OLDER people need more time to recover from injuries; this has been documented for >100 years, since it was noticed that older soldiers in World War I took longer to heal. A recent study by Prof Elaine Fuchs, Robin Chemers Neustein Laboratory of Mammalian Cell Biology and Development, Rockefeller University, New York City, New York, USA, and colleagues examining molecular changes in age-related skin has identified age-related changes that may be responsible for this slowed healing process.
Dr Fuchs explained: “Within days of an injury, skin cells migrate in and close the wound, a process that requires co-ordination with nearby immune cells. Our experiments have shown that with aging, disruptions to communication between skin cells and their immune cells slow down this step.” There are many steps in the complex process of healing, involving various cell types, signalling systems, and molecular pathways, operating over different timescales. Dr Fuchs and her team concentrated their research on the migration of keratinocytes to fill in the wound underneath a scab.
This process was investigated in 2-month-old and 24-month-old mice believed to be roughly equivalent to 20-year-old and 70-year-old humans. It was discovered that in the older mice, wounds often took days longer to close because the keratinocytes were slower to move into the gap in the skin underneath the scab. The underlying cause of this was that the keratinocytes in older mice did not produce proteins known as Skints that are believed to signal to specialised skin immune cells to assist in healing an injury. The researchers could partially reverse this effect by utilising a protein that resident immune cells typically release after injury. When this protein was applied to mouse skin tissue in a petri dish, keratinocyte migration increased, an effect more obvious in older skin tissue.
The study’s authors suggest that a similar method could be used to develop treatments for age-related delays in healing. Dr Fuchs opined: “Our work suggests it may be possible to develop drugs to activate pathways that help ageing skin cells to communicate better with their immune cell neighbours and so boost the signals that normally decline with age.”