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Fibroblast-activation protein (FAP) is a serine protease classified in the dipeptidyl peptidase 4 (DPP4) family. FAP is predominantly expressed in activated fibroblasts such as the cancer-associated fibroblasts (CAFs). FAP expression in CAFs is associated with tumor progression and poor prognosis in solid cancers. Recently, radiolabeled FAP inhibitors (FAPI) has been developed, which enables positron emission tomography (PET) imaging of FAP. FAPI PET/CT can provide a higher tumor-to-background ratio (TBR) than 18 F-fludeoxyglucose PET/CT in various cancers, and thus has attracted substantial attention. As studies on FAPI PET grow in number and size, incidental findings related to non-oncologic conditions have been increasingly reported. FAPI PET uptake has been reported in various conditions such as benign tumors, fibrotic, granulomatosis, scarring/wound, degenerative diseases, and inflammatory diseases.The knowledge of physiological and non-oncologic causes of FAPI uptake is indispensable for accurate FAPI PET/CT interpretation and can help appropriate management of incidental findings on FAPI PET/CT in patients referred for cancer staging indications. In this review article, we describe for each organ system (Brain, Oral mucosa, Salivary Glands, Thyroid, Lung, Myocardium, Breast, Esophagus, Stomach, Intestine, Liver, Gallbladder, Pancreas, Spleen, Kidney, , Uterus, Bone marrow, Joints, Muscle, Vessels, Lymph nodes), the patterns of physiological FAPI uptake and the main causes of non-oncological uptake reported from the literature with FAPI-02, FAPI-04 and FAPI-46. We also illustrate some examples from our institutional database at UCLA.

Background: Left ventricular hypertrophy and heart failure with preserved ejection fraction (HFpEF) are primary manifestations of the cardiorenal syndrome in patients with chronic kidney disease (CKD). Therapies that improve morbidity and mortality in HFpEF are lacking. Cell-based therapies promote cardiac repair in ischemic and non-ischemic cardiomyopathies. We hypothesized that cell-based therapy ameliorates CKD-induced HFpEF., Methods and Results: Yorkshire pigs (n = 26) underwent 5/6 embolization-mediated nephrectomy. CKD was confirmed by increased creatinine and decreased glomerular filtration rate (GFR). Mean arterial pressure (MAP) was not different between groups from baseline to 4 weeks. HFpEF was evident at 4 weeks by increased LV mass, relative wall thickening, end-diastolic pressure, and end-diastolic pressure-volume relationship, with no change in ejection fraction (EF). Four weeks post-embolization, allogeneic (allo) bone marrow-derived mesenchymal stem cells (MSC; 1 × 107 cells), allo-kidney-derived stem cells (KSC; 1 × 107 cells), allo-cell combination therapy (ACCT; MSC + KSC; 1:1 ratio; total = 1 × 107 cells), or placebo (Plasma-Lyte) was delivered via intra-renal artery. Eight weeks post-treatment, there was a significant increase in MAP in the placebo group (21.89 ± 6.05 mmHg) compared to the ACCT group. GFR significantly improved in the ACCT group. EF, relative wall thickness, and LV mass did not differ between groups at 12 weeks. EDPVR improved in the ACCT group, indicating decreased ventricular stiffness., Conclusions: Intra-renal artery allogeneic cell therapy was safe in a CKD swine model manifesting the characteristics of HFpEF. The beneficial effect on renal function and ventricular compliance in the ACCT group supports further research of cell therapy for cardiorenal syndrome., (© The Author(s) 2022. Published by Oxford University Press.)

Therapies for heart failure with preserved ejection fraction (HFpEF) are lacking. Growth hormone-releasing hormone agonists (GHRH-As) have salutary effects in ischemic and nonischemic heart failure animal models. Accordingly, we hypothesized that GHRH-A treatment ameliorates chronic kidney disease (CKD)-induced HFpEF in a large-animal model. Female Yorkshire pigs ( n = 16) underwent 5/6 nephrectomy via renal artery embolization and 12 wk later were randomized to receive daily subcutaneous injections of GHRH-A (MR-409; n = 8; 30 µg/kg) or placebo ( n = 8) for 4 to 6 wk. Renal and cardiac structure and function were serially assessed postembolization. Animals with 5/6 nephrectomy exhibited CKD (elevated blood urea nitrogen [BUN] and creatinine) and faithfully recapitulated the hemodynamic features of HFpEF. HFpEF was demonstrated at 12 wk by maintenance of ejection fraction associated with increased left ventricular mass, relative wall thickness, end-diastolic pressure (EDP), end-diastolic pressure/end-diastolic volume (EDP/EDV) ratio, and tau, the time constant of isovolumic diastolic relaxation. After 4 to 6 wk of treatment, the GHRH-A group exhibited normalization of EDP ( P = 0.03), reduced EDP/EDV ratio ( P = 0.018), and a reduction in myocardial pro-brain natriuretic peptide protein abundance. GHRH-A increased cardiomyocyte [Ca 2+ ] transient amplitude ( P = 0.009). Improvement of the diastolic function was also evidenced by increased abundance of titin isoforms and their ratio ( P = 0.0022). GHRH-A exerted a beneficial effect on diastolic function in a CKD large-animal model as demonstrated by improving hemodynamic, structural, and molecular characteristics of HFpEF. These findings have important therapeutic implications for the HFpEF syndrome., Competing Interests: Competing interest statement: A.V.S and J.M.H. are listed as co-inventors on patents on GHRH analogs, which were assigned to the University of Miami and Veterans Affairs Department. J.M.H. previously owned equity in Biscayne Pharmaceuticals, licensee of intellectual property used in this study. Biscayne Pharmaceuticals did not provide funding for this study. J.M.H. is the chief scientific officer, a compensated consultant, and advisory board member for Longeveron and holds equity in Longeveron. J.M.H. is also the co-inventor of intellectual property licensed to Longeveron. Longeveron did not play a role in the design, conduct, or funding of the study. J.M.H.’s relationships are reported to the University of Miami, and an appropriate management plan is in place. I.H.S. contributed to this manuscript in her personal capacity. The opinions expressed in this article are the author's own and do not reflect the view of the National Institutes of Health, the Department of Health and Human Services, or the United States government.

Aims: Sex differences impact the occurrence, presentation, prognosis, and response to therapy in heart disease. Particularly, the phenotypic presentation of patients with non-ischaemic dilated cardiomyopathy (NIDCM) differs between men and women. However, whether the response to mesenchymal stem cell (MSC) therapy is influenced by sex remains unknown. We hypothesize that males and females with NIDCM respond similarly to MSC therapy., Methods and Results: Male (n = 24) and female (n = 10) patients from the POSEIDON-DCM trial who received MSCs via transendocardial injections were evaluated over 12 months. Endothelial function was measured at baseline and 3 months post-transendocardial stem cell injection (TESI). At baseline, ejection fraction (EF) was lower (P = 0.004) and end-diastolic volume (EDV; P = 0.0002) and end-systolic volume (ESV; P = 0.0002) were higher in males vs. females. In contrast, baseline demographic characteristics, Minnesota Living with Heart Failure Questionnaire (MLHFQ), and 6-min walk test (6MWT) were similar between groups. EF improved in males by 6.2 units (P = 0.04) and in females by 8.6 units (P = 0.04; males vs. females, P = 0.57). EDV and ESV were unchanged over time. The MLHFQ score, New York Heart Association (NYHA) class, endothelial progenitor cell-colony forming units, and serum tumour necrosis factor alpha improved similarly in both groups., Conclusion: Despite major differences in phenotypic presentation of NIDCM in males and females, this study is the first of its kind to demonstrate that MSC therapy improves a variety of parameters in NIDCM irrespective of patient sex. These findings have important clinical and pathophysiologic implications regarding the impact of sex on responses to cell-based therapy for NIDCM., (Published on behalf of the European Society of Cardiology. All rights reserved. © The Author(s) 2020. For permissions, please email: journals.permissions@oup.com.)

Patients have an ongoing unmet need for effective therapies that reverse the cellular and functional damage associated with heart damage and disease. The discovery that ~1%-2% of adult cardiomyocytes turn over per year provided the impetus for treatments that stimulate endogenous repair mechanisms that augment this rate. Preclinical and clinical studies provide evidence that cell-based therapy meets these therapeutic criteria. Recent and ongoing studies are focused on determining which cell type(s) works best for specific patient population(s) and the mechanism(s) by which these cells promote repair. Here we review clinical and preclinical stem cell studies and anticipate future directions of regenerative medicine for heart disease.

Background: Non-ischemic dilated cardiomyopathy (NIDCM) responds variably to intramyocardial injection of mesenchymal stem cells (MSCs). We hypothesized that NIDCM genotype may influence responsiveness to MSC therapy and performed genotyping on all patients in the POSEIDON-DCM trial., Methods: POSEIDON-DCM patients (n = 34) underwent genetic sequence analysis and deletion/duplication testing. The results were classified as positive for pathological variants (PV+; n = 8), negative for any variants (V-; n = 6), or as variants of uncertain significance (VUS; n = 20). All outcomes of therapy were analysed for each category of genetic results., Findings: The 3 groups were indistinguishable at baseline with regard to ejection fraction (EF), demographics, medication use, or functional parameters. V- patients had an increase in EF at 12 months: +13.6% (IQR = +7.8%; +20.5%; p = 0.002), compared with VUS (+6.5%; IQR = +0.9%, +11.1%; p = 0.005) and PV+(-5.9%; IQR = -12.7%, +1.0; p = 0.2; p = 0.01 between groups). Six-minute walk distance improved in V- patients, but not in VUS and PV+. V- patients improved MLHFQ, compared to the other 2 groups, which did not improve over time. EPCCFUs increased by 9.7 ± 1.9 in V- (p = 0.009) compared to VUS and PV+ patients. V- patients had one-year survival (100%) compared with VUS (85%) and PV+ (40%; p = 0.015 log-rank). Similarly, MACE rates were lower in V- (0%) than PV+ (61.9%) or VUS (42.2%; p = 0.021 log-rank)., Interpretation: Our findings support the concept that the genetic profile of NIDCM patients plays a role in responsiveness to MSC therapy, with V- patients more likely to benefit and the converse for PV+. This observation emphasizes the need for further genetic studies, because of important implications for the management of NIDCM syndromes., (Copyright © 2019. Published by Elsevier B.V.)

Aging frailty is a syndrome characterized by a progressive decline in health and clinical symptoms of exhaustion, weight loss, a feeling of slowing down, and a decrease in functional capacity. The biological substrate for frailty is sarcopenia, which is potentiated by chronic inflammation and depletion or impairment of endogenous precursor and stem cells. Current interventions focus on interdisciplinary approaches which include nutritional supplementation, physical exercise, and cognitive intervention. Clinical studies of these preventative approaches have shown inconsistent and modest benefits, further highlighting the unmet clinical need. A variety of pharmacologic and biologic therapies are currently being tested to treat aging. Cell-based therapy represents an attractive option that addresses the pathophysiology of the syndrome. Human allogeneic mesenchymal stem cells (MSCs) which possess immunomodulatory and tissue reparative properties, have been tested in Phase I and Phase II trials. These small early stage studies reveal that allogeneic MSCs administered to frail older adults are feasible to administer, safe and potentially efficacious, ameliorating signs and symptoms of frailty. These studies have formed the basis for larger ongoing trials. Here we review the pathobiology of frailty, and the potential for developing biological strategies to treat this important syndrome., (Copyright © 2019 Elsevier B.V. All rights reserved.)

Background: Ischemic cardiomyopathy (ICM) and dilated cardiomyopathy (DCM) differ in histopathology and prognosis. Although transendocardial delivery of mesenchymal stem cells is safe and provides cardiovascular benefits in both, a comparison of mesenchymal stem cell efficacy in ICM versus DCM has not been done., Methods and Results: We conducted a subanalysis of 3 single-center, randomized, and blinded clinical trials: (1) TAC-HFT (Transendocardial Autologous Mesenchymal Stem Cells and Mononuclear Bone Marrow Cells in Ischemic Heart Failure Trial); (2) POSEIDON (A Phase I/II, Randomized Pilot Study of the Comparative Safety and Efficacy of Transendocardial Injection of Autologous Mesenchymal Stem Cells Versus Allogeneic Mesenchymal Stem Cells in Patients With Chronic Ischemic Left Ventricular Dysfunction Secondary to Myocardial Infarction); and (3) POSEIDON-DCM (Percutaneous Stem Cell Injection Delivery Effects on Neomyogenesis in Dilated Cardiomyopathy). Baseline and 1-year cardiac structure and function and quality-of-life data were compared in a post hoc pooled analysis including ICM (n=46) and DCM (n=33) patients who received autologous or allogeneic mesenchymal stem cells. Ejection fraction improved in DCM by 7% (within-group, P =0.002) compared to ICM (1.5%; within-group, P =0.14; between-group, P =0.003). Similarly, stroke volume increased in DCM by 10.59 mL ( P =0.046) versus ICM (-0.2 mL; P =0.73; between-group, P =0.02). End-diastolic volume improved only in ICM (10.6 mL; P =0.04) and end-systolic volume improved only in DCM (17.8 mL; P =0.049). The sphericity index decreased only in ICM (-0.04; P =0.0002). End-diastolic mass increased in ICM (23.1 g; P <0.0001) versus DCM (-4.1 g; P =0.34; between-group, P =0.007). The 6-minute walk test improved in DCM (31.1 m; P =0.009) and ICM (36.3 m; P =0.006) with no between-group difference ( P =0.79). The New York Heart Association class improved in DCM ( P =0.005) and ICM ( P =0.02; between-group P =0.20). The Minnesota Living with Heart Failure Questionnaire improved in DCM (-19.5; P =0.002) and ICM (-6.4; P =0.03; δ between-group difference P =0.042) patients., Conclusions: Mesenchymal stem cell therapy is beneficial in DCM and ICM patients, despite variable effects on cardiac phenotypic outcomes. Whereas cardiac function improved preferentially in DCM patients, ICM patients experienced reverse remodeling. Mesenchymal stem cell therapy enhanced quality of life and functional capacity in both etiologies., Clinical Trial Registration: URL: http://www.clinicaltrials.gov. Unique identifiers: TAC-HFT: NCT00768066, POSEIDON: NCT01087996, POSEIDON-DCM: NCT01392625., (© 2018 The Authors. Published on behalf of the American Heart Association, Inc., by Wiley.)

Background: The combination of autologous mesenchymal stem cells (MSCs) and cardiac stem cells (CSCs) synergistically reduces scar size and improves cardiac function in ischemic cardiomyopathy. Whereas allogeneic (allo-)MSCs are immunoevasive, the capacity of CSCs to similarly elude the immune system remains controversial, potentially limiting the success of allogeneic cell combination therapy (ACCT)., Objectives: This study sought to test the hypothesis that ACCT synergistically promotes cardiac regeneration without provoking immunologic reactions., Methods: Göttingen swine with experimental ischemic cardiomyopathy were randomized to receive transendocardial injections of allo-MSCs + allo-CSCs (ACCT: 200 million MSCs/1 million CSCs, n = 7), 200 million allo-MSCs (n = 8), 1 million allo-CSCs (n = 4), or placebo (Plasma-Lyte A, n = 6). Swine were assessed by cardiac magnetic resonance imaging and pressure volume catheterization. Immune response was tested by histologic analyses., Results: Both ACCT and allo-MSCs reduced scar size by -11.1 ± 4.8% (p = 0.012) and -9.5 ± 4.8% (p = 0.047), respectively. Only ACCT, but not MSCs or CSCs, prevented ongoing negative remodeling by offsetting increases in chamber volumes. Importantly, ACCT exerted the greatest effect on systolic function, improving the end-systolic pressure-volume relation (+0.98 ± 0.41 mm Hg/ml; p = 0.016). The ACCT group had more phospho-histone H3+ (a marker of mitosis) cardiomyocytes (p = 0.04), and noncardiomyocytes (p = 0.0002) than did the placebo group in some regions of the heart. Inflammatory sites in ACCT and MSC-treated swine contained immunotolerant CD3 + /CD25 + /FoxP3 + regulatory T cells (p < 0.0001). Histologic analysis showed absent to low-grade inflammatory infiltrates without cardiomyocyte necrosis., Conclusions: ACCT demonstrates synergistic effects to enhance cardiac regeneration and left ventricular functional recovery in a swine model of chronic ischemic cardiomyopathy without adverse immunologic reaction. Clinical translation to humans is warranted., (Copyright © 2017 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.)

Rationale: Cell dose and concentration play crucial roles in phenotypic responses to cell-based therapy for heart failure., Objective: To compare the safety and efficacy of 2 doses of allogeneic bone marrow-derived human mesenchymal stem cells identically delivered in patients with ischemic cardiomyopathy., Methods and Results: Thirty patients with ischemic cardiomyopathy received in a blinded manner either 20 million (n=15) or 100 million (n=15) allogeneic human mesenchymal stem cells via transendocardial injection (0.5 cc per injection × 10 injections per patient). Patients were followed for 12 months for safety and efficacy end points. There were no treatment-emergent serious adverse events at 30 days or treatment-related serious adverse events at 12 months. The Major Adverse Cardiac Event rate was 20.0% (95% confidence interval [CI], 6.9% to 50.0%) in 20 million and 13.3% (95% CI, 3.5% to 43.6%) in 100 million ( P =0.58). Worsening heart failure rehospitalization was 20.0% (95% CI, 6.9% to 50.0%) in 20 million and 7.1% (95% CI, 1.0% to 40.9%) in 100 million ( P =0.27). Whereas scar size reduced to a similar degree in both groups: 20 million by -6.4 g (interquartile range, -13.5 to -3.4 g; P =0.001) and 100 million by -6.1 g (interquartile range, -8.1 to -4.6 g; P =0.0002), the ejection fraction improved only with 100 million by 3.7 U (interquartile range, 1.1 to 6.1; P =0.04). New York Heart Association class improved at 12 months in 35.7% (95% CI, 12.7% to 64.9%) in 20 million and 42.9% (95% CI, 17.7% to 71.1%) in 100 million. Importantly, proBNP (pro-brain natriuretic peptide) increased at 12 months in 20 million by 0.32 log pg/mL (95% CI, 0.02 to 0.62; P =0.039), but not in 100 million (-0.07 log pg/mL; 95% CI, -0.36 to 0.23; P =0.65; between group P =0.07)., Conclusions: Although both cell doses reduced scar size, only the 100 million dose increased ejection fraction. This study highlights the crucial role of cell dose in the responses to cell therapy. Determining optimal dose and delivery is essential to advance the field, decipher mechanism(s) of action and enhance planning of pivotal Phase III trials., Clinical Trial Registration: URL: http://www.clinicaltrials.gov. Unique identifier: NCT02013674., (© 2017 American Heart Association, Inc.)

Background: Although human mesenchymal stem cells (hMSCs) have been tested in ischemic cardiomyopathy, few studies exist in chronic nonischemic dilated cardiomyopathy (NIDCM)., Objectives: The authors conducted a randomized comparison of safety and efficacy of autologous (auto) versus allogeneic (allo) bone marrow-derived hMSCs in NIDCM., Methods: Thirty-seven patients were randomized to either allo- or auto-hMSCs in a 1:1 ratio. Patients were recruited between December 2011 and July 2015 at the University of Miami Hospital. Patients received hMSCs (100 million) by transendocardial stem cell injection in 10 left ventricular sites. Treated patients were evaluated at baseline, 30 days, and 3-, 6-, and 12-months for safety (serious adverse events [SAE]), and efficacy endpoints: ejection fraction, Minnesota Living with Heart Failure Questionnaire, 6-min walk test, major adverse cardiac events, and immune biomarkers., Results: There were no 30-day treatment-emergent SAEs. Twelve-month SAE incidence was 28.2% with allo-hMSCs versus 63.5% with auto-hMSCs (p = 0.1004 for the comparison). One allo-hMSC patient developed an elevated (>80) donor-specific calculated panel reactive antibody level. The ejection fraction increased in allo-hMSC patients by 8.0 percentage points (p = 0.004) compared with 5.4 with auto-hMSCs (p = 0.116; allo vs. auto p = 0.4887). The 6-min walk test increased with allo-hMSCs by 37.0 m (p = 0.04), but not auto-hMSCs at 7.3 m (p = 0.71; auto vs. allo p = 0.0168). MLHFQ score decreased in allo-hMSC (p = 0.0022) and auto-hMSC patients (p = 0.463; auto vs. allo p = 0.172). The major adverse cardiac event rate was lower, too, in the allo group (p = 0.0186 vs. auto). Tumor necrosis factor-α decreased (p = 0.0001 for each), to a greater extent with allo-hMSCs versus auto-hMSCs at 6 months (p = 0.05)., Conclusions: These findings demonstrated safety and clinically meaningful efficacy of allo-hMSC versus auto-hMSC in NIDCM patients. Pivotal trials of allo-hMSCs are warranted based on these results. (Percutaneous Stem Cell Injection Delivery Effects on Neomyogenesis in Dilated Cardiomyopathy [PoseidonDCM]; NCT01392625)., Competing Interests: Declaration of Interest: Dr. Hare and Dr. Heldman disclose a relationship with Vestion Inc that includes equity, board membership, and consulting. Dr. Hatzistergos and K. Valasaki disclose a relationship with Vestion Inc that includes equity. Vestion Inc did not participate in funding this work. Dr. Landin, Dr. Hare, A. Khan, and D. DiFede disclose a relationship with Longeveron LLC that includes consulting. Longeveron LLC did not participate in funding this work. D. DiFede discloses a relationship with BDS as consultant. The other authors report no conflicts., (Copyright © 2017 The Authors. Published by Elsevier Inc. All rights reserved.)

Evidence suggests that infusional therapy is a more effective means for administering cytotoxic therapy than intravenous bolus therapy for lymphoma and offers greater potential for therapeutic synergy with rituximab, which has a long half-life. We pooled the results of 3 prospective phase 2 trials evaluating rituximab in combination with 96-hour infusion of cyclophosphamide (187.5-200 mg/m2 per day), doxorubicin (12.5 mg/m2 per day), and etoposide (60 mg/m2 per day) (R-CDE) plus granulocyte-colony-stimulating factor (G-CSF) in 74 patients with HIV-associated, B-cell non-Hodgkin lymphoma, of whom 56 (76%) patients received concurrent highly active antiretroviral therapy (HAART). The complete remission (CR) rate was 70% (95% confidence interval [CI], 59%-81%), and the estimated 2-year failure-free survival and overall survival rates were 59% (95% CI, 47%-71%) and 64% (95% CI, 52%-76%), respectively. Ten (14%) patients had opportunistic infections during or within 3 months of the end of R-CDE, and 17 (23%) patients developed nonopportunistic infections after that time. Six (8%) patients died because of infection; 2 (3%) of those infections were bacterial sepsis during R-CDE, and 4 (5%) were opportunistic infections that occurred between 2 and 8 months after the completion of R-CDE. R-CDE produced a 70% CR rate and a 59% 2-year failure-free survival rate in patients with HIV-associated lymphoma. Consistent with other reports, adding rituximab to cytotoxic therapy in this population may increase the risk for life-threatening infection. Further studies evaluating rituximab in combination with infusional chemotherapy are warranted, but caution is advised.