Abstract 18243: Transplantation of Mesenchymal Cells Rejuvenated by Delivery of Telomerase and Myocardin Genes Promotes Revascularization and Tissue Repair in Ischemic Hindlimbs of Apolipoprotein-e-null Mice

Abstract

Background and Objective: In adult bone marrow and other tissues the number and function of stem cells decline with aging. Myocardin (MyC) and telomerase (TeM), two nuclear proteins, may synergize to prevent senescence and to promote cardiovascular myogenesis. This study analyzed the impact of enhanced expression of MyC and TeM on survival, growth, and differentiation of mesenchymal stem cells (MSC) from old bone marrow and adipose tissues, as well as the therapeutic efficacy of transplantation of TeM + /McC + MSCs in murine hindlimbs with ischemic injury. Methods and Results: MSCs from adipose or bone marrow tissues of young (one month) and old (12 months old) male C57BL/6J and apolipoprotein E deficient (ApoE −/− ) mice were efficiently transduced or co-transduced with the 3 rd generation lentiviral vectors carrying the cDNAs coding for TeM-YFP (yellow fluorescence protein) or MyC-V5 epitope fusion proteins. Transduction with TeM, and to a less extent, MyC, but not empty vectors (mock), elevated MSC viability and BrdU uptake (p<0.05 vs mock controls, at flow cytometry). Colony formation increased in the transduced cells, while apoptosis in response to Fas stimulation was inhibited (Table). Endogenous MyC, cardiac and smooth muscle α-actin occurred in the cells with MyC/TeM cDNA delivery (at immunoblotting). Doppler ultrasound imaging and immunohistochemistry showed marked improvement of blood flow (Figure A, B) and arteriogenesis (Figure C) in the ischemic hindlimbs of ApoE −/− mice transplanted with the TeM + /MyC + transduced MSCs. Conclusions: The simultaneous delivery of the TeM and MyC genes resuscitates MSCs from old adipose and bone marrow tissues by increasing their capacity of survival, proliferation, and differentiation. TeM + /MyC + MSCs possess the potential of repairing ischemic tissues and, when transplanted into the ischemic hindlimb, improve revascularization.