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Bone Marrow Cells Transformed Into Muscle Cells

Posted on: Friday, 8 July 2005, 07:19 CDT

Could lead to treatments for diseases like muscular dystrophy, researchers say

Japanese researchers have transformed an ordinary kind of bone marrow cells into muscle cells, a first step toward the treatment of degenerative conditions such as muscular dystrophy.

There have been earlier reports of limited success in using these marrow stromal cells to create muscle, said Dr. Mari Dezawa, an associate professor at Kyoto University Graduate School of Medicine, and lead author of a report on the work in the July 8 issue of the journal Science.

"However, the ratio was extremely rare and the number of skeletal muscle cells was inadequate for the clinical supply," Dezawa said. "We found a new method to systematically induce skeletal muscle cells on a therapeutic scale in a short time period."

Most researchers in the field have worked with adult bone marrow stem cells, which have the ability to be transformed into many different cells. But "the number of stem cells is quite limited and in most cases they proliferate very slowly," Dezawa said.

Stromal cells, which make up connective tissue, are much more common and can easily be obtained from bone marrow, he said. Recent studies have shown they can be transformed into many different cell types, Dezawa said, and "thus, they are hopeful candidates for use in cell-based therapy."

In the study, marrow stromal cells were isolated from both humans and rats. They were exposed to four different molecules that promote growth and then were injected with the Notch gene, which is known to regulate development of many kinds of tissues, Dezawa said.

"Muscle stem cells contained in the final product are able to self-renew and differentiate into mature skeletal muscle cells and contribute continuously to muscle regeneration," he said, adding, "This is a great benefit for the amelioration of muscle dystrophy."

When the transformed cells were injected into mice and rats with the animal version of muscular dystrophy, the cells grew into working muscle fibers, promoting muscle regeneration without the need for additional cell injections.

Success in using stromal cells in therapy would sidestep two major issues, one scientific and the other ethical. Stromal cell research would eliminate the need to work with adult stem cells or embryonic stem cells. The adult cells are difficult to obtain, Dezawa said, and unless they come from the person to be treated, there is a risk that they will be attacked by the body's immune system.

Embryonic stem cells have an unmatched ability to convert to any kind of cell found in the body, but this type of stem cell research has come under fire because of moral issues surrounding the use of stem cells from human embryos. In the United States, federal funding for embryonic stem cell research is limited to studies using a small number of cell lines.

Other researchers are also working with marrow stromal cells. Last year, researchers at the University of Ulm in Germany reported that they had engineered human stromal cells to form "neuroprogenitor" cells, which are brain cells that could someday be used to replace the cells lost to such degenerative diseases as Alzheimer's and Parkinson's.

But as far as muscle cell research is concerned, Dezawa said, "Our study is quite original. We do not know of someone doing the same sort of work."

More information

Kyoto University Graduate School of Medicine

You can learn about stem cell research and its implications for treatment of disease from the National Institutes of Health.

Source: By Ed Edelson/HealthDay

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