Tissue engineered skeletal muscle is expected to treat muscle defects caused by trauma and disease. However, designing and manufacturing thick and complex tissue engineered skeletal muscle requires vascularization to ensure its internal cell viability and nutrient supply in vitro. In this article, we developed a set of Direct-Writing (DW) bio-printing procedure to manufacture a prevascularized composite construct with Human Umbilical Vein Endothelial Cell (HUVEC) and C2C12 cells for muscle tissue engineering application. We put the cells into the construct during the DW process to obtain the prevascularization and intend to promote its vascularization in vivo later. The constructs with cells or without cells were implanted respectively into nude mice back for 3 weeks, after which the mice healthily live for all the time and all the implants are tightly bonded to the host. From immunohistochemical analysis, CD31-positive blood vessels existed in the implanted samples with cells are more substantial than those without cells, but the implanted samples with HUVEC and C2C12 cells have much more number of small blood vessels distributing evenly. Moreover, the implants with cells, especially that with HUVEC and C2C12 cells, are able to get better fusion with the host skin and subcutaneous tissues. Histological analysis demonstrates that our DW-based constructs have the potential to be getting to vascularize the tissue engineered muscle.

中文翻译：

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血管组织复合材料的血管前复合构建体的直接书写过程和体内评价

组织工程化的骨骼肌有望治疗由外伤和疾病引起的肌肉缺陷。然而，设计和制造厚而复杂的组织工程骨骼肌需要血管化，以确保其内部细胞活力和体外营养供应。在本文中，我们开发了一套直接书写（DW）生物打印程序，以制造带有人脐静脉内皮细胞（HUVEC）和C2C12细胞的血管前复合结构，以进行肌肉组织工程应用。我们在DW过程中将细胞放入构建体中以获得预血管化，并打算在体内促进其血管化后来。将有细胞或无细胞的构建体分别移植回裸鼠3周，此后小鼠一直健康地生活，并且所有植入物都与宿主紧密结合。从免疫组织化学分析，有细胞的植入样品中存在的CD31阳性血管比没有细胞的CD31阳性血管要大，但是具有HUVEC和C2C12细胞的植入样品中的小血管数目要多得多。此外，带有细胞的植入物，尤其是带有HUVEC和C2C12细胞的植入物，能够更好地与宿主皮肤和皮下组织融合。组织学分析表明，我们基于DW的构建体具有使组织工程化的肌肉血管化的潜力。