Study Of Chitosan And Calcium Phosphate Cement With RhBMP-2 Composite In Rabbit Anterior Lumbar Intervertebral Fusion

Objective:The purpose of the study is to observe the effects of Chitosan(CS)-Calcium Phosphate Cement(CPC) with rhBMP-2 as a composite in rabbit anterior lumbar intervertebral fusion.Methods:The scaffold of chitosan-calcium phosphate cement was produced and taken into rhBMP-2 solution,followed by vacuum aspiration and freeze-drying.The porosity and compressive strength of chitosan-calcium phosphate with rhBMP-2 scaffold were measured,and its microstructure was observed via scanning electron microscopy.The scaffolds were implanted intramuscularly,after 4 weeks,the samples were analyzed by histological examination.At the same time New Zealand white rabbits were operated on anterior lumbar intervertebral fusion:the lumbar intervertebral discs were removed and replaced by autografts or scanfolds according to the following four groups:A,autografts.B,CS-CPC.C,CS-CPC/rhBMP-2.D,no implantation.The anterior lumbar intervertebral fusion was evaluated with radiographs analysis, histological examination,and biomechanical testing 12 weeks later.Results:The porosity ofCS-CPC/rhBMP-2 scaffold was 87%,its pore diameter was over 100μm,and modulus of elasticity was 20 MPa.Scanning electron microscope showed that the scaffold had an interconnected pore structure.Four weeks later,we can see microscopic bone formations by histological examination.After 12 weeks,the rabbits in group A and C achieved solid spinal fusion.Fusions achieved in group C were as biomechanically stronger as than those of in group A.The rabbits in group B and D were not found fusions.Conclusion:The CS-CPC/rhBMP-2 scaffold is a three-dimensional porous scaffold,with good biocompatibility,and it is a good bone graft substrate candidate for bone tissue engineering scaffold for lumbar spinal fusion.