Unlocking the Secrets of Regeneration
The protein Wnt has been linked to regenerative capabilities of organisms and their organ systems. In the past it was known that this protein played a central role in the embryonic development of lower level animals, but its exact purpose and place in the vertebrate world was left unknown. For the past 19 years, Randall Moon, who leads the University of Washington's Institute for Stem Cell and Regenerative Medicine, has studied the effects of Wnt and its role in signal processing. His research, along with the research of others now in the field, has led to a better understanding of this protein's use in higher level organisms.
As noted in the article, many animals have evolved the ability to completely regrow lost tissues and limbs. Humans, for example, who create ~10 billion new cells daily, can almost completely regrow their liver. Other human tissues, however, such as pancreatic or heart tissue, tend to scar much more readily instead of regrowing. Moon's long term goal is to use Wnt to get stem cells to differentiate into these types of non-regrowing tissues to help diseased patients. Wnt turns on a pathway responsible for the regeneration of cells. Other Wnt spin-offs, such as Wnt5b inhibit Wnt and essentially block this pathway from occurring. It was noted, for example, that tadpoles only regenerate their limbs fully when the Wnt is active and not inhibited.
Research done by hematologist/oncologist Leonard Zon at Harvard has shed light on another molecule, this one is used to boost the immune response in animals. Some prostaglandins have the ability to help boost production of some stem cells. Zon found one such prostaglandin, PGE2, helped to boost production of blood stem cells. In his research Zon irradiated zebrafish, wiping out their immune system. Zon then injected PGE2 and the animals easily produced new blood stem cell lines. Zon is now working with Moon on research involving the regrowth of tissue in zebrafish and in developing their work for possible human applications.
The question still remains of why the liver but not the pancreas. Other scientists listed in the article have done research of cells that dedifferentiate at the site of an injury and then redifferentiate into cells needed. Other research has been done on inhibitors that stop the growth of cells, which when removed, allowed certain tissues to grow again. The problem with such research is that these mechanisms look very closely related to cancer. In fact, colorectal cancer and melanoma has been shown to be caused when the genes for WTX (a Wnt inhibitor) are mutated and Wnt levels raise to high. Too much or not enough of these growth stimulating molecules can lead to severe problems. Indeed the solution might be found in the balance.
Link: http://www.hhmi.org/bulletin/aug2007/pdf/Regeneration.pdf
As noted in the article, many animals have evolved the ability to completely regrow lost tissues and limbs. Humans, for example, who create ~10 billion new cells daily, can almost completely regrow their liver. Other human tissues, however, such as pancreatic or heart tissue, tend to scar much more readily instead of regrowing. Moon's long term goal is to use Wnt to get stem cells to differentiate into these types of non-regrowing tissues to help diseased patients. Wnt turns on a pathway responsible for the regeneration of cells. Other Wnt spin-offs, such as Wnt5b inhibit Wnt and essentially block this pathway from occurring. It was noted, for example, that tadpoles only regenerate their limbs fully when the Wnt is active and not inhibited.
Research done by hematologist/oncologist Leonard Zon at Harvard has shed light on another molecule, this one is used to boost the immune response in animals. Some prostaglandins have the ability to help boost production of some stem cells. Zon found one such prostaglandin, PGE2, helped to boost production of blood stem cells. In his research Zon irradiated zebrafish, wiping out their immune system. Zon then injected PGE2 and the animals easily produced new blood stem cell lines. Zon is now working with Moon on research involving the regrowth of tissue in zebrafish and in developing their work for possible human applications.
The question still remains of why the liver but not the pancreas. Other scientists listed in the article have done research of cells that dedifferentiate at the site of an injury and then redifferentiate into cells needed. Other research has been done on inhibitors that stop the growth of cells, which when removed, allowed certain tissues to grow again. The problem with such research is that these mechanisms look very closely related to cancer. In fact, colorectal cancer and melanoma has been shown to be caused when the genes for WTX (a Wnt inhibitor) are mutated and Wnt levels raise to high. Too much or not enough of these growth stimulating molecules can lead to severe problems. Indeed the solution might be found in the balance.
Link: http://www.hhmi.org/bulletin/aug2007/pdf/Regeneration.pdf
posted by Jeremy Wurbs at 7:55 PM
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