Scientists from Tokyo Metropolitan University have made a groundbreaking discovery that a protein called platelet-derived growth factor subunit B (PDGF-B) plays a crucial role in repairing and growing muscles. The team led by Associate Professor Yasuko Manabe found that PDGF-B is continuously secreted from skeletal muscle cells and helps to repair muscles by encouraging myoblasts (muscle stem cells) to proliferate. Unexpectedly, they also found that PDGF-B helps muscle fibers grow, which corresponds to fibers contracting more strongly. These findings promise game-changing therapies for treating muscular atrophy and injury.
Myokines are small proteins secreted by skeletal muscle cells that have a wide range of functions, and may act on cells both near and far to where they are made. While a comprehensive understanding of how myokines affect cellular processes is still lacking, it is believed that they play an important role in exercise-related bodily functions, particularly the maintenance of muscle tissue.
Through extensive experiments, the team found that a myokine known as platelet-derived growth factor subunit B, or PDGF-B, is secreted by skeletal muscles without any stimulus. To understand its role, they exposed myoblasts (precursor cells that differentiate into muscle fibers) to PDGF-B and observed that it induced greater proliferation of myoblasts. They also found that PDGF-B impacted cells that had already differentiated, by increasing the diameter of myotubes (a developmental stage of muscle fibers), expressing more Myosin Heavy Chain, and corresponding to increased contractile strength.
The team’s work shows that PDGF-B is involved in muscle regeneration and constitutes a big leap forward for developing effective treatments for muscle injury and atrophy as well as regimens for improving muscle performance. This research was supported by Japan Society for the Promotion of Science (JSPS) KAKENHI Grants-in-Aid for Scientific Research, the Promotion of Science Funding Program for Next Generation World-Leading Researchers, the TMU strategic research fund for innovative research projects and a Tokyo Metropolitan Government Advanced Research Grant.