As many of us know from hard experience, tearing a muscle while exercising can be a real pain. The good news is that injured muscle will usually heal quickly for many of us with the help of satellite cells. Never heard of them? They are the adult stem cells in our skeletal muscles long recognized for their capacity to make new muscle fibers called myotubes.
This striking image shows what happens when satellite cells from mice are cultured in a lab dish. With small adjustments to the lab dish’s growth media, those cells fuse to form myotubes. Here, you see the striated myotubes (red) with multiple cell nuclei (blue) characteristic of mature muscle fibers. The researchers also used a virus to genetically engineer some of the muscle to express a fluorescent protein (green).
When you do a hard workout at the gym, or run a marathon, you generate lots of little tears in muscle. This is usually not a problem and may even lead to improved muscle strength—because the injury activates stem cells in the muscle (called satellite cells) that replicate and form new muscle fibers to repair and rebuild the damaged tissue. But when injuries extend beyond the normal wear and tear—a major injury or resection, for example—this amazing self-healing system isn’t enough. That’s when a self-healing, lab-grown muscle transplant would be particularly useful—but we haven’t yet been able to create this in a dish.
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