BASIC FIBROBLAST-GROWTH-FACTOR IMPREGNATED HYDROGEL MICROSPHERES FOR EMBOLIZATION OF CEREBRAL ARTERIOVENOUS-MALFORMATIONS

To assess the prevention of recanalization at embolized sites in cereb ral arteriovenous malformations, the authors devised a novel embolic m aterial, hydrogel microspheres prepared from poly(ethylene glycol) dia crylate impregnated with basic fibroblast growth factor. In this artic le, preparation of the microspheres, and preliminary study of in vitro and in vivo performance are discussed. Poly(ethylene glycol) diacryla te, prepared from end capping of poly(ethylene glycol) (molecular weig hts, 1,000, 2,000, and 4,000) with acryloyl chloride and benzophenone derived poly(ethylene glycol), prepared from poly(ethylene glycol) (mo lecular weight, 2,000) with benzoyl benzoic acid chloride as a photoin itiator, were dissolved in a buffer solution with or without basic fib roblast growth factor. The mixed solution was dropped stepwise into li quid paraffin with stirring. Ultraviolet light irradiation resulted in the formation of relatively rigid hydrogel microspheres (diameter, 10 0-400 mu m). The in vitro study showed that the higher the molecular w eight of poly(ethylene glycol) diacrylate used, the faster the release rate of immobilized protein. Canine kidneys were embolized with these microspheres via the femoral artery using a microcatheter. Histologic examination showed that microspheres occluded arterioles. The degree of accumulation of fibroblasts and extracellular matrix were larger fo r basic fibroblast growth factor impregnated microspheres than for non impregnated ones. Basic fibroblast growth factor released from microsp heres may help regenerate tissues at arteriovenous malformation sites, and recanalization is expected to be prevented.