HIF-1α induced-VEGF overexpression in bone marrow stem cells protects cardiomyocytes against ischemia

Abstract

Hypoxia inducible factor-1α (HIF-1α) is a proangiogenic transcription factor stabilized and activated under hypoxia. It regulates the expression of numerous target genes, including vascular endothelial growth factor (VEGF) and other cytoprotective proteins. In this study, we hypothesized that bone marrow stem cells (BMSCs) secrete growth factors which protect cardiomyocytes via HIF-1α pathway.Methods-BMSCs were obtained from transgenic mice overexpressing green fluorescent protein (GFP). The study was carried out in vitro using co-culture of BMSCs with cardiomyocytes. LDH release, MTT uptake, DNA fragmentation and annexin-V positive cells were used as cell injury markers. The level of HIF-1α protein as well as its activated form and VEGF were measured by ELISA. The expression of HIF-1α and VEGF in BMSCs were analyzed by quantitative PCR and cellular localization was determined by immunohistochemistry.Results-LDH release was increased and MTT uptake was decreased after exposure of cardiomyocytes to hypoxia for 24 hours, which were prevented by co-culturing cardiomyocytes with BMSCs. Cardiomyocyte apoptosis induced by hypoxia and H 2 O 2 was also reduced by co-culture with BMSCs. VEGF release from BMSCs was significantly increased in parallel with high level of HIF-1α in BMSCs following anoxia or hypoxia in time-dependent manner. Although no significant up-regulation could be seen in HIF-1α mRNA, HIF-1α protein and its activated form were markedly increased and translocated to the nucleus or peri-nuclear area. The increase and translocation of HIF-1α in BMSCs were completely blocked by 2-methoxyestradiol (2-ME2; 5μmol), a HIF-1α inhibitor. Moreover, the protection of cardiomyocytes by BMSC and VEGF secretion were abolished by neutralizing HIF-1α antibodies in a concentration dependent manner (200~ 3200ng/ml).Conclusion-Bone marrow stem cells protect cardiomyocytes by up-regulation of VEGF via activating HIF-1α.

Development of Serum-Free Quality and Quantity Control Culture of Colony-Forming Endothelial Progenitor Cell for Vasculogenesis

“…The increase in host CMCs may have been due to the cardioprotective effects of post-QQc by attenuation of myocardial ischemia through angiovasculogenesis. Dai et al [44] reported that VEGF, the expression of which was upregulated in post-QQc in our study, has antiapoptotic effects on CMCs. Transplanted cells post-QQc may secrete cytokines directly, protecting ischemic or apoptotic CMCs.…”

Mechanical Loading of Stem Cells for Improvement of Transplantation Outcome in a Model of Acute Myocardial Infarction: The Role of Loading History

“…As MDSCs do not appear to contribute directly to cardiomyocyte regeneration through their differentiation into a cardiomyocyte lineage or fusion with existing cardiomyocytes, the likely mechanism for MS-MDSC cardiac recovery is improved angiogenesis, as this has been previously shown to be critical for cardiac repair after injury and disease. 18,41 To support our in vivo results, we explored MDSC behavior in vitro under a variety of conditions. We observed an increased secretion of VEGF after mechanical stimulation, which may partially explain the improvement in MS MDSC engraftment and repair and further supports our earlier results.…”

Improving stem cell engraftment to enhance functional efficacy in cardiovascular disease: where are we now?

“…In addition to Akt signal transduction, many investigators work with hypoxia inducible factor 1 alpha (HIF-1α) and Pim-1 kinase. HIF-1 alpha HIF-1 alpha is a pro-angiogenic transcription factor which regulates the expression of many genes such as vascular endothelial growth factor (VEGF), angiopoietin 1 (ANGPT1) and ANGPT2, placental growth factor (PGF), and platelet-derived growth factor B (PDGFB) (Dai et al, 2007;Manalo et al, 2005). Under hypoxic conditions, hydroxyl reaction does not occur, causing HIF-1 protein to escape from inhibition and be activated, resulting in transcription of many genes and stimulates angiogenesis (Pugh and Ratcliffe, 2003).…”

“…Under hypoxic conditions, hydroxyl reaction does not occur, causing HIF-1 protein to escape from inhibition and be activated, resulting in transcription of many genes and stimulates angiogenesis (Pugh and Ratcliffe, 2003). Basing on the important function of HIF 1 in hypoxic cells, it's expression was introduced in MSCs, which was expected that these MSCs could protect co-culture cardiomyocytes through HIF pathway (Dai et al, 2007).…”