Intraarticular administration of platelet-rich plasma with biodegradable gelatin hydrogel microspheres prevents osteoarthritis progression in the rabbit knee.

OBJECTIVE: To investigate the therapeutic potential of administration of gelatin hydrogel microspheres containing platelet-rich plasma (PRP), by examining its effects on progression of osteoarthritis (OA) in a rabbit model. METHODS: PRP and platelet-poor plasma (PPP) were prepared from rabbit blood. Adult rabbit chondrocytes were cultured in the alginate beads with the presence of 3% PRP or 3% PPP. Glycosaminoglycan (GAG) synthesis was quantified using dimethylmethylene blue assay. To confirm the anabolic effect of PRP in vivo, cartilage matrix gene expression was examined after intraarticular administration of PRP contained in gelatin hydrogel microspheres. The PRP contained in gelatin hydrogel microspheres was administered into the rabbit knee joint twice with an interval of 3 weeks, beginning 4 weeks after anterior cruciate ligament transection (ACLT). Ten weeks after ACLT, gross morphological and histological examinations were performed. RESULTS: PRP significantly stimulated chondrocyte GAG synthesis in vitro. In the knee joint, expression of proteoglycan core protein mRNA in the articular cartilage increased after administration of PRP contained in microspheres. Intraarticular injections of PRP in gelatin hydrogel microspheres significantly suppressed progression of OA in the ACLT rabbit model morphologically and histologically. CONCLUSION: The present findings indicate that sustained release of growth factors contained in PRP has preventive effects against OA progression. These preventive effects appear to be due to stimulation of cartilage matrix metabolism, caused by the growth factors contained in PRP.

Total hip arthroplasty using proximal porous coating stem with distal sleeve: mid-term outcome.

PURPOSE: To report mid-term results of total hip arthroplasty (THA) using the Opti-Fix Plus Hip System (Opti-Fix Hip), and to assess the correlations between peri-implant bone changes and the distal medullary occupancy rate. METHODS: 11 men (13 hips) and 53 women (58 hips) aged 24 to 87 (mean, 61) years underwent THA using the Opti-Fix Hip, with a modular stem and a distal sleeve, and were followed up for a mean of 6.5 (range, 4.8-9.6) years. Clinical outcomes were evaluated using the Japanese Orthopaedic Association (JOA) hip score. Implant stability, bone changes around the implant, and the occupancy rate of the stem in the medullary space were examined radiologically. Bone changes around the implant were assessed based on the radiological evidence of a pedestal, osteolysis, stress shielding, and radiolucent lines. RESULTS: The mean JOA score increased significantly after surgery and was maintained at the latest follow-up. Around the acetabular and femoral components respectively, 38 and 58 hips had radiolucent lines, whereas one and 54 hips developed osteolysis. A pedestal appeared in 21 hips and grade-III or higher stress shielding in 30 hips. Two hips showed loosening of the acetabular components, but none in the femoral components. Osteolysis around the stem was frequently observed in hips with poor distal medullary occupancy. CONCLUSION: Clinical and radiological outcomes of the Opti-Fix Hip were favourable. The low incidence of osteolysis in the distal stem suggests that the proximal circumferential porous coating was effective. Minor osteolysis around the proximal stem was frequently observed, indicating early excessive wear of the polyethylene liner. Its high distal medullary occupancy rate could inhibit stem micromotion and aseptic loosening.

Induction of chondrogenic phenotype in synovium-derived progenitor cells by intermittent hydrostatic pressure.

OBJECTIVE: The aim of this study was to investigate the effect of intermittent hydrostatic pressure (IHP) on chondrogenic differentiation of synovium-derived progenitor cells (SPCs). METHODS: SPCs, bone marrow-derived progenitor cells and skin fibroblasts from rabbits were subjected to IHP ranging from 1.0 to 5.0 MPa. The mRNA expression of proteoglycan core protein (PG), collagen type II and SOX-9 was examined using real-time reverse transcriptase-polymerase chain reaction (RT-PCR). The production of SOX-9 protein and glycosaminoglycan (GAG) by SPCs was analyzed by Western blot and the dimethylmethylene blue assay. In addition, mitogen-activated protein (MAP) kinase inhibitors for c-Jun N-terminal kinase (JNK), extracellular signal-regulated kinase (ERK), and the p38 pathway were used to identify the signal transduction pathways. RESULTS: Real-time RT-PCR showed that mRNA expression of PG, collagen type II and SOX-9 was significantly enhanced only in SPCs receiving 5.0 MPa of IHP. The production of SOX-9 protein and GAG by SPCs was also increased by exposure to 5.0 MPa of IHP. These up-regulated expressions were suppressed by pretreatment with an inhibitor of JNK, but not with inhibitors of ERK or p38. CONCLUSION: Our results demonstrated that the exposure of SPCs to 5.0 MPa of IHP could facilitate induction of the chondrogenic phenotype by the MAP kinase/JNK pathway. This finding suggests the potential for IHP utilization in regenerative treatments for cartilage injuries or osteoarthritis.