Many works focus on the use of polyesters like poly(lactic acid) (PLA) to produce nanofibrous scaffolds for cardiac tissue engineering. However, such scaffolds are hydrophobic and difficult to functionalize. Here, we show that adding 30% of poly(glycerol sebacate) (PGS) elastomer within PLA leads to PLA:PGS scaffolds with improved biological properties, depending on the processing parameters. Two categories of fibers were produced by blend electrospinning, with diameters of 600 and 1300 nm. The resulting fibers were cured at 90°C or 120°C in order to achieve two different crosslinking densities. The designed scaffolds were considered for cytocompatibility, biocompatibility, biodegradability, chemical and mechanical properties. Our results demonstrated that the presence of PGS increases the hydrophilicity of the material and thus improves surface functionalization by Matrigel and laminin coating, a commonly used cell culture matrix. PLA:PGS scaffolds associated with Matrigel and laminin allow an increased material-cell interaction. Moreover, the cardiomyocytes seeded on such scaffolds acquire a morphology similar to that observed in native tissue, this result being more remarkable on fibers having the smallest diameter and the highest PGS crosslinking density. In addition, these scaffolds induce neovascularization without inflammatory response and foreign body giant cell response after grafting on mice's heart. Hence, the improved biocompatibility and the ability to support cardiomyocytes development suggest that thin PLA:PGS scaffolds could be promising biomaterials for cardiac application.

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The cell and tissue culture substrates play a pivotal role in the regulation of cell‐matrix and cell‐cell interactions. The surface properties of the materials control a wide variety of cell functions. Amongst various methods, layer‐by‐layer (LbL) assembly is a versatile surface coating technique for creating controllable bio‐coatings. Here, polysaccharide/protein multilayers are proposed, which are fabricated by immersive LbL assembly and based on the chitosan/fibrinogen pair for improving the adhesion and spreading of cardiomyocytes. Two approaches in LbL assembly are employed for clarifying the effect of the bilayers order and their concentration on cardiomyocytes viability and morphology. Fourier transform infrared spectroscopy (FTIR) measurements show that the adsorption of the biopolymers is enhanced during the LbL deposition in a synergistic manner. Contact angle measurements indicate that the multilayers are alternating from less to more hydrophilic behavior depending on the biopolymer that is added last. Confocal microscopy with immunostained fibrinogen reveals that the amount of the protein is higher when the concentration of the immersion solution is increased, however, for low solution concentration it is speculated that interdigitation between the separate biopolymer layers takes place. This work motivates the use of fibrinogen in polysaccharide/protein multilayers for enhanced cytocompatibility in cardiac tissue engineering.

As part of applications dealing with cardiovascular tissue engineering, drop-cast polyvinylidene fluoride (PVDF) scaffolds have been treated by cold plasma to enhance their adherence to cardiac cells. The scaffolds were treated in a dielectric barrier device where cold plasma was generated in a gaseous environment combining a carrier gas (helium or argon) with/without a reactive gas (molecular nitrogen). We show that an Ar-N2 plasma treatment of 10 min results in significant hydrophilization of the scaffolds, with contact angles as low as 52.4° instead of 132.2° for native PVDF scaffolds. Correlation between optical emission spectroscopy and X-ray photoelectron spectroscopy shows that OH radicals from the plasma phase can functionalize the surface scaffolds, resulting in improved wettability. For all plasma-treated PVDF scaffolds, the adhesion and maturation of primary cardiomyocytes is increased, showing a well-organized sarcomeric structure (α-actinin immunostaining). The efficacy of plasma treatment was also supported by real-time PCR analysis to demonstrate an increased expression of the genes related to adhesion and cardiomyocyte function. Finally, the biocompatibility of the PVDF scaffolds was studied in a cardiac environment, after implantation of acellular scaffolds on the surface of the heart of healthy mice. Seven and 28 days after implantation, no exuberant fibrosis and no multinucleated giant cells were visible in the grafted area, hence demonstrating the absence of foreign body reaction and the biocompatibility of these scaffolds.

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