Today, myocardial infarction is one of the main causes of death in the world. One of the new methods of treating damaged tissues is tissue engineering. On the other hand, conductive nanofibers are special structures that have recently attracted the attention of many researchers in tissue engineering applications, such as cardiac tissue engineering. Therefore, in this research, a widely used blend in medical field, i.e., polyglycerol sebasate (PGS)/polycaprolactone (PCL) nanofibers, were coated with polypyrrole (PPy) conducting polymer using the in-situ chemical polymerization. In order to design a sandwich scaffold, prepared gel from the decellularized myocardium was combined with the PGS/PCL/PPy nanofibrous layers. For this purpose, PGS polymer was first synthesized and then PGS/PCL nanofibers were produced using the electrospinning method. The synthesized PGS was characterized using the H-NMR and FTIR analyses. The response surface methodology (RSM) was used to optimization of electrospinning process parameters as well as polymerization conditions of PPy. FESEM images with EDX and ATR-FTIR analyzes were used to characterization of produced structures. Also, the electrical conductivity and the electroactivity of samples were studied using four-point probe and cyclic voltammetery methods, respectively. Hydrophilicity, biodegradability and biocompatibility of the samples were also studied. Hematoxylin and eosin stain, Masson's trichrome, Alcian blue stain and DNA content were used to eva‎luate the decellularization process. The results showed that among the eight used solvent systems, the CF/DMF two-component solvent system is the best solvent system. The optimal conditions for the electrospinning of PGS/PCL nanofibers were obtained as the polymer concentration of 18 w/v % , the applied voltage of 17 kV and the distance of 20 cm. The monomer concentration of 0.05 M and polymerization time of 3.3 h were also considered by RSM method as optimal polymerization conditions for obtaining coated nanofibers with the smallest diameter and targeted electrical conductivity (0.001 S/cm). By using optimum conditions of electrospinning, PGS/PCL/PPy nanofibers were obtained with a diameter of 411 nm and electrical conductivity of 0.00108 S/cm. The hydrophilicity of the PGS/PCL nanofibrous layer did not change significantly after coating with the PPy. In addition, the presence of redox peaks indicated the electroactivity of in the coated samples. After 6 months, the degradation measurements of the samples showed 39% and 33% weight loss for uncoated and coated samples, respectively. Also, the highest biocompatibility was related to the sample synthesized with 0.05 M pyrrole. Absence of cell nucleus and muscle fibers in hematoxylin-eosin stain and Masson trichrome stain tests indicated good decellularization of myocardial tissue. The DNA content in the decellularized sample decreased by 17 times. The highest cell survival according to the MTS assay was related to the scaffold containing decellularized myocardial gel (PGS/PCL/PPyA/DMG). The behavior of the cells on this scaffold was similar to the PGS/PCL/PPyA sample which the cells spread on the scaffolds. The pathology results showed that the highest cell penetration was related to the PGS/PCL/PPyA/DMG scaffold. Due to the synergistic effect of the presence of PPy and decellularized myocardial gel, the highest percentage of expression of Cx43, MHC and cTnT, cardiac specific proteins, was belonged to the PGS/PCL/PPyA/DMG scaffold (p value<0.001).

داريوش سمناني

محمد قانع، محمد پزشكي

محمد رفيعي نيا، حسين توانايي، شيدا لباف، لاله قاسمي