"Exercise" shown to improve the performance of lab-grown muscle implants

Wake Forest's muscle-implant-stretching machine

We all know that you need to exercise if you want to develop your muscles. As it turns out, however, exercise also makes lab-grown muscle implants more effective when introduced to the body. Scientists from North Carolina’s Wake Forest Baptist Medical Center have discovered that after being gently expanded and contracted, implants placed in lab animals were better able to stimulate new muscle growth than implants that were left “unexercised.”

The implants themselves were made by first extracting cells from small samples of muscle tissue from mice. Those cells were multiplied in the lab, and then applied to a strip of natural biological material at a rate of one million per square centimeter. The base material, which is known for being biocompatible, was derived from pig bladder.

In order to “educate” the strips on how to perform within the body, some of them were then placed in a computer-controlled device that slowly stretched and released them at a rate of three times per minute for the first five minutes of each hour, for five to seven days. Some of those strips, in turn, had extra cells added to them part way through that process.

All of the strips were then implanted in mice (one strip per mouse), which were physically impaired due to the removal of part of the large latissimus dorsi muscle in their backs. The strips were not yet functional as muscle replacements, but the idea was that they would become so after being assimilated into the body, while simultaneously speeding the regrowth of the animals’ own muscle tissue.

Some mice also received strips that had not been subjected to the exercise routine, while another group received no implants at all.

When the mice were later assessed, it was found that the animals receiving the unexercised implants experienced a period of accelerated muscle repair that the implant-less mice did not – that period, however, stopped abruptly. By contrast, the repair period in the mice that received the exercised implants lasted much longer, and the muscle regrowth was more expansive. The results were even better in the mice that received the implants with added extra cells.

It was found that with all of the implants, new muscle tissue grew both within the strip itself, and at the point where it joined the mouse’s own tissue. This suggests that the implants accelerate the body’s natural healing response, and promote the growth of new muscle tissue.

The scientists hope that such implants could eventually be used on humans who have lost large amounts of muscle tissue, or who were born without it due to birth defects such as cleft palate. Researchers from The Netherlands’ Eindhoven University of Technology have also recently reported success in creating lab-grown muscle tissue, using stem cells and blood vessel cells from mice.

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