Oxygen tension and reactive oxygen species affect an age‐related response in human keratinocytes

Abstract

High levels of reactive oxygen species (ROS) can damage key genetic and cellular processes, but low levels are required for redox cell signaling. Accumulation of ROS is directly linked to genetic damage in aging tissues and implicated in delayed wound healing. In this study, we examined the effect of age and oxygen tension in primary human skin keratinocytes using cell migration and level of ROS as the affected functions. Baseline levels of ROS were higher in young keratinocytes (from 22–35 year old patients) grown at 21% oxygen as compared to 4% oxygen. However, we found the opposite with older keratinocytes (from 78–90 year old patients)– higher levels of ROS at 4% oxygen than at 21% oxygen. Both young and old keratinocytes showed decreased rates of cell migration in response to increased ROS. The in vitro scratch assay demonstrated that cells located at the edge of the scratch greatly increased their ROS levels immediately upon scratching and had declined to near baseline after 24 hours. While young cells showed higher levels of ROS at scratch margins than old cells did, the young cells were less effective at removing the ROS. Furthermore the old keratinocytes were most successful in reducing their ROS levels at the scratch margin when grown at 21% oxygen. Recovery of the cells from increased levels of ROS at their scratch margins correlated with their migration rates. These findings indicate that keratinocytes show an age‐related differential response to both oxygen tension and ROS levels (Supported by a McCord Foundation Research Grant, RO1AR053619, and R21AR053936).