“软模板”法调控胶原的仿生矿化研究

Biomimetic mineralization of collagen fibers regulated with“soft template”

在模拟体内pH值=7.4的胶原溶胶-凝胶体系中,加入β-甘油磷酸钠(β-GP)作为矿化的磷源,并引入聚丙烯酸(PAA)和三聚磷酸钠(TPP)作为"软模板"模拟体内非胶原蛋白DMP-1的N端和C端的隔离功能域,调控Ⅰ型胶原的矿化,构建了纳米羟基磷灰石/胶原(n-HA/COL)复合支架材料。并以人脐带间充质干细胞hUMSCs作为种子细胞,探究了其对细胞的粘附、增殖、分化的影响。结果表明,胶原纤维组织与矿化同步进行,陈化处理有利于羟基磷灰石(HAp)晶体的结晶。自组装HAp纳米微粒不仅在胶原纤维外部沉积,也可以在原胶原分子上及胶原微纤维的末端被发现,同时纳米磷酸钙盐沿着胶原微纤维的圆柱形表面分布。细胞培养表明n-HA/COL并没有明显促进hUMSCs细胞的增殖,但能够诱导hUMSCs向成骨细胞分化,促进成骨细胞AKP的表达,并且nHA/COL复合支架材料与成骨诱导液(OICM)联用时诱导效果更加显著。这种以"bottom-up"深度矿化方法为骨支架材料的制备提供了新思路,n-HAp/collagen复合材料有望用于骨组织填充修复。

In this paper,polyacrylic acid(PAA)and sodium tripolyphosphate(TPP)were applied as'soft template'which simulated respectively as the N-and C-terminal domains of the non-collageneous proteins DMP-1in vivo to control the mineralization process of typeⅠcollagen.Experimental pH was settled at 7.4andβsodium glycerophospate was applied as the phosphorus scource.Nano-hydrixyapatite(HAp)/collagen scaffold(nHA/COL)was fabricated in this experiment.In addition,human umbilical cord mesenchymal stem cells(HUMSCs)were selected to study the effects of the materials on the cell adhesion,proliferation,and differentiation.Results showed that self-organization and minimization of the collagen fibers were simultaneous.The aging process contributed to the growth of HAp.Self-assembled HAp nanoparticles depositedboth on the external collagen fibres and the terminal of microfibrils.Nano-calcium phosphate crystals were distributed along the cylindrical surface of the collagen microfibrils.Cell culture showed that n-HA/COL did not significantly promote the proliferation of hUMSCs cells but can induce osteoblast differentiation and to promote AKP expression.Also,the osteogenic effect was more significant when n-HA/COL combined with OICM.This'bottom-up'method of deep mineralization provides a novel approach for preparation of bone compositescaffolds,and the n-HAp/collagen composite is expected to be used for bone repairing and regeneration.