葡萄糖敏感及溫度敏感之可 3D 列印水凝膠犧牲材用於類血管網絡之應用

Abstract

血管化組織工程中最大的困境在於如何維持人工組織的血液循環，儘管現行已有許多文獻開發不同的血管化組織工程技術，但都各有侷限。在本篇論文中，類血管的組織是透過生醫高分子及工程由葡萄糖敏感及溫度敏感之可3D列印水凝膠犧牲材所製備而成。製備此犧牲材需共聚合溫度敏感的高分子（N-異丙基丙烯醯胺, NIPAM）、活性酯離去基團(丙烯酸五氟苯酯, PFPA)，並混合聚乙烯酯(PVA)形成水凝膠網絡，此外，添加少量的奈米纖維素至水凝膠犧牲材中調整其流變學性質以利3D列印。以流變學分析複合水凝膠犧牲材的流動性及熱敏感性可獲得最適合3D列印的比例，優化後的水凝膠犧牲材可透過一般的商用生物3D列印機以30 G(內徑為160 μm)的針頭列印。血管化組織的製程是將生醫高分子溶液澆鑄在3D列印的水凝膠犧牲材上或將水凝膠犧牲材直接列印在生醫高分子中，並利用水凝膠犧牲材葡萄糖敏感的特性，將生醫高分子泡入細胞培養液後，約5分鐘後，便可在生醫高分子內做出客製化的微管道，最後將血管內皮細胞注入生醫高分子內的客製化微管道，讓細胞沿著微管道生長，即可形成類血管網絡。希冀此論文發展出的葡萄糖敏感之可3D列印水凝膠犧牲材能有助於複雜人工組織的列印及血管化組織工程的發展。

A major challenge in vascular engineering is to fabricate 3D vascular constructs with proper blood circulation. In spite of the fact that many methods have been reported to generate vascular constructs, there remain some disadvantages. In this study, a hydrogel crosslinked by boronate ester bonds with 3D printability and self-healing ability was prepared as sacrificial materials to tailor tubular microchannels in a non-sacrificial gel. The preparation of the hydrogel involved the copolymerization of N-isopropylacrylamide for thermoresponsiveness, with pentafluorophenyl acrylate for post-modification, and poly(vinyl alcohol) for gel formation. Besides, cellulose nanofibrils was added to facilitate 3D printing of the hydrogel. The thermoresponsiveness and printability of the hydrogel were investigated by rheology. The optimized hydrogel could be successfully printed through a 30 G nozzle (inner diameter= 160 μm) by a commercial 3D bioprinter. To demonstrate the feasibility in fabricating 3D vascularized constructs, the sacrificial hydrogel was printed and a non-sacrificial gel was cast on the sacrificial hydrogel. This combined gel was immersed into culture medium to elute the sacrificial hydrogel. Interconnecting multichannels in the non-sacrificial gel were achieved in 5 min. Vascular endothelial cells (ECs) seeded in the microchannels of the construct were able to proliferate and attach. The glucose-sensitive, 3D printable sacrificial materials may create complex and easily removable 3D structures for the fabrication of precise vascularized constructs.