RE-186 RE-188 LABELED POLYPEPTIDE MICROSPHERES AS A POTENTIAL RADIATION SYNOVECTOMY AGENT/

Polypeptide microspheres containing polycysteine crosslinked with poly lysine were prepared and radiolabeled with Re-186 and Re-188. High lab eling yields with the microspheres with both Re-186 and Re-188 (97%) w ere obtained, and above 99% retention of radiolabels in water in 24 ho urs was obtained. Rhenium-186 labeled polycysteine and polylysine micr ospheres (1:1 ratio, 20 mu m as mean diameter) were injected intra-art icularly into the rear stifles (knee joints) of normal New Zealand whi te rabbits. About 87% of injected dose was retained in rabbit stifles and adjacent tissues in 96 hours after injection, while most of the ac tivity lost from the joints was excreted in the urine. Due to its simp licity of preparation and radiolabeling, versatility, and biodegradabi lity, this type of conjugate system may become the therapeutics of cho ice for radiation synovectomy.