We tested whether treatment with VEGF as such or slowly released by PAMf differently enhances cell survival, proliferation, and resistance to hypoxia/reoxygenation (H/R) of bone marrow-MSCs. To test whether VEGF or PAMf may exert different effects on RISK and anti-apoptotic mediator, Bcl-2. MSCs were incubated in normal medium for 6 days without VEGF (control group) or with VEGF alone or with PAMf. Yet, MSCs were pre-treated with VEGF or PAMf for 24 hours and then exposed to hypoxia (3% O2) for 72 hours and subsequent 3 hours of reoxygenation (H/R). The effects of treatments on cell proliferation, RISK and post-hypoxic vitality were determined.

Cell proliferation increased about two-fold 6 days after VEGF treatment, but by a lesser extent (a 55% increase) in the presence of PAMf. Also pre-treatment of MSCs with VEGF confirmed a stimulation of cell proliferation, but only pre-treatment with PAMf protected against H/R induced cell death. Effects of VEGF and PAMf on viability were corroborated by RISK and anti-apoptotic signaling modifications. In particular, VEGF increased the amount of phospho-ERK 1/2, compared to the untreated cells, and phospho-Akt and phospho-PKCe, compared to PAMf, whereas PAMf increased the amount of Bcl-2. PAMf suppresses post-hypoxic MSC death, whereas VEGF mainly enhances MSC proliferation in normoxia. The use of PAMf can be considered as a novel approach for enhancing stem cell survival and regeneration in hostile environment of post-ischemic tissue.