Harvard Stem Cell Institute (HSCI) researchers at the Joslin Diabetes Center have for the first time demonstrated that transplanted muscle stem cells can both improve muscle function in mice with a form of muscular dystrophy and replenish the stem cell population for use in the repair of future muscle injuries.
“I’m very excited about this,” said lead author Amy J. Wagers (pictured), a member of the HSCI Principal Faculty and an assistant professor in Harvard's new Department of Stem Cell and Regenerative Biology. “This study indicates the presence of renewing muscle stem cells in adult skeletal muscle and demonstrates the potential benefit of stem cell therapy for the treatment of muscle degenerative diseases such as muscular dystrophy.”
HSCI co-director Doug Melton called Wager's findings "extremely significant. This provides proof of concept for treating a degenerative condition by implanting stem cells," Melton said.
The study was designed to test the concept that skeletal muscle precursor cells could function as adult stem cells and that transplantation of these cells could both repair muscle tissue and regenerate the stem cell pool in a model of Duchenne muscular dystrophy, she said.
Duchenne muscular dystrophy is the most common form of the disease and is characterized by rapidly progressing muscle degeneration. The disease is caused by a genetic mutation and there is currently no cure.
The data from this new study demonstrate that regenerative muscle stem cells can be distinguished from other cells in the muscle by unique protein markers present on their surfaces. The authors used these markers to select stem cells from normal adult muscle and transferred the cells to diseased muscle of mice carrying a mutation in the same gene affected in human Duchenne muscular dystrophy.
“Once the healthy stem cells were transplanted into the muscles of the mice with muscular dystrophy, they generated cells that incorporated into the diseased muscle and substantially improved the ability of the treated muscles to contract,” said Wagers. “At the same time, the transplantation of the healthy stem cells replenished the formerly diseased stem cell pool, providing a reservoir of healthy stem cells that could be re-activated to repair the muscle again during a second injury.”
According to the paper, these cells provide an effective source of immediately available muscle regenerative cells as well as a reserve pool that can maintain muscle regenerative activity in response to future challenges.
“This work demonstrates, in concept, that stem cell therapy could be beneficial for degenerative muscle diseases,” Wagers said.
Illustration: Harvard University.
Joslin Diabetes Center News Release (07/10/08)
Harvard University News Release (07/11/08)
RxPG News (07/12/08)
Science Daily (07/13/08)
Abstract (Cell, Vol. 134, 37-47 (07/11/08))