INVIVO BIOCOMPATIBILITY STUDIES OF MEDISORB(R) 65/35 D,L-LACTIDE GLYCOLIDE COPOLYMER MICROSPHERES

The in vivo biocompatibility testing of 65/35 lactide/glycolide copolymer microspheres in rats was evaluated by histological techniques. In order to characterize the tissue response to these degradable implants, the general tissue reactions at the implant site and also the cell types at the microsphere/tissue interface were determined. Throughout a 150-day implantation period, mild inflammation and unimpaired wound healing were observed. At the microsphere/tissue interface, the observed cell types were macrophages, foreign body giant cells, and fibroblasts. The predominant cell type was the macrophage at 15 days. Thereafter, foreign body giant cells became the predominant cell type, and only macrophages were present at later time periods. This phenomena was considered to be the result of a change in microsphere size by biodegradation. At 150 days, the vast majority of the microspheres were completely degraded, the inflammatory response was minimal, and no adverse tissue reaction was observed. Thus, these materials were regarded as biocompatible from implantation until biodegradation.