Chen Ying-Chieh, Lin Ruei-Zeng, Qi Hao, Yang Yunzhi, Bae Hojae, Melero-Martin Juan M, Khademhosseini Ali
Department of Medicine, Center for Biomedical Engineering, Brigham and Women's Hospital, Harvard Medical School, Boston, MA 02115, USA.
Adv Funct Mater. 2012 May 23;22(10):2027-2039. doi: 10.1002/adfm.201101662. Epub 2012 Feb 21.
The generation of functional, 3D vascular networks is a fundamental prerequisite for the development of many future tissue engineering-based therapies. Current approaches in vascular network bioengineering are largely carried out using natural hydrogels as embedding scaffolds. However, most natural hydrogels present a poor mechanical stability and a suboptimal durability, which are critical limitations that hamper their widespread applicability. The search for improved hydrogels has become a priority in tissue engineering research. Here, the suitability of a photopolymerizable gelatin methacrylate (GelMA) hydrogel to support human progenitor cell-based formation of vascular networks is demonstrated. Using GelMA as the embedding scaffold, it is shown that 3D constructs containing human blood-derived endothelial colony-forming cells (ECFCs) and bone marrow-derived mesenchymal stem cells (MSCs) generate extensive capillary-like networks in vitro. These vascular structures contain distinct lumens that are formed by the fusion of ECFC intracellular vacuoles in a process of vascular morphogenesis. The process of vascular network formation is dependent on the presence of MSCs, which differentiate into perivascular cells occupying abluminal positions within the network. Importantly, it is shown that implantation of cell-laden GelMA hydrogels into immunodeficient mice results in a rapid formation of functional anastomoses between the bioengineered human vascular network and the mouse vasculature. Furthermore, it is shown that the degree of methacrylation of the GelMA can be used to modulate the cellular behavior and the extent of vascular network formation both in vitro and in vivo. These data suggest that GelMA hydrogels can be used for biomedical applications that require the formation of microvascular networks, including the development of complex engineered tissues.
功能性三维血管网络的生成是未来许多基于组织工程的治疗方法发展的基本前提。目前血管网络生物工程的方法主要是使用天然水凝胶作为嵌入支架。然而，大多数天然水凝胶的机械稳定性较差，耐久性也不理想，这些关键限制阻碍了它们的广泛应用。寻找改良的水凝胶已成为组织工程研究的当务之急。在此，证明了可光聚合的甲基丙烯酸明胶（GelMA）水凝胶支持基于人祖细胞的血管网络形成的适用性。使用GelMA作为嵌入支架，结果表明，包含人血源性内皮集落形成细胞（ECFCs）和骨髓源性间充质干细胞（MSCs）的三维构建体在体外可生成广泛的毛细血管样网络。这些血管结构包含由ECFC细胞内液泡在血管形态发生过程中融合形成的独特管腔。血管网络的形成过程依赖于MSCs的存在，MSCs可分化为占据网络腔内位置的周血管细胞。重要的是，研究表明，将负载细胞的GelMA水凝胶植入免疫缺陷小鼠体内会导致生物工程化的人血管网络与小鼠脉管系统之间迅速形成功能性吻合。此外，研究表明，GelMA的甲基化程度可用于在体外和体内调节细胞行为以及血管网络形成的程度。这些数据表明，GelMA水凝胶可用于需要形成微血管网络的生物医学应用，包括复杂工程组织的开发。
