In vivo assessment of the biocompatible properties of resorbable porous materials for pleural implantation

Correcting the pleural cavity space or filling large residual cavities (up to 500-700 cm 3 ), arising as a result of extensive combined resections of the lung or extrapleural pneumolysis in tuberculosis and other lung diseases, still remains a challenging issue. The surgical methods used to correct the pleural cavity space are traumatic in nature. Moreover, various biological and synthetic materials used are not effective enough. Objective : to conduct an in vivo study of the biocompatible properties of laboratory samples of porous materials based on polylactide (PLA) and polycaprolactone (PCL) as potential materials for pleural implants development, as part of the general problem of developing a resorbable porous implant for intra- and extrapleural implantation and in situ formation of a «biological filling» to correct the volume of the pleural cavity. Materials and methods . In vivo subcutaneous implantation was performed in Wistar rats. The experiment involved the following samples: No. 1 - 3.0%; No. 2 - 4.0%; No. 3 - 1.7%. The ratio of the polymers in the solution was, respectively: 3/1, 1/3 and 1/1 PLA/PCL. Highly porous implants were obtained by lyophilization. The porosity of the samples ranged from 96.0% to 98.3%. The Young's modulus was from 100 to 1800 kPa. In the control group, a Mentor silicone implant shell was used. The explantation time was 1, 2, 3, 4, 5, 8, 12, 14 weeks. Histological, histochemical and immunohistochemical studies of explants and surrounding local tissues were conducted. Results . Reaction of local tissues to the implantation of three types of samples of different composition from PLA/PCL, accompanied by material resorption processes, replacement by fibrous tissue, vascularization and encapsulation, without perifocal inflammation and reactive changes, indicates the biocompatibility of the materials studied. In control samples with silicone implant, a long-lasting perifocal reaction from eosinophilic leukocytes was revealed, which prevents us from excluding the possibility of an allergic reaction to the implant material in the surrounding tissues. Conclusion . In vivo experiments on the small animals show the biosafety and high biocompatibility of laboratory samples of bioresorbable highly porous matrices based on polylactide and polycaprolatcon as potential materials for development of pleural implants. Further studies with scaling of laboratory samples and a detailed study of the dynamics of biodegradation of porous matrices in vivo in large animals are required. The need for further improvement in laboratory samples of bioresorbable pleural implants is associated with giving the porous matrices antibacterial, bioactive and X-ray contrast properties.