Assessment of Replication Rates of Human Keratinocytes in Engineered Skin Substitutes Grafted to Athymic Mice

The study assessed the replication rates of human keratinocytes in engineered skin substitutes (ESS) grafted to athymic mice to determine if they exhibit a stem cell phenotype. ESS were pulsed with 5-bromo-2'-deoxyuridine (BrdU) both in vitro and after grafting. The results showed that label uptake in basal keratinocytes decreased over time, with a reorganization of BrdU-positive cells into clusters. In vivo, label retention decreased sharply from day 20 to day 48 post-grafting, while label uptake decreased gradually to day 126. The findings indicated differential rates of label uptake and retention, suggesting a proliferative phenotype with potential for long-term replication in the absence of hair follicles. This proliferative phenotype in keratinocytes of ESS could enhance the biological similarity of engineered skin to natural skin, potentially leading to faster and more stable wound healing.