| It has been previously shown that ventricular cardiac ECM (cECM) derived from the decellularized fetal myocardium promotes both the adhesion and expansion of neonatal cardiomyocytes compared to PLL, neonatal cECM, and adult cECM. Additionally, it is known that the protein composition of cECM change as a function of developmental age. The purpose of this thesis was to elucidate which extant protein or protein complex in native cECM is responsible for driving these phenomena. Following decellularization of adult and fetal Sprague Dawley rat hearts, samples were fractionated according to molecular weight using sodium dodecyl sulfate polyacrylamide electrophoresis (SDS-PAGE). Results from this study indicated enhanced cardiomyocyte proliferation on cECM fractionated from 25-65 kDa. To further explore this phenomenon, fractionated cECM half-gels were transferred to polyvinyl difluoride (PVDF) membranes, keeping the other half of the gel for proteomics analyses. Cardiomyocytes cultured directly on these membranes revealed specific bands of cECM that elicited enhanced cardiomymcyte proliferation, leading to the identification of peptide regions of interest near the N-terminus of fibrillin-1. The first of these regions, denoted the "F1R1" protein, was fabricated and shown to induce enhanced cardiomyocyte proliferation. These data suggest that fibrillin-1 and the F1R1 protein may induce post-natal cardiomyocyte hyperplasticity and could have utility in developing a novel protein therapeutic for cardiac regeneration. |
