Efficacy Of Endothelial Progenitor Cells Research Articles

A Robustly Supported Extracellular Matrix Improves the Intravascular Delivery Efficacy of Endothelial Progenitor Cells

AbstractA major barrier in the multi‐purpose use of implantable materials is an incomplete integration with surrounding tissues, causing foreign body reactions, such as fibrous encapsulation and chronic inflammation. From its viewpoint, a universal method is suggested for cloaking any kind of substrate in specific cell‐made extracellular matrices (ECMs) via robust linkages for delivery of therapeutic cells. In addition, the feasibility of ECM‐coated substrates as endothelial progenitor cells (EPCs)‐laden coronary stent platform for endovascular implantation is investigated. Characteristics and stability of cell‐secreted ECMs anchored on a substrate are evaluated, and structural and componential features are revealed similar to those of native ECMs, with enough strength to enable practical uses. The in vitro experiments demonstrated that the ECM coating effectively supports the adhesion, proliferation, and viability of EPCs and has selectively opposite effects on smooth muscle cells. The in vivo experiments using a porcine coronary model supports that ECM‐coated stents enable endothelial regeneration and inhibit neointimal growth, and the cell‐laden form is more effective than other stents. These results will allow the preparation of tissue‐integrating materials containing cellular microenvironments and safely coat surfaces with cells to enable long‐term implantation and the continuous managing of chronic diseases.

625-P: Metallothionein Improves Angiogenic Function of Endothelial Progenitor Cells via HIF-1α/SDF-1/Akt Pathway in Diabetic Limb Ischemia

Diabetes mellitus associated dysfunction of endothelial progenitor cells (EPCs) may contribute to dysregulation of endothelial regeneration. Metallothionein (MT) acts as an antioxidant in various pathophysiological processes. Whether MT in EPCs has positive angiogenic effects and the mechanisms involved remain unclear. Endothelial MT overexpression (JTMT) mice were made diabetic by high fat diet followed by STZ administration (HFD/STZ). Diabetic hind limb ischemia model was established by femoral artery ligation. Bone marrow derived mononuclear leucocytes (MNCs) collected from JTMT mice were transplanted into db/db mice with hind limb ischemia. Blood reperfusion was monitored and oxidative stress was measured. High glucose and hypoxia conditions in culture were adopted to mimic diabetic ischemia in vitro. MT improved blood perfusion of ischemic hind limb and promoted angiogenesis in HFD/STZ diabetes. Oxidative stress of ischemic muscles was aggravated under diabetic condition, which was reduced in JTMT mice. Compared with WT mice, the expression of HIF-1α, SDF-1, VEGF and p-Akt were all increased in JTMT mice, along with elevation of plasma SDF-1α and VEGF. Moreover, transplantation of MT overexpressed MNCs showed better therapeutic effect on db/db diabetic mice with hind limb ischemia than control or transplantation of normal MNCs. Transplantation was accompanied by elevated HIF-1α, SDF-1 and Akt signaling. Vitro studies demonstrated that MT overexpression reduced high glucose and hypoxia induced EPC dysfunction and preserved high glucose and hypoxia impaired HIF-1α, SDF-1, VEGF and Akt signaling, all of which were abolished by siRNA knockdown of HIF-1α. In conclusion, elevated MT enhances angiogenic function and therapeutic efficacy of EPCs in diabetic limb ischemia. The benefits of MT are predominantly mediated by a HIF-1α/SDF-1/Akt pathway under diabetic ischemia conditions. Disclosure K. Wang: None. X. Dai: None. J. He: None. C. Yang: None. J. Chen: None. K.A. Wintergerst: None. P.N. Epstein: None. L. Cai: None. Y. Tan: None. Funding American Diabetes Association (1-15-BS-018, 1-18-IBS-082 to L.C.); 1-13-JF-53 (to Y.T.)

CXCR7 Agonist TC14012 Improves Angiogenic Function of Endothelial Progenitor Cells in Diabetic Limb Ischemia

Stromal cell-derived factor 1 (SDF-1)-chemokine receptors CXCR4/7 axis plays a vital role in diabetic limb ischemia. Our previous studies demonstrated that elevated CXCR7 improves therapeutic efficacy of endothelial progenitor cells (EPCs) in diabetic limb ischemia. The effects of a specific CXCR7 agonist TC14012 on diabetic hind limb ischemia remains untested. We hypothesize that CXCR7 expression is reduced in diabetic EPCs and TC14012 improve angiogenic function of EPCs in diabetic limb ischemia. Early WT-EPCs were transfected with siRNA against CXCR7, and early db/db-EPCs were infected with CXCR7 lentivirus. Tube formation and capillary density of ischemic gastrocnemius muscle (GS) and soleus muscle (SS) at 4 weeks post-ischemic surgery were adopt for indication of angiogenesis. Diabetic hind limb ischemia (HLI) models were established by femoral artery ligation, followed by administration of TC14012 subcutaneously. Total and cell surface expression of CXCR7 were significantly decreased in EPCs from db/db mice compared with those from WT mice, whereas no significant differences of CXCR4 expression were observed. Tube formation by EPCs from db/db mice was also impaired compared with WT-EPCs. siRNA knockdown of CXCR7 was accompanied by impaired tube formation. Conversely, increasing CXCR7 levels in db/db EPCs completely reversed impaired tube formation function. High glucose (HG) dose dependently decreased the expression of CXCR7 in vitro but not that of CXCR4. HG also impaired tube formation of EPC from WT mice. Tube formation function of HUVEC was impaired after treated with HG (25mM) for 24 hours, which could be prevented by TC14012. Most importantly, TC14012 significantly improved blood flow restoration of ischemic hind limb starting from 2 weeks after ligation and promoted angiogenesis of ischemic GS and SS. Diabetes attenuates CXCR7 expression and impairs angiogenesis of EPCs. TC14012 improves blood reperfusion of diabetic hind limb ischemia. Disclosure K. Wang: None. X. Dai: None. J. Chen: None. P.N. Epstein: None. L. Cai: None. K.A. Wintergerst: None. Y. Qian: None. Y. Tan: None.

Abstract 513: ACE2-EPCs Protect Ecs Majorly Through Their Exosomal Effects on Mitochondria

Angiotensin-converting enzyme 2 (ACE2) is an emerging cardiovascular protective target which mediates the metabolism of angiotensin (Ang) II into Ang (1-7). Our group has demonstrated that ACE2 overexpression enhances the therapeutic efficacy of endothelial progenitor cells (EPCs) for ischemic stroke. Here, we investigated whether ACE2-primed EPCs (ACE2-EPCs) can protect cerebral microvascular endothelial cells (ECs) against injury and dysfunction in an in vitro model, with focusing on their exosomal and cytokine paracrine effects on endothelial mitochondria. Human EPCs were transfected with lentivirus containing null or human ACE2 cDNA (denoted as Null-EPCs, ACE2-EPCs, respectively). Their conditioned culture media, w/wo ultra-centrifugation for depletion of exosomes (ACE2-EPC-CM EX- , Null-EPC-CM EX- , ACE2-EPC-CM and Null-EPC-CM), were used for co-culture experiments. ECs injury and dysfunction model was induced by Ang II (10 -7 M) for 8 hrs before 16 hr co-culture. After that, ECs were collected for analyses of apoptosis, angiogenic ability, mitochondrion functions (ROS production, membrane potential, fragmentation), and gene expressions (ACE2, Nox2 and Nox4). The co-culture medium was collected for measuring the levels of ACE2, Ang II / Ang-(1-7) and growth factors (VEGF and IGF). Our results showed that: 1) ACE2-EPC-CM had higher levels of ACE2, Ang (1-7), VEGF and IGF than that of Null-EPC-CM. 2) Ang II-injured ECs displayed increase of apoptotic rate and reduction in tube formation and migration abilities, which were associated with ACE2 downregulation, Ang II / Ang (1-7) imbalance, Nox2/Nox4 upregulation, ROS overproduction, increase of mitochondrion fragmentation and decrease of membrane potential. 3) ACE2-EPC-CM had better protective effects than Null-EPC-CM on Ang II-injured ECs, which were associated with the improvements on ACE2 expression, Ang II / Ang (1-7) balance and mitochondrial functions. 4) ACE2-EPC-CM EX- and Null-EPC-CM EX- had remarkably reduced effects by over 70% as respectively compared to ACE2-EPCs-CM and Null-EPCs-CM. In conclusion, our data demonstrate that ACE2 overexpression can enhance the protective effects of EPCs on ECs injury, majorly through the exosomal effects on mitochondrial function.

Pinocembrin ex vivo preconditioning improves the therapeutic efficacy of endothelial progenitor cells in monocrotaline-induced pulmonary hypertension in rats

Pulmonary hypertension is still not curable and the available current therapies can only alleviate symptoms without hindering the progression of disease. The present study was directed to investigate the possible modulatory effect of pinocembrin on endothelial progenitor cells transplanted in monocrotaline-induced pulmonary hypertension in rats. Pulmonary hypertension was induced by a single subcutaneous injection of monocrotaline (60mg/kg). Endothelial progenitor cells were in vitro preconditioned with pinocembrin (25mg/L) for 30min before being i.v. injected into rats 2weeks after monocrotaline administration. Four weeks after monocrotaline administration, blood pressure, electrocardiography and right ventricular systolic pressure were recorded. Rats were sacrificed and serum was separated for determination of endothelin-1 and asymmetric dimethylarginine levels. Right ventricles and lungs were isolated for estimation of tumor necrosis factor-alpha and transforming growth factor-beta contents as well as caspase-3 activity. Moreover, protein expression of matrix metalloproteinase-9 and endothelial nitric oxide synthase in addition to myocardial connexin-43 was assessed. Finally, histological analysis of pulmonary arteries, cardiomyocyte cross-sectional area and right ventricular hypertrophy was performed and cryosections were done for estimation of cell homing. Preconditioning with pinocembrin provided a significant improvement in endothelial progenitor cells’ effect towards reducing monocrotaline-induced elevation of inflammatory, fibrogenic and apoptotic markers. Furthermore, preconditioned cells induced a significant amelioration of endothelial markers and cell homing and prevented monocrotaline-induced changes in right ventricular function and histological analysis compared with native cells alone. In conclusion, pinocembrin significantly improves the therapeutic efficacy of endothelial progenitor cells in monocrotaline-induced pulmonary hypertension in rats.

Therapeutic Transplant Efficacy of Endothelial Progenitor Cells is Impaired by NK Cells

Adult stem cells, including endothelial progenitor cells (EPCs), have long been proposed as a source of cells for therapeutic transplantation in cardiovascular (CV) disease. Studies investigating the therapeutic potential of EPCs have shown mixed results, likely due to the negative impact of chronic disease and aging on EPC function in the high CV risk patients enrolled in such studies. Using genetically controlled rats, we have established a model of EPC dysfunction in the setting of hypertension. In the SS/MCWi rat, a genetic model of salt‐sensitive hypertension, EPC function is compromised. Introgression of the 13th chromosome of the Brown Norway rat onto the SS background results in the SS‐13BN/MCWi (BN13) rat, which is protected from both hypertension and EPC dysfunction. Previously, we found increased expression of the natural killer cell receptor/ligand 2B4 (CD244) on the cell membrane of EPCs isolated from SS rats. This increase in CD244 expression was correlated with increased destruction by NK cells from both SS and BN13 rats. Here, we hypothesize that increased membrane expression of CD244 by SS EPCs leads to destruction by NK cells in vivo, which compromises their therapeutic efficacy. We first found that siRNA mediated CD244 knockdown rescued EPCs from NK cell mediated killing in vitro using an LDH release assay. We next used an NK cell depleting antibody to assess whether NK cells were responsible for EPC dysfunction in animals receiving EPCs as therapy. Finally, we transplanted EPCs treated with CD244 siRNA into naïve recipient animals to confirm that CD244 impacts EPC function in vivo. Our results suggest that increased CD244 on the SS EPC membrane leads to increased NK cell mediated killing of SS EPCs in vivo, contributing to the impaired therapeutic efficacy in our model.Support or Funding InformationNational Institutes of Health grant HL082798 awarded to A.S. Greene, PhD; T32 HL007852 PI: H.V. Forster

The use of endothelial progenitor cells combined with barrier membrane for the reconstruction of peri-implant osseous defects: an animal experimental study.

The aim of this research was to study the efficacy of endothelial progenitor cells (EPC) with ß tri-calcium phosphate (β-TCP) and barrier in the treatment of experimental peri-implantitis. Thirty implants were placed in five American foxhounds. Following osseointegration, ligature-induced peri-implantitis was initiated. EPC were isolated from peripheral blood. Two months later, open flap debridement was performed and implants' surface was decontaminated with 24% EDTA. The sites were grafted with β-TCP and collagen membrane (β-TCP group) or β-TCP loaded with EPC and covered with membrane (EPC group) or left un-grafted (OFD group). At 3 months, animals were killed and specimens sent for histomorphometric and micro-CT analysis. Bone height and %BIC served as primary and secondary outcomes. EPC group showed shorter distance to first BIC (3.29 ± 0.69 mm) compared to 4.2 ± 0.92 mm (β-TCP) and 3.82 ± 0.73 mm (OFD). Mean histological BIC was 2-3 folds higher in the EPC group (17.65 ± 3.3%) compared with OFD (7.55 ± 2.24%, p = 0.01) and β-TCP (5.68 ± 2.91%, p = 0.05). BIC greater than 25% was found only in the EPC group. The distance between the implant shoulder to 1st BIC was 2.51 ± 0.7 mm (lingual sites) compared to 3.64 ± 0.8 mm for buccal sites (p < 0.0001). β-TCP loaded with EPC and covered with a membrane-enhanced bone formation around previously contaminated dental implants in an experimental peri-implantitis canine model.

Abstract 13054: Thymosin Beta-4-Treated Endothelial Progenitor Cells Improve Cardiac Function and Vasculogenesis in Diabetic Obese Rats with Myocardial Infarction

Introduction: Diabetes and obesity are associated with endothelial dysfunction and may impair circulating endothelial progenitor cells (EPCs). Thymosin beta-4 (Tβ4), a novel peptide with angiogenic properties, may improve EPC number and function. Hypothesis: We aim to transplant allogenic Tβ4-treated EPCs in Zucker Diabetic Fatty (ZDF) rats with myocardial infarction (MI) and hypothesize that Tβ4-treated EPCs may improve cardiac function, vasculogenesis and upregulate angiogenic cytokines and genes, compared to non-treated EPCs and controls. Methods: The left anterior descending coronary artery was permanently ligated to induce experimental MI on ZDF rats (n=19), divided into MI+saline(n=6); MI+EPCs (n=6) and MI+Tβ4-treated EPCs (n=7). Peripheral blood mononuclear cells were harvested from ZDF rats and isolated using Ficoll density gradient centrifugation and grown on fibronectin-coated plates. EPCs were treated with Tβ4 (1μg/mL) on day 7. At day 10, allogenic EPCs were harvested and transplanted into the peri-infarcted myocardium. Echocardiographic examination including strain assessment, immunohistological assessments and assays of angiogenic cytokines were performed 6 weeks after surgery. Results: Left ventricular (LV) ejection fraction was improved in Tβ4-treated EPCs (72.0±7.6%) and non-treated EPCs rats (80.5±5.9%) compared to control MI rats (64.8±19.7%) (P=0.04). Similar improvement was observed in LV radial strain rate in rats with Tβ4-treated EPCs (-7.22±1.24 1/s) and non-treated EPCs (-6.67±2.66 1/s) compared to MI only (-4.08±3.75 1/s) (P&lt;0.01). Vascular density (CD31) and c-kit density (CD117) were significantly upregulated in Tβ4-treated EPCs rats compared to MI (P=0.03; P=0.005 respectively) and non-treated EPCs rats (P=0.04; P=0.04 respectively). Angiogenic cytokines of PDGF-BB, IGF-1 and VEGF levels were increased by 1.5 fold in Tβ4-treated EPCs and supported by similar trend in mRNA levels compared to non-treated EPCs (P&lt;0.01). Conclusions: ZDF rats with Tβ4-treated EPCs had significant improvement in cardiac function, increased vasculogenesis and upregulation of angiogenic cytokines and genes. This suggests that Tβ4 may be beneficial in enhancing efficacy of EPCs in cell-based therapies.

Glycogen Synthase Kinase-3β Inhibition Augments Diabetic Endothelial Progenitor Cell Abundance and Functionality via Cathepsin B: A Novel Therapeutic Opportunity for Arterial Repair

Progenitor cell therapy is hindered in patients with diabetes mellitus (DM) due to cellular senescence. Glycogen synthase kinase-3β (GSK3β) activity is increased in DM, potentially exacerbating impaired cell-based therapies. Thus, we aimed to determine if and how GSK3β inhibitors (GSKi) can improve therapeutic efficacy of endothelial progenitor cells (EPC) from patients with DM. Patients with DM had fewer EPCs and increased rates of apoptosis. DM EPCs also exhibited higher levels of GSK3β activity resulting in increased levels of phosphorylated β-catenin. Proteomic profiling of DM EPCs treated with GSKi identified 37 nonredundant, differentially regulated proteins. Cathepsin B (cathB) was subsequently confirmed to be differentially regulated and showed 40% less baseline activity in DM EPCs, an effect reversed by GSKi treatment. Finally, in vivo efficacy of cell-based therapy was assessed in a xenotransplant femoral wire injury mouse model. Administration of DM EPCs reduced the intima-to-media ratio, an effect that was further augmented when DM EPCs were pretreated with GSKi yet absent when cathB was antagonized. In DM, increased basal GSK3β activity contributes to accelerated EPC cellular senescence, an effect reversed by small molecule antagonism of GSK3β, which enhanced cell-based therapy after vascular injury.

Abstract 48: Targeting the Endothelial Progenitor Cell Surface Proteome to Identify Novel Mechanisms that Mediate Angiogenic Efficacy and Restore Angiogenesis in a Rodent Model of Vascular Disease

Bone-marrow derived endothelial progenitor cells (EPCs) promote angiogenesis, and clinical trials suggest autologous EPC-based therapy may be effective in treatment of vascular diseases. Albeit promising, variability in the efficacy of EPCs associated with underlying disease states has hindered the realization of EPC-based therapy. Here we identify and characterize EPC dysfunction in a rodent model of vascular disease (SS/Mcwi rat) that exhibits impaired angiogenesis under physiological conditions, and develops cardiovascular disease on a high salt diet. First, we compared the angiogenic responses to EPCs delivered into the skeletal muscle of SS/Mcwi recipient prior to electrical stimulation. Delivery of EPCs from SS/Mcwi donors had no effect on angiogenesis compared to stimulation alone (9.2± 2.2% vs. 7.6 ± 1.7%, respectively). In contrast, introgression of chromosome 13 from a Brown Norway rat onto the SS/Mcwi background (SS-13 BN /Mcwi rat) significantly enhanced the angiogenic function of EPCs (22.3 ± 3.7%) and suggests involvement of genes on chromosome 13. To identify molecular candidates that mediate the angiogenic potential of these cells, we performed a cell surface proteomic analysis. Analysis revealed that EPCs derived from SS/Mcwi rats express significantly more type 2 low-affinity immunoglobulin Fc-gamma (FCGR2, 25% increase) and Natural Killer 2B4 (CD244, 67% increase) receptors than EPCs from the SS-13 BN /Mcwi rat. Genome-wide mRNA sequencing (RNAseq) revealed differential expression of multiple isoforms encoding FCGR2a and CD244 proteins, and qt-PCR confirmed an increase in CD244 and FCGR2a transcripts in SS/Mcwi EPCs. Increased expression of FCGR2a and CD244 receptors are predicted to increase the probability of SS/Mcwi EPCs being targeted for death, providing a mechanistic explanation for their reduced angiogenic efficacy in vivo . Pathway analysis supported this contention, as ‘key’ molecules annotated to cell death paths were differentially expressed in the SS/Mcwi EPC transcriptome. We speculate that screening and neutralization of cell surface proteins that tag ‘diseased’ EPCs for death will enhance regenerative potential of EPC-based therapies, providing a major advance in the field of regenerative medicine.

Cell Therapy for Pulmonary Arterial Hypertension: Potential Efficacy of Endothelial Progenitor Cells and Mesenchymal Stem Cells

Pulmonary arterial hypertension (PAH) presents a challenging problem for health care providers, as effective long-term therapies have been elusive. An emerging paradigm for the pathogenesis of PAH is that endothelial cell injury and apoptosis at the level of the precapillary arteriole could be the initiating event in the pathogenesis of this disease. This hypothesis has spurred research on novel regenerative approaches using stem and progenitor cells. In this review, we compare findings from the latest preclinical and clinical studies using endothelial progenitor cell (EPC) and mesenchymal stem cell (MSC) therapy to treat PAH. Additionally, we highlight recent advances in gene-enhanced cell therapy, an approach that promises to augment the therapeutic potential of EPCs and MSCs especially for the reversal of established PAH. These new regenerative approaches have shown great promise in preclinical studies; however, large, rigorously designed clinical studies will be necessary to establish clinical efficacy.

Transfection of Endothelial Nitric Oxide Synthase Gene Improves Angiogenic Efficacy of Endothelial Progenitor Cells in Rabbits with Hindlimb Ischemia

Background: The present study explored the effect of endothelial nitric oxide synthase (eNOS) gene transfer on the angiogenic potential of ex vivo expanded endothelial progenitor cells (EPCs) in a rabbit model of hindlimb ischemia. Methods: Rabbit peripheral blood EPCs were cultured and transfected with mammalian expression vector pcDNA3.1-eNOS containing full-length human eNOS gene. Ischemia was induced in the right hind limb of three groups of rabbits by ligation of the distal external iliac artery and excision of the common and superficial femoral arteries. In one group of animals, ten days after the surgery, autologous eNOS-EPCs were transplanted intramuscularly in the ischemic limb. Two other groups received an equivalent number of unmodified EPCs or phosphate buffered saline (PBS) respectively. Results: Two weeks after cell transplantation, the in vivo expression of eNOS was detected in limb tissue sections of eNOS-EPCs treated animals. Animals treated with eNOS-EPCs had a significant reduction in ischemic muscle necrosis and inflammation, augmentation in the capillary density (P< 0.05) and angiographic scores demonstrating distal arterial reconstitution and enhanced angiogenesis in comparison to animals transplanted with EPCs or PBS (P< 0.05). Conclusion: We conclude that modification of EPCs by eNOS constitutes an effective strategy to improve the efficacy of EPCs for therapeutic angiogenesis.

Material-based deployment enhances efficacy of endothelial progenitor cells

Cell-based therapies are attractive for revascularizing and regenerating tissues and organs, but clinical trials of endothelial progenitor cell transplantation have not resulted in consistent benefit. We propose a different approach in which a material delivery system is used to create a depot of vascular progenitor cells in vivo that exit over time to repopulate the damaged tissue and participate in regeneration of a vascular network. Microenvironmental conditions sufficient to maintain the viability and outward migration of outgrowth endothelial cells (OECs) have been delineated, and a material incorporating these signals improved engraftment of transplanted cells in ischemic murine hindlimb musculature, and increased blood vessel densities from 260 to 670 vessels per mm(2), compared with direct cell injection. Further, material deployment dramatically improved the efficacy of these cells in salvaging ischemic murine limbs, whereas bolus OEC delivery was ineffective in preventing toe necrosis and foot loss. Finally, material deployment of a combination of OECs with another cell population commonly isolated from peripheral or cord blood, endothelial progenitor cells (EPCs) returned perfusion to normal levels in 40 days, and prevented toe and foot necrosis. Direct injection of an EPC/OEC combination was minimally effective in improving limb perfusion, and untreated limbs underwent autoamputation in 3 days. These results demonstrate that vascular progenitor cell utility is highly dependent on the mode of delivery, and suggest that one can create new vascular beds for a variety of applications with this material-controlled deployment of cells.

Additive effects of endothelial progenitor cells combined with ACE inhibition and β-blockade on left ventricular function following acute myocardial infarction

Animal studies have demonstrated the efficacy of endothelial progenitor cells (EPCs) in preventing left ventricular (LV) remodelling following myocardial infarction (MI). Preliminary human studies are underway, yet no studies have demonstrated efficacy in combination with standard medical therapy, i.e. angiotensin-converting enzyme (ACE) inhibitors and beta-blockers. Nude rats underwent left anterior descending coronary artery ligation to induce MI. Animals were randomised to receive no treatment (MI, n = 5), quinapril 200 mg/L + metoprolol 2 g/L (ACE/BB, n = 5), two million EPCs intravenously (EPC, n = 5)or both (ACE/BB + EPC [n = 5]), then sacrificed after two weeks treatment. ACE/BB resulted in a 75% reduction in fibrosis in the region remote from the MI (p < 0.05), but EPC therapy had little effect here. Conversely, EPC therapy induced neovascularisation at the peri-infarct rim, thereby preventing peri-infarct apoptosis by 81% (p < 0.05). Acting via different but complementary mechanisms, the combination of ACE/BB + EPCs resulted in a greater overall improvement in LV function on echocardiography than either therapy alone. Clinical trials using stem cell therapy in conjunction with standard medical treatment are warranted.