Conductive bacterial nanocellulose-polypyrrole patches promote cardiomyocyte differentiation

The low endogenous regenerative capacity of the heart, added to the prevalence of cardiovascular diseases, triggered the advent of cardiac tissue engineering in the last decades. The myocardial niche plays a critical role in directing the function and fate of cardiomyocytes; therefore, engineering a biomimetic scaffold holds excellent promise. We produced an electroconductive cardiac patch of bacterial nanocellulose (BC) with polypyrrole nanoparticles (Ppy NPs) to mimic the natural myocardial microenvironment. BC offers a 3D interconnected fiber structure with high flexibility, which is ideal for hosting Ppy nanoparticles. BC-Ppy composites were produced by decorating the network of BC fibers (65 ± 12 nm) with conductive Ppy nanoparticles (83 ± 8 nm). Ppy NPs effectively augment the conductivity, surface roughness, and thickness of BC composites despite reducing scaffolds’ transparency. BC-Ppy composites were flexible (up to 10 mM Ppy), maintained their intricate 3D extracellular matrix-like mesh structure in all Ppy concentrations tested, and displayed electrical conductivities in the range of native cardiac tissue. Furthermore, these materials exhibit tensile strength, surface roughness, and wettability values appropriate for their final use as cardiac patches. In vitro experiments with cardiac fibroblasts and H9c2 cells confirmed the exceptional biocompatibility of BC-Ppy composites. BC-Ppy scaffolds improved cell viability and attachment, promoting a desirable cardiomyoblast morphology. Biochemical analyses revealed that H9c2 cells showed different cardiomyocyte phenotypes and distinct levels of maturity depending on the amount of Ppy in the substrate used. Specifically, the employment of BC-Ppy composites drives partial H9c2 differentiation toward a cardiomyocyte-like phenotype. The scaffolds increase the expression of functional cardiac markers in H9c2 cells, indicative of a higher differentiation efficiency, which is not observed with plain BC. Our results highlight the remarkable potential use of BC-Ppy scaffolds as a cardiac patch in tissue regenerative therapies.This work was supported by the Spanish Ministry of Science and Innovation (MICINN) through the National Research Agency (AEI) and European Regional Development Funds (ERDF/FEDER), project BIOCARDIO ref RTI2018-096320–B-C21, project BIOSOFT-REGE ref PID2021-122645OB-I00, the CERCA Program/Generalitat de Catalunya, the ‘Severo Ochoa’ Programme for Center of Excellence in R&D (CEX2019-000917), the Programme/Generalitat de Catalunya (2017-SGR-359), the Severo Ochoa Programme of the Spanish Ministry of Science and Innovation (MICINN─Grant SEV-2014–0425, 2015–2019 and CEX2018–000,789-S, 2019–2023), and the projects FIP-PALOMA, FIP-BEAT, and the PDC2022-133755-I00/AEI/10.13039/501100011033 European Union NextGeneration EU/PRTR. This research was also supported by the European Union’s Horizon 2020 research and innovation program H2020-MSCA-COFUND-2016 (DOC-FAM, Grant Agreement No. 754397). This project also received the support of a La Caixa INPhINIT Fellowship (ID 100010434) with project code LCF/BQ/DR19/11740025. S.Y.S. is enrolled in the Materials Science Ph.D. program of the UAB. S.Y.S. and A.L. participate in the Spanish National Research Council (CSIC) interdisciplinary platform for sustainable plastics towards a circular economy (SusPlast), in the Aerogels COST ACTION (CA 18125), and in CSIC-Conexión Nanomedicine, EPNOE network, and Red Nanocare 2.0. The authors acknowledge the use of Biorender.com.Peer ReviewedPostprint (published version