Tissue regeneration linked to genes

Brian D Williams (talon57@well.com)
Fri, 2 Oct 1998 07:11:11 -0700 (PDT)

Tissue regeneration linked to genes

NEW YORK, Sep 30 (Reuters) -- A group of researchers say they are close to identifying a group of genes linked to complex tissue regeneration in mice. They believe their findings could further research into human organ and limb regeneration after trauma or illness.

After injury, wound healing in mammals usually involves repair through cell proliferation rather than regeneration, which involves replacement of damaged tissues. Mammals usually cannot regenerate complex body structures, which can result in loss of function. However, scientists at the Wistar Institute in Philadelphia, Pennsylvania, say they have now identified a strain of mice that ``undergo rapid and complete wound closure that resembles regeneration.'' Their report is published this week in the Proceedings of the National Academy of Sciences.

``What is remarkable,'' they say, is that these wound closures
``not only display full healing but also show the recovery of
normal architecture,'' including the regrowth of skin, cartilage, blood vessel, hair follicles, and sebaceous glands -- all without scarring.

After discovering that the ``MRL/MpJ'' strain of mice was able to effect an apparent regeneration of damaged ear tissue, the authors examined the mouse's genome (genetic 'blueprint') to seek out genes associated with this process. The discovery of a mouse capable of regeneration is particularly important, the scientists say, since the genetic code of mice is both well-understood and similar to that of humans.

The researchers say they have identified various areas of the mouse genome thought to be home to ``at least five unlinked (mouse) genes that can contribute to (this) healing.''

They report that one of the suspect genes is located in a chromosomal region similar to that responsible for regeneration in amphibians -- many species of which are capable of regrowing whole limbs. Another gene has been linked to the production of retinoic acid, a protein involved in mammalian tissue development and the growth of skin.

In an interview with Reuters Health, Dr. Giovanni Rovera, director of the Wistar Institute, explained that the final identification of these genes will be only the beginning of regeneration research. ``We understand so little,'' he said, ''but I think we are one step closer.''

He believes the next logical step would be an exact identification of the genes themselves. At the present time, he said, all we have determined is an 'address' for the genes. ``I would compare it to saying 'this is the town where these genes live,''' he explained.

Of course, the 'holy grail' of this type of research would be the development of a medical means of allowing humans to regrow limbs, organs, or damaged spinal cords. However, Rovera cautioned that experts ``suspect that regeneration of an organ or a limb is controlled by many elements, of which these genes are only representing one of those many elements.''

SOURCE: Proceedings of the National Academy of Sciences 1998;95:11792-11797.