Abstract 359: The Production of Acellular Cardiac Extracellular Matrix from P3 Murine Heart

Abstract

Introduction: Understanding the role of extracellular matrix (ECM) in the creation of the cellular microenvironment during tissue formation and regeneration could be vital in extending this capability to injured adult tissue. To date the only confirmed mammalian heart tissue regeneration/regrowth has been in neonatal murine heart, with the regenerative capacity ceasing after day P3. By focusing on ECM from P3 heart tissue we hope to elucidate its contribution to regenerative plasticity and transfer this capacity to injured adult myocardium. Hypothesis: Detergent decellularization protocols used in adult tissues can be modified to function on a neonatal scale, serving to remove the cellular components of the neonatal heart, leaving structurally intact ECM to serve as a scaffold for the generation of cardiac tissue equivalents. Materials and Methods: Murine P3 hearts were perfused with 1% SDS in water at 20mm Hg for 12 hrs. Following detergent decellularization, perfusion with water, 1% Triton X-100, PBS and culture media restored biocompatibility to the isolated ECM. P1 and P7 primary cardiomyocytes expressing the mCherry red fluorescent protein reporter under control of the alpha myosin promoter were isolated by enzymatic disassociation and cultured in the heart matrix in a perfusion based bioreactor. Results: The decellularized ECM demonstrated removal of 97% of native DNA when compared to control by pico-green dsDNA binding assay. Histologic analysis demonstrated an absence of cell nuclei by H & E and DAPI staining. The preservation of the matrix structure and the maintenance of matrix immunoreactivity (collagen IV) were also demonstrated histologically. Following infusion of P1 or P7 mCherry positive cells, contractile behavior of the recellularized heart constructs was observed, and markers of cardiac linage (alpha-actinin in mCherry positive cells) were present. Conclusions: Neonatal heart matrix can be effectively decellularized. With appropriate modification of perfusion parameters, pediatric ECM structure can be preserved. This isolated matrix can serve as a scaffold for growth and maintenance of immature and mature cardiomyocytes, supporting continued contractility of cultured cells.