Proliferative enhancement of human adipose tissue-derived stromal cells by protocatechuic acid from alpinia oxyphylla in vitro

In an effort to find drugs for facilitating proliferation of transplanted stem cells to provide adequate new tissue, the influence of PCA from A. oxyphylla on the proliferation capacity of hADSCs in vitro was examined. Human ADSCs could differentiate into neuron-like cells in vitro, and protect PC-12 cells from apoptosis induced by serum deprivation. Cell counts showed that treatment of hADSCs with 0.5 mmol/L, 1.0 mmol/L and 1.5 mmol/L of PCA for 48 h increased the cell numbers in a dose-dependent manner. In addition, the cell numbers of hADSCs at various time points after treatment of 1.5 mmol/L PCA were increased in a time-dependent manner. Flow cytometric analysis of DNA content demonstrated the cell cycle progress from Gl phase to S phase. The most pronounced effect was seen with 1.5 mmol/L PCA, where the fraction of cells in S phase increased more than 2 folds, accompanied by a significant increase in the fraction of cells in G2/M phase and a significant decrease in the fraction of cells in G0/G1 phase. Western blot analysis revealed the elevated expression of cyclin Dl in hADSCs induced by 1.5 mmol/L PCA treatment. Furthermore, cyclin Dl-siRNA transfection significantly inhibited the promotion of cell proliferation by PCA. Flow cytometric analysis of the cell surface antigens, osteogenic induction and adipogenic induction demonstrated that after PCA treatment, hADSCs retained their morphological and functional characteristics of multipotential mesenchymal progenitors. The proliferative enhancement of PCA suggests the possibility that PCA may be useful in hADSCs-mediated therapy.