Growth Characteristics of Human Adipose-Derived Stem Cells During Long Time Culture Regulated by Cyclin A and Cyclin D1

Abundant and less passaged cells are highly expected in clinical application since repeated subculture reduces stem cell characteristics. Long time culture of stem cells without passage is therefore needed. The growth and cell viability of human adipose-derived stem cells (hADSCs) were investigated by live/dead staining, cck-8 kits, and hemocytometer every day in 30 days of culture. The stem cell characteristics of hADSCs at the beginning and the end of culture were detected by flow cytometry and histochemical staining. hADSCs can be cultured up to the 30th day in one passage while maintaining high level cell viability and their stem cell characteristics. In addition, the cells displayed two plateau phases and three logarithmic phases during 1 month of culture. Increasing expression of cyclin A at protein level resulted in an increase in the percentage of hADSCs in the S and G2/M phases, while decreasing protein level of cyclin D1 induced a decline in the proportion of hADSCs in the G0/G1 phase, regulating cells to move into rapid proliferation. This study demonstrates that a great quantity of hADSCs can be obtained in vitro by prolonging the culture time of each passage. And cyclin A and cyclin D1 affect the distribution of cell cycle and regulate the growth of hADSCs.