Expression of senescence markers in human PDL stem cells after long-term cultivation in vitro

Abstract

Cell senescence is a continuous irreversible process, ending with cell death. Long-term in vitro cultivation leads to decreased proliferation ability, disruption in cellular morphology and function in somatic cells. The aim of the present study was to investigate the markers of cell cycle arrest and senescence after long-term cultivation of periodontal ligament stem cells (PDLSC). The cells were isolated from routinely extracted third molars via enzymatic digestion and cultured continuously up to passage 16. Cell count and population doubling were evaluated at each passage. The enzymatic activity of telomerase and β-galactosidase were assessed, as these are well-known markers for cell senescence and aging. The results demonstrated two peaks with significantly increased cellular proliferation rate at passage 6 and passage 12. Slight differences in the proliferative ability were identified between cells from 1st and 16th passages without any statistical significance. Significant decrease in telomerase activity was observed starting immediately after the first passaging. β-Galactosidase activity was found to be uninterrupted following long-term in vitro cultivation. Our study indicates that the PDL stem cells did not show a significant decrease in the proliferation ability up to the 16th passage.

Keywords

• periodontal ligament stem cells
• long-term cultivation
• stem cells senescence
• β-galactosidase
• telomerase