多通道挤出3D生物打印血管化骨支架用于长骨大段骨缺损的修复

Rapid reconstruction of vascularized network in the large defect of long bone is a crucial parameter in maintaining cellular survival and enhancing bone repair. Vascularized bone scaffolds on the basis of growth factor stimulation, dynamic regulation, cell co-culture, and arteriovenous circulation in vivo are difficult to provide adequate blood and nutrients for bone tissue repair in a short period of time, which seriously limits their application. The current study intends to fabricate the vascularized bone scaffold with stable interface interaction through multichannel extrusion 3D bioprinting, meantime effectively mimic the hierarchical characteristics of native tissue by regulating the physical/biological properties of bone- and vascular-mimetic inks. In addition, synergistic effect of tissue-specific delivery of bone morphogenetic protein and vascular endothelial growth factor on osteogenesis and vascularization in vitro will be investigated. Finally, the strength of shear-thinning hydrogels, the design of complex microvascular morphology, and the flow rate of microfluidic perfusion are systematically investigated for further improving the permeability coefficient and differentiation level of vascular endothelial cells. The intrinsic mechanism that promoted the regeneration of macrovessels and microvascular network simultaneously provides theoretical guidance and technical support for the preparation of high-performance vascularized bone scaffold to meet more clinical requirements.

长骨大段骨缺损中血管化网络结构的快速重建是维持细胞存活和增强骨修复的关键因素。基于生长因子刺激、动态调节、细胞共培养及体内动静脉循环等方法获得的血管化骨支架，仍然很难在短时间内提供充足的血液及营养物质促进骨修复，从而限制其应用。本项目拟基于多通道挤出3D生物打印技术制备具有连续稳定界面作用的血管化骨支架，并通过调控骨/血管仿生生物墨水的物理及生物学性能，有效模拟血管化骨组织的复合多层次结构。同时，实现双生长因子骨形态蛋白和血管内皮生长因子在复合支架中不同动力学特征的组织特异性可持续释放，并对其促进骨修复及血管形成的协同作用机理进行验证。深入揭示剪切变稀水凝胶的强度、微血管形貌设计及微流体灌注流速对血管内皮细胞扩散渗透系数和分化水平的影响，弄清血管化骨支架中大血管和内皮化微血管同时再生的内在机理，为构建满足更多功能需求的血管化骨支架提供理论基础与技术支持。

由骨肿瘤、创伤和其他骨疾病导致的长骨大段骨缺损不易自我修复，至今仍然是临床上亟需解决的难题。目前报道的骨组织工程支架存在着血液、氧气以及营养物质供应不足的问题，无法有效满足长骨大段骨缺损修复的需求。为了解决当前骨组织工程支架中的局限性，本项目按照预期研究计划，顺利开展了以下主要工作：（1）研究了微血管通道结构与血管化程度的“构效”关系，开发了一种具有仿生分层微结构的骨免疫调节3D生物打印支架用于促进长骨大段骨缺损修复；（2）提出了高分子纳米药物与基因工程结合的新思路，构建了一种具有可控基因释放及表达能力的电活性支架，用于促进桡骨缺损的高效率愈合；（3）建立了基于多层静电纺丝纤维膜的高性能化组织修复新平台，实现了活体组织成像诊断与治疗-修复一体化的高效协同；（4）发展了双仿生超分子网络新材料，构建了一系列具有良好湿态组织粘附能力的水凝胶用于促进组织修复与再生；（5）设计了极端条件下可耐低温的双网络水凝胶支架，并结合刺激响应性智能高分子纳米材料实现在骨组织修复中的多功能性应用。在本项目的资助下，以第一/通讯作者身份在国际高水平发表SCI论文16篇（10分以上有12篇），授权国家发明专利9项。研究成果为新一代长骨大段骨缺损治疗的骨组织工程支架提供了新思路新手段，也有助于推动血管化骨支架在骨科实际临床的应用步伐。