Heart failure is a disease of epidemic proportion, and is a leading cause of mortality in the world. Since cardiac myocytes are terminally differentiated cells with minimal intrinsic ability to self-regenerate, cardiac tissue engineering has emerged as one of the most realistic therapeutic strategies for cardiac repair. We have previously proven the ability of carbon nanotube scaffolds to promote cardiomyocytes proliferation, maturation and long-term survival. Here, we tested if 3-dimensional scaffolds of carbon nanotube-based composites can also promote cardiomyocyte growth, electrophysiological maturation, and formation of functional syncytia. To this purpose, we developed an elastomeric scaffold which consists of a microporous and self–standing material made of polydimethylsiloxane (PDMS) containing micrometric cavities, and integrated multi-wall carbon nanotubes (MWCNTs) into the scaffold. We combined microscopy, cell biology and calcium imaging, to investigate whether neonatal rat ventricular myocytes (NRVMs) cultured on the 3D-PDMS+MWCNT acquire a more viable and mature phenotype compared to control. We found that, when cultured in the 3D-PDMS+MWCNTs, NRVMs showed improved viability (p < 0.005 at day3) and more defined and mature sarcomeric phenotype compared to 3D PDMS control. These modifications were associated with an increase of connexin-43 gene expression, gap junction areas (p < 0.005 at day 3), and a more mature electrophysiological phenotype of syncytia and calcium transients. Finally, 3D-PDMS+MWCNT boosted NRVMs proliferation (p < 0.005 at day 3) while hindering cardiac fibroblasts proliferation compared to control PDMS. Thus, 3D-PDMS+MWCNT has the ability to promote viability, proliferation and functional maturation of cardiac myocytes. These properties are essential in cardiac tissue engineering and offer novel perspectives in the development of innovative therapies for cardiac repair.
