliopathy is the main cause for impaired angiogenesis and reduced neovascularization that lead to microvascular injury and vascular complications. The pathogenic basis for vascular complications arising from diabetes is complex. Elucidation of key underlying mechanisms will help the development of novel therapies and the discovery of potential biomarkers. The ability to generate functional endothelial cells (ECs) from induced pluripotent stem cells (iPSCs) from small amounts of blood is a novel and powerful tool for cell-based therapies. Human iPSC-derived ECs (iPS-ECs) have a broad range of clinical applications including cell-based therapy, disease modelling and drug screening; they can be used in mechanistic studies towards the development of novel therapies and in the discovery of new biomarkers to be applied in regenerative medicine and treatment of diabetic vasculopathy. Here we utilize transcriptomic and proteomic technologies to assess patient-specific iPS-ECs from diabetic (DiPS-ECs) and non-diabetic (NiPS-ECS) donors 1,2,3,4 in order to investigate the mechanisms driving endotheliopathy in diabetes. Our in vitro and in vivo models recapitulate the effects of hyperglycaemia on the vasculature in the clinical setting. RNA-seq data showed that genes and proteins involved in angiogenesis and EC function were significantly downregulated in DiPS-ECs in comparison to NiPS-ECS (n=3, p Conflict of Interest None

Diabetic macular edema (DME) remains a leading cause of vision loss worldwide. DME is commonly treated with intravitreal injections of vascular endothelial growth factor (VEGF) neutralising antibodies. Anti-VEGFs are effective but not all patients fully respond to them. Given their potential side effects, inconvenience and high cost, identifying who may not respond appropriately to anti-VEGFs and why is essential. Herein, we determine first the response to anti-VEGFs in a cohort of DME patients using spectral-domain optical coherence tomography scans obtained throughout the first year of treatment. We found that in 28% of eyes full clearance of fluid occurred at any time during the first year (“full responders”); in 66% fluid cleared only partly (“partial responders”); in 6% fluid remained unchanged (“non-responders”). To understand this differential response, we generated induced pluripotent stem cells (iPS) from “full responders” and “non-responders” and from diabetic subjects with no DME and age-matched non-diabetic volunteers and differentiated them into endothelial cells (iPS-ECs). Monolayers of iPS-ECs derived from diabetics showed marked and prolonged increased permeability upon exposure to VEGF when compared with non-diabetic controls; the response was significantly exaggerated in iPS-ECs from “non-responders” when compared with “full responders”. Moreover, phosphorylation of key cellular proteins in response to VEGF, including VEGFR2, and gene expression profiles, such as Neuronal Pentraxin 2 (NPTX2) expression, differed between “full responders” and “non-responders”. In the current study, iPS were used to predict patient response to anti-VEGF and identify key mechanisms underpinning the differential outcomes observed in the clinic. This approach has identified NPTX2 as playing a significant role in patient-linked responses and has potential as a new therapeutic target for DME.

Vascular endothelial cell (EC) dysfunction plays a key role in diabetic complications. This study discovers significant upregulation of Quaking-7 (QKI-7) in iPS cell-derived ECs when exposed to hyperglycemia, and in human iPS-ECs from diabetic patients. QKI-7 is also highly expressed in human coronary arterial ECs from diabetic donors, and on blood vessels from diabetic critical limb ischemia patients undergoing a lower-limb amputation. QKI-7 expression is tightly controlled by RNA splicing factors CUG-BP and hnRNPM through direct binding. QKI-7 upregulation is correlated with disrupted cell barrier, compromised angiogenesis and enhanced monocyte adhesion. RNA immunoprecipitation (RIP) and mRNA-decay assays reveal that QKI-7 binds and promotes mRNA degradation of downstream targets CD144, Neuroligin 1 (NLGN1), and TNF-α-stimulated gene/protein 6 (TSG-6). When hindlimb ischemia is induced in diabetic mice and QKI-7 is knocked-down in vivo in ECs, reperfusion and blood flow recovery are markedly promoted. Manipulation of QKI-7 represents a promising strategy for the treatment of diabetic vascular complications., Vascular endothelial cell (EC) dysfunction contributes to the occurrence of diabetic complications. Here the authors report that in diabetic conditions, upregulation of the RNA binding protein QKI-7 in ECs due to the imbalance of RNA splicing factors CUG-BP and hnRNPM contributes to EC dysfunction, and that in vivo QKI-7 silencing improves blood flow recovery in diabetic mice with limb ischemia.

Dysfunction of endothelial cells (ECs) and vascular smooth muscle cells (VSMCs) leads to ischaemia, the central pathology of cardiovascular disease. Stem cell technology will revolutionise regenerative medicine, but a need remains to understand key mechanisms of vascular differentiation. RNA-binding proteins have emerged as novel post-transcriptional regulators of alternative splicing and we have previously shown that the RNA-binding protein Quaking (QKI) plays roles in EC differentiation. In this study, we decipher the role of the alternative splicing isoform Quaking 6 (QKI-6) to induce VSMC differentiation from induced pluripotent stem cells (iPSCs). PDGF-BB stimulation induced QKI-6, which bound to HDAC7 intron 1 via the QKI-binding motif, promoting HDAC7 splicing and iPS-VSMC differentiation. Overexpression of QKI-6 transcriptionally activated SM22 (also known as TAGLN), while QKI-6 knockdown diminished differentiation capability. VSMCs overexpressing QKI-6 demonstrated greater contractile ability, and upon combination with iPS-ECs-overexpressing the alternative splicing isoform Quaking 5 (QKI-5), exhibited higher angiogenic potential

Dysfunction of endothelial cells (ECs) and vascular smooth muscle cells (VSMCs) leads to ischaemia, the central pathology of cardiovascular disease. Stem cell technology will revolutionise regenerative medicine, but a need remains to understand key mechanisms of vascular differentiation. RNA-binding proteins have emerged as novel post-transcriptional regulators of alternative splicing and we have previously shown that the RNA-binding protein Quaking (QKI) plays roles in EC differentiation. In this study, we decipher the role of the alternative splicing isoform Quaking 6 (QKI-6) to induce VSMC differentiation from induced pluripotent stem cells (iPSCs). PDGF-BB stimulation induced QKI-6, which bound to HDAC7 intron 1 via the QKI-binding motif, promoting HDAC7 splicing and iPS-VSMC differentiation. Overexpression of QKI-6 transcriptionally activated SM22 (also known as TAGLN), while QKI-6 knockdown diminished differentiation capability. VSMCs overexpressing QKI-6 demonstrated greater contractile ability, and upon combination with iPS-ECs-overexpressing the alternative splicing isoform Quaking 5 (QKI-5), exhibited higher angiogenic potential in vivo than control cells alone. This study demonstrates that QKI-6 is critical for modulation of HDAC7 splicing, regulating phenotypically and functionally robust iPS-VSMCs. These findings also highlight that the QKI isoforms hold key roles in alternative splicing, giving rise to cells which can be used in vascular therapy or for disease modelling. This article has an associated First Person interview with the first author of the paper.

The mortality rate for (cardio)-vascular disease is one of the highest in the world, so a healthy functional endothelium is of outmost importance against vascular disease. In this study, human induced pluripotent stem (iPS) cells were reprogrammed from 1 ml blood of healthy donors and subsequently differentiated into endothelial cells (iPS-ECs) with typical EC characteristics. This research combined iPS cell technologies and next-generation sequencing to acquire an insight into the transcriptional regulation of iPS-ECs. We identified Endothelial cell-specific molecule 1 (ESM1) as one of the highest expressed genes during EC differentiation, playing a key role in EC enrichment and function by regulating connexin 40 (CX40) and eNOS. Importantly, ESM1 enhanced the iPS-ECs potential to improve angiogenesis and neovascularisation in in vivo models of angiogenesis and hind limb ischemia. These findings demonstrated for the first time that enriched functional ECs are derived through cell reprogramming and ESM1 signalling, opening the horizon for drug screening and cell-based therapies for vascular diseases. Therefore, this study showcases a new approach for enriching and enhancing the function of induced pluripotent stem (iPS) cell-derived endothelial cells from a very small amount of blood through ESM1 signalling, which greatly enhances their functionality and increases their therapeutic potential. © AlphaMed Press 2018.

Vascular endothelial cell (EC) dysfunction plays a key role in diabetic complications. This study discovers significant upregulation of Quaking-7 (QKI-7) in iPS cell-derived ECs when exposed to hyperglycemia, and in human iPS-ECs from diabetic patients. QKI-7 is also highly expressed in human coronary arterial ECs from diabetic donors, and on blood vessels from diabetic critical limb ischemia patients undergoing a lower-limb amputation. QKI-7 expression is tightly controlled by RNA splicing factors CUG-BP and hnRNPM through direct binding. QKI-7 upregulation is correlated with disrupted cell barrier, compromised angiogenesis and enhanced monocyte adhesion. RNA immunoprecipitation (RIP) and mRNA-decay assays reveal that QKI-7 binds and promotes mRNA degradation of downstream targets CD144, Neuroligin 1 (NLGN1), and TNF-α-stimulated gene/protein 6 (TSG-6). When hindlimb ischemia is induced in diabetic mice and QKI-7 is knocked-down in vivo in ECs, reperfusion and blood flow recovery are markedly promoted. Manipulation of QKI-7 represents a promising strategy for the treatment of diabetic vascular complications.

The fight against vascular disease requires functional endothelial cells (ECs) which could be provided by differentiation of induced Pluripotent Stem Cells (iPS Cells) in great numbers for use in the clinic. However, the great promise of the generated ECs (iPS‐ECs) in therapy is often restricted due to the challenge in iPS‐ECs preserving their phenotype and function. We identified that Follistatin‐Like 3 (FSTL3) is highly expressed in iPS‐ECs, and, as such, we sought to clarify its possible role in retaining and improving iPS‐ECs function and phenotype, which are crucial in increasing the cells’ potential as a therapeutic tool. We overexpressed FSTL3 in iPS‐ECs and found that FSTL3 could induce and enhance endothelial features by facilitating β‐catenin nuclear translocation through inhibition of glycogen synthase kinase‐3β activity and induction of Endothelin‐1. The angiogenic potential of FSTL3 was also confirmed both in vitro and in vivo. When iPS‐ECs overexpressing FSTL3 were subcutaneously injected in in vivo angiogenic model or intramuscularly injected in a hind limb ischemia NOD.CB17‐Prkdcscid/NcrCrl SCID mice model, FSTL3 significantly induced angiogenesis and blood flow recovery, respectively. This study, for the first time, demonstrates that FSTL3 can greatly enhance the function and maturity of iPS‐ECs. It advances our understanding of iPS‐ECs and identifies a novel pathway that can be applied in cell therapy. These findings could therefore help improve efficiency and generation of therapeutically relevant numbers of ECs for use in patient‐specific cell‐based therapies. In addition, it can be particularly useful toward the treatment of vascular diseases instigated by EC dysfunction. Stem Cells 2018;36:1033–1044