Figure 2.

In vitro lifespan and senescence-associated β-galactosidase activity of MPF and PF cells. A. Cumulated cell population doubling rates were determined in primary MPF and PF cells using a standard 3T3 cell culture protocol. B. Senescence-associated β-galactosidase activity (SA-β-gal)-positive cell numbers of the different passages MPF and PF cells. Data shown are means ± SEM (n = 3). The a, b, c, and d indicate significant differences (p < 0.05). C. The representative photographs (40× magnification) of different passages MPF and PF cells showing SA-β-gal activity.