There is currently no cure for osteoarthritis (OA), although there are ways to manage it, but most require quite invasive surgeries. There is a resident mesenchymal progenitor cell (MPC) population within the synovial membrane of the joint that have the ability to differentiate into bone, fat, and cartilage. We hypothesise that in vivo and in vitro cell surface marker expression comparisons of the MPCs can determine which population has the highest chondrogenic capacity and is best suited for future clinical trials. Method optimisation protocol: Synovial biopsies (2 or 5mm) were obtained from patients undergoing surgery. The biopsies were digested in either collagenase type I, IA, IV or II at a concentration of 0.5 or 1.0 mg/mL. Digestion was conducted at 37°C for 30, 60, 90 or 120min. To assay for the number of MPCs obtained, the cell suspension was stained with CD90 (a synovial MPC marker) and magnetically purified. The purified cells were then assayed by flow cytometry (Co-stained with a live/dead cell marker, BV510) or bright-field microscopy. Study protocol: Synovial tissues were digested in type IV collagenase for two hours to obtain a single cell suspension. The cells were subsequently stained with mesenchymal stem cell markers, including CD 90, CD 271, CD 44, CD73, and CD105, a macrophage marker, CD68. The macrophages were excluded and the remaining cells were index sorted into 96-well plates. The cells were expanded, and underwent 21-day chondrogenic, adipogenic, and osteogenic differentiation. Differentiation was assayed using RT-qPCR and histological methods. Additionally, the cells were re-analysed for marker expression after culturing. Optimisation: Synovial biopsies of 5mm produced a greater number of live CD90+ cells than 2mm biopsies. It was observed that type IV collagenase at 1mg/ML treatment for 120 min (hip) and 90 min (knee) obtained the greatest number of CD90+ MPCs from the synovium. Results: A single cell was isolated from an OA hip biopsy and was positive for the markers CD90, CD44, CD73, and negative for the markers CD68, CD271, CD105. Following differentiation, PCR analysis suggested that the cell line was able to differentiate into chondrocytes and adipocytes, but not osteoblasts. Histology data agreed with the PCR data with the adipocytes and chondrocytes having positive staining, whereas the osteoblasts were negative. FACS analysis following proliferation showed that the expression in vivo versus in vitro was the same except CD105 that became positive after proliferation in vitro. MPCs express cell surface markers that provide information as to populations have the best cartilage regeneration abilities. By determining the properties of the MPCs in OA hips that allow for better chondrogenic differentiation abilities in vitro, selecting the optimal cells for regenerating cartilage can be done more efficiently for novel cell therapies for OA

Aberrant infrapatellar fat metabolism is a notable feature provoking inflammation and fibrosis in the progression of osteoarthritis (OA). Irisin, a secretory subunit of fibronectin type III domain containing 5 (FNDC5) regulate adipose morphogenesis, energy expenditure, skeletal muscle, and bone metabolism. This study aims to characterize the biological roles of Irisin signaling in an infrapatellar fat formation and OA development. Injured articular specimens were harvested from 19 patients with end-stage knee OA and 11 patients with the femoral neck fracture. Knee joints in mice that overexpressed Irisin were subjected to intra-articular injection of collagenase to provoke OA. Expressions of Irisin, adipokines, and MMPs probed with RT-quantitative PCR. Infrapatellar adiposity, articular cartilage damage, and synovial integrity verified with histomorphometry and immunohistochemistry. Infrapatellar adipose and synovial tissues instead of articular cartilage exhibited Irisin immunostaining. Human OA specimens showed 40% decline in Irisin expression than the non-OA group. In vitro, the gain of Irisin function enabled synovial fibroblasts but not chondrocytes to display minor responses to the IL-1β provocation of MMP3 and MMP9 expression. Of note, Irisin signaling reduced adipogenic gene expression and adipocyte formation of mesenchymal progenitor cells. In collagenase-mediated OA knee pathogenesis, forced FNDC5 expression in articular compromised the collagenase-induced infrapatellar adipose hypertrophy, synovial hypercellularity, and membrane hyperplasia. These adipose-regulatory actions warded off the affected knees from cartilage destruction and gait aberrance. Likewise, intra-articular injection of Irisin recombinant protein mitigated the development of infrapatellar adiposity and synovitis slowing down the progression of cartilage erosion and walking profile irregularity. Affected joints and adipocytes responded to the Irisin recombinant protein treatment by reducing the expressions of cartilage-deleterious adipokines IL-6, leptin, and adiponectin through regulating PPAR&gamma, function. Irisin dysfunction is relevant to the existence of end-stage knee OA. Irisin signaling protects from excessive adipogenesis of mesenchymal precursor cells and diminished inflammation and cartilage catabolism actions aggravated by adipocytes and synovial cells. This study sheds emerging new light on the Irisin signaling stabilization of infrapatellar adipose homeostasis and the perspective of the therapeutic potential of Irisin recombinant protein for deescalating knee OA development

Introduction and aims. Growth plate cartilage is responsible for bone growth in children. Injury to growth plate can often lead to faulty bony repair and bone growth deformities, which represents a significant clinical problem. This work aims to develop a biological treatment. Methods. Recent studies using rabbit models to investigate the efficacy of bone marrow mesenchymal stem cells (MSC) to promote cartilage regeneration and prevent bone defects following growth plate injury have shown promise. However, translational studies in large animal models (such as lambs), which more closely resemble the human condition, are lacking. Results. Very recently, our labs have shown that ovine bone marrow MSC are multipotential and can form cartilage-like tissue when transplanted into mice. However, using a growth plate injury model in lambs, analogous to those described in the rabbit, autologous marrow MSC seeded into gelatine scaffold containing chondrogenic factor TGF-1, failed to promote growth plate regeneration. T o date, no large animal studies have reported successful regeneration of injured growth plate cartilage using MSC highlighting the possibility that ex vivo expanded MSC may not represent a viable cellular therapy for growth plate injury repair. In addition, using a growth plate injury repair model in young rats, our studies have also focused on understanding mechanisms of the faulty repair and identifying potential targets for enhancing growth plate regeneration using endogenous progenitor cells. We have observed that bony repair of injured growth plate is preceded sequentially by inflammatory, fibrogenic, chondrogenic and osteogenic responses involving both intramembranous and endochondral ossification mechanisms. We have observed infiltration of mesenchymal progenitor cells into the injury site, some of which have the potential to differentiate to osteoblasts or chondrocytes and contribute to the bony repair of the injured growth plate. Conclusion. This presentation will focus on our studies examining the efficacy of ex vivo expanded autologous MSC to enhance growth plate regeneration in the ovine model and work using a rat model aimed at identifying potential targets for enhancing cartilage regeneration by mobilising endogenous stromal progenitor cells

Aims

This study explored the shared genetic traits and molecular interactions between postmenopausal osteoporosis (POMP) and sarcopenia, both of which substantially degrade elderly health and quality of life. We hypothesized that these motor system diseases overlap in pathophysiology and regulatory mechanisms.

Periosteum is important for bone homoeostasis through the release of bone morphogenetic proteins (BMPs) and their effect on osteoprogenitor cells. Smoking has an adverse effect on fracture healing and bone regeneration. The aim of this study was to evaluate the effect of smoking on the expression of the BMPs of human periosteum. Real-time polymerase chain reaction was performed for BMP-2,-4,-6,-7 gene expression in periosteal samples obtained from 45 fractured bones (19 smokers, 26 non-smokers) and 60 non-fractured bones (21 smokers, 39 non-smokers). A hierarchical model of BMP gene expression (BMP-2 > BMP-6 > BMP-4 > BMP-7) was demonstrated in all samples. When smokers and non-smokers were compared, a remarkable reduction in the gene expression of BMP-2, -4 and -6 was noticed in smokers. The comparison of fracture and non-fracture groups demonstrated a higher gene expression of BMP-2, -4 and -7 in the non-fracture samples. Within the subgroups (fracture and non-fracture), BMP gene expression in smokers was either lower but without statistical significance in the majority of BMPs, or similar to that in non-smokers with regard to BMP-4 in fracture and BMP-7 in non-fracture samples. In smokers, BMP gene expression of human periosteum was reduced, demonstrating the effect of smoking at the molecular level by reduction of mRNA transcription of periosteal BMPs. Among the BMPs studied, BMP-2 gene expression was significantly higher, highlighting its role in bone homoeostasis.