MicroRNA-127-3p Inhibits In Vitro Osteogenesis and Dampens Trauma-Induced Heterotopic Ossification In Vivo.

MicroRNAs are small non-coding RNAs that regulate cellular pathways by targeting multiple mRNAs, playing critical roles in skeletal development and homeostasis. Our previous miRNA profiling studies identified higher levels of miR-127-3p in the hypertrophic zone of developing human growth plates while another group found this miRNA to be more highly expressed in murine hindlimb cartilage compared to calvarial bone. Other published work revealed elevated circulating miR-127-3p levels in osteoporotic patients and in long bones of ovariectomized mice. Collectively, these findings suggest a role for miR-127-3p in regulating bone formation. To fill a knowledge gap, we designed a study to determine the function of miR-127-3p in regulating osteogenic differentiation of human bone marrow-derived mesenchymal stromal cells (hBMSCs). While inhibition of miR-127-3p had no effect, mimic overexpression robustly inhibited in vitro osteogenesis. Bulk RNA-sequencing showed a number of cellular pathways affected, including suppression of proliferation-related pathways, which was confirmed by decreased BrdU incorporation. To assess the translational potential of the bone suppressing function of this miRNA, we utilized a pre-clinical mouse model of trauma-induced heterotopic ossification involving Achilles tendon transection. Local delivery of miR-127-3p mimics via peptide-based nanoparticle technology significantly reduced ectopic bone formation at the proximal site of the transected tendon. These studies demonstrate that approaches to overexpress miR-127-3p and induce bone suppressing activity may be of therapeutic value as a means to treat many forms of heterotopic ossification.