Using PEGylated nano-liposomes to target tissue invaded by a foreign body

The ability of nano (approximately 100 nm) sterically stabilized liposomes (nSSLs) to target tissue invaded by a foreign body was demonstrated. Radioactively labeled nSSL remote loaded with the anti-inflammatory drug methylprednisolone hemisuccinate (MPS), to form nSSL-MPS, were injected i.v. to mice that, 2 or 3 weeks earlier, had either a thorn or a needle implanted in a hind leg. Twenty-four hours post-nSSL-MPS injection, animals were sacrificed, and the level of liposomes in the vicinity of the foreign body, in comparison to the tissue in the contralateral (normal) leg, was measured. The level of liposomes in the tissue surrounding the foreign body was twice as high as the level of liposomes found in the normal leg. Furthermore, the level of liposomes in the normal leg was similar to the level of liposomes measured in the legs of control animals that did not have an implanted foreign body and were treated with nSSL-MPS. The implications of these findings and the clinical applications of liposomal targeting are discussed.