基于3D生物打印构建杂化式组织工程气管的实验研究

From the clinical point of tracheal transplantation, the innovative research aims at developing bionic and contronable tracheal grafts with good property of bioactivity, micro-structure, and mechanical performance, which is the fundamental scientific issue to fulfill the precise and customized needs in tracheal repair and reconstruction.3D bioprinting has been regarded as a bridge to achieve rapid translational application from bench to bedside, which will be the most promising approach when combined with bionic tissue engineering and regeneration medicine. .This project includes three parts: (1) to fabricate a porous tubular substitute (PTS) by 3D bioprinting and locally inject the sustained delivery carrier loaded with SDF-1/ hBMP-2/ MNCs in order to promote tissue regeneration during transplantation.（2) to integrate the printed “C-type” half-pipe bellow scaffold with the decellularized allogenic tracheal matrice to develop the type 1 hybrid graft. The scaffold provides radial force for strengthening the compressive property to alleviate the corruption of integrity and the decreasing of mechanical strength, which effectively prevents the graft from softening and collapse after transplantation to the greatest extent;(3) to prefabricate the type 2 hybrid graft composed of polymers,cells and growth factors in a layer-by-layer fashion. This printed hybrid graft would show its own appropriate bioactivities ,mechanical properties and regeneration potential. Dynamic observation and functional assessment of the reconstructed tracheas will be conducted afterwards.

从气管移植的临床角度看，创新研究出仿生可控，兼具良好生物活性、适宜微观结构和足够机械强度的气管替代物，是气管修复重建真正实现精准化和个性化需求的基本科学问题。3D 生物打印是组织工程研究实现快速临床转化的桥梁技术，是气管替代物研制最具探索价值的学术方向。本课题拟开展：（1）采用3D打印制备网孔结构管状替代物，移植术中局部注射负载干细胞和生长因子的水凝胶缓释体促进组织再生。（2）由3D打印“C”型半管波纹支架，将其与脱细胞同种异体基质进行整合，制备杂化式Ⅰ型气管替代物。该支架从外围加强基质的径向支撑力即抗压性能，弥补脱细胞所导致的基质结构完整性破坏和机械力下降，最大限度防止移植术后替代物软化与塌陷。（3）采用3D打印结合静电纺丝技术，将聚合物材料与富含生长因子的细胞悬液交替打印，构建出具有良好生物活性、适宜机械强度和再生潜力的杂化式Ⅱ型气管替代物，对移植术后再生气管进行动态观察和功能评价。

从气管移植的临床角度看，创新研究出仿生可控，兼具良好生物活性、适宜微观结构和足够机械强度的气管替代物，是气管修复重建真正实现精准化和个性化需求的基本科学问题。基于3D生物打印，将组织工程、再生医学与同种异体移植有机整合，利用3D生物打印的可控设计和仿生制造，研制杂化式（hybrid）气管替代物，在确保生物活性与生物安全性的前提下，不仅可解决同种异体移植术后免疫排斥、再血管化和上皮再生等难题，而且能够解决脱细胞同种异体机械力学性能与受体组织相匹配以及供体短缺等问题，从而在结构和功能上实现气管替代物的研制与应用。.本项目主要解决的关键技术与创新点如下：.（1） 3D打印PCL多孔气管支架具有与新鲜气管相似的形态结构、良好的生物力学性能，其性能与孔径大小成反比。气管支架的孔径结构有利于细胞的粘附与增殖，3D打印气管管壁适宜的孔径大小为200 μm。表面修饰有助于改善PCL材料的亲细胞性，经纳米二氧化硅修饰后的3D打印气管具有良好的生物相容性和较低的免疫原性。.（2）改良DEM方案脱细胞循环经2个周期后，气管基质的生物力学指标与原生气管相似，且具有优良的生物相容性能和较低的免疫原性。本改良脱细胞方案具有制备周期短、节约成本、污染风险小等优点。.（3）20% Pluronic F-127水凝胶可作为支持BMSCs增殖及分化的适宜载体。Pluronic F-127水凝胶富含生长因子或诱导液会更有利于细胞进一步生长与分化。3D打印多孔气管支架经20% Pluronic F-127修饰后，具有优良的生物相容性。.（4）3D打印多孔气管补片（杂化式Ⅰ型气管替代物）结合富有BMSCs及生长因子的水凝胶载体，成功地构建了气管局部窗形缺损修补的动物模型。经Pluronic F-127修饰后的3D打印多孔“C”形外支架与脱细胞基质有机结合制作的杂化式气管替代物，成功地构建了气管节段缺损修复的动物模型。.（5）采用3D生物打印结合静电纺丝技术，制备组织工程补片（杂化式Ⅱ型气管替代物）及其动物模型构建（进行中）。