RNA-Seq investigation and in vivo study the effect of strontium ranelate on ovariectomized rat via the involvement of ROCK1

Strontium ranelate (SrR) is an anti-osteoporosis drug with excellent osteogenic and angiogenic capacity. In this study, we aimed to investigate the osteogenesis and angiogenesis effects of SrR and the underlying mechanism involved. RNA-Seq was conducted to examine the effects of SrR on gene expression in ovariectomy rat bone marrow mesenchymal stem cells (OVX-rBMSCs). To validate the different expressed gene in vitro, the effects of gene interference and overexpression in osteogenic induction environment of OVX-rBMSCs and in primary osteoblasts were studied. RNA-Seq showed that ROCK1 significantly increased after SrR treatment in OVX-rBMSCs, and further validated by real-time PCR and western blotting. Overexpression of ROCK1 promoted osteogenic differentiation of OVX-rBMSCs and induced cell viability and inhibited apoptosis of primary osteoblasts, which was reversed by inhibition of ROCK1 by RNA interference or ROCK1 inhibitor (Y-27632) after SrR treatment. Furthermore, the SrR was loaded on nano-structured hydroxyapatite (nano-HAp) particulates to promote osteogenesis and angiogenesis in repairing of the femoral condyle bone defect using ovariectomy rat model. Taken together, ROCK1 is one of the targets that SrR promotes the osteogenic differentiation of OVX-rBMSCs and cell viability of primary osteoblasts, the nano-HAp particles could act as carriers for SrR to repair bone defects.