Adult Cardiac Progenitor Research Articles

Sunitinib malate induces cell death in adult human cardiac progenitor cells

Sunitinib malate is known to cause cardiotoxicity in a sub-population of patients, with heart failure seen in more severe cases. Cardiac progenitor cells (CPCs) have been identified in adult human myocardium and contribute to overall tissue maintenance, with previous work identifying negative impacts of sunitinib on these cells. This study aimed to characterise the toxic effects of sunitinib in human CPCs, applying sunitinib concentrations equivalent to clinical plasma levels to these cells in vitro. Cell viability was reduced by 26.5 ± 6.6 % by 2 μM sunitinib for 24 h (p < 0.01); this concentration also induced fold-change increases in gene expression of: calpain (3.1 ± 0.73, p < 0.05), FAS (2.3 ± 0.8, p < 0.05) and BAX (1.9 ± 0.2, p < 0.05), and a decrease in BCL-2 (3.5 ± 0.0, p < 0.001), vs. control (1.0 ± 0.0). This was affirmed by sunitinib inducing fold changes in protein expression of: calpain-1 (2.5 ± 0.5, p < 0.05); FAS receptor (2.1 ± 0.2, p < 0.05) and BAX (2.1 ± 0.2, p < 0.05) vs. control (1.0 ± 0.0). These results indicated that sunitinib induced apoptosis in CPCs, but negative annexin V staining and lack of protection by caspase inhibitors indicated this was not the cell death pathway activated. Further investigation found sunitinib was concentrated in the lysosomes and autophagosomes within CPCs, but did not induce accumulation of acidic organelles. In conclusion, these data confirm that cell death is caused by sunitinib in CPCs at concentrations equivalent to clinical plasma levels, inducing cell death pathway signals that lead to non-apoptotic cell death.

Science Is a Self-Correcting Discipline: Revisiting the Biological Potential of Adult Cardiac Progenitors.

Science Is a Self-Correcting Discipline: Revisiting the Biological Potential of Adult Cardiac Progenitors.

The Vascular Niche for Adult Cardiac Progenitor Cells.

Research on cardiac progenitor cell populations has generated expectations about their potential for cardiac regeneration capacity after acute myocardial infarction and during physiological aging; however, the endogenous capacity of the adult mammalian heart is limited. The modest efficacy of exogenous cell-based treatments can guide the development of new approaches that, alone or in combination, can be applied to boost clinical efficacy. The identification and manipulation of the adult stem cell environment, termed niche, will be critical for providing new evidence on adult stem cell populations and improving stem-cell-based therapies. Here, we review and discuss the state of our understanding of the interaction of adult cardiac progenitor cells with other cardiac cell populations, with a focus on the description of the B-CPC progenitor population (Bmi1+ cardiac progenitor cell), which is a strong candidate progenitor for all main cardiac cell lineages, both in the steady state and after cardiac damage. The set of all interactions should be able to define the vascular cardiac stem cell niche, which is associated with low oxidative stress domains in vasculature, and whose manipulation would offer new hope in the cardiac regeneration field.

Abstract 16769: Intravenous Injection of Neonatal Cardiac Mesenchymal Stem Cells is a Viable Alternative Route to Treat Acute Myocardial Infarction

Introduction: Cardiovascular disease is major cause of morbidity and mortality around the world and major health care burden indeed. Ischemic heart disease (IHD) and myocardial ischemia (MI) are most devastating cardiovascular disease. Multiple stem cell/ cardiac progenitor cell therapy has been reported previously to treat cardiovascular disease safely. However randomized clinical trials with adult cardiac progenitor cells or cardiosphere-derived cells unable to show long-term efficacy. We have our unique source of human neonatal cardiac tissue derived neonatal cardiac mesenchymal stem cells (nMSCs). Systemic administration is preferred route of stem cell delivery in order to consecutive dosage for most of the clinical trials. We hypothesized that nMSCs have unique proteome profile, which supports their survival, migration and homing. They home to the injured myocardium when administered intravenously (IV) to a wild type male rat subjected to MI. Methods: This model was created in 6-week-old Brown-Norway Rats. Rats were subjected to an anterior myocardial Infraction (MI) by permanent LAD ligation. The rats were treated with nMSCs (1^10 6 cells/Kg, 5^10 6 cells/Kg and 10^10 6 cells/Kg) along with placebo and sham, which are delivered intravenously by tail vein injection. Rats are once again treated with nMSCs/placebo 4 days after MI. Baseline echocardiography is performed 24 hours after MI. Results: LVEF was significantly higher in the nMSC-treated group than in the placebo group. Other parameters, including fractional shortening (FS) and decreased end-systolic volume (ESV), were also significantly improved when compared with the placebo group, and other LV functional parameter, including cardiac output/body weight and posterior wall thickness tended towards improvement of remodeled heart. Conclusions: Twice intravenous administration of nMSCs for MI attenuate the progressive deterioration of left ventricle and adverse remodeling of rat heart.

Differences in Mitochondrial Membrane Potential Identify Distinct Populations of Human Cardiac Mesenchymal Progenitor Cells.

Adult human cardiac mesenchymal progenitor cells (hCmPC) are multipotent resident populations involved in cardiac homeostasis and heart repair. Even if the mechanisms have not yet been fully elucidated, the stem cell differentiation is guided by the mitochondrial metabolism; however, mitochondrial approaches to identify hCmPC with enhanced stemness and/or differentiation capability for cellular therapy are not established. Here we demonstrated that hCmPCs sorted for low and high mitochondrial membrane potential (using a lipophilic cationic dye tetramethylrhodamine methyl ester, TMRM), presented differences in energy metabolism from preferential glycolysis to oxidative rates. TMRM-high cells are highly efficient in terms of oxygen consumption rate, basal and maximal respiration, and spare respiratory capacity compared to TMRM-low cells. TMRM-high cells showed characteristics of pre-committed cells and were associated with higher in vitro differentiation capacity through endothelial, cardiac-like, and, to a lesser extent, adipogenic and chondro/osteogenic cell lineage, when compared with TMRM-low cells. Conversely, TMRM-low showed higher self-renewal potential. To conclude, we identified two hCmPC populations with different metabolic profile, stemness maturity, and differentiation potential. Our findings suggest that metabolic sorting can isolate cells with higher regenerative capacity and/or long-term survival. This metabolism-based strategy to select cells may be broadly applicable to therapies.

Isolation, growth kinetics, and immunophenotypic characterization of adult human cardiac progenitor cells.

The discovery of cardiac progenitor cells (CPCs) has raised expectations for the development of cell-based therapy of the heart.Although cell therapy is emerging as a novel treatment for heart failure, several issues still exist concerning an unambiguous definition of the phenotype of CPC types. There is a need to define and validate the methods for the generation of quality CPC populations used in cell therapy applications. Considering the critical roles of cardiac cell progenitors in cellular therapy, we speculate that long term culture might modulate the immunophenotypes of CPCs. Hence, a strategy to validate the isolation and cell culture expansion of cardiac cell populations was devised. Isolation of three subpopulations of human CPCs was done from a single tissue sample using explant, enzymatic isolation, and c-kit+ immunomagnetic sorting methods. The study assessed the effects of ex vivo expansion on proliferation, immunophenotypes, and differentiation of CPCs. Additionally, we report that an explant culture can take over 2 months to achieve similar cell yields, and cell sorting requires a much larger starting population to match this expansion time frame. In comparison, an enzymatic method is expected to yield equivalent quantities of CPCs in 2-3 weeks, notably at a significantly lower cost, which may intensify their use in therapeutic approaches. We determined that ex vivo expansion caused changes in cellular characteristics, and hence propose validated molecular signatures should be established to evaluate the impact of ex vivo expansion for a safe cell therapy product.

P3479Sequential stimulation and inhibition of lysophosphatidic acid receptor 4 are critical for cardiac differentiation and repair

Abstract Background The clinical application of cell therapy to repair the damaged heart needs to understand the precise differentiation process of stem cells and the characteristics of cardiac progenitor cells. Purpose We examined the cardiac-specific markers that expressed on the cell surface and determined their functional significance during cardiac differentiation. Methods and results We screened cell-surface expressing proteins on cardiac progenitor cells at differentiation day 3 compared to undifferentiated pluripotent stem cells (PSCs). Among candidates, we identified lysophosphatidic acid receptor 4 (LPAR4) that is a G protein-coupled receptor. During in vitro differentiation of mouse PSCs toward cardiac cells, LPAR4 expression peaked for 3–5 days and then and declined immediately. Also in vivo, LPAR4 was specifically expressed in the early stage of heart development in embryos and disappeared completely in adults, suggesting that stimulatory signal of LPAR4 at an early stage should be shut off for further progression of differentiation. We next have identified the LPAR4 downstream signaling molecule, p38MAPK, by comparing PSCs and LPAR4 knockdown PSCs. In both mouse and human PSCs, ODP (LPAR4 specific agonist) followed by p38MAPK blocker (SB203580) treatment significantly increased cardiac differentiation efficiency. Furthermore, we investigated whether LPAR4 is the maker for adult cardiac progenitor cells. We found that LPAR4-positive cells were rarely present in normal adult mouse hearts, but LPAR4-positive cells were increased when the heart was damaged. LPAR4-positive cells from adult hearts differentiated into cardiomyocytes. After myocardial infarction (MI), the sequential stimulation and inhibition of LPAR4 with ODP and p38MAPK blocker resulted in the reduction of infarct size and improvement of left ventricular dysfunction. Conclusion We demonstrated that LPAR4 is a cardiac progenitor-specific marker and its functional significance during cardiac differentiation and regeneration. Our findings provide a new insight in cell-free cardiac repair by the modulation of progenitor-specific downstream signaling. Acknowledgement/Funding Grants from “Strategic Center of Cell and Bio Therapy” (grant number: HI17C2085) and “Korea Research-Driven Hospital” (HI14C1277)

Effects of Spaceflight and Simulated Microgravity on YAP1 Expression in Cardiovascular Progenitors: Implications for Cell-Based Repair.

Spaceflight alters many processes of the human body including cardiac function and cardiac progenitor cell behavior. The mechanism behind these changes remains largely unknown; however, simulated microgravity devices are making it easier for researchers to study the effects of microgravity. To study the changes that take place in cardiac progenitor cells in microgravity environments, adult cardiac progenitor cells were cultured aboard the International Space Station (ISS) as well as on a clinostat and examined for changes in Hippo signaling, a pathway known to regulate cardiac development. Cells cultured under microgravity conditions, spaceflight-induced or simulated, displayed upregulation of downstream genes involved in the Hippo pathway such as YAP1 and SOD2. YAP1 is known to play a role in cardiac regeneration which led us to investigate YAP1 expression in a sheep model of cardiovascular repair. Additionally, to mimic the effects of microgravity, drug treatment was used to induce Hippo related genes as well as a regulator of the Hippo pathway, miRNA-302a. These studies provide insight into the changes that occur in space and how the effects of these changes relate to cardiac regeneration studies.

Metabolic flux analyses to assess the differentiation of adult cardiac progenitors after fatty acid supplementation

Myocardial infarction is the most prevalent of cardiovascular diseases and pharmacological interventions do not lead to restoration of the lost cardiomyocytes. Despite extensive stem cell therapy studies, clinical trials using cardiac progenitor cells have shown moderate results. Furthermore, differentiation of endogenous progenitors to mature cardiomyocytes is rarely reported.A metabolic switch from glucose to fatty acid oxidation occurs during cardiac development and cardiomyocyte maturation, however in vitro differentiation protocols do not consider the lack of fatty acids in cell culture media. The aim of this study was to assess the effect of this metabolic switch on control and differentiated adult cardiac progenitors, by fatty acid supplementation.Addition of oleic acid stimulated the peroxisome proliferator-activated receptor alpha pathway and led to maturation of the cardiac progenitors, both before and after transforming growth factor-beta 1 differentiation. Addition of oleic acid following differentiation increased expression of myosin heavy chain 7 and connexin 43. Also, total glycolytic metabolism increased, as did mitochondrial membrane potential and glucose and fatty acid transporter expression.This work provides new insights into the importance of fatty acids, and of peroxisome proliferator-activated receptor alpha, in cardiac progenitor differentiation. Harnessing the oxidative metabolic switch induced maturation of differentiated endogenous stem cells.(200 words)

BNIP3L/NIX and FUNDC1-mediated mitophagy is required for mitochondrial network remodeling during cardiac progenitor cell differentiation

ABSTRACTCell-based therapies represent a very promising strategy to repair and regenerate the injured heart to prevent progression to heart failure. To date, these therapies have had limited success due to a lack of survival and retention of the infused cells. Therefore, it is important to increase our understanding of the biology of these cells and utilize this information to enhance their survival and function in the injured heart. Mitochondria are critical for progenitor cell function and survival. Here, we demonstrate the importance of mitochondrial autophagy, or mitophagy, in the differentiation process in adult cardiac progenitor cells (CPCs). We found that mitophagy was rapidly induced upon initiation of differentiation in CPCs. We also found that mitophagy was mediated by mitophagy receptors, rather than the PINK1-PRKN/PARKIN pathway. Mitophagy mediated by BNIP3L/NIX and FUNDC1 was not involved in regulating progenitor cell fate determination, mitochondrial biogenesis, or reprogramming. Instead, mitophagy facilitated the CPCs to undergo proper mitochondrial network reorganization during differentiation. Abrogating BNIP3L- and FUNDC1-mediated mitophagy during differentiation led to sustained mitochondrial fission and formation of donut-shaped impaired mitochondria. It also resulted in increased susceptibility to cell death and failure to survive the infarcted heart. Finally, aging is associated with accumulation of mitochondrial DNA (mtDNA) damage in cells and we found that acquiring mtDNA mutations selectively disrupted the differentiation-activated mitophagy program in CPCs. These findings demonstrate the importance of BNIP3L- and FUNDC1-mediated mitophagy as a critical regulator of mitochondrial network formation during differentiation, as well as the consequences of accumulating mtDNA mutations.Abbreviations: Baf: bafilomycin A1; BCL2L13: BCL2 like 13; BNIP3: BCL2 interacting protein 3; BNIP3L: BCL2 interacting protein 3 like; CPCs: cardiac progenitor cells; DM: differentiation media; DNM1L: dynamin 1 like; EPCs: endothelial progenitor cells; FCCP: carbonyl cyanide-4-(trifluoromethoxy)phenylhydrazone; FUNDC1: FUN14 domain containing 1; HSCs: hematopoietic stem cells; MAP1LC3B/LC3: microtubule-associated protein 1 light chain 3 beta; MFN1/2: mitofusin 1/2; MSCs: mesenchymal stem cells; mtDNA: mitochondrial DNA; OXPHOS: oxidative phosphorylation; PPARGC1A: PPARG coactivator 1 alpha; PHB2: prohibitin 2; POLG: DNA polymerase gamma, catalytic subunit; SQSTM1: sequestosome 1; TEM: transmission electron microscopy; TMRM: tetramethylrhodamine methyl ester

Regenerating the field of cardiovascular cell therapy.

The retraction of >30 falsified studies by Anversa et al. has had a disheartening impact on the cardiac cell therapeutics field. The premise of heart muscle regeneration by the transdifferentiation of bone marrow cells or putative adult resident cardiac progenitors has been largely disproven. Over the past 18 years, a generation of physicians and scientists has lost years chasing these studies, and patients have been placed at risk with little scientific grounding. Funding agencies invested hundreds of millions of dollars in irreproducible work, and both academic institutions and the scientific community ignored troubling signals over a decade of questionable work. Our collective retrospective analysis identifies preventable problems at the level of the editorial and peer-review process, funding agencies and academic institutions. This Perspective provides a chronology of the forces that led to this scientific debacle, integrating direct knowledge of the process. We suggest a science-driven path forward that includes multiple novel approaches to the problem of heart muscle regeneration.

In situ transcriptome characteristics are lost following culture adaptation of adult cardiac stem cells

Regenerative therapeutic approaches for myocardial diseases often involve delivery of stem cells expanded ex vivo. Prior studies indicate that cell culture conditions affect functional and phenotypic characteristics, but relationship(s) of cultured cells derived from freshly isolated populations and the heterogeneity of the cultured population remain poorly defined. Functional and phenotypic characteristics of ex vivo expanded cells will determine outcomes of interventional treatment for disease, necessitating characterization of the impact that ex vivo expansion has upon isolated stem cell populations. Single-cell RNA-Seq profiling (scRNA-Seq) was performed to determine consequences of culture expansion upon adult cardiac progenitor cells (CPCs) as well as relationships with other cell populations. Bioinformatic analyses demonstrate that identity marker genes expressed in freshly isolated cells become undetectable in cultured CPCs while low level expression emerges for thousands of other genes. Transcriptional profile of CPCs exhibited greater degree of similarity throughout the cultured population relative to freshly isolated cells. Findings were validated by comparative analyses using scRNA-Seq datasets of various cell types generated by multiple scRNA-Seq technology. Increased transcriptome diversity and decreased population heterogeneity in the cultured cell population may help account for reported outcomes associated with experimental and clinical use of CPCs for treatment of myocardial injury.

MicroRNA-210-3P improves the survival potential of adult mouse cardiac progenitor cells

MicroRNA-210-3P improves the survival potential of adult mouse cardiac progenitor cells

Mitophagy is Required for Proper Mitochondrial Network Remodeling during Cardiac Progenitor Cell Differentiation

Cell based therapies represent a very promising strategy to repair and regenerate the injured heart to prevent progression to heart failure. To date, cell based therapies have had limited success due to a lack of survival and retention of the infused cells. Therefore, it is important to increase our understanding of the biology of these cells and utilize this information to enhance their survival and function in the unfavorable environment of the injured heart. Mitochondria are critical for progenitor cell function and survival. Here we demonstrate the importance of mitochondrial autophagy, or mitophagy, in the differentiation process in adult cardiac progenitor cells (CPCs). We found that mitophagy is rapidly induced upon initiation of differentiation in CPCs. We also found that mitophagy was mediated by the mitophagy receptors pathway, rather than the PINK1/Parkin pathway. Mitophagy receptors Nix and Fundc1, but not Bnip3, were upregulated during differentiation. Mitophagy mediated by Nix and Fundc1 was not involved in regulating progenitor cell fate determination, mitochondrial biogenesis, or reprogramming. Instead, mitophagy facilitated the CPCs to undergo proper mitochondrial network reorganization during differentiation. Abrogating Nix/Fundc1‐mediated mitophagy during differentiation led to mitochondrial fragmentation and failure to form an interconnected mitochondrial network. It also led to increased susceptibility to hydrogen peroxide mediated cell death during differentiation. Finally, aging is associated with accumulation of mtDNA mutations in cells and we found that acquiring mtDNA mutations selectively disrupted the differentiation‐activated mitophagy program in CPCs. These findings demonstrate the importance of Nix/Fundc1‐mediated mitophagy as a critical regulator of mitochondrial network formation in differentiating progenitor cells, as well as the consequences of accumulating mtDNA mutations.Support or Funding InformationA.B. Gustafsson is supported by an AHA Established Investigator Award, and by NIH R21AG052280, R01HL087023, R01HL132300 and P01HL085577. M.A. Lampert is supported by the UCSD Graduate Training Program in Cellular and Molecular Pharmacology grant T32GM007752. A.M. Orogo is supported in part by the UCSD Graduate Training Program in Cellular and Molecular Pharmacology through an institutional training grant from the National Institute of General Medical Sciences T32GM007752, and National Institutes of Health NRSA Predoctoral Fellowship F31HL123309.This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Redox-dependent BMI1 activity drives in vivo adult cardiac progenitor cell differentiation.

Accumulation of reactive oxygen species (ROS) is associated with several cardiovascular pathologies and with cell cycle exit by neonanatal cardiomyocytes, a key limiting factor in the regenerative capacity of the adult mammalian heart. The polycomb complex component BMI1 is linked to adult progenitors and is an important partner in DNA repair and redox regulation. We found that high BMI1 expression is associated with an adult Sca1+ cardiac progenitor sub-population with low ROS levels. In homeostasis, BMI1 repressed cell fate genes, including a cardiogenic differentiation program. Oxidative damage nonetheless modified BMI1 activity in vivo by derepressing canonical target genes in favor of their antioxidant and anticlastogenic functions. This redox-mediated mechanism is not restricted to damage situations, however, and we report ROS-associated differentiation of cardiac progenitors in steady state. These findings demonstrate how redox status influences the cardiac progenitor response, and identify redox-mediated BMI1 regulation with implications in maintenance of cellular identity in vivo.

Polo-Like Kinase 2 is Dynamically Regulated to Coordinate Proliferation and Early Lineage Specification Downstream of Yes-Associated Protein 1 in Cardiac Progenitor Cells.

BackgroundRecent studies suggest that adult cardiac progenitor cells (CPCs) can produce new cardiac cells. Such cell formation requires an intricate coordination of progenitor cell proliferation and commitment, but the molecular cues responsible for this regulation in CPCs are ill defined.Methods and ResultsExtracellular matrix components are important instructors of cell fate. Using laminin and fibronectin, we induced two slightly distinct CPC phenotypes differing in proliferation rate and commitment status and analyzed the early transcriptomic response to CPC adhesion (<2 hours). Ninety‐four genes were differentially regulated on laminin versus fibronectin, consisting of mostly downregulated genes that were enriched for Yes‐associated protein (YAP) conserved signature and TEA domain family member 1 (TEAD1)‐related genes. This early gene regulation was preceded by the rapid cytosolic sequestration and degradation of YAP on laminin. Among the most strongly regulated genes was polo‐like kinase 2 (Plk2). Plk2 expression depended on YAP stability and was enhanced in CPCs transfected with a nuclear‐targeted mutant YAP. Phenotypically, the early downregulation of Plk2 on laminin was succeeded by lower cell proliferation, enhanced lineage gene expression (24 hours), and facilitated differentiation (3 weeks) compared with fibronectin. Finally, overexpression of Plk2 enhanced CPC proliferation and knockdown of Plk2 induced the expression of lineage genes.ConclusionsPlk2 acts as coordinator of cell proliferation and early lineage commitment in CPCs. The rapid downregulation of Plk2 on YAP inactivation marks a switch towards enhanced commitment and facilitated differentiation. These findings link early gene regulation to cell fate and provide novel insights into how CPC proliferation and differentiation are orchestrated.

Dnmt3a-mediated inhibition of Wnt in cardiac progenitor cells improves differentiation and remote remodeling after infarction.

Adult cardiac progenitor cells (CPCs) display a low capacity to differentiate into cardiomyocytes in injured hearts, strongly limiting the regenerative capacity of the mammalian myocardium. To identify new mechanisms regulating CPC differentiation, we used primary and clonally expanded Sca-1+ CPCs from murine adult hearts in homotypic culture or coculture with cardiomyocytes. Expression kinetics analysis during homotypic culture differentiation showed downregulation of Wnt target genes concomitant with increased expression of the Wnt antagonist, Wnt inhibitory factor 1 (Wif1), which is necessary to stimulate CPC differentiation. We show that the expression of the Wif1 gene is repressed by DNA methylation and regulated by the de novo DNA methyltransferase Dnmt3a. In addition, miR-29a is upregulated early during CPC differentiation and downregulates Dnmt3a expression, thereby decreasing Wif1 gene methylation and increasing the efficiency of differentiation of Sca-1+ CPCs in vitro. Extending these findings in vivo, transient silencing of Dnmt3a in CPCs subsequently injected in the border zone of infarcted mouse hearts improved CPC differentiation in situ and remote cardiac remodeling. In conclusion, miR-29a and Dnmt3a epigenetically regulate CPC differentiation through Wnt inhibition. Remote effects on cardiac remodeling support paracrine signaling beyond the local injection site, with potential therapeutic interest for cardiac repair.

Sex Differences of Human Cardiac Progenitor Cells in the Biological Response to TNF-α Treatment.

Adult cardiac progenitor cells (CPCs), isolated as cardiosphere-derived cells (CDCs), represent promising candidates for cardiac regenerative therapy. CDCs can be expanded in vitro manyfolds without losing their differentiation potential, reaching numbers that are appropriate for clinical applications. Since mechanisms of successful CDC survival and engraftment in the damaged myocardium are still critical and unresolved issues, we aimed at deciphering possible key factors capable of bolstering CDC function. In particular, the response and the phenotype of CDCs exposed to low concentrations of the multifunctional cytokine tumor necrosis factor α (TNF-α), known to be capable of activating cell survival pathways, have been investigated. Furthermore, differential biological responses of CDCs from male and female donors, in terms of cell cycle progression and cell spreading, have also been assessed. The results obtained indicate that (i) the intracellular signaling activated in our experimental conditions is most likely due to the prosurvival and proliferative signaling of TNF-α receptor 2 and that (ii) cells from female patients appear more responsive to TNF-α treatment in terms of cell cycle progression and migration ability. In conclusion, the present report highlights the hypothesis that TNF-stimulated CDCs isolated from females may represent a promising candidate for cardiac regenerative therapy applications.

ANGPTL8 reverses established adriamycin cardiomyopathy by stimulating adult cardiac progenitor cells.

Established adriamycin cardiomyopathy is a lethal disease. When congestive heart failure develops, mortality is approximately 50% in a year. It has been known that ANGPTLs has various functions in lipid metabolism, inflammation, cancer cell invasion, hematopoietic stem activity and diabetes. We hypothesized that ANGPTL8 is capable of maintaining heart function by stimulating adult cardiac progenitor cells to initiate myocardial regeneration. We employed UTMD to deliver piggybac transposon plasmids with the human ANGPTL8 gene to the liver of rats with adriamycin cardiomyopathy. After ANGPTL8 gene liver delivery, overexpression of transgenic human ANGPTL8 was found in rat liver cells and blood. UTMD- ANGPTL8 gene therapy restored LV mass, fractional shortening index, and LV posterior wall diameter to nearly normal. Our results also showed that ANGPTL8 reversed established ADM cardiomyopathy. This was associated with activation of ISL-1 positive cardiac progenitor cells in the epicardium. A time-course experiment shown that ISL-1 cardiac progenitor cells proliferated and formed a niche in the epicardial layer and then migrated into sub-epicardium. The observed myocardial regeneration accompanying reversal of adriamycin cardiomyopathy was associated with upregulation of PirB expression on the cell membrane of cardiac muscle cells or progenitor cells stimulated by ANGPTL8.

178. Effect of Heme Oxygenase-1 Overexpression on DNA Synthesis of Adult Cardiac Progenitor Cells Under Hypoxia

Although the studies in animals and humans have shown that the beneficial effects of adult c-kit+ cardiac progenitor cells (CPCs) on left ventricle function and remodeling post-myocardial infarction persist for several weeks and up to 1 year after CPC administration, the vast majority (>95%) of transplanted CPCs in animal studies die or vanish shortly after cell administration. Additionally, the less blood flow in the scar tissue after heart attack results in the oxygen reduced to 1 - 2% (hypoxia) which makes the cardiac microenvironment inadequate for cell DNA synthesis, thereby implying that gene manipulations on the transplanted CPCs that limit cell death under hypoxia may enhance the efficacy (and thus clinical applicability) of cell therapy. One of the most powerful cytoprotective proteins known is heme oxygenase-1 (HO-1). To test the hypothesis that HO-1 gene may improve newly synthesized DNA level in CPCs under hypoxia, adult CPCs were isolated and sorted from wild-type (WT), HO-1 transgenic (TG) or knockout (KO) mouse hearts. The c-kit positivity in all live CPCs was 60 - 65% detected by FACS with specific monoclonal anti-c-kit antibody in which Mast cells were used as positive control and CHO cells as negative control. HO-1 protein overexpression in HO-1TG CPCs was confirmed by FACS and immunoblotting (2.8-fold greater than that in WT CPCs); in contrast, HO-1KO CPCs had no HO-1. A hypoxia chamber system containing 1% of O2, 5% of CO2, and 94% of nitrogen was employed to mimic the damaged environment in the cardiac scar tissue. Furthermore, Bromodeoxyuridine (BrdU), an analog of thymidine that can be incorporated into the newly synthesized DNA of replicating cells in S-phase, was used to determine DNA synthesis levels in CPCs. Cells were cultured for 16 h and then labeled with BrdU for 30 min before BrdU immunofluorescent staining. Under normal oxygen tension (21% of O2), HO-1TG CPCs exhibited an significant increase in nuclear BrdU intensity relative to either WT or HO-1KO CPCs (+88% vs WT group, and +63% vs HO-1KO group), indicating that the new DNA synthesis in HO-1TG CPCs are very active during cell mitosis as compared to WT or HO-1KO CPCs. Under hypoxic condition (1% of O2), although new DNA synthesis in S-phase in all of the groups was much less active, HO-1TG CPCs showed even greater differences (+2.4-fold vs WT, +2.0-fold vs HO-1KO) in the extent of BrdU nuclear incorporation as compared with WT or HO-1KO CPC group (FigFig), providing a strong evidence that HO-1 gene plays an important role in protecting CPCs under hypoxia via promotion of new DNA synthesis in BrdU-labeled cell mitosis. These results demonstrate that HO-1 gene promotes new DNA synthesis during mitoses in adult CPCs not only under normal oxygen condition but also in the hypoxia environment, therefore HO-1TG CPCs may provide higher survival rate than WT and HO-1KO CPCs. The data support the hypothesis that HO-1 gene improves the survival and reparative ability of adult CPCs via enhancing newly synthesized DNA in replicating cells in S-phase under hypoxia. Thus, the adult CPCs carried HO-1 gene as a new approach may have potentially clinical application to increase the efficacy of cell therapy for patients with heart attack.View Large Image | Download PowerPoint Slide