Hyperglycemia alters cell-cycle regulatory proteins in human amnion-derived mesenchymal stromal cells

Human amnion-derived mesenchymal stromal cells (hAMSCs) represent a promising cell source for regenerative and experimental applications; however, culture conditions during in vitro expansion critically influence their biological properties. In this study, we investigated how hyperglycemic culture conditions affect the expression of key cell-cycle regulatory proteins in hAMSCs in vitro. Cells isolated from term placentas were exposed to normoglycemic (5 mM) or hyperglycemic (25 mM) glucose for 24 and 48 h, with equimolar mannitol included as an osmotic control. Cells exhibited mesenchymal stromal-like characteristics, supported by flow cytometric analysis and trilineage differentiation capacity. Protein levels of proliferation-associated markers (PCNA, cyclins D3, E, and B1) and cell-cycle inhibitors (p53, p57, and p27) were assessed by Western blotting. Exposure to high glucose (25 mM) for 48 h significantly downregulated PCNA, Cyclins D3, E, and B1. Interestingly, p53 and p57 were also reduced after 48 h under hyperglycemic conditions, while p27 expression remained unchanged. Notably, a decrease in p57 was detected even at 24 h, indicating early sensitivity to glucose stress. High glucose exposure was found to disrupt cell cycle regulation in hAMSCs in a time-dependent manner by suppressing both proliferative and inhibitory markers. These findings suggest that sustained hyperglycemia perturbs cell-cycle regulatory networks in hAMSCs and may limit their robustness in metabolically compromised environments.