Implications of Regeneration
The overriding question in regeneration research is the feasibility of regeneration in humans. Just as the question in genetics research is the implications in human manipulation, the possibility of regenerating human tissues has been the prevailing challenge to researchers. Currently the complex human immune response that we have evolved triggers healing instead of regeneration. Does this mean the ability to regenerate has been lost through selective pressure, or does the proper signaling mechanisms just need to be turned on? (1) Questions involved in human regenerative capabilities are many and far from being completely answered.
One promising development has been in laboratory mice. An immunologist at the Wistar Institute in Philadelphia noticed that the immune suppressed mice she was working with displayed remarkable regenerative capabilities for a mammal. Holes punched in the ears for tags not only healed, but regrew cartilage and hair follicles (9). Mice also have the ability to regenerate the tips of their toes and tail (14).
One key question then becomes how these mice regenerated holes in their ears. Some human tissues, like blood and the liver, currently have the ability to regenerate. Instead of using dedifferentiation however, the tissues turn to stem cells set-aside during embryogenisis. Regeneration of the tip of the finger uses a similar method. The ability to dedifferentiate appears to be absent outside urodeles. Is starting dedifferentiation simply a matter of turning on the right genes? Neurotrophic factors also appear to be absent in humans as well (15).
Some researchers are aggressively defending that regeneration can and will happen in human limbs (9). Though this currently seems impractical, other areas of regeneration could be more promising in the near future. Regeneration of individual sections of damaged tissue, such as deep wounds or burns, may be on the horizon. Research has also been extensive in trying to find ways to regenerate spinal tissue. Organ regeneration has the implication of decreasing the need for donors. Overall, no one can predict where research will be within the next five years, but progress is definitely being made in understanding the mechanics of limb regeneration.
Image Courtesy of Dr. Steven Scadding, <http://www.uoguelph.ca/zoology/devobio/210labs/regen1.html>
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