In situ tissue engineering is an emerging field aiming at the generation of ready-to-use three-dimensional tissues. One solution to supply a proper vascularization of larger tissues to provide oxygen and nutrients is the arteriovenous loop (AVL) model. However, for this model, suitable scaffold materials are needed that are biocompatible/non-immunogenic, slowly degradable, and allow vascularization. Here, we investigate the suitability of the known gelatin methacryloyl (GelMA)-based hydrogel for in-situ tissue engineering utilizing the AVL model. Rat AVLs are embedded by two layers of GelMA hydrogel in an inert PTFE chamber and implanted in the groin. Constructs were explanted after 2 or 4 weeks and analyzed. For this purpose, gross morphological, histological, and multiphoton microscopic analysis were performed. Immune response was analyzed based on anti-CD68 and anti-CD163 staining of immune cells. The occurrence of matrix degradation was assayed by anti-MMP3 staining. Vascularization was analyzed by anti-α-smooth muscle actin staining, multiphoton microscopy, as well as expression analysis of 53 angiogenesis-related proteins utilizing a proteome profiler angiogenesis array kit. Here we show that GelMA hydrogels are stable for at least 4 weeks in the rat AVL model. Furthermore, our data indicate that GelMA hydrogels are biocompatible. Finally, we provide evidence that GelMA hydrogels in the AVL model allow connective tissue formation, as well as vascularization, introducing multiphoton microscopy as a new methodology to visualize neovessel formation originating from the AVL. GelMA is a suitable material for in situ and in vivo TE in the AVL model.

原位组织工程是一个新兴领域，旨在生成即用型三维组织。为较大组织提供适当血管化以提供氧气和营养的一种解决方案是动静脉环 (AVL) 模型。然而，对于该模型，需要具有生物相容性/非免疫原性、可缓慢降解并允许血管化的合适支架材料。在这里，我们研究了已知的基于明胶甲基丙烯酰基 (GelMA) 的水凝胶对原位的适用性利用 AVL 模型的组织工程。大鼠 AVL 被两层 GelMA 水凝胶嵌入惰性 PTFE 室中，并植入腹股沟。构建体在 2 或 4 周后外植并分析。为此，进行了大体形态学、组织学和多光子显微镜分析。基于免疫细胞的抗CD68和抗CD163染色分析免疫反应。通过抗MMP3染色测定基质降解的发生。通过抗-α分析血管化- 平滑肌肌动蛋白染色、多光子显微镜检查，以及使用蛋白质组分析仪血管生成阵列试剂盒对 53 种血管生成相关蛋白的表达分析。在这里，我们表明 GelMA 水凝胶在大鼠 AVL 模型中至少稳定 4 周。此外，我们的数据表明 GelMA 水凝胶具有生物相容性。最后，我们提供证据表明 AVL 模型中的 GelMA 水凝胶允许结缔组织形成以及血管化，将多光子显微镜作为一种新方法来可视化源自 AVL 的新血管形成。GelMA 是AVL 模型中原位和体内TE的合适材料。