Bone tumours may recur locally even after wide surgical excision and systemic chemotherapy. Local control of growth may be accomplished by the addition of cytostatic drugs such as methotrexate (MTX) to bone cement used to fill the defect after surgery and to stabilise the reconstructive prosthesis. We have studied the elution kinetics of MTX and its solvent N-methyl-pyrrolidone (NMP) from bone cement and their biological activities in five cell lines of osteosarcoma and in osteoblasts, and compared them with the effects of the parent compounds alone and in combination. Our findings show that MTX is released continuously over months at concentrations highly cytotoxic to osteosarcoma cells and suggest that the impregnated bone cement would be effective in the long term. Proliferating osteoblasts, however, were much less sensitive towards MTX. The dose-response relationship for NMP and experiments with MTX/NMP-mixtures show that the eluted concentrations of solvent are not toxic and do not influence the effects of MTX. We suggest that bone cement containing MTX dissolved in NMP releases the drug in a suitable and effective way and may be of value in the treatment of bone tumours

Summary. Methotrexate chemotherapy (commonly used in treating cancers and rheumatoid arthritis) creates an inflammatory condition in bone, decreasing osteogenesis, enhancing adipogenesis, increasing osteoclastogenesis, leading to bone loss and marrow adiposity; treatment with fish oil or folinic acid counteracts these negative effects and prevents bone loss. Introduction. Chemotherapy with anti-metabolite methotrexate (MTX) is commonly used in treating cancers and rheumatoid arthritis; however it is known to cause bone loss for which currently there are no adjunct preventative treatments. Methods and Materials. Using a rat model, this study investigated the damaging effects in bones caused by daily MTX injections (0.75mg/kg) for 5 consecutive days (mimicking induction phase treatment for childhood leukaemia) and also the potential protective benefits of omega-3 fatty acid-rich fish oil at different doses (0.25, 0.5 or 0.75 mL/100g BW) in comparison to antidote folinic acid (given i.p at 0.75mg/kg 6 hours post MTX, which is clinically used to reduce MTX toxicities in soft tissues). Results. Histological analysis showed that MTX significantly reduced primary spongiosa bone height and metaphyseal trabecular bone volume. MTX also significantly reduced density of osteoblasts at the secondary spongiosa. Ex vivo differentiation assays with bone marrow stromal cell populations of treated rats revealed a significant reduction in osteogenic differentiation but an increase in adipogenesis. Consistently, RT-PCR gene expression study within the stromal cell population revealed a lower expression of osteogenic transcription factors Runx2 and Osx and bone matrix protein osteocalcin but a significantly upregulated adipogenesis-related genes FABP4 and PPARγ, indicating that MTX chemotherapy induces a switch in the differentiation potential towards adipogenesis at the expense of osteogenesis. MTX increased the density of osteoclasts within the metaphyseal bone as revealed by histological analysis and osteoclast precursor cell pool as shown by ex vivo osteoclastogenesis assay with bone marrow samples. Consistently, mRNA expression of proinflammatory and osteoclastogenic cytokines IL-1, IL-6, TNF-α, and the RANKL/OPG ratio were significantly upregulated by MTX. Supplementary treatment with fish oil (0.5mL/100g BW) or folinic acid significantly preserved metaphyseal trabecular bone volume, osteoblast density, and bone marrow stromal cell osteogenic differentiation and suppressed MTX-induced adipogenesis. These supplements also prevented MTX-induced increased osteoclast density, osteoclastogenesis, and expression of proinflammatory and osteoclastogenic cytokines. Conclusion. These results suggest that MTX chemotherapy creates an inflammatory condition in bone resulting in increased osteoclast formation and decreased osteoblast formation thus leading to bone loss, and that supplementary treatment with fish oil at 0.5mL/100g BW or folinic acid counteract these negative effects, helping to conserve bone formation, suppress bone resorption and bone marrow adiposity, and thus prevent bone loss during MTX chemotherapy

Curettage and packing with polymethylmethacrylate cement is a routine treatment for giant-cell tumour (GCT) of bone. We performed an in vitro evaluation of the cytotoxic effect of a combination of cement and methotrexate, doxorubicin and cisplatin on primary cell cultures of stromal GCT cells obtained from five patients. Cement cylinders containing four different concentrations of each drug were prepared, and the effect of the eluted drugs was examined at three different time intervals. We found that the cytotoxic effect of eluted drugs depended on their concentration and the time interval, with even the lowest dose of each drug demonstrating an acceptable rate of cytotoxicity. Even in low doses, cytotoxic drugs mixed with polymethylmethacrylate cement could therefore be considered as effective local adjuvant treatment for GCTs

Objectives

To review the current best surgical practice and detail a multi-disciplinary approach that could further reduce joint replacement infection.

Short intense electrical pulses transiently increase the permeability of the cell membrane, an effect known as electroporation. This can be combined with antiblastic drugs for ablation of tumours of the skin and subcutaneous tissue. The aim of this study was to test the efficacy of electroporation when applied to bone and to understand whether the presence of mineralised trabeculae would affect the capability of the electric field to porate the membrane of bone cells.

Different levels of electrical field were applied to the femoral bone of rabbits. The field distribution and modelling were simulated by computer. Specimens of bone from treated and control rabbits were obtained for histology, histomorphometry and biomechanical testing.

After seven days, the area of ablation had increased in line with the number of pulses and/or with the amplitude of the electrical field applied. The osteogenic activity in the ablated area had recovered by 30 days. Biomechanical testing showed structural integrity of the bone at both times.

Electroporation using the appropriate combination of voltage and pulses induced ablation of bone cells without affecting the recovery of osteogenic activity. It can be an effective treatment in bone and when used in combination with drugs, an option for the treatment of metastases.