Scientists have discovered a molecular pathway that works through the immune system to apparently reestablish a developmental program that is beneficial for the repair and regeneration of damaged kidney tissues. This discovery may lead to new therapies for repairing injury in the kidney, and perhaps in a number of other organ systems as well. Acute kidney injury is a significant cause of kidney disease, cardiovascular complications, and early death, affecting as many as 16 million children and adults in the United States. There are currently no effective treatments for acute kidney injury--a growing problem in hospitals and clinics, according to the study's co-senior authors, Dr. Richard Lang, from Cincinnati Children's Hospital Medical Center, and Dr. Jeremy Duffield, from Brigham and Women's Hospital of Harvard Medical School. The newly discovered molecular repair pathway involves white blood cells called macrophages--part of the immune system--that respond to tissue injury by producing a protein called Wnt7b. The research team identified the macrophage-Wnt7b pathway during experiments in mice with induced kidney injury. Wnt7b is already known to be important to the formation of kidney tissues during embryonic organ development. In this study, the scientists found that the protein helped initiate tissue repair and regeneration in injured kidneys. “Our findings suggest that by migrating to the injured kidney and producing Wnt7b, macrophages are re-establishing an early molecular program for organ development that also is beneficial to tissue repair," said Dr. Lang. "This study also indicates the pathway may be important to tissue regeneration and repair in other organs." This research was conducted by an international team from eight research institutions and was reported online on February 16, 2010 in PNAS.
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