Objective: To investigate the effect of endothelial progenitor cell (EPC) on regulating proliferation and apoptosis of bone marrow mesenchymal stem cell (BMSC) in the indirect co-culture system.
Methods: BMSC and EPC were cultivated and identified in vitro.Using transwell inserts to establish EPC and BMSC indirect co-culture system.Experimental groups were prepared as follows: BMSC/EPC indirect co-culture: BMSC were co-cultured with EPC that were separated in transwell insert.
Control: BMSC/BMSC were indirect co-cultured at the same cell counts with the experimental groups. Colony forming unit-fibroblast(CFU-F) assay was studied with three types of EPC/BMSC ratios (1: 1, 10: 1, 100: 1) to assess the capacity and efficiency for cell self-renewal.In addition, flow cytometry technique was used to detect the cell cycle at co-cultured 3 days and the cell apoptosis at co-cultured 3, 7, 10 d.
Results: Under indirect co-culture condition,EPC could significantly promote cell cycle progress and enhance capacity of cell self-renewal. Co-cultured EPC resulted in an accumulation of BMSC at S phase [experimental group: (15.72 ± 2.93)%, control group: (2.02 ± 0.66)%, P < 0.01]. CFU-F assay showed that the self-renewal capacity of EPC: BMSC/10: 1 group [(50.98 ± 6.32)%] and 100:1 group[(57.87 ± 14.06)%] were significantly higher than that in control group [(33.07 ± 9.60)% and (30.06 ± 7.20)%](P < 0.01). However,EPC had a slight but non-significant down-regulated effect on BMSC apoptosis(P > 0.05).
Conclusions: Under indirect co-culture condition, EPC could enhance the proliferation of BMSC, but could not regulate cell apoptosis in vitro.