Satellite myoblast and mesenchymal stem cell injections decrease fatty degeneration after rotator cuff tear in rats

Abstract

PurposeRotator cuff (RC) tears cause fatty degeneration, aggravated by delayed treatment. Surgical repair alone cannot reverse fatty degeneration. It was aimed to test if local injections of satellite cell-derived myoblasts or satellite myoblasts (SM) from the deltoid region and mesenchymal stem cells (MSCs) from the subcutaneous abdominal fat pad would stimulate myogenesis and decrease adipogenesis in the rat model of fatty degenerated RC tear.MethodsA standardized RC tear surgery was performed on both shoulders of 24 Wistar albino rats at t = 0, and rats were followed for 8 weeks to create a chronic degeneration model. The animals were randomly divided into repair + SM and MSC (n = 12) or repair only (n = 12) groups. Transosseous repair with or without stem cell-based injection was performed on the right shoulder of all rats on week 8, with additional injections on weeks 9 and 10. The left shoulders were used as control. The animals were followed until week 14 for recovery.ResultsHistological and histomorphometric analyses were performed in week 14. The repair + SM and MSC group had a significantly greater supraspinatus muscle mass than the repair only and control groups. The adipose tissue ratio was significantly lower in the repair + SM and MSC groups versus the repair only and control groups.ConclusionHistologically, the repair + SM and MSC group had improved muscle and tendon organization. In treating chronically degenerated RC tear in a rat model, surgical repair combined with injections of SM and MSC improved fatty degeneration, tendon healing and myogenesis.Level of EvidenceLevel III. Satellite myoblast (SM) and mesenchymal stem cell (MSC) injections improve fatty degeneration reversal after rotator cuff tear in rats. The experimental design shows the details of interventions performed on the control, repair only and repair + SM and MSC groups. The plots in the results section show a decrease in the adipose tissue ratio and an increase in the muscle tissue ratio in the repair + SM and MSC group. The asterisks signify a statistically significant difference. The histological preparations show the differences in the adipose tissue and muscle tissue ratios between the groups. image