Stem cell therapy eases muscular dystrophy: study

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http://ca.news./s/afp/080121/health/health_disease_genetics_dystrophy

Sun Jan 20, 7:54 PM

PARIS (AFP) - A treatment for muscular dystrophy may be within view

after US scientists reported Sunday they used stem cell transplants to

improve muscle function in mice afflicted with the disease.

This is the first time transplanted embryonic stem cells have been

shown to restore defective muscles in mice models of the wasting

disease, according to the study.

" We envision eventually developing a stem-cell therapy for humans, "

said University of Texas molecular biologist Rita Perlingeiro, who led

the research.

" These cells can be transplanted into the muscle, and they cause

muscle regeneration, " she said, adding that any therapy for humans was

still years away.

Muscular dystrophy is an umbrella term covering nearly a dozen

genetic, degenerative diseases that primarily affect muscles.

The condition, which afflicts mainly males, is caused by an absence of

dystrophin, a protein essential for keeping muscle cells intact and alive.

The most common childhood form, Duchenne muscular dystrophy, shows up

at age three or four. Its victims rarely live into their thirties.

In the study, researchers report on a new technique which allowed them

to coax embryonic mouse cells into becoming muscle cells that were

injected directly into rodents with the Duchenne form of the disease.

" The problem has been that embryonic cells make everything, " said

Perlingeiro. " The trick is to pull out only the one type you want. "

In order to do this the researchers manipulated a gene called Pax3

that is active in the earliest stages of stem cell development --

before the cells become, in other words, blood, bone, muscle or other

specialised tissue in the body.

In a first set of experiments, the results were mixed.

" We grew muscle in vitro -- in the Petri dish -- but when we injected

the cells into the mice there were still some left-over

undifferentiated cells, and these caused tumours, " Perlingeiro told AFP.

To filter out all the unwanted cells, the researchers used fluorescent

dyes that made it easier to identify the different types of cells.

This time, when the purified batch of muscle cells was injected into

the hind legs of mice with muscular dystrophy, the cells penetrated

deep into the muscle, an indication that they were growing and

reproducing as intended.

Many of the muscle fibres also contained the all-important dystrophin

that is lacking in muscular dystrophy patients.

In tests measuring muscle development, the muscles contracted with

three times as much force as control mice who had the disease but had

not been given the treatment. The results were in fact closer to

normal mice, the study reported.

And even after three months, there were no tumours.

The next step, said Perlingeiro, is to extend the same technique to

humans. " We should be able to use the same strategy, " she said.

Combining these findings with recent breakthroughs in the generation

of pluripotent stem cells from adult human skin -- thus avoiding the

ethical quandaries of using human embryo stem cells -- would hasten

the process, she said.