Center for Biomedical Engineering, Brown University, Providence, RI, 02912, USA.
School of Engineering, Brown University, Providence, RI, 02912, USA.
Biomaterials. 2021 Mar;270:120684. doi: 10.1016/j.biomaterials.2021.120684. Epub 2021 Jan 20.
Mechanical forces are an essential element to early tissue formation. However, few techniques exist that can quantify the mechanical microenvironment present within cell-dense neotissues and organoid structures. Here is a versatile approach to measure microscale, cellular forces during mesenchymal condensation using specially tailored, hyper-compliant microparticles (HCMPs). Through monitoring of HCMP deformation over both space and time, measurements of the mechanical forces that cells exert, and have exerted on them, during tissue formation are acquired. The current study uses this technology to track changes in the mechanical microenvironment as mesenchymal stem cells self-assemble into spheroids and condense into cohesive units. An array analysis approach, using a high-content imaging system, shows that cells exert a wide range of tensile and compressive forces during the first few hours of self-assembly, followed by a period of relative equilibrium. Cellular interactions with HCMPs are further examined by applying collagen coating, which allows for increased tensile forces to be exerted compared to non-coated HCMPs. Importantly, the hyper-compliant nature of our force sensors allows for increased precision over less compliant versions of the same particle. This sensitivity resolves small changes in the microenvironment even at the earliest stages of development and morphogenesis. The overall experimental platform provides a versatile means for measuring direct and indirect spatiotemporal forces in cell-dense biological systems.
机械力是早期组织形成的一个重要因素。然而，目前能够定量分析细胞密集型新生组织和类器官结构中机械微环境的技术很少。本文介绍了一种通用的方法，使用特制的超顺应性微颗粒（HCMP）来测量间充质凝聚过程中的微尺度细胞力。通过监测 HCMP 在空间和时间上的变形，可以获取细胞在组织形成过程中施加和受到的机械力的测量值。本研究使用该技术跟踪细胞自组装成球体并凝聚成有凝聚力的单位时机械微环境的变化。使用高内涵成像系统的阵列分析方法表明，细胞在自组装的最初几个小时内会施加广泛的拉伸和压缩力，随后会进入相对平衡的阶段。通过施加胶原涂层进一步研究了细胞与 HCMP 的相互作用，这使得与未涂层的 HCMP 相比，可以施加更大的拉伸力。重要的是，我们的力传感器的超顺应性允许在早期发育和形态发生阶段提高对微环境微小变化的检测精度。总体实验平台为测量细胞密集型生物系统中的直接和间接时空力提供了一种通用的方法。
