I'm sure you've all already noticed that Rejuvenation Research Vol 12 Number 1 is available online. I'm late as usual in pointing it out, but better late than never. I should draw your attention to one of the papers, "Unexpected Regeneration in Middle-Aged Mice", as the full PDF version is presently free for access in one of the journal publisher's occasional promotions.
Complete regeneration of damaged extremities, including both the epithelium and the underlying tissues, is thought to occur mainly in embryos, fetuses, and juvenile mammals, but only very rarely in adult mammals. Surprisingly, we found that common strains of mice are able to regenerate all of the tissues necessary to completely fill experimentally punched ear holes, but only if punched at middle age.
Although young postweaning mice regrew the epithelium without typical pre-scar granulation tissue, they showed only minimal regeneration of connective tissues. In contrast, mice punched at 5-11 months of age showed true amphibian-like blastema formation and regrowth of cartilage, fat, and dermis, with blood vessels, sebaceous glands, hair follicles, and, in black mice, melanocytes.
These data suggest that at least partial appendage regeneration may be more common in adult mammals than previously thought and call into question the common view that regenerative ability is lost with age. The data suggest that the age at which various inbred mouse strains become capable of epimorphic regeneration may be correlated with adult body weight.
Now this is interesting indeed. You'll recall the MRL mice that show unexpected regenerative powers, something that has been known for a few years now. What these researchers have shown is that several other species of lab-bred mice have similar unexpected regenerative capabilities. This leads me to expect that, in the years ahead, scientists will uncover a complex and interrelated network of controlling genes and biochemical processes that can be manipulated at several points to produce exceptional healing in mammals. That discovery process will look much like the ongoing work attending metabolic changes in calorie restriction - a lot of potential controlling genes, much confusion and contradiction in the early years, and progress to initial therapies on a timescale of 10 to 15 years.