Effects of high plating densities on in vitro and in vivo differentiation capability of immortalized human mesenchymal stem cells

Objective To determine whether different cell plating densities could influence the potential differentiation of immortalized human mesenchymal stem cells (hMSC-TERT). Methods Extensive characterization was performed for two independent cell lines derived from parental hMSCTERT cell line based on different plating densities during expansion in culture: 1∶2 (hMSC-TERT2) and 1∶20 (hMSC-TERT20).Their adipocytic, osteogenic, neuronal differentiation potential in vitro and multidirectional differentiation potential in vivo were analyzed by immunohistochemistry for pathologic tissue markers. Results hMSC-TERT2 formed cellular adipose foci and mineralized tuberculum after in vitro induction while hMSC-TERT20 showed adipocytes but no adipose foci or mineralized tuberculum.The positive rate of h MSC-TERT2 formed tissues on VIM, GFAP and LCA (89.17%±5.97%, 72.5%±10.11% and 76.67%±11.15%) under SCID murine skin were more than that of hMSC-TERT20 formed tissues (0.33%±0.65%, 9.58%±4.29% and 22.08%±6.95%). Conclusion The cell lines derived at high plating density may have more powerful differentiation potential in vitro and in vivo than those derived at low cell plating density. Key words: Telomerase; Mesenchymalstemcells; Inductiondifferentiation; Invivodifferentiation; Platingdensity