Tissue reactions after long-term intracerebral implantation of three different types of biodegradable polylactide rods in the rat.

Abstract

To investigate acute and late tissue reactions following intracerebral implantation of three different biodegradable DL-polylactids: Resomer R104 + R203 (1 + 1) (SU48), Resomer R203 (SU49), and DL-polylactid-co-trimethylencarbonat (SU50). Polylactide (PL) rods and small pieces of silicon (control) were stereotactically implanted in the forebrain of 60 Wistar rats. Twenty-eight, 70, and 112 days after implantation, five animals of each group (SU48, SU49, SU50, control) were sacrificed. Tissue slices of the paraffin-embedded brains were stained with hematoxylin and eosin (HE) for histological evaluation. Independent from the investigated sample, the site of implantation was visible on the brain sections as a clearly demarcated tissue defect surrounded by minimal inflammatory cellular reactions. Although not significant, implantation of SU50 caused the most distinct invasion of foamy macrophages. Despite SU48, which 112 days after implantation was surrounded by a thin layer of predominantly gliotic fibers, demarcation of surrounding brain tissue was of minor degree. The PL rods investigated in this study caused no significant early and late tissue alterations. Both the good biocompatibility of these samples and a high flexibility with regard to degradation time and release kinetics allow either long protracted drug release or short-term application of substances.