Mini-muscle implants gave aging mice some benefits of exercise

Tiny implants made from a mouse’s own muscle stem cells produced exercise-like health benefits in aging and obese mice, according to research from the Chinese Academy of Sciences and the National Clinical Research Center for Orthopedics, as reported by New Atlas. The researchers developed the implants by taking stem cells from the animals’ quadriceps and guiding them to become mature muscle tissue. The cells were then combined with a commercially available soluble matrix gel before being placed beneath the skin on the mice’s backs. Unlike many muscle stem-cell transplants, which often fail to survive for more than a few days because of rejection or oxygen demands, these grafts remained in place for more than 81 days during the experiments. The implanted tissue formed its own blood supply and began contracting spontaneously. The treated mice showed a range of changes associated with healthier aging. Their muscle mass increased, bone density improved, and blood sugar and cholesterol levels fell. The grafts were also associated with regeneration in tissues including muscle, bone, liver and brain. On tests of memory and spatial learning, mice receiving the implants performed better than they had before treatment, according to the report. The researchers also modified some of the grafts to produce parathyroid hormone, which the muscle cells would not normally make. In mice whose parathyroid glands had been removed, the engineered tissue restored production of the hormone and brought blood calcium and phosphate levels back to what the report described as safe levels. The work is based entirely on experiments in mice and does not show that people could obtain the same effects without exercising. It may, however, offer researchers a possible direction for future treatments involving stem cells, genetic engineering or hormone production, particularly for people unable to exercise because they are bed-bound or disabled. New Atlas reported that the implants showed no signs of cancerous growth or migration during the study. The research was published in Nature Aging.