Here is news of a research tool for those developing ways to target and destroy senescent cells. A successful method should minimize the contribution of cellular senescence to degenerative aging and thus extend healthy life - this is one of the necessary biotechnologies for human rejuvenation that is closest to actual implementation:
Researchers have long known that the gene, p16INK4a (p16), plays a role in aging and cancer suppression by activating an important tumor defense mechanism called 'cellular senescence'. The [team] has developed a strain of mice that turns on a gene from fireflies when the normal p16 gene is activated. In cells undergoing senescence, the p16 gene is switched on, activating the firefly gene and causing the affected tissue to glow.
Throughout the entire lifespan of these mice, the researchers followed p16 activation by simply tracking the brightness of each animal. They found that old mice are brighter than young mice, and that sites of cancer formation become extremely bright, allowing for the early identification of developing cancers. "With these mice, we can visualize in real-time the activation of cellular senescence, which prevents cancer but causes aging. We can literally see the earliest molecular stages of cancer and aging in living mice."
The researchers used these mice to make several unexpected discoveries. First, the group was able to track the accumulation of senescent cells in aging mice by assessing how brightly each mouse glowed. Surprisingly, the brightest animals were no more likely to die from spontaneous cancer than dimmer animals of the same age. That is, the number of senescent cells in the mouse did not predict its risk of dying.
Another surprise came from the disparities in p16 levels among the mice. The authors studied a large group of genetically identical animals that were all housed in the same way and fed the same diet. However, despite identical genetic and environmental conditions, the brightness of individual mice at any given age was highly variable, suggesting that factors beyond genetics and diet influence aging.