The mechanics of host cell repopulation of engineered tissues

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Project Summary/Abstract We propose to determine how the hemodynamic environment regulates the attachment, invasion, and differentiation of host cells into “off-the-shelf” decellularized tissue engineered heart valves (TEHVs). We hypothesize that dynamic mechanical stretch and fluid shear stress regulate repopulation of the TEHV matrix by enhancing and aligning 3D matrix adhesions and activating latent TGF-beta from the matrix. To test our hypothesis, biopolymer scaffolds seeded with fibroblasts will be cast in stretchable wells and microfluidic chambers until remodeled into isotropic or aligned neo-tissues and then decellularized in situ. We will then quantify the extent to which vascular and circulating cells adhere to and invade the matrix under cyclic stretch (Aim 1) and dynamic flow conditions (Aim 2) relevant to in vivo implantation. Cell attachment, infiltration, proliferation, apoptosis, phenotype, and endothelial-to-mesenchymal transition markers will be quantitatively monitored over time. TGF-beta activation and 3D matrix adhesion protein content and alignment will be examined, and associated signal transduction pathways will be interrogated to determine the mechanisms governing the cell responses. The results from this systematic study will have a direct impact on TEHV development by determining the signals that aid (or hinder) host cell repopulation of the valve matrix with the goal of optimizing valve design for adaptive remodeling under complex in vivo conditions.