The Experimental Study Paramagnetic Fiber Composites Induced Bone Defect Repair

Bone defect can be caused by many reasons, such as trauma, infection, tumor and congenital malformation. Autografts, allografts, ceramic and synthetic polymers have been used as implant materials for bone repair and remodeling. Among these substitutes, autografts have been accepted as a golden standard. However, current existing bone substitute materials still have their own drawbacks that make them not able to meet clinical requirements. Hence artificial substitutes with improved osteoinduction and osteoconduction are still in need urgently.In this work, a novel paramagnetic nanofibrous composite scaffold with porous architecture was fabricated with poly lactide acid, hydroxyapatite nanoparticles and paramagnetic y-Fe2O3nanoparticles using electrospinning technique. As a composite, each of the elements involved in the scaffold played certain roles. The nanofibres of poly lactide acid organized a biocompatible and biodegradable nanofibrous scaffold for cells, the architecture mimicking natural extracellular matrix. Hydroxyapatite nanoparticles offer the scaffold osteoconduction, and paramagnetic y-Fe2O3nanoparticles provide paramagnetic property to the scaffold.The scaffold capacity of inducing bone regeneration and remodeling in situ under an applied magnetic field was investigated in white rabbit model of lumbar transvers defect using radiological analysis of CT, micro CT and pathological analysis. Autogenous iliac bone graft was taken as a control. Biocompatibility of the scaffold was assessed in aspect of systemic reaction and tissue reaction. Total protein, ALT, GGT and Cr in serum post implant surgery were examined. Morphologies of the liver and kidney were studied by pathological observation.Experimental results indicated:(1) The scaffold was degraded gradually post surgery when monocyte-macrophage as well as osteoblast cells were recruited and surrounded the scaffold. The deposition of new matrix and new vessels were observed on day10after scaffold implantation. Applied magnetic field enhanced the inducing osteogenesis effect of the scaffold and increased new bone tissue formation and remodeling.(2) The scaffold exhibited good compatibility when implanted in the bone defect. No significant evidence was detected showing biologic toxicity. Nutritional level, body weight, ALT level, GGT level and Cr level in serum of the animals were within normal limit after received the scaffold implantation. No significant pathological changes of kidney and liver were observed. No severe tissue reaction which may affect the bone remodeling and healing was noticed after the implantation.