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The regeneration of large bone defects remains clinically challenging. The aim of our study was to use a rat model to use nasal chondrocytes to engineer a hypertrophic cartilage tissue which could be remodelled into bone in vivo by endochondral ossification.\ud \ud Primary adult rat nasal chondrocytes were isolated from the nasal septum, the cell numbers expanded in monolayer culture and the cells cultured in vitro on polyglycolic acid scaffolds in chondrogenic medium for culture periods of 5–10 weeks. Hypertrophic differentiation was assessed by determining the temporal expression of key marker genes and proteins involved in hypertrophic cartilage formation. The temporal changes in the genes measured reflected the temporal changes observed in the growth plate. Collagen II gene expression increased 6 fold by day 7 and was then significantly downregulated from day 14 onwards. Conversely, collagen X gene expression was detectable by day 14 and increased 100-fold by day 35. The temporal increase in collagen X expression was mirrored by increases in alkaline phosphatase gene expression which also was detectable by day 14 with a 30-fold increase in gene expression by day 35. Histological and immunohistochemical analysis of the engineered constructs showed increased chondrocyte cell volume (31–45 μm), deposition of collagen X in the extracellular matrix and expression of alkaline phosphatase activity. However, no cartilage mineralisation was observed in in vitro culture of up to 10 weeks. On subcutaneous implantation of the hypertrophic engineered constructs, the grafts became vascularised, cartilage mineralisation occurred and loss of the proteoglycan in the matrix was observed. Implantation of the hypertrophic engineered constructs into a rat cranial defect resulted in angiogenesis, mineralisation and remodelling of the cartilage tissue into bone. Micro-CT analysis indicated that defects which received the engineered hypertrophic constructs showed 38.48% in bone volume compared to 7.01% in the control defects.\ud \ud Development of tissue engineered hypertrophic cartilage to use as a bone graft substitute is an exciting development in regenerative medicine. This is a proof of principal study demonstrating the potential of nasal chondrocytes to engineer hypertrophic cartilage which will remodel into bone on in vivo transplantation. This approach to making engineered hypertrophic cartilage grafts could form the basis of a new potential future clinical treatment for maxillofacial reconstruction.

Infection is the major reason of GTR/GBR membrane failure in clinical application. In this work, we developed GTR/GBR nanofiber membranes with localized drug delivery function to prevent infection. Metronidazole (MNA), an antibiotic, was successfully incorporated into electrospun polycaprolactone (PCL) nanofibers at different concentrations (0, 1, 5, 10, 20, 30, and 40 wt% polymer). To obtain the optimum anti-infection membrane, we systematically investigated the physical-chemical and mechanical properties of the nanofiber membranes with different drug contents. The interaction between PCL and MNA was identified by molecular dynamics simulation. MNA released in a controlled, sustained manner over 2 weeks and the antibacterial activity of the released MNA remained. The incorporation of MNA improved the hydrophilicity and in vitro biodegradation rate of PCL nanofibers. The nanofiber membranes allowed cells to adhere to and proliferate on them and showed excellent barrier function. The membrane loaded with 30% MNA had the best comprehensive properties. Analysis of subcutaneous implants demonstrated that MNA-loaded nanofibers evoked a less severe inflammatory response than pure PCL nanofibers. These results demonstrate the potential of MNA-loaded nanofiber membranes as GTR/GBR membrane with antibacterial and anti-inflammatory function for extensive biomedical applications.

The effects of devitrification of an ionomer glass with a molar composition 4.5SiO(2).3Al(2)O(3).1.5P(2)O(5).3CaO.2CaF(2) on cement formation and in vitro biocompatibility were investigated. Differential thermal analysis was used to study the phase evolution in the glass, and to determine the heat treatments for production of glass-ceramics. X-ray diffraction patterns from glass frit heat-treated at 750 degrees C for 2h contained peaks corresponding to apatite (JCPDS 15-876), whereas for samples heat-treated at 950 degrees C for 2h apatite and mullite (JCPDS 15-776) were the major phases detected. Transmission electron microscopy (TEM) confirmed that apatite and apatite-mullite phases were present after heat treatments at 750 degrees C and 950 degrees C respectively. Glass and glass-ceramics were ground to prepare

Cytokines, including TNF alpha and IL-l beta, are central to the chronic inflammatory process and tissue damage that characterises diseases such as rheumatoid arthritis. The mechanisms responsible for long-term generation of these molecules are poorly understood. We have previously demonstrated impaired activity of Na, K-ATPase, a key enzyme regulating intracellular cation levels, on rheumatoid mononuclear cells. Mimicking this 'defect' on normal mononuclear cells with ouabain has been shown to induce TNF alpha and, in particular, IL-l beta production, whereas IL-6 synthesis was suppressed. A similar pattern of cytokine generation was noted when mononuclear cells were treated with the sodium ionophore, monensin. Induction of cytokine production was related to up-regulation of the appropriate mRNA, although enhanced secretion of processed IL-l beta was also observed. The mechanism underlying these cellular responses appears to involve sodium/calcium exchange across the cell membrane. Impaired Na,K-ATPase activity might promote pro-inflammatory cytokine secretion in patients with rheumatoid arthritis.

Introduction The morphology of a substrate on which cells are seeded is known to affect cells in multiple ways including morphology, proliferation differentiation and matrix production. However, it is difficult to characterise the effects of mechanical loading on cells seeded in scaffolds of different morphology but identical chemistry. The aim of this project is to create polyurethane foam and fibre scaffolds from the same linear polyurethane and to analyse the effect of scaffold morphology on mechanical properties, cell viability, and cell morphology. The current work aims to produce scaffolds of sufficient mechanical strength for mechanical stimulation experiments. Materials and Methods Foams were fabricated from a polypropylene oxide polyol and a toluene diisocyanate (TDI) by the direct foaming technique. Fibres were fabricated by dissolving the foam overnight in a 20wt% solution of dimethylacetamide under stirring conditions. The fibres were spun using an electrospinning rig with a 15kV electric field, 30cm working distance, flow rate of 3.5ml/hr and collected on a rotating drum. MC-3T3-E1 osteoblastic cells were seeded onto 2cm diameter, thin discs of each scaffold type at a density of 100 x 10 cells per sample. The seeded scaffolds were then left for 1hr to allow cell attachment before immersion in 3ml of media and culture for 21 days with a media change every 3 days. The distribution of viable cells was analysed by an assay of metabolic activity (MTS). Results Both foam and fibre morphologies are suitable for support of cell growth over medium term culture periods (21 days). Cell viability analysis showed no significant difference between the two morphologies. Microscopy analysis indicated cell attachment and survival within the pores of the foam scaffold with cells adhering to the struts. Both scaffolds can be cut into disk or dumbbell shapes suitable for mechanical stimulation in compression or tension respectively.