A molecular pathway that works through the immune system to regenerate damaged kidney tissues and may lead to new therapies for repairing injury in a number of organs systems has been discovered by scientists.
The study, led by Cincinnati Children's Hospital Medical Center and the Brigham and Women's Hospital of Harvard Medical School, has been reported in this week's Proceedings of the National Academy of Sciences (PNAS).
The study may have significant medical ramifications as currently there are no effective treatments for acute kidney injury - a growing problem in hospitals and clinics, according to the study's senior co-authors, Richard Lang, Ph.D., a researcher in the divisions of Pediatric Ophthalmology and Developmental Biology at Cincinnati Children's, and Jeremy Duffield, M.D., Ph.D., a researcher at Brigham and Women's Hospital. Acute kidney injury is a significant cause of kidney disease, cardiovascular complications and early death.
The new 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. Scientists 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 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."
Wnt7b is part of the Wnt family of proteins, which are known to help regulate cells as they proliferate, grow and become specific cell types for the body. Wnt proteins have also been linked to the regulation of stem cells in bone marrow and skin, which suggested to researchers of the current study that Wnt might have a role in tissue regeneration.