Zhu Wenjuan, Han Xiaoning, Deng Linhong, Wang Xiang
Institute of Biomedical Engineering and Health Sciences, Changzhou University, 213164 Changzhou, Jiangsu, China.
School of Pharmacy, Changzhou University, 213164 Changzhou, Jiangsu, China.
ACS Omega. 2025 May 6;10(19):19675-19681. doi: 10.1021/acsomega.5c00639. eCollection 2025 May 20.
Tissue densification is a fundamental biological process involved in development, regeneration, and disease, significantly influencing tissue mechanics and cellular mechanical microenvironments. However, the effects of tissue densification on mechanical properties, the roles of key cytoskeletal components, and their responses to external mechanical stress remain poorly understood. In this study, fibroblast-collagen microtissues were cultured on polydimethylsiloxane (PDMS) microstring scaffolds with different mechanical constraints to generate low- and high-densification microtissues. High-precision indentation force sensor analysis demonstrated that increased densification enhanced microtissue stiffness, accelerated stress relaxation, and elevated energy dissipation. Pharmacological disruption of cytoskeletons revealed the critical role of F-actin in regulating stiffness and viscoelastic resistance in a densification-dependent manner: in high-densification microtissues, F-actin had a greater impact on stiffness and dissipated energy, but a reduced effect on stress relaxation. Furthermore, under 50% strain indentation, high-densification microtissues exhibited irreversible deformation and increased cellular injury. Injured regions showed reduced stiffness, shorter stress relaxation time constants, and higher energy dissipation, indicating structural and cellular damage. These results enhance our understanding of tissue mechanobiology by elucidating the interplay between tissue densification, cytoskeletal mechanics, and injury responses, providing valuable insights for optimizing tissue mechanical microenvironments and improving the mechanical compatibility of biomaterials.
组织致密化是一个涉及发育、再生和疾病的基本生物学过程，对组织力学和细胞机械微环境有显著影响。然而，组织致密化对力学性能的影响、关键细胞骨架成分的作用及其对外部机械应力的反应仍知之甚少。在本研究中，将成纤维细胞 - 胶原蛋白微组织培养在具有不同机械约束的聚二甲基硅氧烷（PDMS）微丝支架上，以生成低密度和高密度致密化微组织。高精度压痕力传感器分析表明，致密化程度增加会提高微组织的刚度、加速应力松弛并增加能量耗散。细胞骨架的药理学破坏揭示了F - 肌动蛋白在以致密化依赖方式调节刚度和粘弹性阻力方面的关键作用：在高密度致密化微组织中，F - 肌动蛋白对刚度和耗散能量的影响更大，但对应力松弛的影响较小。此外，在50%应变压痕下，高密度致密化微组织表现出不可逆变形并增加细胞损伤。损伤区域显示出刚度降低、应力松弛时间常数缩短和能量耗散增加，表明存在结构和细胞损伤。这些结果通过阐明组织致密化、细胞骨架力学和损伤反应之间的相互作用，增强了我们对组织机械生物学的理解，为优化组织机械微环境和提高生物材料的机械兼容性提供了有价值的见解。
