Exercise Daily,your stem cells will thank you

Author:  Falishia Sloan

Institution:  Eastern Virginia Medical School
Date:  January 2008

In research published in the January issue of Cell Metabolism, researchers found evidence that exercise could induce stem cells known as satellite cells to buff up muscles. These scientists from the Program on Differentiation and Cancer, Center for Genomic Regulation (CRG) and Center for Neurodegenerative Diseases (CIBERNED), Pompeu Fabra University, Barcelona, Spain suggest that exercise could have a more profound effect on your muscles than you think.

"As we learn more about how muscles grow in adults, we may uncover new methods for restoring lost muscle mass in the elderly and ill," said Pura Muñoz-Cánoves of Universitat Pompeu Fabra in Barcelona, Spain.

Fibers known as myofibers, which are generally referred to as muscle cells, make up skeletal muscles, the cells of which contain many genetic material-containing nuclei. It is common knowledge that muscles compensate for working harder, as they do during exercise, for example, by increasing in size.

This increase in size is actually the result of the augmentation of each individual myofiber. Though the method by which this occurs is still a mystery to scientists, past evidence suggests that myofiber growth is governed by a need to preserve equilibrium between the overall volume of fibers and the number of nuclei. Mature myofibers are not able to undergo cellular division, and therefore needed extra nuclei must come from muscle stem cells, which are known as satellite cells. Once the need for more nuclei has been established, the muscle stem cells follow a series of proceedings that ultimately culminate in growth of the myofiber, which includes proliferation, migration, and incorporation into the myofiber.

The researchers of this study have shown that the growth of myofibers is greatly dependent on a local rise in interleukin-6 (IL-6), a cytokine that is an inflammatory signal. The results of this research provide the first clear method for the incorporation of the muscle stem cells into the muscle fibers, as well as the first indication that a cytokine is involved in the method.

Researchers deduced these results after conducting research in which the muscles of a group of animals were made to work harder, after which they exhibited an increase in IL-6 after only one day that persisted for two weeks before beginning to lower again. This is comparable to their control group of mice, where the IL-6 in their muscles was practically imperceptible. The scientists also found that IL-6 acts by kick-starting the production of muscle stem cells. In addition, they found that the IL-6 was produced within muscle fibers, as well as in their muscle stem cells (satellite cells), which procured muscle growth. Comparably, the mice with the muscles sans IL-6 failed to exhibit any amplification in size after numerous weeks of overloading.

Conversely, an excess of IL-6 was found by the scientists to have negative effects. "Having excess IL-6 is bad, but its local translation is required for muscle growth," stated Muñoz-Cánoves, a scientist of the study.

Muñoz-Cánoves also stated that the results of this study could be the beginning of a new swarm of research targeted to discovering how adult muscle grows, and such research may eventually lead to new muscle-building therapies.

She said, "Treatments could be designed to compensate for or block the pathways leading to muscle loss. In muscles that have already lost mass, you might also be able to stimulate muscle growth."

Further research may lead to reversing or improving treatments for muscle loss that is secondary to aging, as well as common in diseases such as AIDS and cancer.

Written by Falishia Sloan

Reviewed by Neil Majithia

Published by Pooja Ghatalia.