Photo/IllutrationThe Asahi Shimbun

Japanese researchers said they found a way to culture in vitro special cells that can regenerate damaged muscle fibers, a development that could lead to cures for difficult-to-treat conditions.

“Transplantation of the cultured cells will increase the amount of muscle fibers,” said Chihiro Akazawa, a professor of regenerative medicine at Tokyo Medical and Dental University and a member of the team. “The discovery could result in treatments for muscular dystrophy and other diseases.”

The findings of the team of scientists primarily from Tokyo Medical and Dental University and Osaka University were published in the U.S. scientific journal Stem Cell Reports on Jan. 12.

When muscles are damaged, muscle satellite cells on the surface of muscle fibers start dividing to proliferate and then turn into muscle fibers to repair the damage.

If muscle satellite cells are removed from the body, they soon start to transform. That has made it difficult to grow and proliferate muscle satellite cells in vitro while preventing them from turning into muscle fibers.

To solve the problem, the team examined the muscular tissue of a patient who underwent surgery for an injured knee. The scientists found that muscle satellite cells are wrapped in two layers of multiple types of a protein called laminin.

The researchers cultured muscle satellite cells on a layer of one laminin type after they were soaked in liquid containing other kinds of the protein. The cells proliferated without transforming.

The team also confirmed that the cultivated cells turned into muscle fibers when they were transplanted into the legs of mice.