Forsyth Scientists Discover Early Key To Regeneration

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Forsyth Scientists Discover Early Key To Regeneration

http://www.medicalnewstoday.com/medicalnews.php?newsid=58919

Science may be one step closer to understanding how a limb can be

grown or a spinal cord can be repaired. Scientists at The Forsyth

Institute have discovered that some cells have to die for

regeneration to occur. This research may provide insight into

mechanisms necessary for therapeutic regeneration in humans,

potentially addressing tissues that are lost, damaged or non-

functional as a result of genetic syndromes, birth defects, cancer,

degenerative diseases, accidents, aging and organ failure. Through

studies of the frog (Xenopus) tadpole, the Forsyth team examined the

cellular underpinnings of regeneration.

The Xenopus tadpole is an ideal model for studying regeneration

because it is able to re-grow a fully functioning tail and all of

its components, including muscle, vasculature, skin, and spinal

cord. The Forsyth scientists studied the role that apoptosis, a

process of programmed cell death in multi-cellular organisms, plays

in regeneration. The research team, led by Levin, Ph.D.,

Director of the Forsyth Center for Regenerative and Developmental

Biology, found that apoptosis has a novel role in development and a

critical role in regeneration. According to Dr. Levin, " Simply put,

some cells have to die for regeneration to happen. "

The findings will be published in the January 1, 2007 issue of

Developmental Biology (v301i1). " We were surprised to see that some

cells need to be removed for regeneration to proceed, " said Ai-Sun

Tseng, Ph.D. the paper's first author. " It is exciting to think that

someday this process could be managed to allow medically therapeutic

regeneration. "

Summary of Study

In the context of efforts to understand biophysical controls of

regenerative processes, The Forsyth Center for Regenerative and

Developmental Biology investigated the dynamics of cell number

control in the regenerating tail bud. Previous research in the field

has shown that one mechanism by which cell number is controlled is

by programmed cell death, which has been shown to be involved in

sculpting of growing tissue in a number of developmental systems

including heart, limb and craniofacial patterning. This study shows

that despite the massive tissue proliferation required to build the

tail, an early apoptotic event is required for regeneration. Normal

regeneration of the tail includes a small focus of apoptotic cells;

when apoptosis is inhibited during the first 24 hours, regeneration

cannot proceed and the growth of nerve axons becomes abnormal. Later

inhibition of apoptosis has no effect, suggesting that the

programmed death of a specific cellular component is a very early

step in the regeneration program. One possible model is that tissues

normally contain a population of cells whose purpose is to prevent

massive growth in the region surrounding them. Future work by the

Levin group will identify the cells that must die, in order to try

to understand the signals that cells utilize for growth control.