The spine journal : official journal of the North American Spine Society
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Tumor necrosis factor-α (TNF-α) is a regulatory cytokine that can increase the activity of enzymes such as ADAMTS (a disintegrin and metalloproteinase with thrombospondin motifs), which degrade disc matrix. ADAMTS are enzymes that break down disc matrix and thereby mediate disc degeneration. Bone morphogenetic protein-7 (BMP-7), on the other hand, stimulates synthesis of the disc extracellular matrix and is a potential therapeutic molecule for the treatment of disc degeneration. However, the effects of BMP-7 on TNF-α and ADAMTS are unknown. ⋯ BMP-7 antagonizes TNF-α-induced activation of NFκB and up-regulation of ADAMTS, leading to decreased degradation of disc matrix macromolecules. These data indicate that BMP-7 has a dual mechanism of action on disc metabolism: (1) the previously well-described positive effect on disc matrix synthesis and (2) an anticatabolic effect that is described here. This understanding is important as BMP-7 is being considered for treatment of disc degeneration.
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Carragee et al. reported an accelerated progression of lumbar intervertebral disc (IVD) degeneration after discography in a human trial. Local anesthetics and contrast agents have exhibited toxicity to cardiac, renal, and neuronal cells. We hypothesize that local anesthetics or contrast agents commonly injected into the disc space during discography may result in cytotoxicity in vitro. In this study, we compared the cytotoxicity of these agents, alone or in combination, using nucleus pulposus (NP) and annulus fibrosus (AF) cells in a three-dimensional (3D) culture system. ⋯ Cell death was observed when AF and NP cells were incubated in a dose- and time-dependent manner with local anesthetics and contrast agents commonly used for discography. Relative toxicity of these compounds was noted in the order of bupivacaine, lidocaine, iopamidol, and iohexol. Future studies of the effects of these agents in organ culture or animal models are indicated to predict what happens in vivo.
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Although the use of mesenchymal stem cells (MSC) with scaffolds for bone repair has been considered an effective method, the interactions between implanted materials and bone tissues have not been fully elucidated. At some specific sites, such as the vertebral body (VB) of the spine, the process of bone repair with implanted biomaterials is rarely reported. Recently, adipose tissue was found to be an alternative source of MSC besides bone marrow. However, the strategy of using adipose-derived stromal (ADS) cells with bioactive scaffold for the repair of spinal bone defects has seldom been studied. ⋯ Adipose-derived stromal cells maintained in culture on a scaffold and treated with osteogenic induction with growth factor ex vivo could be used to enhance bone repair in vivo.
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Osteoconductive porous ceramic bone graft materials supplemented with mesenchymal precursor cells (MPC) derived from autologous bone marrow aspirates have been shown to stimulate successful interbody and posterolateral spine fusion in preclinical models. Recent advances in immunomagnetic cell sorting have enabled purification and isolation of pluripotent stem cells from marrow aspirates and have expanded stem cell technology to allogeneic cell sources. Allogeneic MPC technology combined with appropriate synthetic biomaterial carriers could provide both the osteogenic and osteoconductive components needed for successful posterolateral spine fusion without the need for autologous bone harvest or expensive recombinant protein technology. ⋯ Adult allogeneic mesenchymal precursor cells delivered via a hydroxyapatite:tricalcium phosphate carrier were both safe and efficacious in this ovine spine fusion model. Results from this preclinical study support that allogeneic mesenchymal precursor cells produced fusion efficacy similar to that achieved using iliac crest autograft, thereby providing a safe and viable option to achieve successful posterolateral spine fusion.