Effectiveness of synovial fluid mesenchymal stem cells embedded in alginate beads for treatment of steroid-induced avascular necrosis of the femoral head

Treatment of early stage avascular necrosis of the femoral head (AVNFH) is still challenging for clinicians today. Core decompression with the implantation of mesenchymal stem cells (MSCs) has become popular and been proven to be an effective therapy for ANNFH. Synovial fluid MSCs, which can be easily harvested by joint aspiration, reportedly have the potential to differentiate into bone and cartilage. The purpose of this investigation is to evaluate the effectiveness of core decompression plus the implantation of alginate beads embedded with synovial fluid MSCs (ABSMSCs) in bone regeneration in the treatment of steroid-induced AVNFH in a rabbit model. An in vitro study is carried out to evaluate the bioactivity and osteogenic differentiation of synovial fluid MSCs in the environment formed by alginate beads. In an in vivo study, the application of ABSMSCs was combined with bone decompression to treat steroid-induced AVNFH in a rabbit model. Bone mineral density, radiography and histology were used to evaluate the bone growth of the femoral head after the rabbits had been euthanized 6 weeks after surgery. The results obtained in vitro showed that the synovial fluid MSCs in the environment of alginate beads had the potential to differentiate toward bone growth. In vivo, the treatment of steroid-induced AVNFH in a rabbit model by core decompression plus the implantation of ABSMSCs preserved the bone density and sphericity of the femoral head and promoted bone regeneration. Implantation of ABSMSCs is a novel and effective therapy for AVNFH. Hopefully, this application will improve the outcome of early stage AVNFH and facilitate the harvesting of stem cells.