Molecular Imaging for Comparison of Different Growth Factors on Bone Marrow-Derived Mesenchymal Stromal Cells' Survival and Proliferation In Vivo

Introduction. Bone marrow-derived mesenchymal stromal cells (BMSCs) have emerged as promising cell candidates but with poor survival after transplantation. This study was designed to investigate the efficacy of VEGF, bFGF, and IGF-1 on BMSCs' viability and proliferation both in vivo and in vitro using bioluminescence imaging (BLI). Methods. BMSCs were isolated from β-actin-Fluc(+) transgenic FVB mice, which constitutively express firefly luciferase. Apoptosis was induced by hypoxia preconditioning for up to 24 h followed by flow cytometry and TUNEL assay. 10(6) BMSCs with/without growth factors were injected subcutaneously into wild type FVB mice's backs. Survival of BMSCs was longitudinally monitored using bioluminescence imaging (BLI) for 5 weeks. Protein expression of Akt, p-Akt, PARP, and caspase-3 was detected by Western blot. Results. Hypoxia-induced apoptosis was significantly attenuated by bFGF and IGF-1 compared with VEGF and control group in vitro (P < 0.05). When combined with matrigel, IGF-1 showed the most beneficial effects in protecting BMSCs from apoptosis in vivo. The phosphorylation of Akt had a higher ratio in the cells from IGF-1 group. Conclusion. IGF-1 could protect BMSCs from hypoxia-induced apoptosis through activation of p-Akt/Akt pathway.