Analysis of expression status and relationship between senescence- related genes and pancreatic function-related genes in human islets of various ages

Background Although studies on senescence-related genes using human islets have been performed, the expression of senescence-related genes and their association with functional genes in islets remain insufficiently investigated. We aimed to determine whether and what types of senescent related genes are expressed in islets and identify their correlations with pancreatic function-related genes by using islets from individuals of various ages isolated for islet transplantation. Methods Islet from deceased donors of both sexes and different ages were used for analysis. The expression status of senescence-related genes (GLS1, IL-6, IL-8, p16, p21, and SA-β-gal) and pancreatic function-related genes (GCG and INS) was examined by RT-qPCR, and their relationships with age were investigated. Results We obtained isolated human islets from 18 deceased multiorgan donors. There was no correlation between donor age and each senescence-related gene. Regarding correlations between donor age and pancreatic function-related genes, age was positively correlated only with INS (r = 0.49, p = 0.03). Meanwhile, INS expression was not correlated with GLS1 (r = 0.23, p = 0.34), IL-6 (r=-0.06, p = 0.79), or IL-8 (r=-0.1, p = 0.12), but positively related with p16 (r = 0.89, p < 0.0001), p21 (r = 0.51, p = 0.02), and SA-β-gal (r = 0.52, p = 0.02). Conclusion We did show the functional potential of even aged islets, which were originally thought to be functionally impaired. We were unable to identify any senescence-related genes expressed in islets from various ages. Therefore, a new index would need to be established to evaluate not only actual chronological age but also organ- and cell-specific age.