i3S - Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Rua Alfredo Allen 208, 4200-135, Porto, Portugal; INEB - Instituto de Engenharia Biomédica, Universidade do Porto, Porto, Portugal.
i3S - Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Rua Alfredo Allen 208, 4200-135, Porto, Portugal; INEB - Instituto de Engenharia Biomédica, Universidade do Porto, Porto, Portugal; FEUP - Faculdade de Engenharia, Universidade do Porto, Porto, Portugal.
Biomaterials. 2021 Dec;279:121222. doi: 10.1016/j.biomaterials.2021.121222. Epub 2021 Oct 25.
Modular tissue engineering approaches open up exciting perspectives for the biofabrication of vascularized tissues from the bottom-up, using micro-sized units such as spheroids as building blocks. While several techniques for 3D spheroid formation from multiple cell types have been reported, strategies to elicit the extra-spheroid assembly of complex vascularized tissues are still scarce. Here we describe an injectable approach to generate vascularized dermal tissue, as an example application, from spheroids combining fibroblasts and endothelial progenitors (OEC) in a xeno-free (XF) setting. Short-term cultured spheroids (1 day) were selected over mature spheroids (7 days), as they showed significantly higher angiogenic sprouting potential. Embedding spheroids in fibrin was crucial for triggering cell migration into the external milieu, while providing a 3D framework for in-gel extra-spheroid morphogenesis. Migrating fibroblasts proliferated and produced endogenous ECM forming a dense tissue, while OEC self-assembled into stable capillaries with lumen and basal lamina. Massive in vitro interconnection between sprouts from neighbouring spheroids rapidly settled an intricate vascular plexus. Upon injection into the chorioallantoic membrane of chick embryos, fibrin-entrapped pre-vascularized XF spheroids developed into a macrotissue with evident host vessel infiltration. After only 4 days, perfused chimeric capillaries with human cells were present in proximal areas, showing fast and functional inosculation between host and donor vessels. This method for generating dense vascularized tissue from injectable building blocks is clinically relevant and potentially useful for a range of applications.
模块化组织工程方法为从底层向上构建血管化组织提供了令人兴奋的前景，使用微球等微尺寸单元作为构建块。虽然已经报道了多种从多种细胞类型形成 3D 微球的技术，但引发复杂血管化组织的额外球体组装的策略仍然很少。在这里，我们描述了一种可注射方法，以从结合成纤维细胞和内皮祖细胞（OEC）的微球中生成血管化的皮肤组织，作为示例应用，该方法在无动物（XF）环境中进行。与成熟的微球（7 天）相比，短期培养的微球（1 天）被选择，因为它们显示出更高的血管生成发芽潜力。将微球嵌入纤维蛋白中对于触发细胞迁移到外部环境至关重要，同时为凝胶外球体形态发生提供了 3D 框架。迁移的成纤维细胞增殖并产生内源性 ECM，形成致密的组织，而 OEC 自我组装成具有腔和基底膜的稳定毛细血管。来自相邻微球的芽之间的大量体外相互连接迅速形成复杂的血管丛。将纤维蛋白包埋的预血管化 XF 微球注射到鸡胚的尿囊膜中，会发育成具有明显宿主血管浸润的大组织。仅 4 天后，近端区域就出现了灌注的带有人类细胞的嵌合毛细血管，显示出宿主和供体血管之间快速而功能的吻合。这种从可注射构建块生成致密血管化组织的方法具有临床相关性，并且可能对一系列应用有用。
