Can natural processes of aging be reversed?
Every older person is probably familiar with these problems: the skin becomes wrinkled in old age and more and more hairs fall out in men. These processes are typically hallmarks of aging, but researchers have now been able to reverse these signs.
In their current study, scientists from the University of Alabama at Birmingham found that the typical signs of aging can be reversed. Thus, age-related hair loss and wrinkled skin could soon no longer be a problem for aging people. The doctors published the results of their study in the English-language journal "Cell Death & Disease".
Researchers are reversing signs of aging in mice
In a model on mice, the researchers succeeded for the first time in reversing the signs of aging. If a mutation that leads to mitochondrial dysfunction was induced in the mice, the animals developed wrinkled skin and extensive, visible hair loss within only a few weeks. When the function of the mitochondria was restored, however, by switching off the gene responsible for mitochondrial dysfunction, the animals' smooth skin returned and the fur also grew again. Afterwards, the mouse could no longer be distinguished from a healthy mouse of the same age, the scientists explain.
A decrease in mitochondrial function occurs during aging
It is important that the mutation takes place in a gene that affects mitochondrial function. Numerous mitochondria in cells produce 90 percent of the chemical energy that cells need to survive, the experts say. A decrease in mitochondrial function occurs in humans during aging. Mitochondrial dysfunction can trigger age-related diseases. Depletion of DNA in mitochondria is also associated with human mitochondrial diseases, cardiovascular diseases, diabetes, age-related neurological disorders and cancer, the experts explain.
Reversal of the mutation resulted in smooth skin and hair growth
The mutation in the mouse model was induced by adding the antibiotic doxycycline to food or drinking water. This causes a so-called depletion of the mitochondrial DNA, since the enzyme for replicating the DNA becomes inactive. After a few weeks, the mice developed gray hair, reduced hair density, hair loss, slow movements and lethargy. These changes were reminiscent of natural aging. Wrinkled skin was observed four to eight weeks after the mutation was induced, and the females developed larger skin folds than the male rats. By reversing the mutation, hair loss and wrinkled skin could be reversed.
What effects did the mutation have on the animals?
The skin of mice with induced mutation showed an increased number of skin cells, an abnormal thickening of the outer skin layer, dysfunctional hair follicles and an increased inflammation, which seemed to contribute to the skin pathology, explain the doctors. These effects are similar to the so-called extrinsic aging of the skin in humans. The mice with depleted mitochondrial DNA also showed an altered expression of four age-associated markers in cells.
There were disturbances in the balance of the skin
The skin also showed disturbances in the balance between matrix metalloproteinase enzymes and their tissue-specific inhibitor - a balance of these two is necessary to maintain the collagen fibers in the skin that prevent wrinkles, the researchers explain. The mitochondria of mice with induced mutation had a reduced content of mitochondrial DNA, changed mitochondrial gene expression and instability of the large complexes in mitochondria that are involved in oxidative phosphorylation.
Mitochondria: Reversible regulators of skin aging and hair loss
The reversal of the mutation restored the mitochondrial function as well as the skin and hair pathology. This showed that mitochondria are reversible regulators of skin aging and hair loss, explains study author Dr. Keshav Singh of the University of Alabama at Birmingham in a press release.
More research is needed
More experimentation is now needed to determine whether phenotypic changes in other organs can also be reversed by restoring mitrochondrial DNA. (as)