Transplantation of stem cells from various sources into infarcted hearts has the potential to promote myocardial regeneration. However, the regenerative capacity is limited partly as a result of the low survival rate of the transplanted cells in the ischemic myocardium. In the present study, we tested the hypothesis that combining cell and angiogenic gene therapies would provide additive therapeutic effects via co-injection of bone marrow-derived mesenchymal stem cells (MSCs) with an adeno-associated viral vector (AAV), MLCVEGF, which expresses vascular endothelial growth factor (VEGF) in a cardiac-specific and hypoxia-inducible manner.
MSCs isolated from transgenic mice expressing green fluorescent protein and MLCVEGF packaged in AAV serotype 1 capsid were injected into mouse hearts at the border of ischemic area, immediately after occlusion of the left anterior descending coronary, individually or together. Engrafted cells were detected and quantified by real-time polymerase chain reaction and immunostaining. Angiogenesis and infarct size were analyzed on histological and immunohistochemical stained sections. Cardiac function was analyzed by echocardiography.
We found that co-injection of AAV1-MLCVEGF with MSCs reduced cell loss. Although injection of MSCs and AAV1-MLCVEGF individually improved cardiac function and reduced infarct size, co-injection of MSC and AAV1-MLCVEGF resulted in the best improvement in cardiac function as well as the smallest infarct among all groups. Moreover, injection of AAV1-MLCVEGF induced neovasculatures. Nonetheless, injection of MSCs attracted endogenous stem cell homing and increased scar thickness.
Co-injection of MLCVEGF and MSCs in ischemic hearts can result in better cardiac function and MSC survival, compared to their individual injections, as a result of the additive effects of each therapy.
"MSC co-transplantation with hematopoietic stem cells in a hematopoietic stem cell transplant promotes hematopoietic regeneration although donor MSCs are not detected in recipient bone marrow at late time points following transplantation [57,58]. In cardiac infarction models, MSCs promote cardiac remodeling through secretion of paracrine factors detectable 2 weeks post-transplantation  although the majority of MSCs die within 4 days of transplantation . Together, these studies suggest that MSCs are rapidly lost following transplantation and this may represent a protective mechanism that prevents their secretome from being altered when transplanted into an inflamed or fibrotic environment. "
[Show abstract][Hide abstract] ABSTRACT: Introduction
Mesenchymal stem cells (MSCs) reside in a variety of tissues and provide a stromal role in regulating progenitor cell function. Current studies focus on identifying the specific factors in the niche that can alter the MSC secretome, ultimately determining the effectiveness and timing of tissue repair. The purpose of the present study was to evaluate the extent to which substrate and mechanical strain simultaneously regulate MSC quantity, gene expression, and secretome.
MSCs (Sca-1+CD45-) isolated from murine skeletal muscle (muscle-derived MSCs, or mMSCs) via fluorescence-activated cell sorting were seeded onto laminin (LAM)- or collagen type 1 (COL)-coated membranes and exposed to a single bout of mechanical strain (10%, 1 Hz, 5 hours).
mMSC proliferation was not directly affected by substrate or strain; however, gene expression of growth and inflammatory factors and extracellular matrix (ECM) proteins was downregulated in mMSCs grown on COL in a manner independent of strain. Focal adhesion kinase (FAK) may be involved in substrate regulation of mMSC secretome as FAK phosphorylation was significantly elevated 24 hours post-strain in mMSCs plated on LAM but not COL (P <0.05). Conditioned media (CM) from mMSCs exposed to both LAM and strain increased myoblast quantity 5.6-fold 24 hours post-treatment compared with myoblasts treated with serum-free media (P <0.05). This response was delayed in myoblasts treated with CM from mMSCs grown on COL.
Here, we demonstrate that exposure to COL, the primary ECM component associated with tissue fibrosis, downregulates genes associated with growth and inflammation in mMSCs and delays the ability for mMSCs to stimulate myoblast proliferation.
"The low homing rate and local survival rate of the transplanted cells, affected by endogenous and environmental factors in the ischemic tissue, such as hypoxia, oxidative stress and inflammation, which may result in apoptosis of transplanted cells
[4-6], restrain the application of this technique. Strategies to improve cardiac homing and engraftment of stem cells may improve the outcome of this approach
[7-12]. One interesting strategy is the combination of cell and gene therapy
[Show abstract][Hide abstract] ABSTRACT: Mesenchymal stem cells (MSCs) have potential for the treatment of myocardial infarction. However, several meta-analyses revealed that the outcome of stem cell transplantation is dissatisfactory. A series of studies demonstrated that the combination of cell- and gene therapy was a promising strategy to enhance therapeutic efficiency. The aim of this research is to investigate whether and how the combination of overexpression of hypoxia-inducible factor-1alpha (HIF-1alpha) and co-transplantation of mesenchymal stem cells can enhance cardiac repair in myocardial infarction.
We investigated the therapeutic effects of myocardial transfection of HIF-1alpha and co-transplantation of MSCs on cardiac repair in myocardial infarction by using myocardial transfection of HIF-1alpha via an adenoviral vector. Myocardial infarction was produced by coronary ligation in Sprague-Dawley (SD) rats. Animals were divided into 6 groups randomly: (1) HIF-1alpha + MSCs group: Ad-HIF-1alpha (6 x 109 plate forming unit) and MSCs (1 x 106) were intramyocardially injected into the border zone simultaneously; (2) HIF-1alpha group: Ad-HIF-1alpha (6 x 109 plate forming unit) was injected into the border zone; (3) HIF-1alpha-MSCs group: Ad-HIF-1alpha transfected MSCs (1 x 106) were injected into the border zone; (4) MSCs group: MSCs (1 x 106) were injected into the border zone; (5) Control group: same volume of DMEM was injected; (6) SHAM group. Cardiac performance was then quantified by echocardiography as well as molecular and pathologic analysis of heart samples in peri-infarcted region and infarcted region at serial time points. The survival and engraftment of transplanted MSCs were also assessed.
Myocardial transfection of HIF-1alpha combined with MSC transplantation in the peri-infarcted region improved cardiac function 4 weeks after myocardial infarction. Significant increases in vascular endothelial growth factor (VEGF) and stromal cell-derived factor-1alpha (SDF-1alpha) expression, angiogenesis, and MSC engraftment, as well as decreased cardiomyocyte apoptosis in peri-infarcted regions in the hearts of the HIF-1alpha + MSCs group were detected compared to the MSCs group and Control group.
These findings suggest that myocardial transfection of HIF-1alpha and co-transplantation of mesenchymal stem cells enhance cardiac repair in myocardial infarction, indicating the feasibility and preliminary safety of a combination of myocardial transfection of HIF-1alpha and MSC transplantation to treat myocardial infarction.
"Since the preferred sources of stem cells in most clinical trials are autologous, the factors that contribute to changes in MSCs with age require investigation (Yu et al., 2011). MSCs can secrete cytokines that encourage angiogenesis and inhibit apoptosis (Kang et al., 2009; Pons et al., 2009). The protective role of Sirt1 may be a normal function of endothelial cells (Potente et al., 2007; Ota et al., 2008), but to our knowledge its impact in MSCs has not yet studied. "
[Show abstract][Hide abstract] ABSTRACT: Decline in the function of stem cells with age, such as other cells of the body, results in an imbalance between loss and renewal. Increasing age of the donor thus diminishes the effectiveness of MSCs (mesenchymal stem cells) transplantation in age-related diseases. The clinical use of stem cell therapies needs autologous stem cell transplantation; it is essential therefore to study the repair ability and survivability of cells before transplantation. Bone marrow derived MSCs possess multi-lineage differentiation potential, but aging adversely affects their therapeutic efficacy. MSCs from young (2-3 months) and aged (23-24 months) GFP (green fluorescent protein)-expressing C57BL/6 mice were isolated and their regenerative potential was assessed in vitro. Real-time RT-PCR (reverse transcriptase-PCR) showed significantly higher expression of Sirt1 in MSCs isolated from young than older animals. Down-regulation of VEGF (vascular endothelial growth factor), SDF-1 (stromal-cell-derived factor 1), AKT (also known as protein kinase B) and up-regulation of p53, p21, Bax and p16 occurred in aged cells. Tube formation, wound healing and proliferative abilities of the young MSCs were better than the aged MSCs. The results suggest that age-related increased expression of apoptotic and senescent genes, with concomitant decrease in Sirt1 gene expression, inhibits to some extent stem cell functioning.
Cell Biology International 02/2012; 36(8):747-53. DOI:10.1042/CBI20110183 · 1.93 Impact Factor
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