Some time back, somewhere, I read that business people have just about the biggest vocabularies of all professions. False. Not even close. My doctor brother knows all the words I do (me businessman) – and a whole lot more.
The other day I was looking through an issue of one of his Journals of the American Medical Association and had to use a dictionary so often that I’d lose the sense of a passage and have to start over. Exactly similar to reading something in a nearly forgotten foreign language.
Nonetheless, I’ve never met a periodical I didn’t like and this was no exception. The most interesting bit (so far) was entitled: “Re- ‘evolutionary’ Regenerative Medicine”* which asks: “Can an evolutionary perspective on the mechanisms used by ‘lowly’ organisms inform the approach to human tissue regeneration?”
Through most of the article the authors use the example of a newt, or more specifically one minus a limb. How does it grow back and why won’t they, damaged heart tissue, etc grow back in humans? Seems that science has long thought that a limb-bud (blastema) was made of “multipotent” cells (like stem cells I guess) that somehow took appropriate new form.
Turns out not to be the case. Instead, the already specialized cells (cartilage, bone, neural, and muscle) of the stump/bud are enabled to re-enter the cell cycle and proliferate anew. Furthermore, “A crucial step would likely entail ‘lifting the brakes’ on cell division, but only transiently, to avoid uncontrolled proliferation and tumor formation.”
It sort of follows that mammals and other species might have lost to cancer the ability to regenerate. Those of our (way) distant ancestors that did finagle new stuff also developed cancer at an unsurvivable rate. I think that’s what they mean. Does make you wonder about how newts et al made it through though.
Anyway, they figured out that inhibition of a certain tumor suppressing gene mediated newt limb regeneration. In humans the suppression of a homologous gene does not. Seems that the culprit is a certain ‘alternative reading frame protein’ which isn’t found in any species capable of regeneration. This ARF is frequently inactivated in human cancers.
The above described existing route to a new limb (for some creatures) is then different than the one based upon stem cells and has several advantages warranting further research. Some tissues don’t seem to have stem cells. Methods to steer stem cell development towards a specific destiny haven’t been worked out nor has a means of reintroduction of new into diseased or damaged tissue.
No brainer then huh?
Also, seems obvious that those against stem cell research must not be avid readers of JAMA. Final (for now) point of interest is that a work of art graces the covers of each issue and that three recent ones have borne works from our (Figge Art Museum’s that is) vault. Cover of this issue pictured below.
*Re”evolutionary”Regenerative Medicine; H.M Blau; J.H. Pomerantz; JAMA 1/5/11; p87