Gene therapy strategy to enhance survival and function of endothelial progenitor cells (EPC) in the infarct environment

Abstract

Endothelial progenitor cells (EPC) are endothelial cell precursors originating in the hematopoietic compartment of the bone marrow, and are thought to be a useful substrate for clinical neovascularization in patients with coronary or peripheral ischemic artery disease. However the prevailing pro-oxidant and pro-inflammatory milieu of the infarct environment (IE) markedly reduces EPC engraftment, survival and function after transplantation or mobilization with cytokines. As a strategy to enhance the viability of EPC in the cytotoxic IE, we genetically modified human EPC with retroviral vectors (MSCV) expressing heme oxygenase-1 (HO-1) and Akt and exposed the cells to a simulated IE of hypoxia (1% O2), oxidative stress (300 μM H2O2) and inflammatory cytokine stimulation (25 ng/ml TNF-α). EPC's were transduced with 10 MOI of MSCV-HO-1 and 10 MOI of MSCV-Akt and exposed to IE for 24 hr. HO-1 and Akt co-expression markedly decreased reactive oxygen species generation and significantly reduced the number of annexin V- and propidium iodide-positive cells, leading to enhanced cell viability. Compared to GFP-transduced control cells, adhesion of EPC to extracellular matrix substrates was enhanced in HO-1/Akt modified cells in the IE. We conclude that genetic modification of EPC with HO-1 and Akt markedly enhances their survival and function in the IE and may facilitate their role in neovascularization and healing of ischemic and infarcted myocardium. Supported by grants from the HSFO to LG Melo and CA Ward.