Department of Bioengineering, University of Pennsylvania, Philadelphia, Pennsylvania19104, United States.
ACS Biomater Sci Eng. 2022 Apr 11;8(4):1427-1442. doi: 10.1021/acsbiomaterials.1c01440. Epub 2022 Mar 24.
Granular hydrogels are formed through the packing of hydrogel microparticles and are emerging for various biomedical applications, including as inks for 3D printing, substrates to study cell-matrix interactions, and injectable scaffolds for tissue repair. Granular hydrogels are suited for these applications because of their unique properties including inherent porosity, shear-thinning and self-healing behavior, and tunable design. The characterization of their material properties and biological response involves technical considerations that are unique to modular systems like granular hydrogels. Here, we describe detailed methods that can be used to quantitatively characterize the rheological behavior and porosity of granular hydrogels using reagents, tools, and equipment that are typically available in biomedical engineering laboratories. In addition, we detail methods for 3D cell invasion assays using multicellular spheroids embedded within granular hydrogels and describe steps to quantify features of cell outgrowth (e.g., endothelial cell sprouting) using standard image processing software. To illustrate these methods, we provide examples where features of granular hydrogels such as the size of hydrogel microparticles and their extent of packing during granular hydrogel formation are modulated. Our intent with this resource is to increase accessibility to granular hydrogel technology and to facilitate the investigation of granular hydrogels for biomedical applications.
颗粒状水凝胶是通过水凝胶微球的堆积形成的，正逐渐应用于各种生物医学领域，包括 3D 打印墨水、研究细胞-基质相互作用的基质以及用于组织修复的可注射支架。颗粒状水凝胶具有独特的性能，包括固有孔隙率、剪切变稀和自修复行为以及可调设计，非常适合这些应用。其材料性能和生物反应的表征涉及到一些技术方面的考虑，这些考虑因素对于颗粒状水凝胶等模块化系统来说是独特的。在这里，我们描述了详细的方法，可以使用通常在生物医学工程实验室中可用的试剂、工具和设备来定量表征颗粒状水凝胶的流变行为和孔隙率。此外，我们还详细介绍了使用嵌入颗粒状水凝胶中的多细胞球体进行 3D 细胞侵袭分析的方法，并描述了使用标准图像处理软件量化细胞外突（例如，内皮细胞发芽）特征的步骤。为了说明这些方法，我们提供了一些示例，其中调节了颗粒状水凝胶的一些特征，例如水凝胶微球的大小及其在颗粒状水凝胶形成过程中的堆积程度。我们希望这个资源可以增加颗粒状水凝胶技术的可及性，并促进颗粒状水凝胶在生物医学应用中的研究。
