Investigation of cardiomyocytes maturation platform using cell-derived matrix and poly(L-lactide-co-caprolactone) nanofiber

摘要

Introduction: Embryonic or induced pluripotent stem cells-derived cardiomyocytes are very promising for cardiac cell therapy and drug screening. Despite the great potential, their phenotype is often considered immature. To improve the maturity of cardiomyocytes, we have investigated a platform using fibroblast-derived extracellular matrix (FDM) and polymer nanofiber. Our hypothesis is that current platform may provide some benefits, originated from structural (nanofiber) and compositional (FDM) cues. Materials and Methods: Aligned poly(L-lactide-co-caprolactone) (PLCL) nanofibers are prepared using electrospinning. After NIH3T3 fibroblasts were seeded and cultivated onto the PLCL nanofiber for 5 days, those cells were then decellularized using detergent and enzymes, producing PLCL/FDM. The efficacy of PLCL/FDM was first examined via H9c2 cardiomyoblasts differentiation and neonatal rat cardiomyocyte maturation, along with the test of control (fibronectin (FN)-coated PLCL) (n=3, each group). From the heart ventricles of Sprague-Dawley rats (1-3 day old), the cardiac cells were isolated and further purified using a preplating method. H9c2 was subject to differentiation for 7 days in DMEM supplemented with 1% fetal bovine serum (FBS) and 50 nM retinoic acid (R2625, Sigma). Neonatal cardiomyocytes were cultivated in DMEM with 10% FBS. Results and Discussion: FDM was successfully deposited on the PLCL nanofiber, as confirmed by scanning electron microscope, Fourier transform infrared spectroscopy, and immunofluorescence (FN and collagen Ⅰ). Cardiomyogenic differentiation of H9c2 was much better in the PLCL/FDM, with more upregulated protein markers (α-actinin and connexin 43) and gene expression (Tnnt, Actc1) over PLCL. For neonatal cardiomyocytes, when several maturation indexes were examined, cells on PLCL/FDM exhibited a significant increase in the percentage of rod-shape cardiomyocytes and multi-nucleation, respectively. However sarcomere length was comparable for the two groups. Although the exact mechanism is unclear at this time, it seems that current PLCL/FDM holds multiple intrinsic cues, clearly distinguished from FN-coated PLCL in terms of composition, topography and stiffness. Further study continues to investigate the effect of tunable ECM stiffness. Conclusions: Taken together, PLCL/FDM can give rise to favorable microenvironments that support better cardiomyogenic differentiation and cardiomyocytes maturation in vitro.