Despite the development of skeletal or mesenchymal stem cell (MSC) constructs aimed at creating viable cartilage and bone, few studies have examined the effects of cytokines present in rheumatoid arthritis (RA) and osteoarthritis (OA) synovial tissues, or inhibition of these, on such constructs. This work addresses these issues using both in vitro and in vivo approaches and examines potential ways of overcoming the effects of cytokines on the integrity of cartilage and bone constructs. Synovial samples were obtained from RA or OA (n=10) patients undergoing elective hip or knee arthroplasty at Southampton General Hospital. Full ethical approval was obtained. Control bone marrow-derived stromal cells were obtained from patients undergoing emergency fractured neck of femur repair, cultured in basal, osteogenic (ascorbate and dexamethasone) and chondrogenic (transforming growth factor beta (TGFbeta3)) conditions. Differentiation towards bone and cartilage was assessed using alkaline phosphatase (ALP) staining, ALP and DNA biochemical assays and analysis of osteogenic/chondrogenic gene expression using real time polymerase chain reaction (rt-PCR). Exogenous interleukin-1 (IL-1) (10ng/mL), tumour necrosis factor alpha (TNFalpha) (10ng/mL) or interleukin-6 (IL-6) (100ng/mL) was added and effects on differentiation noted. RA and OA synovial samples were digested, cultured for 48 hours then centrifuged to produce supernatants. Cytokine profiles were determined using ELISA. These supernatants were then added to MSCs and their effects on differentiation assessed. Mesenchymal cultures in osteogenic media with IL-1 showed an additive osteogenic effect on biochemical assays. TNF exerted a less marked and IL-6 no apparent effect on osteogenic differentiation. ALP expression by rt-PCR correlated with these findings. Addition of supernatants to mesenchymal cultures produced a marked osteogenic profile that was IL-1 and TNFalpha concentration dependent, correlating with lower supernatant dilutions on initial ELISA analysis. Preliminary studies indicate that exogenous IL-1 and TNFalpha modulate the osteogenic phenotype in MSCs in vitro. OA and RA synovial supernatants affect skeletal cell differentiation. Variations in cytokine profiles between supernatants require analysis for potential confounders. A larger study is underway to investigate these effects, the effects of cytokines on skeletal cell differentiation on commercially available scaffolds both in vitro and in an in vivo murine model of bone formation.
Analysis of the different phases of the gait cycle has been shown to demonstrate differences in pathological osteoarthritic gait. These differences can be quantified and their improvement following total hip arthroplasty has been shown, allowing use of gait analysis as a tool in evaluating function after total hip replacements. The purpose of this study was to determine the degree of improvement in gait attained after resurfacing hip arthroplasty. Ten patients with monoarthritic hips were evaluated using gait analysis preoperatively and 1 year postoperatively. The results indicate that there is a significant improvement in the patients gait during the first postoperative year following resurfacing arthroplasty. There is a 30% increase in the Harris Hip score, 100% increase in the velocity of walking. 51% increase in stride length, 30% improvement in the ground reaction force and 33% improvement in cadence at 1 year. These improvements in gait mirror those shown previously following Total hip arthroplasty and show that following resurfacing procedures gait parameters are comparable to able-bodied controls. We have concluded that resurfacing hip arthroplasty can greatly improve the gait characteristics of patients with unilateral degenerative hip arthritis.
