What do zombie cells do to your ageing?

Zombie cells are cells that stop dividing but also do not die. They accumulate as you get older and in doing so contribute to ageing and age-related diseases. The evidence that they play a role in this is robust, supported by multiple large review studies. The biggest problem lies in what zombie cells secrete. They pump a mixture of inflammatory substances into their surroundings. Those substances damage neighbouring healthy cells and can even 'infect' them: healthy cells are brought into a senescence-like state as a result. In this way the damage slowly spreads through the tissue. Zombie cells are not, however, exclusively harmful. They normally act as a brake on cancer cells: a cell that is at risk of becoming malignant effectively puts itself out of action through senescence. They also play a regulatory role in the formation of scar tissue after a wound, and during the early development of the embryo they are outright necessary. The problem therefore lies not in the existence of zombie cells, but in the fact that they accumulate during ageing and disrupt the balance. What can you do about it? Two types of therapy are being investigated: agents that selectively kill zombie cells (senolytics), and agents that dampen the harmful secretion. Both look promising in early research, but there are as yet no broad clinical recommendations. In mice, a small RNA molecule was able to reverse the activity of zombie cells, resulting in a longer lifespan. That is interesting, but still far from a therapy for humans. Laboratory studies also suggest that certain plant compounds (polyphenols) can inhibit senescence in skin cells, although this has been demonstrated exclusively in cell cultures, not in humans.