Methacrylated recombinant collagen peptide as human collagen mimicking 3D hydrogel model for cardiac tissue engineering

Collagen is the most abundant protein in the myocardial ECM. It not only provides structural support for cells and tissues, but also mediates many biological processes. Up to now, animal-derived collagen has often been used to mimic human collagen in 3D scaffolds for cardiac disease modeling and tissue engineering purposes. However, increasing concerns associated with animal derived materials, batch-to-batch variations, and the inability to tune the properties of collagen in a well-controlled manner result in a need for an alternative. Methacrylated Recombinant Collagen Peptide (RCP-MA, Fujifilm) is a collagen mimicking peptide based on human collagen I, containing no animal-derived components. RCP-MA is highly reproducible and enriched with arginine-glycine-aspartic acid (RGD) sequences to allow control over its cell-adhesive properties. Moreover, RCP-MA is modified to contain methacrylic groups that enable chemical crosslinking and hydrogel fabrication with a stiffness ranging from 1 kPa to ~300 kPa.
In this study, we explored RCP-MA as a 3D hydrogel in vitro platform for cardiac tissue engineering. We demonstrated that, using RCP-MA of different degrees of methacrylation, we could fabricate hydrogels that mimic the stiffness of normal and pathological myocardium, respectively. High cell viability (>90%) was found up to ten days of culture inside the RCP-MA. Moreover, elongated and electromechanically coupled human induced pluripotent stem cell derived cardiomyocytes (hiPSC-CMs) were found, indicating the biocompatibility of RCP-MA. Next, we investigated how changes in myocardial stiffness, happening upon injury, affect co-cultures of hiPSC-CMs and cardiac fibroblasts (cFBs). hiPSC-CMs and cFBs demonstrated an altered phenotype and function in response to a stiff ECM as apposed to a soft ECM, suggesting that the injured myocardial tissue stiffness guides cellular function in vivo and might hamper the regenerative potential of newly injected or recruited cells. Taken together, these results propose RCP-MA as an attractive alternative to animal-derived collagen for cardiac disease modeling.