Development of a per-operative procedure for concentrated bone marrow adjunction in postero-lateral lumbar fusion: radiological, biological and clinical assessment.

PURPOSE: Addition of bone marrow to the bone graft in the postero-lateral lumbar arthrodesis is a widely used technique. Bone marrow brings stem cells and growth factors contained in the platelets, favorable for bone growth. Adjunction of concentrated bone marrow should create better conditions and may increase bone growth. METHODS: Simple blind randomized clinical, prospective, monocentric trial was conducted. Fifteen patients underwent lumbar arthrodesis. During surgery, a fraction of the bone marrow harvested was centrifuged. One side received this concentrate with autologous bone and ceramics; the other side received the same graft with unconcentrated bone marrow. A quantitative study, realised with a volume calculating software on CT-scan images, determined the cortical bone volume in the graft post-operatively and at 3 months. The osteoprogenitor cells, nucleated cells and platelet concentrations were determined. RESULTS: The biological study found an average concentration of six times for the nucleated cells, 3.5 times for the platelets and 2.2 times for the osteoprogenitor cells. The comparison of the mean cortical bone volumes post-operatively and at 3 months was not significantly different. CONCLUSIONS: Despite the concentration obtained, there was no increase of bone growth by adding concentrated bone marrow. However, the number of stem cells in bone marrow was low and maybe a stronger concentration is needed to obtain a difference. The 3D reconstruction of the graft and the analysis of the graft's volume using a novel software was efficient according to the similarity of the graft's volume post-operatively in all patients.

Arsenic induces expression of the multidrug resistance-associated protein 2 (MRP2) gene in primary rat and human hepatocytes.

Metals, such as arsenic or cadmium, have recently been demonstrated to interact with metabolic pathways, including phase I and phase II enzymes and the phase III efflux pump P-glycoprotein. In the present study, we investigated the effects of heavy metals and metalloids on the expression of the multidrug resistance-associated protein 2 (MRP2), a major hepatic transporter. Treatment of primary rat hepatocytes by sodium arsenite [As(III)], sodium arsenate and potassium antimony tartrate, but not cadmium chloride, was shown to markedly increase MRP2 mRNA and protein levels; As(III)-mediated induction was dose- and time-dependent and paralleled a strong increase in MRP2 amounts as assessed by Western blotting. As(III) was also demonstrated to markedly up-regulate MRP2 gene expression in primary human hepatocytes. MRP2 mRNA induction occurring in As(III)-treated rat hepatocytes was fully blocked by actinomycin D, indicating that it required active gene transcription. It was associated with an activation of the c-Jun N-terminal kinase pathway and with a reduction of cellular glutathione levels. Quercetin, a flavonoid compound known to block As(III)-related induction of P-glycoprotein, was also found to prevent up-regulation of MRP2 gene expression in rat hepatocytes exposed to As(III). Such an effect was unlikely to be due to alteration of JNK pathway since quercetin failed to abolish As(III)-induced JNK phosphorylation. It may rather be linked to the increase of cellular glutathione levels by quercetin, thus limiting the depleting effects of As(III) on glutathione amounts. Finally, these results confirm that some metals strongly regulate expression of detoxifying proteins, including biliary drug transporters.