According to a study from Stanford University School of Medicine researchers, Old human cells regain their younger more vigorous form when they are stimulated to temporarily express amino acids known to be associated with embryonic growth.
In addition, the study also found older mice were able to repossess vigorous muscle activity after transplantation of skeletal muscle stem cells that were subjected to the same protein revitalizing treatment.
Yamanaka factors are the special proteins used in this experiment. These factors are used to convert a mature cell into induced pluripotent stem cells (iPS cells). Induced pluripotent stem cells can replicate or multiply to all cell types in the body, irrespective of their cell of origin. Therefore, iPS cells are currently a subject of intense research in regenerative medicine.
Researchers have discovered the ability of iPS cells to induce old human cells and reverse the molecular changes associated with aging. This resulted in the mature cells to become remarkably similar to their younger selves.
Vittorio Sebastiano, PhD, assistant professor of obstetrics and gynecology and the Woods Family Faculty Scholar in Pediatric Translational Medicine said, “We’ve wondered for some time if it might be possible to simply rewind the aging clock without inducing pluripotency. Now we’ve found that, by tightly controlling the duration of the exposure to these protein factors, we can promote rejuvenation in multiple human cell types.”
Since early 2000s, the researchers have been seeking a method to rejuvenate mature tissues when they first realized the potential role of systemic factors in making old tissues younger.
Sebastiano and his fellow researchers generate iPS cells from adult cells by repeatedly treating them for 10-14 days with proteins crucial for embryonic growth. The researchers achieved this by allowing the mature human cells to receive brief RNA messages encoded with instructions to synthesize the Yamanaka proteins. As the cells came into contact with the proteins, they were found to reverse the developmental timeline gradually transforming them to embryonic pluripotent cells similar to their cells of origin. During this process, the cells remove molecular tags responsible for differentiation and aging from their DNA.
Researchers now aim to shorten the duration of exposure to Yamanaka proteins to check if this could reverse aging without entering the pluripotency stage. A study conducted on mice in the Salk Institute for Biological Studies found mice affected with premature aging disorder achieved increase in their life span by more than 20% when they were induced to express the Yamanaka factors. However, it remains to be seen if these results can be replicated in humans as well.