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Muscle mice offer hope

Wednesday 29 August 2007

New hope has been offered for muscular dystrophy sufferers, following research that has shed further light on how muscles develop in animals, The Guardian reported. This research “is expected to lead to new treatments for serious muscle wasting diseases such as muscular dystrophy, and larger, leaner cattle for farmers”, the newspaper stated.

The research is a preliminary animal study and provides direction for further pre-clinical studies only. It is too soon to suggest any use in humans for the proteins studied.

Where did the story come from?

Professor Se-Jin Lee, from the Johns Hopkins University School of Medicine in Baltimore, US, carried out this research. The study was funded by the National Institute of Health, the Muscular Dystrophy Association, and Merck Research Laboratories. The author declared an interest: owning stock of the company producing the growth factor, and in receiving royalties from any future sales of the growth factor. The study was published in the open access medical journal, PLoS ONE .

What kind of scientific study was this?

This was an experimental animal study of mice. Mice were genetically engineered so that they did not produce a protein called myostatin, which is known to regulate muscle growth. In previous studies, these mice have been shown to have double the muscle mass of normal mice.

In this experiment, these genetically engineered mice were also altered so that they produced an excess of another protein – follistatin – which is known to regulate the effects of myostatin.

The muscle mass (weight) in a selection of four muscles was measured to see what effect the presence of the different protein had on the mice.

What were the results of the study?

The mice which were bred to have no myostatin had about double the muscle mass of normal mice and this new research shows that, in the mice who also produced follistatin, this increase is further doubled. These mice then have about four times the muscle mass of normal mice.

What interpretations did the researchers draw from these results?

The researcher concludes that “these findings demonstrate that the capacity for increasing muscle growth … is much more extensive than previously appreciated and suggest that muscle mass may be controlled at least in part by … myostatin.”

An explanation of the full implications or meaning of this finding is not included in the report.

What does the NHS Knowledge Service make of this study?

This is an experimental study of genetically engineered mice, in which a single author has succeeded in manipulating the proteins so that the muscle mass in the mice is increased fourfold.

Further explanation and a description of how this research may be applied are required before any conclusion about its relevance to humans can be made.

Sir Muir Gray adds...

It has been estimated that very few – 5 in 5,000 – chemicals that are tested in the laboratory and on animals ever make it to human studies, and only 1 of those 5 may be safe and effective enough to reach pharmacy shelves. The process between an initial positive result in an animal study and final approval for use in humans can take many years.

Analysis by Bazian
Edited by NHS Website

Links to the headlines

Mightier mouse offers hope to muscular dystrophy sufferers.

The Guardian, 29 August 2007

Links to the science

Lee S.

Quadrupling Muscle Mass in Mice by Targeting TGF-beta Signaling Pathways.

PLoS ONE 2007; 2:e789