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Scientists Demonstrate Mammalian Tissue Regeneration
telomerewhythere writes "A quest that began over a decade ago with a chance observation has reached a milestone: the identification of a gene that may regulate regeneration in mammals. The absence of this single gene, called p21, confers a healing potential in mice long thought to have been lost through evolution and reserved for creatures like flatworms, sponges, and some species of salamander. 'Unlike typical mammals, which heal wounds by forming a scar, these mice begin by forming a blastema, a structure associated with rapid cell growth and de-differentiation as seen in amphibians. According to the Wistar researchers, the loss of p21 causes the cells of these mice to behave more like embryonic stem cells than adult mammalian cells, and their findings provide solid evidence to link tissue regeneration to the control of cell division. "Much like a newt that has lost a limb, these mice will replace missing or damaged tissue with healthy tissue that lacks any sign of scarring," said the project's lead scientist.' Here is the academic paper for those with PNAS access."
I have a feeling you should know something about the subject before weighing in.
p21 knockout mice don't appear to get cancer more than wild-type mice, interestingly enough...
It's interesting, because p53 is a major regulator of p21 expression, and p21 itself is a major player in regulating cell cycle progression into S-phase, thus controlling cell replication. p53 knockouts, on the other hand, are extremely prone to cancer, as p53 is one of the most important tumor-suppressor genes.
The paper is interesting because the authors demonstrate that two separate strains of mice that contain a p21 deficiency can both regenerate differentiated tissue (measured by looking at ear-hole closure), supporting the link between p21/cell cycle progression and tissue regeneration. Whether this is of consequence therapeutically is a different story, but I'd be very interested to see the same study repeated in wild-type mice being fed or injected a small molecule p21 inhibitor.