Biocompatibility and long-term toxicity of InnoPol implant, a biodegradable polymer scaffold

InnoPol, a poly((D,L)-lactic-co-glycolic acid) [PLGA] 65/35 scaffold manufactured by special gas foaming methods in Korea, was subjected to tests to evaluate the degradation and tissue compatibility characteristics and long-term systemic toxicity in mice and rats. C57BL/6 mice and SD rats were implanted subcutaneously with 3-mm- and 1-mm-thick InnoPol circular discs, 10 mm in diameter, respectively, and sacrificed 8, 12, and 24 weeks after implantation. No test material-related effects were observed in mortality, clinical signs, body weight gain, food and water consumption, ophthalmologic signs, urinalysis, hematology, serum biochemistry parameters and organ weights of all animals implanted with InnoPol. Also, there were no systemic symptoms including metabolic alterations and inflammatory reactions in either mice or rats. In addition, no gross pathological findings, except skin lesions around the implantation sites, were found in the major organs. Although mild inflammation at the site of InnoPol implantation was confirmed from hematoxylin and eosin or Masson's trichrome staining at 8-12 weeks, the reactions had disappeared at 24 weeks following complete degradation of the scaffold, leaving granulomatous tissues that were similar to surgical wounds in sham operation controls without implants. These results suggest that InnoPol possesses good mechanical properties and tissue compatibility and does not cause any systemic toxicity other than transient local inflammatory reactions at the implantation site, and that it might be useful in applications as a medical device for implantation.