Scientists regenerate rat muscle tissue, with an eye toward human applications

Stem cells in rats and mice have been mobilized to form new muscle tissue "in situ" (i.e., in the body), possibly paving the way for similar treatment in people with damaged muscle regions (Photo: Shutterstock)

Muscle lost through traumatic injury, congenital defect, or tumor ablation may soon be regenerated from within. A team of researchers at Wake Forest Baptist Medical Center has shown how stem cells in the body of mice and rats can be mobilized to form new muscle in damaged regions.

"Working to leverage the body’s own regenerative properties, we designed a muscle-specific scaffolding system that can actively participate in functional tissue regeneration," explains Sang Jin Lee, senior author on the study. This scaffold was implanted in the rats' tibialis anterior muscle (which is found below the knee), serving as a kind of home for the muscle progenitor cells to grow and develop.

After four weeks, a significant population of host stem cells and a mature network of blood vessels had formed within the scaffolds, with the most effective scaffold holding up to four times the number of cells of plain scaffolds thanks to its myogenic factor – a protein, in this case insulin-like growth factor 1, that binds to specific DNA sequences to encourage or accelerate the formation of muscular tissue (in a process called myogenesis).

Current treatment for large-scale muscle repair involves surgically moving a segment of muscle from one part of the body to another, resulting in reduced functionality at the donor site (and usually also at the implant site, compared to pre-injury or pre-tumor).

A new technique already under development involves taking a smaller number of healthy muscle cells from the body, expanding them in the lab, and then combining with a natural and/or synthetic biomaterial scaffold for later implantation. But this requires a donor tissue biopsy and it often results in a heterogenous (diverse) sample of cells that's difficult to standardize ahead of the extensive cell expansion process.

"Our aim was to bypass the challenges of both of these techniques and to demonstrate the mobilization of muscle cells to a target-specific site for muscle regeneration," Lee says.

Having achieved that goal, the scientists will now evaluate whether the regenerated muscle can restore function. They will also test the clinical feasibility of using the approach in humans and other large animals.

A paper describing the research appeared in the journal Acta Biomaterialia.

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