Accumulated evidence indicates that local cell origins may ingrain differences in the phenotypic activity of human osteoblasts. We hypothesized that these differences may also exist in osteoblasts harvested from the same bone type at periarticular sites, including those adjacent to the fixation sites for total joint implant components. Human osteoblasts were obtained from the acetabulum and femoral neck of seven patients undergoing total hip arthroplasty (THA) and from the femoral and tibial cuts of six patients undergoing total knee arthroplasty (TKA). Osteoblasts were extracted from the usually discarded bone via enzyme digestion, characterized by flow cytometry, and cultured to passage three before measurement of metabolic activity, collagen production, alkaline phosphatase (ALP) expression, and mineralization.Aims
Methods
The exact aetiology and pathogenesis of microdamage-induced long bone fractures remain unknown. These fractures are likely to be the result of inadequate bone remodelling in response to damage. This study aims to identify an association of osteocyte apoptosis, the presence of osteocytic osteolysis, and any alterations in sclerostin expression with a fracture of the third metacarpal (Mc-III) bone of Thoroughbred racehorses. A total of 30 Mc-III bones were obtained; ten bones were fractured during racing, ten were from the contralateral limb, and ten were from control horses. Each Mc-III bone was divided into a fracture site, condyle, condylar groove, and sagittal ridge. Microcracks and diffuse microdamage were quantified. Apoptotic osteocytes were measured using TUNEL staining. Cathepsin K, matrix metalloproteinase-13 (MMP-13), HtrA1, and sclerostin expression were analyzed.Objectives
Methods
The aim of this study was to evaluate the role of peripheral blood derived mononucleated cells (PBMC) in osteochondral repair. We compared the healing of a critical size osteochondral defect in the medial femoral condyle and lateral trochlear sulcus in an ovine model.
Mesenchymal stem cells (MSCs) have potential for therapeutic repair of cartilage and bone but still require optimization in terms of their capacity to deposit an appropriate extracellular matrix (ECM). Adult human cartilage has a limited capacity for repair and is unusual in that it is one of the few tissues where injury is not followed by an influx of monocytes. We are studying the effects of co-culturing primary monocytes with MSCs differentiating along chondrogenic lineage but in addition we needed to investigate the effects of the monocytes on the mature chondrocytes that will result from the MSCs and will also be present in the host tissue. Human articular cartilage chondrocytes were isolated from human donors undergoing knee replacement surgery for osteoarthritis (OA) with full ethical consent. Cultures were expanded and cells used below passage five for co-culture experiments. Monocytes were prepared from fresh heparinized human blood samples by Ficoll gradient. Co-cultures consisted of either chondrocyte micromasses overlaid with monocytes, or chondrocytes and monocytes seeded together within a collagen/glycosaminoglycan scaffold (Chondromimetic, Tigenix UK). Media, cell pellets and scaffolds were analysed for extracellular matrix (ECM) proteins and proteases by dot blot, western blot, zymography and immunohistochemistry. Human chondrocytes maintained stable micromasses and laid down an ECM for at least 40 days. Human monocytes eventually formed a proliferating cell population with a rounded morphology on top of the chondrocyte micromasses. These cells established an adherent population with a fibroblastic morphology when replated on plastic. Analysis of chondrocyte ECM proteins indicated that monocytes affected deposition of types I and II collagen, decorin and fibronectin and the overall amounts of gelatinases released. RTPCR demonstrated a decrease in type I collagen expression and a concomitant increase in MMP13 expression. The precise interaction between monocytes and and chondrocytes has yet to be established but is thought to involve a mixture of contact and paracrine factors. In this study co-culture of monocytes with chondrocytes resulted in phenotypic changes to the chondrocytes which may warrant the inclusion of monocytes in cartilage/bone repair and also provide information as to the responses of OA chondrocytes to external stimuli.
Mesenchymal stem cells (MSC) are an attractive cell population for regeneration of mesenchymal tissue such as bone and cartilage. Various studies have demonstrated the repair capacity of MSCs and even their usefulness in treating critical size defects. Much of the work conducted on adult stem cells has focused on MSCs found within the bone marrow stroma. Adipose tissue, like bone marrow, is derived from the embryonic mesenchyme and contains a stroma that is easily isolated. The aim of the present study is to evaluate the differentiation capability of adipose-tissue derived stem cells (ASC) extracted from the infrapatellar fat pad. Human infrapatellar fat pad tissue was obtained from patients undergoing total joint replacement for osteoarthritis with full ethical consent. A multipotent progenitor cell population was derived after collagenase digestion from the adipose tissue. The ASCs were induced to differentiate towards adipogenic, chondrogenic, and osteogenic lineages for 21 days both in normoxic and hypoxic cell culture conditions. The differentiation and multilineage potential was assessed according to cell morphology and in vitro detection of tissue-specific differentiation molecules.Introduction
Materials and Methods
