Mechanical Properties of Collagen-Fibrin Co-Gels

Achieving desired mechanical properties is critical to meeting the functional requirements of engineered tissues. Mechanical function is inextricably linked to tissue structure. For example, replacement of fibrin with collagen during the healing process results in compositional heterogeneity which governs mechanical strength and function. Artificial tissues engineered using biopolymers such as fibrin and collagen can undergo a remodeling process that produces a compositionally and structurally complex tissue equivalent (TE) with anisotropic mechanical properties. TE functionality is assessed in part through mechanical testing, but the TE response is dependent on multi-scale interactions, which are dependent on a heterogeneously distributed microstructure, and are therefore difficult to interpret. In order to unravel the coupling between TE microstructure and macroscopic mechanical behavior, we have developed a multi-scale modeling framework for incorporating single component microstructural networks [1]. To expand our modeling framework, it is necessary to incorporate interpenetrating fibrin and collagen networks. This issue is particularly critical towards understanding the remodeling process that occurs in fibrin gels, which gradually replace fibrin with collagen networks. In this work, we have begun to investigate interpenetrating fibrin-collagen co-gels by varying the co-gel composition and subjecting the gels to uniaxial mechanical tests [2]. This study lays the experimental foundation for determining how to construct interpenetrating networks for our multiscale modeling framework, which will ultimately allows us to better assess and predict TE mechanics and produce better engineered tissues.