In vivo biocompatibility and degradability of a novel injectable-chitosan-based implant

A novel injectable-chitosan-based delivery system with low cytotoxicity was fabricated in the study. The chitosan microspheres with small particle siz e, low crystallinity and good sphericity were prepared by a spray-drying me thod followed by treating with a crosslinker. In the study, a naturally occ urring crosslinking reagent (genipin), which has been used in herbal medici ne and in the production of food dyes, was used to crosslink the chitosan m icrospheres. The glutaraldehyde-crosslinked counterparts were used as a con trol. Histological study of the genipin-crosslinked chitosan microspheres i njected intramuscularly into the skeletal muscle of a rat model showed a le ss inflammatory reaction than its glutaraldehyde-crosslinked counterparts. The results of the scanning electron microscopic examination indicated that the glutaraldehyde-crosslinked chitosan microspheres retrieved at 12-week postoperatively were already degraded into a loose and porous structure. Ho wever, the degradation of the genipin-crosslinked chitosan microspheres was not significant after 20 weeks of implantation. The results of the study d emonstrated that the genipin-crosslinked chitosan microspheres have a super ior biocompatibility and a slower degradation rate than the glutaraldehyde- crosslinked chitosan microspheres. Accordingly, the genipin-crosslinked chi tosan microspheres may be a suitable polymeric carrier for long-acting inje ctable drug delivery. (C) 2001 Elsevier Science Ltd. All rights reserved.