Biocompatibility and fibrous response of polymethylmethacrylate in skeletal muscles

Polymethylmethacrylate (PMMA) is a synthetic polymer produced in microspheres form, used in many biomedical areas. Objective: To determine the PMMA injections biocompatibility in striated muscle tissue of Wistar rats. Methods: In vivo biocompatibility and fibrous tissue healing were assessed by histopathological evaluation at 2, 4, 8, and 16 weeks after implantation in 3 groups of adult rats. Group 1, with 20 adult rats, was injected with 30% PMMA gel in the ventral muscle. Other two groups with 20 and 5 rats were studied as control subjects. Group 2 was injected with the same amount of saline solution in the ventral muscle, while the subjects in group 3 underwent anesthesia and surgical incision. Results: After two weeks, a histiocytic inflammatory response was observed in group 1. The capsule formation where type I collagen predominated and a septum between the spheres, rich in collagen type III, which resulted in a stable foreign-body granuloma. No evidence of lymphocytic local reaction, tissue suffering, or necrosis was observed. Conclusion: PMMA is biocompatible when injected into the striated muscle tissue of Wistar rats. There was a fibrous response induced by PMMA showing microspheres surrounded by stable histiocytic granuloma without evidence of toxic or antigenic activities.