Sensitive detection of cell-derived force and collagen matrix tension in microtissues undergoing large-scale densification.
Proc Natl Acad Sci U S A 2021;
118:2106061118. [PMID:
34470821 DOI:
10.1073/pnas.2106061118]
[Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Mechanical forces generated by cells and the tension of the extracellular matrix (ECM) play a decisive role in establishment, homeostasis maintenance, and repair of tissue morphology. However, the dynamic change of cell-derived force during large-scale remodeling of soft tissue is still unknown, mainly because the current techniques of force detection usually produce a nonnegligible and interfering feedback force on the cells during measurement. Here, we developed a method to fabricate highly stretchable polymer-based microstrings on which a microtissue of fibroblasts in collagen was cultured and allowed to contract to mimic the densification of soft tissue. Taking advantage of the low-spring constant and large deflection range of the microstrings, we detected a strain-induced contraction force as low as 5.2 µN without disturbing the irreversible densification. Meanwhile, the microtissues displayed extreme sensitivity to the mechanical boundary within a narrow range of tensile stress. More importantly, results indicated that the cell-derived force did not solely increase with increased ECM stiffness as previous studies suggested. Indeed, the cell-derived force and collagen tension exchanged dramatically in dominating the microtissue strain during the densification, and the proportion of cell-derived force decreased linearly as the microtissue densified, with stiffness increasing to ∼500 Pa. Thus, this study provides insights into the biomechanical cross-talk between the cells and ECM of extremely soft tissue during large-extent densification, which may be important to guide the construction of life-like tissue by applying appropriate mechanical boundary conditions.
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