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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.

AIMS CONCERT-HF is an NHLBI-sponsored, double-blind, placebo-controlled, Phase II trial designed to determine whether treatment with autologous bone marrow-derived mesenchymal stromal cells (MSCs) and c-kit positive cardiac cells (CPCs), given alone or in combination, is feasible, safe, and beneficial in patients with heart failure (HF) caused by ischaemic cardiomyopathy. METHODS AND RESULTS Patients were randomized (1:1:1:1) to transendocardial injection of MSCs combined with CPCs, MSCs alone, CPCs alone, or placebo, and followed for 12 months. Seven centres enrolled 125 participants with left ventricular ejection fraction of 28.6 ± 6.1% and scar size 19.4 ± 5.8%, in New York Heart Association class II or III. The proportion of major adverse cardiac events (MACE) was significantly decreased by CPCs alone (-22% vs. placebo, P = 0.043). Quality of life (Minnesota Living with Heart Failure Questionnaire score) was significantly improved by MSCs alone (P = 0.050) and MSCs + CPCs (P = 0.023) vs. placebo. Left ventricular ejection fraction, left ventricular volumes, scar size, 6-min walking distance, and peak oxygen consumption did not differ significantly among groups. CONCLUSIONS This is the first multicentre trial assessing CPCs and a combination of two cell types from different tissues in HF patients. The results show that treatment is safe and feasible. Even with maximal guideline-directed therapy, both CPCs and MSCs were associated with improved clinical outcomes (MACE and quality of life, respectively) in ischaemic HF without affecting left ventricular function or structure, suggesting possible systemic or paracrine cellular mechanisms. Combining MSCs with CPCs was associated with improvement in both these outcomes. These results suggest potential important beneficial effects of CPCs and MSCs and support further investigation in HF patients.

Here, we present an O2-independent/HIF-1α (Hypoxia inducible factor-1α)-dependent mechanism that regulates developmental and regenerative growth of mammalian cardiomyoblasts. An autocrine feedback mechanism of GH/IGF1/SST (Growth hormone/Insulin-like growth factor 1/Somatostatin) signaling, mediated by GHRH/GHRH-R (Growth hormone-releasing hormone/GHRH-Receptor), is established specifically in NKX2-5 (NK2 Homeobox 5) expressing myocardial cells which affects HIF-1α stability through cAMP (cyclic adenosine monophosphate) or cGMP (cyclic guanosine monophosphate) activity. cAMP-mediated HIF-1α stabilization fuels Warburg metabolism and enhances NKX2-5 expression, limiting the developmental and regenerative growth of cardiomyoblasts. In contrast, cGMP-mediated HIF-1α inhibition (or knock-out of HIF-1α) redirects glycolytically derived citrate toward long-chain saturated fatty acid biosynthesis, leading to enhanced developmental and regenerative growth of cardiomyoblasts. These findings suggest that HIF1α-mediated glycolysis serves as a rate-limiting, O2-independent sensor of cardiomyogenesis and that targeting GHRH/GHRH-R signaling could be a therapeutic strategy for regenerating the mammalian heart post-injury.

Cells previously thought to mainly form nerves in the heart turn out to be very important in cardiac muscle formation., The degree to which populations of cardiac progenitors (CPCs) persist in the postnatal heart remains a controversial issue in cardiobiology. To address this question, we conducted a spatiotemporally resolved analysis of CPC deployment dynamics, tracking cells expressing the pan-CPC gene Isl1. Most CPCs undergo programmed silencing during early cardiogenesis through proteasome-mediated and PRC2 (Polycomb group repressive complex 2)–mediated Isl1 repression, selectively in the outflow tract. A notable exception is a domain of cardiac neural crest cells (CNCs) in the inflow tract. These “dorsal CNCs” are regulated through a Wnt/β-catenin/Isl1 feedback loop and generate a limited number of trabecular cardiomyocytes that undergo multiple clonal divisions during compaction, to eventually produce ~10% of the biventricular myocardium. After birth, CNCs continue to generate cardiomyocytes that, however, exhibit diminished clonal amplification dynamics. Thus, although the postnatal heart sustains cardiomyocyte-producing CNCs, their regenerative potential is likely diminished by the loss of trabeculation-like proliferative properties.

Introduction: Bronchopulmonary dysplasia (BPD) or chronic lung injury of newborn is a life-threatening condition in preterm infants with few effective therapies. Mesenchymal stem cells (MSC) are a promising therapeutic strategy for BPD. The ideal MSC source for BPD prevention is however unknown. Umbilical cord tissue (UCT) MSC may potentially have more anti-inflammatory and pro-angiogenic properties. Hypothesis: We hypothesized that the UCT-MSC will have superior lung regenerative effect in BPD owing to superior anti-inflammatory and pro-angiogenic properties as compared to BM-MSC. Methods: Newborn rats (n=10-12/group) were randomly assigned to normoxia or hyperoxia (85% O 2 ) from postnatal day (P) 1 to 21 were given intra-tracheal (IT) BM or UCT-MSC (1 x 10 6 cells/50 μl), or placebo (PL) on P3. Results: Hyperoxia PL-treated pups had marked alveolar simplification, vascular rarefaction, remodeling and lung inflammation. Administration of both BM-MSC and UCT-MSC significantly improved alveolar structure, vascular density, pulmonary hypertension, vascular remodeling and lung inflammation. However, the improvement in alveolar structure and lung inflammation was more marked in hyperoxic pups who received UCT-MSC. In vitro studies demonstrated greater TSG-6 and IL-10 expression in UCT-MSC as compared to BM-MSC. Moreover, lung epithelial cells incubated with UCT-MSC conditioned media had greater wound healing following scratch injury. Conclusion: These findings demonstrate that while both BM and UCT-MSC have lung regenerative effects, UCT-MSC have greater anti-inflammatory and alveolar protective effects in experimental BPD. These findings have significant implications for cellular therapy in BPD, as it suggests that UCT-MSC are a superior cellular source for preterm lung protection.

Bronchopulmonary dysplasia (BPD) is a life-threatening condition in preterm infants with few effective therapies. Mesenchymal stem or stromal cells (MSCs) are a promising therapeutic strategy for BPD. The ideal MSC source for BPD prevention is however unknown. The objective of this study was to compare the regenerative effects of MSC obtained from bone marrow (BM) and umbilical cord tissue (UCT) in an experimental BPD model. In vitro, UCT-MSC demonstrated greater proliferation and expression of anti-inflammatory cytokines as compared to BM-MSC. Lung epithelial cells incubated with UCT-MSC conditioned media (CM) had better-wound healing following scratch injury. UCT-MSC CM and BM-MSC CM had similar pro-angiogenic effects on hyperoxia-exposed pulmonary microvascular endothelial cells. In vivo, newborn rats exposed to normoxia or hyperoxia (85% O2) from postnatal day (P) 1 to 21 were given intra-tracheal (IT) BM or UCT-MSC (1 × 106 cells/50 μL), or placebo (PL) on P3. Hyperoxia PL-treated rats had marked alveolar simplification, reduced lung vascular density, pulmonary vascular remodeling, and lung inflammation. In contrast, administration of both BM-MSC and UCT-MSC significantly improved alveolar structure, lung angiogenesis, pulmonary vascular remodeling, and lung inflammation. UCT-MSC hyperoxia-exposed rats however had greater improvement in some morphometric measures of alveolarization and less lung macrophage infiltration as compared to the BM-MSC-treated group. Together, these findings suggest that BM-MSC and UCT-MSC have significant lung regenerative effects in experimental BPD but UCT-MSC suppresses lung macrophage infiltration and promotes lung epithelial cell healing to a greater degree.

Background Aging frailty, characterized by decreased physical and immunological functioning, is associated with stem cell depletion. Human allogeneic mesenchymal stem cells (allo-hMSCs) exert immunomodulatory effects and promote tissue repair. Methods This is a randomized, double-blinded, dose-finding study of intravenous allo-hMSCs (100 or 200-million [M]) vs placebo delivered to patients (n = 30, mean age 75.5 ± 7.3) with frailty. The primary endpoint was incidence of treatment-emergent serious adverse events (TE-SAEs) at 1-month postinfusion. Secondary endpoints included physical performance, patient-reported outcomes, and immune markers of frailty measured at 6 months postinfusion. Results No therapy-related TE-SAEs occurred at 1 month. Physical performance improved preferentially in the 100M-group; immunologic improvement occurred in both the 100M- and 200M-groups. The 6-minute walk test, short physical performance exam, and forced expiratory volume in 1 second improved in the 100M-group (p = .01), not in the 200M- or placebo groups. The female sexual quality of life questionnaire improved in the 100M-group (p = .03). Serum TNF-α levels decreased in the 100M-group (p = .03). B cell intracellular TNF-α improved in both the 100M- (p < .0001) and 200M-groups (p = .002) as well as between groups compared to placebo (p = .003 and p = .039, respectively). Early and late activated T-cells were also reduced by MSC therapy. Conclusion Intravenous allo-hMSCs were safe in individuals with aging frailty. Treated groups had remarkable improvements in physical performance measures and inflammatory biomarkers, both of which characterize the frailty syndrome. Given the excellent safety and efficacy profiles demonstrated in this study, larger clinical trials are warranted to establish the efficacy of hMSCs in this multisystem disorder. Clinical Trial Registration www.clinicaltrials.gov: CRATUS (#NCT02065245).

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)

SUMMARYWhether the heart’s organ-founding, progenitor cell gene regulatory networks (CPC-GRNs) are sustained after birth and can be therapeutically evoked for regeneration in response to disease, remains elusive. Here, we report a spatiotemporally resolved analysis of CPC-GRN deployment dynamics, through the pan-CPC-GRN gene Isl1. We show that the Isl1-CPC-GRNs that are deployed during early cardiogenesis and generate the cardiomyocyte majority from mesoderm, undergo programmed silencing through proteasome- and PRC2-mediated Isl1 repression, selectively in the arterial pole. In contrast, we identify a neural crest (CNC)-specific Wnt/β-catenin/Isl1-CPC-GRN that is deployed through the venous pole during cardiac growth and partitioning, and contributes a minority of cardiomyocytes which, in turn, expand massively to build ~10% of the biventricular myocardium. These “dorsal CNCs” continue to sporadically generate cardiomyocytes throughout postnatal growth which, however, are non-proliferative, suggesting that partitioning-like, fetal proliferation signals could be therapeutically targeted to evoke clonal expansion capacity in postnatal CNC-cardiomyocytes for heart regeneration.

Rationale: Culture-expanded cells originating from cardiac tissue that express the cell surface receptor cKit are undergoing clinical testing as a cell source for heart failure and congenital heart disease. Although accumulating data support that mesenchymal stem cells (MSCs) enhance the efficacy of cardiac cKit + cells (CSCs), the underlying mechanism for this synergistic effect remains incompletely understood. Objective: To test the hypothesis that MSCs stimulate endogenous CSCs to proliferate, migrate, and differentiate via the SDF1/CXCR4 and stem cell factor/cKit pathways. Methods and Results: Using genetic lineage-tracing approaches, we show that in the postnatal murine heart, cKit + cells proliferate, migrate, and form cardiomyocytes, but not endothelial cells. CSCs exhibit marked chemotactic and proliferative responses when cocultured with MSCs but not with cardiac stromal cells. Antagonism of the CXCR4 pathway with AMD3100 (an SDF1/CXCR4 antagonist) inhibited MSC-induced CSC chemotaxis but stimulated CSC cardiomyogenesis ( P P Conclusions: Together these findings show that MSCs exhibit profound, yet differential, effects on CSC migration, proliferation, and differentiation and suggest a mechanism underlying the improved cardiac regeneration associated with combination therapy using CSCs and MSCs. These findings have important therapeutic implications for cell-based therapy strategies that use mixtures of CSCs and MSCs.

Microgravity-induced alterations in the autonomic nervous system (ANS) contribute to derangements in both the mechanical and electrophysiological function of the cardiovascular system, leading to severe symptoms in humans following space travel. Because the ANS forms embryonically from neural crest (NC) progenitors, we hypothesized that microgravity can impair NC-derived cardiac structures. Accordingly, we conducted in vitro simulated microgravity experiments employing NC genetic lineage tracing in mice with cKit(CreERT2/+), Isl1nLacZ, and Wnt1-Cre reporter alleles. Inducible fate mapping in adult mouse hearts and pluripotent stem cells (iPSCs) demonstrated reduced cKit(CreERT2/+)-mediated labeling of both NC-derived cardiomyocytes and autonomic neurons (P

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.

Introduction: A major roadblock for generating human pluripotent stem cell (hPSCs) derivatives highly enriched in cardiomyogenic precursors (CPCs), has been the lack of CPC-specific cell surface markers. Hypothesis: Based on observations that adult CPCs are responsive to growth hormone-releasing hormone (GHRH) signaling, we hypothesized that the GHRH receptor (GHRHR) is a specific cell-surface marker for hPSC-derived CPCs. Methods: We performed temporal analysis of GHRHR expression in an in-vitro model of human cardiogenesis using induced hPSCs (hiPSCs) and SOX10::GFP embryonic hPSCs (hESCs) ; and mouse ( in-vivo ) cardiogenesis in wild-type (WT), MEF2c-AHF-Cre, Wnt1-Cre2 and cKit-CreERT2/+ reporter mice. Results: Gene expression and confocal immunofluorescence analyses during chemically-defined, stage-specific, cardiac lineage differentiation indicated that GHRHR is not expressed in undifferentiated hiPSCs or during specification into primitive streak-like Brachyury + or Mesp1 + precardiac cells; but is induced in cardiogenic mesoderm-like cells, at the stage of commitment into NKX2.5 + and/or ISL1 + CPCs ( p =0.001) and persists in Troponin-T + cardiomyocytes. Similarly, experiments modeling cardiac neural crest (CNC) with SOX10::GFP hESCs indicated that GHRHR is not expressed by GFP + CNCs but is induced following differentiation into NKX2.5 + and/or ISL1 + derivatives. Importantly, stimulation with 1μm recombinant GHRH during days 5-7 of hiPSCs differentiation increased NKX2.5 expression 2.5-fold, an effect that was abolished by exposure to 1μM Somatostatin, a GHRH antagonist ( p =0.0009). Last, in vivo analyses in WT , MEF2c-AHF-Cre, Wnt1-Cre2 and cKit-CreERT2/+ reporter embryonic and postnatal hearts corroborated that GHRHR specifically marks NKX2.5 + mesoderm- and CNC-lineage descendants in vivo, whereas GHRHR is not expressed by Wnt1-Cre2 and cKit-CreERT2/+ CNCs descendants that are Nkx2.5 – . Conclusions: Together these findings indicate that GHRHR is universally expressed by NKX2.5 + /ISL1 + CPCs and cardiomyocytes of both mesoderm and CNC origin. Therefore, GHRHR appears to be a valuable cell-surface marker for the selection and enrichment of CPCs from hPSCs for biomedical and regenerative medicine applications.

Background Impaired endogenous stem cell repair capacity is hypothesized to be a biologic basis of frailty. Therapies that restore regenerative capacity may therefore be beneficial. This Phase 1 study evaluated the safety and potential efficacy of intravenous, allogeneic, human mesenchymal stem cell (allo-hMSC)-based therapy in patients with aging frailty. Methods In this nonrandomized, dose-escalation study, patients received a single intravenous infusion of allo-hMSCs: 20-million (n = 5), 100-million (n = 5), or 200-million cells (n = 5). The primary endpoint was incidence of any treatment-emergent serious adverse events measured at 1 month postinfusion. The secondary endpoints were functional efficacy domains and inflammatory biomarkers, measured at 3 and 6 months, respectively. Results There were no treatment-emergent serious adverse events at 1-month postinfusion or significant donor-specific immune reactions during the first 6 months. There was one death at 258 days postinfusion in the 200-million group. In all treatment groups, 6-minute walk distance increased at 3 months (p = .02) and 6 months (p = .001) and TNF-α levels decreased at 6 months (p < .0001). Overall, the 100-million dose showed the best improvement in all parameters, with the exception of TNF-α, which showed an improvement in both the 100- and 200-million groups (p = .0001 and p = .0001, respectively). The 100-million cell-dose group also showed significant improvements in the physical component of the SF-36 quality of life assessment at all time points relative to baseline. Conclusions Allo-hMSCs are safe and immunologically tolerated in aging frailty patients. Improvements in functional and immunologic status suggest that ongoing clinical development of cell-based therapy is warranted for frailty.

Although human mesenchymal stem cells (hMSCs) have been tested in ischemic cardiomyopathy, few studies exist in chronic nonischemic dilated cardiomyopathy (NIDCM).The authors conducted a randomized comparison of safety and efficacy of autologous (auto) versus allogeneic (allo) bone marrow-derived hMSCs in NIDCM.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.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).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).

Background: Clinical trials have shown a sustained beneficial effect of bone marrow mesenchymal stem cells (MSCs) as a therapy for acute and chronic heart failure (HF). Clinical grade cell manufacturing of autologous and allogeneic MSCs is becoming a standard procedure. This study investigates the differences of bone marrow MSC isolation and expansion in favorable in vitro conditions. We compared MSC production from both healthy young donors and chronic HF patients. Methods: We analyzed MSC manufacturing records from five clinical trials: TAC-HFT (Ischemic cardiomyopathy (CMP), patient and donors), POSEIDON (Ischemic CMP, donors), POSEIDON DCM (Dilated CMP, donors), TRIDENT (Ischemic CMP, donors), and CRATUS (Frailty, donors). Results: All cells expressed CD105, CD90 and lacked hematopoietic marker CD45. The age of healthy donors (25.5 ± 0.7 y.o., N=24) and HF patients (56.1 ± 2.5, y.o., N=23), was significantly different (P Conclusions: Despite equivalent numbers of MNCs, healthy young donors generate significantly more MSCs than HF patients, due to increased growth rate and higher number of resident stromal bone marrow stem cells. MSC migration was impaired in HF patients compared to healthy donors. HF appears to be an independent factor for MSC renewal capacity and culture phenotype.

Introduction: A multitude of structural, haemodynamic and electromechanical cardiovascular disorders have been observed in humans following space-travel. These abnormalities are thought to emerge from transient alterations in autonomic nervous system (ANS). However, since the ANS is cardiac neural crest (CNC)-derived, whether microgravity-induced cardiomyopathies reflect CNC dysfunction, is unknown. Hypothesis: Impairment of CNCs underlies microgravity-induced cardiomyopathies. Methods: Myocardial explants from adult cKit CreERT2/+ ;IRG mice (n=5/group), as well as cKit CreERT2/+ ;IRG- derived (iPSC Kit-Cre ; n=6/group) and Wnt1-Cre;tdTomato -derived (iPSC Wnt1-Cre ; n=18/group) induced pluripotent stem cells, were cultured under static (SC) or simulated microgravity conditions (rotary cell-culture system; RCCS). Results: CNC lineage-tracing in cardiac explants illustrated that, compared to SC, RCCS abolished the pool of cKit + CNCs in adult hearts, indicated by quantitation of cKit CreERT2 - mediated EGFP expression ( p Kit-Cre yielded fewer beating EBs ( p =0.0005), and ~10-fold reduction in EGFP + cardiomyocytes ( p =0.01), in RCCS vs . SC. Microarray analyses suggested that RCCS-mediated alterations in BMP and Wnt/β-catenin pathways, downregulated ANS and CNC-related gene programs, and enhanced vasculogenic differentiation without affecting the expression of cardiac mesoderm-related genes. Differences were verified by quantitative PCR. Modeling CNC development in iPSC Wnt1-Cre further confirmed an RCCS-mediated dramatic impairment in development and function of CNCs, indicated by quantitation of tdTomato expression in day-10 and day-21 beating embryoid bodies ( p Conclusions: Together these data indicate that microgravity negatively regulates the development and function of CNCs, thus partly explaining the cellular and molecular mechanisms of microgravity-induced cardiomyopathies. Moreover, these findings are expected to have important implications in space exploration, since they suggest an essential role for gravity in vertebrate development.

A novel protease designated protease-A-17N-1, was purified from the haloalkalophilic Bacillus sp. 17N-1, and found active in media containing dithiothreitol and EDTAK(2). This enzyme maintained significant activity from pH 6.00 to 9.00, showed optimum k(cat)/K-m value at pH 7.50 and 33 degrees C. It was observed that only specific inhibitors of cysteine proteinases inhibited its activity. The pH-(k(cat)/K-m) profile of protease-A-17N-1 was described by three pK(a)s in the acid limb, and one in the alkaline limb. Both are more likely due t3o the protonic dissociation of an acidic residue, and the development and subsequent deprotonation of an ion-pair, respectively, in its catalytic site, characteristic for cysteine proteinases. Moreover, both the obtained estimates of rate constant k(1) and the ratio k(2)/k(-1) at 25 degrees C, from the temperature-(k(cat)/K-m) profile of protease-A-17N-1, were found similar to those estimated from the proton inventories of the same parameter, verifying the reliability of the latter methodology. Besides, the bowed-downward proton inventories of k(cat)/K-m, as well as the large inverse SIE observed for this parameter, in combination with its dependence versus temperature, were showed unambiguously that k(cat)/K-m = k(1). Such results suggest that the novel enzyme is more likely to be a cysteine proteinase functioning via a general acid-base mechanism. J Biochem

Introduction: Activation of cardiac cell cycle re-entry is considered the primary therapeutic strategy for cardiomyocyte (CM) regeneration. However, the role of cardiac cell-cycle control in cardiomyogenesis remains elusive. Here, we combined RNA interference and stem cell modeling to investigate the role of Retinoblastoma (RB) in human cardiomyogenesis. Hypothesis: RB regulates proliferation and differentiation of cardiac progenitors (CPCs) but not CM replication. Methods: H9 human embryonic stem cells (hESCs) stably expressing tetracycline (tet)-inducible shRNAs against RB (hESCshRB) or hemagglutinin-tagged RB (hESCHA-RB) were tet-induced at selected time-points during or after CM differentiation. Results: Analysis of ser-608 illustrated stage-specific differences in the degree of RB inactivation during normal hESCs-cardiogenesis. Transient shRB knockdown in hESCshRB-derived embryoid bodies (EBs) during the CPC-stage (EB-days 5-8), significantly upregulated GATA4, ISL1, CTNNI, and cKit transcription (p Conclusions: These findings suggest that RB regulates proliferation and differentiation of human CPCs in a cell-autonomous manner, via a CCND-CDK4/6-E2F3 mechanism. Conversely, CM replication may be enhanced via cell-cell interactions with MSCs and/or CSCs, but not cell-autonomously via RB inactivation.

Two thermophilic extracellular proteases, designated Lmm-protease-Lh ( approximately 29 kDa) and Hmm-protease-Lh ( approximately 62 kDa), were purified from the Lactobacillus helveticus from kefir, and found active in media containing dithiothreitol; the activity of Lmm-protease-Lh was increased significantly in media containing also EDTAK(2). Both novel proteases maintained full activity at 60 degrees C after 1-h incubation at 10 degrees C as well as at 80 degrees C, showing optimum k(cat)/K(m) values at pH 7.00 and 60 degrees C. Only irreversible inhibitors specific for cysteine proteinases strongly inhibited the activity of both novel enzymes, while they remained unaffected by irreversible inhibitors specific for serine proteinases. Both enzymes hydrolyzed the substrate Suc-FR-pNA via Michaelis-Menten kinetics; conversely, the substrate Cbz-FR-pNA was hydrolyzed by Lmm-protease-Lh via Michaelis-Menten kinetics and by Hmm-protease-Lh via substrate inhibition kinetics. Valuable rate constants and activation energies were estimated from the temperature-(k(cat)/K(m)) profiles of both enzymes, and useful results were obtained from the effect of different metallic ions on their Michaelis-Menten parameters.