Abstract
Understanding relationships between mechanical stimuli and cellular responses require measurements of evolving tissue structure and mechanical properties. We developed a 3D tissue bioreactor that couples to both the stage of a custom multimodal microscopy system and a biaxial mechanical testing platform. Time dependent changes in microstructure and mechanical properties of fibroblast seeded cruciform fibrin gels were investigated while cultured under either anchored (1.0:1.0 stretch ratio) or strip biaxial (1.0:1.1) conditions. A multimodal nonlinear optical microscopy-optical coherence microscopy (NLOM-OCM) system was used to delineate noninvasively the relative spatial distributions of original fibrin, deposited collagen, and fibroblasts during month long culture. Serial in-culture mechanical testing was also performed to track the evolution of bulk mechanical properties under sterile conditions. Over the month long time course, seeded cells and deposited collagen were randomly distributed in equibiaxially anchored constructs, but exhibited preferential alignment parallel to the direction of the 10% stretch in constructs cultured under strip biaxial stretch. Surprisingly, both anchored and strip biaxial stretched constructs exhibited isotropic mechanical properties (including progressively increasing stiffness) despite developing a very different collagen microstructural organization. In summary, our biaxial bioreactor system integrating both NLOM-OCM and mechanical testing provided complementary information on microstructural organization and mechanical properties and, thus, may enable greater fundamental understanding of relationships between engineered soft tissue mechanics and mechanobiology.
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This work was supported, in part, by the National Science Foundation (CBET-1033660 to A.T.Y and CMMI-1161423 to J.D.H.) and National Institutes of Health (R01 EB-008836 to L.E. Niklason and J.D.H.).
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Associate Editor Sean S. Kohles oversaw the review of this article.
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Bai, Y., Lee, PF., Humphrey, J.D. et al. Sequential Multimodal Microscopic Imaging and Biaxial Mechanical Testing of Living Multicomponent Tissue Constructs. Ann Biomed Eng 42, 1791–1805 (2014). https://doi.org/10.1007/s10439-014-1019-3
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DOI: https://doi.org/10.1007/s10439-014-1019-3