Potential of Migration and Tissue Reactions to Intraperitoneally Implanted Polymethyl Methacrylate in Wistar Rats

Abstract

Objective: This study aimed to evaluate the performance of polymethyl methacrylate (PMMA) when implanted into the peritoneal cavities of Wistar rats, specifically its potential for migration to the examined organs and possible tissue reactions at the implantation site. Methods: Adult male Wistar rats (290-400 g) were distributed randomly into 2 groups: P4 (n=20), to which 0.4 mL of PMMA was administered; and P2 (n= 0), to which was 2 mL of PMMA were administered. These groups were subsequently divided into 4 subgroups according to the day on which euthanasia occurred (day 1, 7, 14, or 28). Results: The changes in animal weight prior to PMMA implantation and after euthanasia were compared. No nodules or signs of PMMA implantation or any other macroscopic alterations were observed in the spleen, kidneys, lungs, or liver. However, mild-to-moderate inflammatory infiltration in which macrophages, lymphocytes, and neutrophils predominated was observed in at least 1 of the 4 organs examined from each animal during the experimental time points. Mild inflammatory responses were observed that were rich in histiocytes and giant cells and featured increased numbers of blood vessels and fibroblasts in the pericapsular regions of the studied organs. In 29 cases, a greyish material compatible with PMMA was identified. There was no migration of PMMA into the parenchyma of the examined organs. The changes in the tissues were the same regardless of the volume of implanted PMMA. Following staining with HE, the PMMA particles in the tissues were a grayish color, measuring approximately 30-40 μm in size, and were found to have stimulated histiocytic reactions in 29 examined organs. Conclusions: The results showed that the most affected tissues were the visceral peritoneum of the spleen and the kidneys from group P2. Our study may contribute to add a new proof of testing implants.