[Histological changes in intraperitoneal onlay mesh (IPOM) with synthetic and biological meshes. Results of the chronic experiment]. / Gistologicheskie izmeneniya pri intraperitoneal'noi plastike (IPOM) sinteticheskimi i biologicheskimi endoprotezami. Rezul'taty khronicheskogo eksperimenta.

OBJECTIVE: The objective of the study was to analyze histological changes in the site of the meshes FTOREX, FTOREX coated with carboxymethylcellulose, Ventralight ST, Symbotex, REPEREN-16-2 and decellularized porcine peritoneum on the parietal peritoneum of the pig. MATERIAL AND METHODS: At laparoscopy, 6 different meshes were placed intraperitoneally in each of the 3 pigs. After 90 days, the animals were taken out of the experiment. After staining with hematoxylin and eosin, quantitative morphometry and counting the number of vessels and cells in the interstitium in the areas of the mesh and peritoneum were performed. An immunohistochemical study with an antibody to pancytokeratins assessed the state of the initial peritoneum and neoperitoneum. RESULTS: According to morphological characteristics, the meshes were divided into 3 groups: 1) with fluoropolymer coating FTOREX, 2) Ventralight ST and Symbotex, 3) REPEREN and decellularized peritoneum. In group 1, the surface area of the mesh threads was optimal in terms of the arrangement and arrangement of the threads relative to each other. This contributed to the formation of a relatively dense fibrous framework and a place to preserve the underlying peritoneum involved in the formation of the neoperitoneum. Despite the smallest surface area of the threads, in group 3, the greatest fibroblastic reaction was noted. Inflammatory changes were the least pronounced in group 1. They were the greatest in group 3, where there was a pronounced leukocyte reaction, combined with the processes of metaplasia, the development of fibrinoid necrosis, and the progression of the secondary inflammatory process. In group 1, the optimal ratio of newly formed vessels was noted, in group 2 - veins prevailed over arteries, in group 3 - the number of vessels was minimal. Immunohistochemical study showed that in group 1, mesothelial cells covered almost the entire surface of the implant, and there were also areas of preserved basic peritoneum. In group 2, mesothelium also covered most of the surface of the meshes, but the underlying peritoneum was absent. In group 3, on the contrary, a significant number of extended areas not covered with mesothelium were revealed. CONCLUSION: The conducted morphological and morphometric study showed that the most balanced ratio of the components of the newly formed fibrous tissue and blood vessels is observed when using implants with a fluoropolymer coating FTOREX. At the same time, the remaining basic peritoneum actively participated in the formation of the neoperitoneum. The Ventralight ST and Symbotex meshes also contributed to the formation of a full-fledged fibrous tissue and adequate vascular proliferation, however, they prevented the preservation of the underlying peritoneum, which practically excluded its participation in the formation of the neoperitoneum. The REPEREN mesh and decellularized porcine peritoneum led to the least balanced cell and vascular proliferation and the greatest fibroplastic reaction, which could further negatively affect the state of the formed scar.

[Applying HIFU for the obliteration of the veins in the experiment ].

The effect of high-intensity focused ultrasound (HIFU) on venous wall structure was studied in the rabbit model. Special setup was developed for ultrasound generation and vessel targeting. Methods. The essential part of the setup is spherical focusing power irradiator with following characteristics: power supply voltage of 25 V, frequency of 1.9 MHz, ultrasound intensity in the focal spot ~8.7 kW/cm2. Results. Single 15-s exposure of the femoral vein to HIFU resulted in partial desquamation of the endothelium, vacuolization of myocyte cytoplasm, misarrangement and coagulation of collagen fibers. Pulsed HIFU (5 pulses for 5 s each) caused protein coagulation in all layers of venous wall (v. cava posterior) as well as the appearance of the areas of fibrinoid necrosis, severe endothelial desquamation, and intimal detachment. HIFU-induced collagen structural changes in media and adventitia of the vein suggest that HIFU exposure resulted in local temperature increase up to ~60°Ð¡. In some experiments, adjacent to the vein muscles were also exposed to HIFU. In this case, edema of the interstitium and muscle fibers was registered, as well as fragmentation and coagulation of some fibers, altered staining patterns and neutrophil infiltration. These changes could be attributed to the development of acute muscle injury (acute fasciitis). Perivascular adipose tissue also demonstrated edema and lipolysis, red blood cell diapedesis, and leukocyte infiltration. Conclusion. The observations on structural changes in the venous wall after HIFU exposure could lay the ground for future experiments on HIFU - mediated obliteration.