In a study using human muscle tissue, a team of scientists led by McGowan Institute faculty members Johnny Huard, PhD, and Bruno Péault, PhD, isolated and characterized stem cells taken from blood vessels (known as myoendothelial cells) that are easily isolated using cell-sorting techniques, proliferate rapidly, and can be differentiated in the laboratory into muscle, bone and cartilage cells. These characteristics may make them ideally suited as a potential therapy for muscle injuries and diseases.
“Finding this population of stem cells in a human source represents a major breakthrough for us because it brings us much closer to a clinical application of this therapy,” said Dr. Huard, the Henry J. Mankin Professor and vice chair for Research in the Department of Orthopaedic Surgery at the University of Pittsburgh School of Medicine. “To make this available as a therapy, we would take a muscle biopsy from a patient with a muscle injury or disease, remove the myoendothelial cells, and treat the cells in the lab. The stem cells would then be re-injected into the patient to repair the muscle damage. Because this is an autologous transplant, meaning from the patient to himself, there is not the risk of rejection you would have if you took the stem cells from another source.”
Eight years ago, Dr. Huard’s laboratory team first identified a unique population of muscle-derived stem cells with the ability to repair muscle. Dr. Péault, a professor in the Department of Pediatrics, Cell Biology and Physiology at the University of Pittsburgh School of Medicine, recognized the importance of determining the origin of these muscle-derived stem cells. His team applied, among others, techniques of confocal microscopy and cell sorting by flow cytometry that led to the discovery in human muscle biopsies that these myoendothelial cells are located adjacent to the walls of blood vessels.
According to their study, myoendothelial cells taken from the blood vessels are much more efficient at forming muscle than other sources of stem cells known as satellite and endothelial cells. In mice, 1,000 myoendothelial cells transplanted into injured skeletal muscle produced, on average, 89 muscle fibers, compared with 9 and 5 muscle fibers for endothelial and satellite cells, respectively. Also, myoendothelial cells show no tendency to form tumors, a concern of other stem cell therapies.
Illustration: McGowan Institute for Regenerative Medicine.
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