Human muscle stem cells successfully isolated

Scientists have effectively isolated human muscle stem cells, revealing that the cells could robustly duplicate and fix impaired muscles when attached onto an injured location, according to a new paper published in Stem Cell Reports.
The laboratory discovery makes way for prospective therapy for patients with significant muscle injury, paralysis, or genetic disorders like muscular dystrophy.
“We’ve shown definitively that these are bona-fide stem cells that can self-renew, proliferate, and respond to injury,” said Dr. Jason Pomerantz, an assistant professor of plastic and reconstructive surgery at University of California San Francisco.
When muscles are injured or diseased, they can suffer a loss of the existing stem cells needed to heal properly, which has posed a significant obstacle for treating patients impaired by muscle injury and paralysis, Pomerantz said.
Doctors have had exceptional success repairing nerves in damaged muscles, but if the treatment takes too much time, the available stem cells and ability to regenerate is lost. This results in damaged muscles not reconnecting with nerve tissue and a loss of ability.
“This is partly why we haven’t had major progress in treating these patients in 30 years,” Pomerantz said in a news release. “We know we can get the axons there, but we need the stem cells for there to be recovery.”
Cells on the boundaries of muscle fibers were known to behave as stem cells in mice, adding to muscle growth and repair. Until recently, however, it wasn’t apparent if human satellite cells performed the same way, and researchers didn’t know how to separate them from human tissue and modify them to help care for individuals with muscle damage.
Fixing damaged tissues
In the new study, researchers acquired surgical biopsies of muscles and used antibody discoloration to indicate that human satellite cells can be recognized by their co-expression of a transcription factor and two particular exterior proteins.
This discovery allowed the study team to segregate populations of human satellite cells and graft them onto the damaged muscles of mice. Inside of five weeks, the human cells effectively incorporated into the muscles and split to create families of daughter stem cells, restoring the stem cell niche and mending the damaged tissue.
“This gives us hope that we will be able to extract healthy stem cells from other muscles in the patient’s body and transplant them at the site of injury,” Pomerantz said. “If replenishing a healthy muscle stem cell pool facilitates reinnervation and recovery, it would be a significant leap forward.”
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