Wrinkles and hair loss are inevitable consequences of aging. Store aisles, TV commercials, and internet ads are full of products and services to help people deal with our aging bodies. These solutions can only hold off or cover up aging for so long. But what if two aspects of aging, wrinkled skin and hair loss, could truly be reversed?
Advances in medicine have resulted in an increase in our lifespan from about 65 years in 1946 to about 80 years today. About 36 percent of the population today is 65 and older, and some predict that one in four people will live to be over 95 years old. However, science hasn’t yet found the fountain of youth that slows or stops the aging process.
The skin is the largest organ of the body and the most visible manifestation of aging. The aging of the skin is dictated by both genetics and environmental factors. We have known for decades that ultraviolet (UV) light from the sun causes sunburns, dark spots in the skin, wrinkles, dryness, a leathery texture, lesions and cancer. Both UVA and UVB rays cause damage, despite claims from the tanning industry that UVA rays are safe. Despite what we know, the mechanisms responsible for skin aging aren’t well understood.
Inside every cell in the body, the mitochondria is a small structure called an organelle that produces 90 percent of the energy for all the cell’s functions. Like the nucleus, which houses the DNA of the human genome, the mitochondria also holds some DNA. As people age, mitochondrial function declines, due partly to degradation and mutation of mitochondrial DNA. Changes in mitochondrial DNA are also associated with diseases including cardiovascular disease, diabetes, age-associated neurological disorders and cancer.
To examine the role of mitochondrial DNA depletion in aging, scientists used a type of mouse with a mutated gene that causes mitochondria to lose DNA and become dysfunctional. Within four to eight weeks, the mice developed wrinkled skin, hair loss and low energy. Female mice developed more severe wrinkles than male mice. The scientists observed few changes to other organs, suggesting the importance of mitochondria in skin. All of these symptoms can be reversed completely by turning off the mutated gene. This establishes the role of mitochondria in skin aging and hair loss.
The wrinkled skin these mice developed resembled the wrinkles seen in intrinsic aging, the natural process of aging, as well as extrinsic aging, caused by external factors like excess sun exposure or long-term smoking. Among the skin changes seen in the mice were an increase in the number of skin cells, thickening of the outer layer, dysfunctional hair follicles and inflammation. All these features are observed in skin wrinkled by extrinsic aging. The wrinkled skin also exhibited alterations in the molecules that maintain the proper levels of collagen fibers in the skin, which prevent wrinkling.
The role of mitochondria in skin aging and hair loss is surprising and it could open the door for additional therapies to counteract the effects of age on our skin. Perhaps we can turn the clock back after all.