基于仿骨基质功能的凝胶优化及类血管网络设计的血管化组织工程骨构建

The vascularization in bone tissue engineering remains a big challenge. As the supply of oxygen and nutrients to the implant is often limited by insufficient vascularization, and normal cell functions are affected due to the weak bioactivity of the scaffold. Vascularization and scaffold bioactivity are keys to the success of traditional engineering bone tissue. This research aims to induce the vascularization of engineered bone tissues by combining the functional biomimetic bone maxtric and preconstruction of vascular network. The osteogeneic function of cells is abtained from the biomimetic of bone maxtric, meanwhile the "vascular-like structure" fibres provide the edothelial cells an scaffold to form blood vessels in the bone matrix, following the degradation of fibres and the expression of cell functions. The design of mimicking bone maxtric: the chemical enviroment for cell adhesion or differentiation can be abtained by peptide modified Alginate(Alg) and the cell adhesive activity of Collagen(Col). This complex scaffold possed stable mechanical properties at first, and the "rigid" network of Alg will prevent from the constraction when Col degrades, then the graded degradation of hydrogel network mediated by MMPs originated from cells will creat cavities for cell spreading and differentiation. The design of vascular-like structure: it is consisted of collagen microfibers where endothelial cells are seeded on,then fibers degrades in osteoblast contained bone-like matrix,resulting in the formation of vessel-like network. With interactive between the endothelial contained network and functional expressions of osteoblast, the regeneration of this tissue will be enhanced.

血管化是骨组织工程领域研究的焦点。由于血管化不足造成细胞供养障碍，以及支架生物活性不足影响细胞的正常功能表达，是传统组织工程骨再生失败的关键。本研究结合骨基质仿生与血管网络的预构建实现血管化组织工程骨的构建：骨基质仿生赋予其中细胞好的成骨功能，镶嵌于其中的接种血管内皮细胞的纤维行使"血管化"功能，纤维的降解及细胞功能的表达形成具有内在血管化结构的骨仿生结构。仿骨基质设计：胶原（Col）的细胞粘附活性和多肽修饰的海藻酸钠（Alg）模拟细胞成骨的化学环境；复合凝胶具有一定初始力学强度，Alg的刚性防止胶原降解产生的收缩性，细胞分泌的MMP酶介导的凝胶网络降解调控细胞铺展的空间促进细胞分化。仿血管结构设计：基于Col纺丝的微纤维接种血管内皮细胞获得"仿血管"结构，利用其在含成骨细胞的"仿骨基质"水凝胶中的降解，形成类血管网络。含内皮细胞的网络与成骨细胞功能的表达将互相促进，增强组织再生能力。

血管化是骨组织工程领域研究的焦点。由于血管化不足造成细胞供养障碍，以及支架生物活性不足影响细胞的正常功能表达，是传统组织工程骨再生失败的关键。本研究基于骨基质仿生功能设计以及血管网络的预构建，成功实现了血管化组织工程骨的仿生构建：骨基质仿生赋予其中细胞优良的成骨功能，镶嵌于其中的接种血管内皮细胞的纤维的降解，及血管内皮细胞的功能表达，成功实现了 “血管化”功能的仿生。通过材料设计及细胞粘附位点的引入，以及恰当的酶引入诱导的可控降解，获得了既具有一定力学强度又具有可控的细胞铺展空间形成的基质设计，有效促进细胞增殖与功能表达；基于胶原纺丝的微纤维接种血管内皮细胞成功获得“仿血管”结构，酶的引入及细胞自身分泌酶的调控可有效降解纤维，实现 “仿骨基质”水凝胶中的血管通路的形成。血管通路的构建协同作用于成骨细胞，显著改善了仿骨构建体的成骨功能表达。