Abstract 16799: Decellularized Cardiac Extracellular Matrix Increases Cardiomyocyte Elongation and Contractility

Abstract

Background: Cardiomyocyte elongation has been linked to enhanced myofilament organization, which contributes to overall cell contractility and functionality. While tissue scaffolds have been engineered to induce cell elongation using topographical cues, decellularized cardiac extracellular matrix (dECM) bioscaffolds are known to be bioactive and retain native cues for cell organization and regeneration, including the alignment of stem cells. However, the effects of the native extracellular matrix on cardiomyocyte elongation and contractility are still unknown. Hypothesis: We hypothesized that dECM increases elongation and contractility of neonatal rat ventricular cardiomyocytes (NRVCMs) versus engineered collagen constructs, resulting in physiologically-relevant, scalable tissues for cardiovascular tissue engineering. Methods and Results: Adult rat hearts were harvested and perfusion-decellularized through the coronary vasculature under constant pressure. Hearts were sectioned on a vibratome transversally to create 300 μm-thick rings of the left ventricle. Collagen (type 1) rings of the same size as the dECM rings were made by using rat tail collagen (2.0 mg/ml). Ten million NRVCMs were isolated, purified, and injected into the left ventricle of dECM or collagen rings (n=12 each). Cell survival, distribution, elongation, and alignment were evaluated after 14 days by using immunofluorescence and confocal microscopy. The dECM significantly increased nuclear elongation (major to minor axis ratio of 1.585 for cells in dECM vs. 1.37 in collagen, n=6 each, p<0.01). Microscopic contractions were observed in dECM as early as day 3 (n=3). The number of spontaneous contractions of cells in dECM (n=5) was significantly greater than that in collagen (n=3) (p<0.01), as observed by atomic force microscopy. Conclusion: In conclusion, dECM increased cellular elongation and contraction frequency of neonatal rat ventricular cardiomyocytes, suggesting the presence of tissue-specific cues in the extracellular environment of cardiomyocytes is beneficial for tissue function. Studies utilizing human stem-cell derived cardiomyocytes are underway to verify the organizational, functional, and physiologic properties of recellularized dECM.