取向性仿生双相磷酸钙支架的制备、结构评价和初步应用

目的利用三维凝胶叠层成型法(3DGellamination)制备出取向性仿生双相磷酸钙生物陶瓷支架,并在体外对支架的结构进行三维重建和相关评价。方法2003年11月至2005年3月,以犬股骨头的松质骨样本显微CT(MicroCT)图像为基础,提取其中的图像信息,利用三维凝胶叠层成型法制备出具有仿骨小梁结构的双相磷酸钙(BCP)仿生生物陶瓷支架。随后对支架进行MicroCT扫描,用三维结构参数对支架和松质骨样本进行三维评价和比较。并利用体外细胞培养技术观察细胞在支架表面的生长情况。同时将复合骨髓间充质细胞的支架植入股骨头负重区的骨缺损内,初步观察其治疗效果。结果本方法制备出的股骨头仿生支架具有良好的三维空间结构,支架小梁具有一定的方向性,呈板状模型,其轴向方向的弹性模量和强度分别达到(464.0±36.0)MPa和(5.6±0.8)MPa。细胞在支架表面大量生长。动物实验结果表明,支架与周围骨床结合紧密,骨质沿支架小梁表面生长。结论本研究制备的BCP多孔支架的小梁具有一定的取向性,支架具有良好的生物相容性、一定的力学强度和良好的适于血管长入的空间结构。

The preparation, structure evaluation and preliminary application of biomimetic biphasic calcium phosphate scaffold

OBJECTIVE: To fabricate biomimetic biphasic calcium phosphate BCP ceramic scaffolds using three-dimensional (3D) gel-lamination technology and evaluated their structure with 3D parameters and related method. METHODS: Series two-dimensional images of femoral head's specimen of dogs were obtained by micro-computed tomography (Micro-CT). According to these images, porous biomimetic biphasic calcium phosphate (BCP) ceramic scaffolds with oriented trabecular structure were fabricated by three-dimensional (3D) gel-lamination technology. And then, the three-dimensional structure of the scaffolds were reconstructed by computer according to Micro-CT images of these scaffolds and evaluated by three-dimensional parameters. These parameters included bone volume fraction (BVF, BV/TV), bone surface/bone volume (BS/BV) ratio, trabecular thickness (Tb.Th), trabecular number (Tb.N), trabecular spacing (Tb.Sp) and structure model index (SMI). The biomechanical properties and biocompatibility of these scaffolds were also evaluated in the study. Six scaffolds, which were combined with BMCs (bone mesenchymal cells, BMCs), were planted into the bone defect of six dogs' femoral head respectively. RESULTS: There was no significant difference between trabecular samples and BCP scaffolds in BV/TV, Tb.Th, Tb.N, and Tb.Pf (P > 0.05). The trabecular system of the scaffold, which had some orientation, represented plate-like model. With a micro-porous porosity of 62%, the average compressive modulus and ultimate strength along the axis of the scaffolds reached (464.0 +/- 36.0) MPa and (5.6 +/- 0.8) MPa respectively. The results of animal test indicated that the trabeculae of these scaffolds were covered by a layer of new bone after 10 weeks of operation. CONCLUSION: Porous BCP scaffolds have been produced with oriented microarchitectural features designed to facilitate vascular invasion and cellular attachment and with initial mechanical properties comparable to those of trabecular bone.