VARIATION OF TELOMERASE ACTIVITY AND MORPHOLOGY IN PORCINE MESENCHYMAL STEM CELLS AND FIBROBLASTS DURING PROLONGED IN VITRO CULTURE

The purpose of this study was to examine the telomerase activity, population doubling time (PDT), morphological alterations, and the cell cycle status with activity of senescence-associated-beta-galactosidase in porcine mesenchymal stem cells (MSCs) and fibroblasts during an extended in vitro culture. MSCs and fibroblasts were isolated from bone marrow and ear skin of a miniature pig, respectively, and cultured up to 20 passages. The analysis was carried out in MSCs and fibroblasts at 1, 5, 10, 15, and 20 passages. Relative telomerase activity (RTA) levels were significantly (P < 0.05) higher in MSCs than in fibroblasts at all the passages. The PDT and cellular size slightly increased in MSCs at later passages. In contrast, fibroblasts had significantly (P < 0.05) increased PDT and cellular size, and the morphology revealed senescent-like abnormal type after passage 10. Further, the high incidence of beta-galactosidase stained cells was observed in fibroblasts compared to that of MSCs at passage 15, and cell cycle stage at G0/G1 phase was significantly (P < 0.05) increased in the fibroblasts at 15 and 20 passages compared to that of MSCs. Based on these observations, we concluded that porcine MSCs possessed more tolerance against senescence and aging compared to fibroblasts following prolonged in vitro culture.