Keratinocyte senescence effects on differentiation and migration in a skin equivalent

Abstract

Keratinocyte telomere shortening has been demonstrated in autologous skin grafts from burn patients. Telomere shortening leads to keratinocyte replicative senescence in vitro. Wound healing is clearly delayed in telomerase knockout mice with telomere dysfunction. Our goal was to test the effect of keratinocyte replicative senescence on differentiation and migration using a human skin equivalent model. 14 day old skin equivalents were wounded using an excimer laser, then cultured for another 14 days. Tissues were harvested at various time points after wounding. Paraffin sections were stained to determine morphology and protein expression. Results were compared to early‐passage keratinocyte controls. Skin equivalents with aged keratinocytes showed reduced stratification, proliferation, and laminin‐5 staining in the basement membrane. Stratification proteins were unchanged. Interestingly, keratinocyte migration was accelerated. Decreased basement membrane staining and accelerated keratinocyte migration might be explained by increased matrix metalloproteinase expression, which will be determined later. Our previous studies suggest these changes can be rescued by telomerase.