title: Accumulation of protein-loaded long-circulating micelles and liposomes in subcutaneous Lewis lung carcinoma in mice.
abstract: OBJECTIVE
  The purpose of our work was to compare the biodistribution and tumor accumulation of a liposome- or micelle-incorporated protein in mice bearing subcutaneously-established Lewis lung carcinoma.
  
  
  METHODS
  A model protein, soybean trypsin inhibitor (STI) was modified with a hydrophobic residue of N-glutaryl-phosphatidyl-ethanolamine (NGPE) and incorporated into both polyethyleneglycol(MW 5000)-distearoyl phosphatidyl ethanolamine (PEG-DSPE) micelles (< 20 nm) and PEG-DSPE-modified long-circulating liposomes (ca. 100 nm). The protein was labeled with 111In via protein-attached diethylene triamine pentaacetic acid (DTPA), and samples of STI-containing liposomes or micelles were injected via the tail vein into mice bearing subcutaneously-established Lewis lung carcinoma. At appropriate time points, mice were sacrificed and the radioactivity accumulated in the tumor and main organs was determined.
  
  
  RESULTS
  STI incorporated into PEG-lipid micelles accumulates in subcutaneously established Lewis lung carcinoma in mice better than the same protein anchored in long-circulating PEG-liposomes.
  
  
  CONCLUSIONS
  Small-sized long-circulating delivery systems, such as PEG-lipid micelles, are more efficient in the delivery of protein to Lewis lung carcinoma than larger long-circulating liposomes.
authors.affiliation: Center for Imaging and Pharmaceutical Research, Department of Radiology, Massachusetts General Hospital and Harvard Medical School, Charlestown 02129, USA.
authors.forename: V
authors.initials: V
authors.lastname: Weissig
authors.forename: K R
authors.initials: KR
authors.lastname: Whiteman
authors.forename: V P
authors.initials: VP
authors.lastname: Torchilin
mesh_terms: D000818:Animals; D018827:Carcinoma, Lewis Lung / Q000378:metabolism*; D004337:Drug Carriers; D008081:Liposomes; D051379:Mice; D008810:Mice, Inbred C57BL; D008823:Micelles; D011506:Proteins / Q000008:administration & dosage* / Q000493:pharmacokinetics; D014018:Tissue Distribution
chemical_list: D004337:Drug Carriers; D008081:Liposomes; D008823:Micelles; D011506:Proteins