Abstract 343: Embryonic Extracellular Matrix and Cardiomyocyte Maturation

Background: The progression of cell maturation is governed by intrinsic factors, but also by interaction with the milieu in which they reside. The extracellular matrix (ECM) from rapidly developing tissue should form a rich signaling environment for cellular development. Hypothesis: Murine embryonic ECM can be prepared by detergent decellularization that is morphologically preserved, biocompatible for cell culture, and at E13.5, substantial enough to permit vascular catheterization and recellularization by perfusion. When used as a scaffold for cell culture, it can be shown to have a salutatory effect on the morphologic and physiologic maturation of post-natal cardiomyocytes (CM). Methods and Results: To test the contribution of embryonic ECM to the performance of cardiomyocytes in culture, we undertook the isolation of ECM from developing murine embryos. Using a detergent decellularization protocol, we established an acellular scaffold that was shown to be free of native cells and returned to a biocompatible state, to serve as a scaffold for cell culture. Primary P7 mCherry expressing cardiomyocytes were isolated and introduced by perfusion into the embryonic ECM heart. The same cells were also plated, and the performance of the two culture modalities was compared at 3 and 28 days. Histologic comparison demonstrated the maintenance of the rod cellular morphology. Analysis of cellular contractile performance by video microscopy demonstrated improved contractile performance of CMs when cultured on ECM and paced at 1 Hz (3 Day plated contraction velocity/relaxation velocity (μm/sec) 1.18±0.3/0.91±0.2 and ECM contraction velocity/relaxation velocity (μm/sec) 6.65±1.0/4.52±0.7). At 28 days plated contraction velocity/relaxation velocity was (μm/sec) 2.71±0.2/1.59±0.1 and ECM contraction velocity/relaxation velocity was (μm/sec) 8.83±4.2/6.20±2.6). Conclusion: Biocompatible, acellular morphologically preserved embryonic ECM can be extracted from E13.5 murine embryos. By E13.5 the structural integrity of the acellular matrix can sustain vascular perfusion for delivery of P7 cardiomyocytes to internal organoid structures. These ECM preparations support the maturation and physiologic performance of cardiomyocytes.