Study of the cellular senescence process in human umbilical cord Wharton's jelly-derived mesenchymal stem cells

Introduction: Embryonic stem cells are candidates for the treatment of regenerative medicine, but their use is faced with limitations due to ethical issues. The human umbilical cord-derived mesenchymal stem cells (MSCs) are appropriate options because the cells have no ethical difficulties and have self-renewal. Senescence is known as a gradual functional loss that heterogeneously occurs in multiple organ systems. Objective: The objective of this study was to investigate the cellular senescence process in human umbilical cord Wharton's jelly-derived mesenchymal cells. Materials and Methods: Umbilical cord was obtained from healthy newborns at the General Hospital of Tabriz. Under sterile conditions, Wharton's jelly was removed from the blood vessels and minced into small pieces of about 0.5 mm. These were cultured in Dulbecco's Modified Eagle's Medium (MSC medium). Real-time polymerase chain reaction for p16INK4a and senescence-associated β-galactosidase (SA-β-gal) staining was performed to investigate the cellular senescence process. Results: The results showed the different expressions in the different passages, but it was significantly increased from the fifth passage compared to the first passage. SA-β-gal staining also showed increased colour intensity in the fifth passage compared to the first passage. Conclusion: SA-β-gal is not a specific marker for senescence, while p16INK4a is a specific marker. Further studies are required for the investigation of the senescence mechanism, such as the evaluation of genes involved in the senescence.