BIODEGRADATION AND BRAIN-TISSUE REACTION TO POLY(D,L-LACTIDE-CO-GLYCOLIDE) MICROSPHERES

The therapeutic application of neuroactive molecules in neuroscience i s limited, due to the problems posed by the administration of these dr ugs (peripheral metabolism, systemic effect and passage of the blood-b rain barrier). One solution is the implantation in the brain of biodeg radable polymer devices with controlled release of a neuroactive drug. The biodegradation and tissue reaction of the copolymer poly(D,L-lact ide-co-glycolide) microspheres prepared by the solvent evaporation met hod, radiosterilized and stereotactically implanted in the rat brain w ere studied by routine staining, immunohistochemistry and transmission electronic microscopy. The brain tissue reaction observed was a non-s pecific astrocytic proliferation and a macrophagous-microglial cell re action, typically found following damage to the central nervous system . Some foreign-body giant cells were observed and the inflammatory and macrophagous reaction decreased dramatically after 1 month and almost ended after 2 months when the microspheres were totally biodegraded. The copolymer poly(D,L-lactide-co-glycolide) microspheres may be consi dered biocompatible to the brain tissue.