Human bone marrow-derived mesenchymal stem cells secrete brain-derived neurotrophic factor which promotes neuronal survival in vitro

Bone marrow-derived mesenchymal stem cells (MSCs) are of therapeutic interest in a variety of neurological diseases. In this study, we wished to determine whether human MSCs secrete factors which protect cultured rodent cortical neurons from death by trophic factor withdrawal or nitric oxide (NO) exposure. Medium conditioned by MSCs attenuated neuronal death under these conditions, a process which was dependent on intact PI₃kinase/Akt pathway signaling. Trophic withdrawal and NO exposure in cultured cortical neurons led to reduction in Akt signaling pathways, whereas NO administration activated p38 MAPkinase in neuronal cultures. Addition of MSC-conditioned medium significantly activated the PI3kinase/Akt pathway and in neurons exposed to NO, MSC-conditioned medium reduced p38 signaling. We show that MSCs secrete brain-derived neurotrophic factor (BDNF) and addition of anti-BDNF neutralising antibodies to MSC-conditioned medium attenuated its neuroprotective effect. Exposure of neurons to BDNF increased activation of Akt pathways and protected neurons from trophic factor withdrawal. These observations determine the mechanisms of neuroprotection offered by MSC-derived factors and suggest an important role for BDNF in neuronal protection.     

Reduction of myocardial infarct size by human mesenchymal stem cell conditioned medium

Although paracrine effects of mesenchymal stem cells (MSCs) have been suggested previously, cardioprotection by human MSC secretions has never been demonstrated. Human MSC-conditioned medium (CM) was collected by following a clinically compliant protocol. In a porcine model of ischemia and reperfusion injury, intravenous and intracoronary MSC-CM treatment significantly reduced myocardial nuclear oxidative stress as determined by immunostaining for 8-hydroxy-2′-deoxyguanosine. In addition, expression levels of phospho-SMAD2 and active caspase 3 were diminished following CM treatment, suggesting that TGF-β signaling and apoptosis were reduced. This was associated with a 60% reduction in infarct size and marked improvement of systolic and diastolic cardiac performance as assessed with echocardiography and pressure volume loops. Fractionation studies revealed that only the fraction of the CM containing products > 1000 kDa (100–220 nm) provided cardioprotection in a mouse model of ischemia and reperfusion injury. This indicates that the responsible paracrine factor of human MSCs is likely a large complex rather than a single small molecule. These data identify human MSC-CM as a promising therapeutic option to reduce myocardial infarct size in patients with acute MI and suggest that the use of stem cell secretions could extend the applicability of stem cells for therapeutic purposes.     

Ischemic cardiac tissue conditioned media induced differentiation of human mesenchymal stem cells into early stage cardiomyocytes

Mesenchymal stem cells (MSCs) are multipotent, can be easily expanded in culture and hence are an attractive therapeutic tool for cardiac repair. MSCs have tremendous potential to transdifferentiate to cardiac lineage both in vitro and in vivo. The present study examined the differentiation capacity of conditioned media derived from ischemic cardiac tissue on human MSCs. Human Bone marrow-derived MSCs after due characterization by immunocytochemistry and flow cytometry for MSC specific markers were induced by culture media derived from ischemic (n = 13) and non-ischemic (n = 18) human cardiac tissue. Parallel cultures were treated with 5-azacytidine (5-azaC), a potent cardiomyogen. MSCs induced with ischemic conditioned media formed myotube like structures, expressed sarcomeric Troponin I, alpha myosin heavy chain proteins and were positive for cardiac specific markers (Nkx2.5, human atrial natriuretic peptide, myosin light chain-2a, GATA-4) as was observed in 5-azaC treated cells. However, uninduced MSCs as well as those induced with non-ischemic cardiac conditioned media still maintained the fibroblast morphology even after 3 weeks post-induction. Transmission electron microscopic studies of cardiomyocyte-like cells derived from MSCs revealed presence of sarcomeric bands but failed to show gap junctions and intercalated discs as of adult cardiomyocytes. These findings demonstrate that ischemic cardiac conditioned media induces morphological and molecular changes in MSCs with cardiac features, but at a primitive stage. Proteomics analysis of the ischemic conditioned media revealed differential expression of three relevant proteins (C-type lectin superfamily member 13, Testis-specific chromodomain protein Y2 and ADP/ATP translocase 1), whose exact role in cardiac regeneration needs further analysis.     

Mesenchymal stem cell therapy: A promising cell‐based therapy for treatment of myocardial infarction

For decades, mesenchymal stem (MSCs) cells have been used for cardiovascular diseases as regenerative therapy. This review is an attempt to summarize the types of MSCs involved in myocardial infarction (MI) therapy, as well as its possible mechanisms effects, especially the paracrine one in MI focusing on the studies (human and animal) conducted within the last 10 years. Recently, reports showed that MSC therapy could have infarct‐limiting effects after MI in both experimental and clinical trials. In this context, various types of MSCs can help cardiac regeneration by either revitalizing the cardiac stem cells or revascularizing the arteries and veins of the heart. Furthermore, MSCs could produce paracrine growth factors that increase the survival of nearby cardiomyocytes, as well as increase angiogenesis through recruitment of stem cell from bone marrow or inducing vessel growth from existing capillaries. Recent research suggests that the paracrine effects of MSCs could be mediated by extracellular vesicles including exosomes. Exosomal microRNAs (miRNAs) released by MSCs are promising therapeutic hotspot target for MI. This could be attributed to the role of miRNA in cardiac biology, including cardiac regeneration, stem cell differentiation, apoptosis, neovascularization, cardiac contractility and cardiac remodeling. Furthermore, gene‐modified MSCs could be a recent promising therapy for MI to enhance the paracrine effects of MSCs, including better homing and effective cell targeted tissue regeneration. Although MSC therapy has achieved considerable attention and progress, there are critical challenges that remains to be overcome to achieve the most effective successful cell‐based therapy in MI.     

The mesenchymal stem cell secretome: A new paradigm towards cell-free therapeutic mode in regenerative medicine

Mesenchymal Stem Cells (MSCs) have been shown to be a promising candidate for cell-based therapy. The therapeutic potential of MSCs, towards tissue repair and wound healing is essentially based on their paracrine effects. Numerous pre-clinical and clinical studies of MSCs have yielded encouraging results. Further, these cells have been shown to be relatively safe for clinical applications. MSCs harvested from numerous anatomical locations including the bone marrow, adipose tissue, Wharton’s jelly of the umbilical cord etc., display similar immunophenotypic profiles. However, there is a large body of evidence showing that MSCs secrete a variety of biologically active molecules such as growth factors, chemokines, and cytokines. Despite the similarity in their immunophenotype, the secretome of MSCs appears to vary significantly, depending on the age of the host and niches where the cells reside. Thus, by implication, proteomics-based profiling suggests that the therapeutic potential of the different MSC populations must also be different. Analysis of the secretome points to its influence on varied biological processes such as angiogenesis, neurogenesis, tissue repair, immunomodulation, wound healing, anti-fibrotic and anti-tumour for tissue maintenance and regeneration. Though MSC based therapy has been shown to be relatively safe, from a clinical standpoint, the use of cell-free infusions can altogether circumvent the administration of viable cells for therapy. Understanding the secretome of in vitro cultured MSC populations, by the analysis of the corresponding conditioned medium, will enable us to evaluate its utility as a new therapeutic option. This review will focus on the accumulating evidence that points to the therapeutic potential of the conditioned medium, both from pre-clinical and clinical studies. Finally, this review will emphasize the importance of profiling the conditioned medium for assessing its potential for cell-free therapy therapy.     

Adenoviral expression of vascular endothelial growth factor splice variants differentially regulate bone marrow-derived mesenchymal stem cells

Bone marrow-derived mesenchymal stem cells (MSCs) are being explored for clinical applications, and genetic engineering represents a useful strategy for boosting the therapeutic potency of MSCs. Vascular endothelial growth factor (VEGF)-based gene therapy protocols have been used to treat tissue ischemia, and a combined VEGF/MSC therapeutics is appealing due to their synergistic paracrine actions. However, multiple VEGF splice variants exhibit differences in their mitogenicity, chemotactic efficacy, receptor interaction, and tissue distribution, and the differential regulatory effects of multiple VEGF isoforms on the function of MSCs have not been characterized. We expressed three rat VEGF-A splice variants VEGF120, 164, and 188 in MSCs using adenoviral vectors, and analyzed their effects on MSC proliferation, differentiation, survival, and trophic factor production. The three VEGF splice variants exert common and differential effects on MSCs. All three expressed VEGFs are potent in promoting MSC proliferation. VEGF120 and 188 are more effective in amplifying expression of multiple growth factor and cytokine genes. VEGF164 on the other hand is more potent in promoting expression of genes associated with MSC remodeling and endothelial differentiation. The longer isoform VEGF188, which is preferentially retained by proteoglycans, facilitates bone morphogenetic protein-7 (BMP7)-mediated MSC osteogenesis. Under serum starvation condition, virally expressed VEGF188 preferentially enhances serum withdrawal-mediated cell death involving nitric oxide production. This work indicates that seeking the best possible match of an optimal VEGF isoform to a given disease setting can generate maximum therapeutic benefits and minimize unwanted side effects in combined stem cell and gene therapy.     

Bone marrow mesenchymal stem cells for post-myocardial infarction cardiac repair: microRNAs as novel regulators

Transplantation of bone marrow-derived mesenchymal stem cells (MSCs) is safe and may improve cardiac function and structural remodelling in patients following myocardial infarction (MI). Cardiovascular cell differentiation and paracrine effects to promote endogenous cardiac regeneration, neovascularization, anti-inflammation, anti-apoptosis, anti-remodelling and cardiac contractility, may contribute to MSC-based cardiac repair following MI. However, current evidence indicates that the efficacy of MSC transplantation was unsatisfactory, due to the poor viability and massive death of the engrafted MSCs in the infarcted myocardium. MicroRNAs are short endogenous, conserved, non-coding RNAs and important regulators involved in numerous facets of cardiac pathophysiologic processes. There is an obvious involvement of microRNAs in almost every facet of putative repair mechanisms of MSC-based therapy in MI, such as stem cell differentiation, neovascularization, apoptosis, cardiac remodelling, cardiac contractility and arrhythmias, and others. It is proposed that therapeutic modulation of individual cardiovascular microRNA of MSCs, either mimicking or antagonizing microRNA actions, will hopefully enhance MSC therapeutic efficacy. In addition, MSCs may be manipulated to enhance functional microRNA expression or to inhibit aberrant microRNA levels in a paracrine manner. We hypothesize that microRNAs may be used as novel regulators in MSC-based therapy in MI and MSC transplantation by microRNA regulation may represent promising therapeutic strategy for MI patients in the future.     

Mesenchymal Stromal Cell Secreted Sphingosine 1-Phosphate (S1P) Exerts a Stimulatory Effect on Skeletal Myoblast Proliferation

Bone-marrow-derived mesenchymal stromal cells (MSCs) have the potential to significantly contribute to skeletal muscle healing through the secretion of paracrine factors that support proliferation and enhance participation of the endogenous muscle stem cells in the process of repair/regeneration. However, MSC-derived trophic molecules have been poorly characterized. The aim of this study was to investigate paracrine signaling effects of MSCs on skeletal myoblasts. It was found, using a biochemical and morphological approach that sphingosine 1-phosphate (S1P), a natural bioactive lipid exerting a broad range of muscle cell responses, is secreted by MSCs and represents an important factor by which these cells exert their stimulatory effects on C2C12 myoblast and satellite cell proliferation. Indeed, exposure to conditioned medium obtained from MSCs cultured in the presence of the selective sphingosine kinase inhibitor (iSK), blocked increased cell proliferation caused by the conditioned medium from untreated MSCs, and the addition of exogenous S1P in the conditioned medium from MSCs pre-treated with iSK further increased myoblast proliferation. Finally, we also demonstrated that the myoblast response to MSC-secreted vascular endothelial growth factor (VEGF) involves the release of S1P from C2C12 cells. Our data may have important implications in the optimization of cell-based strategies to promote skeletal muscle regeneration.     

Bone marrow-derived mesenchymal stem cells inhibit vascular smooth muscle cell proliferation and neointimal hyperplasia after arterial injury in rats

We investigated whether mesenchymal stem cell (MSC)-based treatment could inhibit neointimal hyperplasia in a rat model of carotid arterial injury and explored potential mechanisms underlying the positive effects of MSC therapy on vascular remodeling/repair. Sprague-Dawley rats underwent balloon injury to their right carotid arteries. After 2 days, we administered cultured MSCs from bone marrow of GFP-transgenic rats (0.8 × 10⁶ cells, n = 10) or vehicle (controls, n = 10) to adventitial sites of the injured arteries. As an additional control, some rats received a higher dose of MSCs by systemic infusion (3 × 10⁶ cells, tail vein; n = 4). Local vascular MSC administration significantly prevented neointimal hyperplasia (intima/media ratio) and reduced the percentage of Ki67 + proliferating cells in arterial walls by 14 days after treatment, despite little evidence of long-term MSC engraftment. Notably, systemic MSC infusion did not alter neointimal formation. By immunohistochemistry, compared with neointimal cells of controls, cells in MSC-treated arteries expressed reduced levels of embryonic myosin heavy chain and RM-4, an inflammatory cell marker. In the presence of platelet-derived growth factor (PDGF-BB), conditioned medium from MSCs increased p27 protein levels and significantly attenuated VSMC proliferation in culture. Furthermore, MSC-conditioned medium suppressed the expression of inflammatory cytokines and RM-4 in PDGF-BB-treated VSMCs. Thus, perivascular administration of MSCs may improve restenosis after vascular injury through paracrine effects that modulate VSMC inflammatory phenotype.     

Effects of inflammatory factors on mesenchymal stem cells and their role in the promotion of tumor angiogenesis in colon cancer

Mesenchymal stem cells (MSCs), which are modulated by cytokines present in the tumor microenvironment, play an important role in tumor progression. It is well documented that inflammation is an important part of the tumor microenvironment, so we investigated whether stimulation of MSCs by inflammatory cytokines would contribute to their ability to promote tumor growth. We first showed that MSCs could increase C26 colon cancer growth in mice. This growth-promoting effect was further accelerated when the MSCs were pre-stimulated by inflammatory factors IFN-γ and TNF-α. At the same time, we demonstrated that MSCs pre-stimulated by both inflammatory factors could promote tumor angiogenesis in vivo to a greater degree than untreated MSCs or MSCs pre-stimulated by either IFN-γ or TNF-α alone. A hen egg test-chorioallantoic membrane (HET-CAM) assay showed that treatment of MSC-conditioned medium can promote chorioallantoic membrane angiogenesis in vitro, especially treatment with conditioned medium of MSCs pretreated with IFN-γ and TNF-α together. This mechanism of promoting angiogenesis appears to take place via an increase in the expression of vascular endothelial growth factor (VEGF), which itself takes place through an increase in signaling in the hypoxia-inducible factor 1α (HIF-1α)-dependent pathway. Inhibition of HIF-1α in MSCs by siRNA was found to effectively reduce the ability of MSC to affect the growth of colon cancer in vivo in the inflammatory microenviroment. These results indicate that MSCs stimulated by inflammatory cytokines such as IFN-γ and TNF-α in the tumor microenvironment express higher levels of VEGF via the HIF-1α signaling pathway and that these MSCs then enhance tumor angiogenesis, finally leading to colon cancer growth in mice.     

Extracellular vesicles released from mesenchymal stromal cells stimulate bone growth in osteogenesis imperfecta

Background

Systemic infusion of mesenchymal stromal cells (MSCs) has been shown to induce acute acceleration of growth velocity in children with osteogenesis imperfecta (OI) despite minimal engraftment of infused MSCs in bones. Using an animal model of OI we have previously shown that MSC infusion stimulates chondrocyte proliferation in the growth plate and that this enhanced proliferation is also observed with infusion of MSC conditioned medium in lieu of MSCs, suggesting that bone growth is due to trophic effects of MSCs. Here we sought to identify the trophic factor secreted by MSCs that mediates this therapeutic activity.

Paracrine Effect of Mesenchymal Stem Cells Derived from Human Adipose Tissue in Bone Regeneration

Mesenchymal stem cell (MSC) transplantation has proved to be a promising strategy in cell therapy and regenerative medicine. Although their mechanism of action is not completely clear, it has been suggested that their therapeutic activity may be mediated by a paracrine effect. The main goal of this study was to evaluate by radiographic, morphometric and histological analysis the ability of mesenchymal stem cells derived from human adipose tissue (Ad-MSC) and their conditioned medium (CM), to repair surgical bone lesions using an in vivo model (rabbit mandibles). The results demonstrated that both, Ad-MSC and CM, induce bone regeneration in surgically created lesions in rabbit''s jaws, suggesting that Ad-MSC improve the process of bone regeneration mainly by releasing paracrine factors. The evidence of the paracrine effect of MSC on bone regeneration has a major impact on regenerative medicine, and the use of their CM can address some issues and difficulties related to cell transplants. In particular, CM can be easily stored and transported, and is easier to handle by medical personnel during clinical procedures.     

Synergistic Actions of Hematopoietic and Mesenchymal Stem/Progenitor Cells in Vascularizing Bioengineered Tissues

Poor angiogenesis is a major road block for tissue repair. The regeneration of virtually all tissues is limited by angiogenesis, given the diffusion of nutrients, oxygen, and waste products is limited to a few hundred micrometers. We postulated that co-transplantation of hematopoietic and mesenchymal stem/progenitor cells improves angiogenesis of tissue repair and hence the outcome of regeneration. In this study, we tested this hypothesis by using bone as a model whose regeneration is impaired unless it is vascularized. Hematopoietic stem/progenitor cells (HSCs) and mesenchymal stem/progenitor cells (MSCs) were isolated from each of three healthy human bone marrow samples and reconstituted in a porous scaffold. MSCs were seeded in micropores of 3D calcium phosphate (CP) scaffolds, followed by infusion of gel-suspended CD34⁺ hematopoietic cells. Co-transplantation of CD34⁺ HSCs and CD34⁻ MSCs in microporous CP scaffolds subcutaneously in the dorsum of immunocompromized mice yielded vascularized tissue. The average vascular number of co-transplanted CD34⁺ and MSC scaffolds was substantially greater than MSC transplantation alone. Human osteocalcin was expressed in the micropores of CP scaffolds and was significantly increased upon co-transplantation of MSCs and CD34⁺ cells. Human nuclear staining revealed the engraftment of transplanted human cells in vascular endothelium upon co-transplantation of MSCs and CD34⁺ cells. Based on additional in vitro results of endothelial differentiation of CD34⁺ cells by vascular endothelial growth factor (VEGF), we adsorbed VEGF with co-transplanted CD34⁺ and MSCs in the microporous CP scaffolds in vivo, and discovered that vascular number and diameter further increased, likely owing to the promotion of endothelial differentiation of CD34⁺ cells by VEGF. Together, co-transplantation of hematopoietic and mesenchymal stem/progenitor cells may improve the regeneration of vascular dependent tissues such as bone, adipose, muscle and dermal grafts, and may have implications in the regeneration of internal organs.     

Stem cell therapy independent of stemness

Mesenchymal stem cell (MSC) therapy is entering a new era shifting the focus from initial feasibility study to optimization of therapeutic efficacy. However, how MSC therapy facilitates tissue regeneration remains incompletely characterized. Consistent with the emerging notion that secretion of multiple growth factors/cytokines (trophic factors) by MSC provides the underlying tissue regenerative mechanism, the recent study by Bai et al demonstrated a critical therapeutic role of MSC-derived hepatocyte growth factor (HGF) in two animal models of multiple sclerosis (MS), which is a progressive autoimmune disorder caused by damage to the myelin sheath and loss of oligodendrocytes. Although current MS therapies are directed toward attenuation of the immune response, robust repair of myelin sheath likely requires a regenerative approach focusing on long-term replacement of the lost oligodendrocytes. This approach appears feasible because adult organs contain various populations of multipotent resident stem/progenitor cells that may be activated by MSC trophic factors as demonstrated by Bai et al This commentary highlights and discusses the major findings of their studies, emphasizing the anti-inflammatory function and trophic cross-talk mechanisms mediated by HGF and other MSC-derived trophic factors in sustaining the treatment benefits. Identification of multiple functionally synergistic trophic factors, such as HGF and vascular endothelial growth factor, can eventually lead to the development of efficacious cell-free therapeutic regimens targeting a broad spectrum of degenerative conditions.     

Mesenchymal stem cells in regenerative medicine applied to rheumatic diseases: Role of secretome and exosomes

Over the last decades, mesenchymal stem cells (MSCs) have been extensively studied with regard to their potential applications in regenerative medicine. In rheumatic diseases, MSC-based therapy is the subject of great expectations for patients who are refractory to proposed treatments such as rheumatoid arthritis (RA), or display degenerative injuries without possible curative treatment, such as osteoarthritis (OA). The therapeutic potential of MSCs has been demonstrated in several pre-clinical models of OA or RA and both the safety and efficacy of MSC-based therapy is being evaluated in humans. The predominant mechanism by which MSCs participate to tissue repair is through a paracrine activity. Via the production of a multitude of trophic factors with various properties, MSCs can reduce tissue injury, protect tissue from further degradation and/or enhance tissue repair. However, a thorough in vivo examination of MSC-derived secretome and strategies to modulate it are still lacking. The present review discusses the current understanding of the MSC secretome as a therapeutic for treatment of inflammatory or degenerative pathologies focusing on rheumatic diseases. We provide insights on and perspectives for future development of the MSC secretome with respect to the release of extracellular vesicles that would have certain advantages over injection of living MSCs or administration of a single therapeutic factor or a combination of factors.     

Conditioned medium enhances the fusion capability of rat bone marrow mesenchymal stem cells and cardiomyocytes

Mesenchymal stem cells (MSCs) show accelerated regeneration potential when these cells experience hypoxic stress. This “preconditioning” has shown promising results with respect to cardio-protection as it stimulates endogenous mechanisms resulting in multiple cellular responses. The current study was carried out to analyze the effect of hypoxia on the expression of certain growth factors in rat MSCs and cardiomyocytes (CMs). Both cell types were cultured and assessed separately for their responsiveness to hypoxia by an optimized dose of 2,4,-dinitrophenol (DNP). These cells were allowed to propagate under normal condition for either 2 or 24 h and then analyzed for the expression of growth factors by RT-PCR. Variable patterns of expression were observed which indicate that their expression depends on the time of re-oxygenation and extent of hypoxia. To see whether the growth factors released during hypoxia affect the fusion of MSCs with CMs, we performed co-culture studies in normal and conditioned medium. The conditioned medium is defined as the medium in which CMs were grown for re-oxygenation till the specified time period of either 2 or 24 h after hypoxia induction. The results showed that the fusion efficiency of cells was increased when the conditioned medium was used as compared to that in the normal medium. This may be due to the presence of certain growth factors released by the cells under hypoxic condition that promote cell survival and enhance their fusion or regenerating ability. This study would serve as another attempt in designing a therapeutic strategy in which conditioned MSCs can be used for ischemic diseases and provide more specific therapy for cardiac regeneration.     

Mesenchymal Stem Cell Seeding of Porcine Small Intestinal Submucosal Extracellular Matrix for Cardiovascular Applications

In this study, we investigate the translational potential of a novel combined construct using an FDA-approved decellularized porcine small intestinal submucosa extracellular matrix (SIS-ECM) seeded with human or porcine mesenchymal stem cells (MSCs) for cardiovascular indications. With the emerging success of individual component in various clinical applications, the combination of SIS-ECM with MSCs could provide additional therapeutic potential compared to individual components alone for cardiovascular repair. We tested the in vitro effects of MSC-seeding on SIS-ECM on resultant construct structure/function properties and MSC phenotypes. Additionally, we evaluated the ability of porcine MSCs to modulate recipient graft-specific response towards SIS-ECM in a porcine cardiac patch in vivo model. Specifically, we determined: 1) in vitro loading-capacity of human MSCs on SIS-ECM, 2) effect of cell seeding on SIS-ECM structure, compositions and mechanical properties, 3) effect of SIS-ECM seeding on human MSC phenotypes and differentiation potential, and 4) optimal orientation and dose of porcine MSCs seeded SIS-ECM for an in vivo cardiac application. In this study, histological structure, biochemical compositions and mechanical properties of the FDA-approved SIS-ECM biomaterial were retained following MSCs repopulation in vitro. Similarly, the cellular phenotypes and differentiation potential of MSCs were preserved following seeding on SIS-ECM. In a porcine in vivo patch study, the presence of porcine MSCs on SIS-ECM significantly reduced adaptive T cell response regardless of cell dose and orientation compared to SIS-ECM alone. These findings substantiate the clinical translational potential of combined SIS-ECM seeded with MSCs as a promising therapeutic candidate for cardiac applications.     

Autologous mesenchymal stem cell transplantation induce VEGF and neovascularization in ischemic myocardium

Neovascularization induced by vascular endothelial growth factor (VEGF) represents an appealing approach for treating ischemic heart disease. However, VEGF therapy has been associated with transient therapeutic effects and potential risk for hemangioma growth. Adult mesenchymal stem cells (MSCs) derived from bone marrow are a promising source for tissue regeneration and repair. In order to achieve a safe and persistent angiogenic effect, we have explored the potential of autologous MSCs transplantation to enhance angiogenesis and cardiac function of ischemic hearts. One week after myocardial infarction induced by occlusion of left anterior descending artery, autologous MSCs expanded in vitro was administrated intramyocardially into the infarct area of the same donor rats. By 2 months, MSCs implantation significantly elevated VEGF expression levels, accompanied by increased vascular density and regional blood flow in the infarct zone. The neovascularization resulted in a decreased apoptosis of hypertrophied myocytes and markedly improved the left ventricular contractility (ejection fraction: 79.9+/-7.6% vs. 37.2+/-6.9% in control animals). Therefore, mechanisms underlying MSCs improvement of cardiac functions may involve neovascularization induced by differentiation of MSCs to endothelial cells and para-secretion of growth factors, in addition to the apoptosis reduction and previously reported cardiomyocytes regeneration. Two months after cell transplantation, there are significant improvement of left ventricular function. Hence, autologous MSCs transplantation may represent a promising therapeutic strategy free of ethical concerns and immune rejection, for neovascularization in ischemic heart diseases.