Bone marrow derived stromal cells modified by adenovirus-mediated HIF-1α double mutant protect cardiac myocytes against CoCl2-induced apoptosis

Bone marrow derived stromal cells (MSCs) can prevent the apoptosis of ischemic cardiomyocytes (CMCs). This anti-apoptosis activity may be related to an activation of the HIF-1α signal pathway in MSCs. Therefore, we investigated protective effects of an adenovirus (Ad)-mediated active form of HIF-1α (HIF-1α-Ala564-Ala803) modified MSCs on CMCs against CoCl2-induced apoptosis. At normoxia, pAd-HIF1α-Ala564-Ala803 exhibited a stable HIF-1α protein expression in MSCs. Compared with the single CMC culture, the TGF-β1 level and the Bcl-2 expression were significantly increased, concomitant with a reduced expression of caspase-3, the LDH release and TUNEL-positive CMCs in CMC and MSC, β-galactosidase (LacZ)-MSC or HIF-1α-Ala564-Ala803-MSC coculture exposed to CoCl2. Furthermore, these effects were more prominent in CMC and HIF-1α-Ala564-Ala803-MSC coculture than in CMC and MSC or LacZ-MSC coculture exposed to CoCl2. Pre-transfection of TGF-β1-small interfering RNA (siRNA) effectively inhibited the TGF-β1 level, resulting in a dramatic reduction in the Bcl-2 expression as well as an increased level of apoptosis in CMC and HIF-1α-Ala564-Ala803-MSC coculture exposure to CoCl2, whereas pre-transfection of green fluorescent protein (GFP)-siRNA had no such effects. These data suggest that HIF1α-Ala564-Ala803 modified MSCs have better protective effects of CMCs against the CoCl2-induced apoptosis and these protective effects are at least partly TGF-β1-mediated.