In Vitro Assessment and Preliminary In Vivo Characterization of Innovative Hybrid Materials for Biomedical Applications

Hybrid materials are gaining increasing attention for several applications since they properly combine biological and synthetic components, leveraging the advantages of both; thus, these materials can integrate with the host organism to support proper functions, offering new promising solutions, especially in the biomedical field. In this study, we developed hybrid membranes by combining decellularized porcine pericardium with a commercial polycarbonate urethane, available in two formulations: without (AR) and with microsilica particles (AR-LT). These membranes were characterized through chemical and physical analyses; their cytocompatibility was assessed in vitro via direct contact tests, and their biocompatibility was checked in vivo by implanting the materials in a subdermal pouch in a rat animal model. Three kinds of mechanical tests have been performed to check different mechanical features: tensile test to rupture, to measure the mechanical resistance in terms of elastic modulus, failure strain (FS), and ultimate tensile strength (UTS); cyclic tests to assess the effects of repetitive loadings on the mechanical resistance; and stress-relaxation tests to assess the time-dependent behavior. The physicochemical analyses demonstrated that the two components well adhere to each other, with traces of the polymer on the pericardial side of the membranes. Considering mechanical response, coupling pericardium with the polymer causes a reduction of FS and UTS compared to the individual components. Hybrid materials show a viscoelastic behavior while loading cycles do not cause significant changes in their tensile resistance. In vitro tests showed no cytotoxic effects, with cell proliferation observed for up to 7 days. In vivo, 8 weeks after implantation, the hybrid membranes exhibited better integration with host tissue compared to the polymer alone (control), and the polymeric component did not show any sign of degradation. The improved integration was demonstrated by increased neovascularization around the implant, reduced fibrotic capsule thickness, lower expression of interleukin-6 (IL-6), and stable body weight of the rats throughout the experiment. This study highlights the potential of the hybrid membranes for tissue engineering applications, combining favorable biocompatibility and adequate mechanical features.