血管组织工程用可降解磷脂聚氨酯支架及其对细胞行为的影响

To reveal the role of phospholipid polymer in regeneration of vascular tissues, especially, the effects on immune cells that play a key role in the regeneration, phospholipid polyurethanes will herein be employed to investigate their influences on blood immune cells, which can largely improve patency of synthetic vascular grafts because of their excellent hemocompatibility. Thus, novel biodegradable phospholipid polyurethanes as surface modifying macromolecules will be designed, synthesized, and characterized. These phospholipid polyurethanes will be blended into waterborne biodegadable polyurethanes for vascular tissue engineering scaffolds. A series of three-dimensional interconnected porous scaffolds will be fabricated using the biodegradable phospholipid polyurethane blends by freeze-drying. Their properties, such as pore size, antithrombogenicity, matching with native vessel compliance, biodegradable rate, and mechanical properties, will be controlled by varying the ratios of the phospholipid polyurethane and waterborne biodegradable polyurethane in these blends, concentrations of these blends emulsions and process to obtain optimal scaffolds of these phospholipid polyurethane blends. The interaction between cells and these obtained scaffolds will be comprehensively studied in vitro, including monocyte-derived macrophages (MDM), endothelial cells (ECs) and vascular smooth muscle cells (VSMCs). The influences of the obtained scaffolds and their degradation products on the MDM phenotype will be assessed by assaying cell attachment, activation (intracellular protein expression, esterase and acid phosphatase (AP) activity) as well as pro- and anti-in?ammatory cytokines (TNF-a? and IL-10, respectively) to verify a low in?ammatory, high wound-healing phenotype monocyte, and the negative effects of the foreign body reaction induced by phospholipids in these scaffolds. Also, the interactive co-cellular response of MDM and VSMCs (or ECs) onto the novel biodegradable phospholipid polyurethane scaffolds will be investigated to evaluate that the phospholipid functional groups and their contents onto the scaffolds impact on these functional cells behaviours in regeneration of vascular tissues , in particular, on MDM phenotype. Finally, we are able to explore the mechanism that the wound-healing phenotype MDM induced by phospholipid polyurethanes scaffolds can promote appropriate functional phenotypes of VSMCs and ECs. The goal of this project is to optimize biomaterial chemistry for applications in small diameter vascular tissue engineering.

旨在揭示磷脂聚合物在血管组织再生过程中所起的作用，特别是对在血管组织再生中起重要作用的免疫细胞的影响。本课题以具有优异抗凝血性能，能大大提高人工血管通畅率的磷脂聚合物为研究对象,设计、制备可完全生物降解的磷脂聚氨酯，将其作为表面改性大分子与水性可降解聚氨酯共混，用冷冻干燥法制备三维多孔支架，通过调节各组分比例、溶液浓度、制备工艺等控制支架的孔结构、力学性能及降解速度，获得具有优异抗凝血性能，与天然血管相近的力学顺应性，降解速率可调控的人工血管组织工程支架。采用体外细胞培养分别研究磷脂聚氨酯支架及其降解产物对单核/巨噬细胞表型的影响，对内皮细胞和平滑肌细胞生长的影响，以及细胞对支架降解的影响。并通过细胞共培养，研究支架上不同功能细胞之间的相互作用。探讨支架中磷脂及其含量对血管组织再生功能细胞的影响，尤其是对单核/巨噬细胞行为的影响，为小血管组织工程支架的设计提供有益的理论基础和科学依据。

本研究获得了一系列力学性能较好、乳液稳定的、生物安全性更高的LDI型生物可降解水性聚氨酯，并在此聚氨酯结构中引入仿细胞膜结构磷脂酰酰胆碱。通过冷冻干燥法和静电纺丝制备得到了多种结构的三维多孔支架，可达到软组织修复所要求的强度，适用于各类软组织工程修复使用。此LDI型生物可降解水性聚氨酯材料表面具有良好的亲水性，从而具有优良的抗蛋白吸附能力，几乎不粘附和激活血小板，具有优良的血液相容性。此LDI型聚氨酯膜和支架均有良好的细胞相容性，降解产物无毒，适宜各种细胞生长，且在急性炎症期其能有效的促进巨噬细胞从促炎型M1向修复型M2转变，促进组织的修复和再生。LDI型生物可降解聚氨酯支架用于脑组织的修复，能够促进神经轴突再生，且有新生的小血管的生成。此系列可降解聚氨酯支架在肌腱，神经、脊髓等器官及组织修复方面展现出了巨大的潜力。