Magnetic Nano Fiber Composite Materials To Repair Bone Defect Of Pathological Experiments

How to effectively and efficiently repair bone defects is the great challenge today. Due to their innate drawbacks, autograft and isograft bone substitute are not widely applied in the clinical application. Tissue engineering and regenerative medicine provide the efficient method for repairing bone defects. The design of the scaffold and assessment of bone regeneration capability in vitro and in vivo are the hot spot in field of bone tissue engineering.Polylactic acid is the biocompatible synthetic material and the FDA approved product for clinical application. Nano hydroxyapatite is the basic element of human normal bone and possesses superior bone conductivity and bone binding capability. Owing to the fact that bone could be considered as organic-synthetic material, polylactic acid and nano hydroxyapatite composite materials are drawing people’s increasing attention.Electrospinning technique could prepare the nanofibrous scaffold. The prepared scaffolds possess many advantages such as porosity, high aspect ratio, and so on. In addition, the scaffolds are able to mimic the geometrical size and microscopic structure of the natural extracellular matrix to the greatest extent. So scaffolds via electrospinning have been widely applied into tissue engineering.We prepared the composite scaffold by electrospinning of PDLLA solution containing both commercially nano hydroxyapatite (nHAP) and ferric oxide nanoparticles (γ-Fe2O3). Both nHAP and γ-Fe2O3were well distributed in the PDLLA fiber matrix. The diameter of the nanofibers were in the range of500～800nm. The fibers were randomly distributed in the scaffold and formed a porous and nanofibrous networkIn vivo assessment the bone formation capability revealed that all the samples could facilitate bone formation without conspicuous inflammation. However, the new bone formation was significantly enhanced on the magnetic composite scaffold. This suggested that this magnetic scaffold might be a relatively suitable scaffold for bone tissue engineering.In addition, we injected multiwall carbon nanotubes solution into subcutaneous tissue of back in healthy Balb/c mouse and tumor bearing Balb/c mouse. Then we evaluated the tissue distribution and long-term toxicity of multiwall carbon nanotubes in vivo and analyzed the effect of multiwall carbon nanotubes on tumor angiogenesis. Histological analysis revealed that the main organs including liver, spleen, lung, heart and kidney did not show conspicuous injury and multiwall carbon nanotubes had obvious inhibitory effects on tumor angiogenesis. This phenomenon was still needed our continuous efforts to explore its underlying mechanism.