title: Effect of lipid composition on incorporation of trastuzumab-PEG-lipid into nanoliposomes by post-insertion method: physicochemical and cellular characterization.
abstract: BACKGROUND
  Anti-HER2 immunoliposomes are promising nanotechnology based systems for active targeting of breast tumors, which depends on the amount of incorporated antibody.
  
  
  OBJECTIVE
  In this work, we investigated the possible effect of lipid composition on the incorporation of trastuzumab-PEG-PE micelles into nanoliposomes and on their subsequent specific cellular targeting.
  
  
  METHODS
  Trastuzumab (anti-HER2 monoclonal antibody) was monothiolated and conjugated to maleimide-PEG-PE micelles. Liposomes of different lipid compositions were prepared by the thin layer hydration. Trastuzumab-PEG-PE micelles were incorporated into the liposomes by the post-insertion method. The percentage of lipid mixing was determined based on fluorescence resonance energy transfer. Cellular binding and uptake of rhodamine-labeled immunoliposomes were studied in SKBR-3 (HER2(+++)) and MCF-7 (HER2(+)) cells. Also, antitumor cell activity of the immunoliposomes was compared to free trastuzumab and the liposomes.
  
  
  RESULTS
  The lipid mixing of trastuzumab-PEG-PE micelles depended on the liposome composition. The immunoliposomes containing DPPC, cholesterol and PEG-PE showed prominent lipid mixing. The lipid mixing was consistent with the cell binding results which showed an efficient and specific binding of the immunoliposomes to SKBR-3 cells. Antitumor cell activity of the immunoliposomes in SKBR-3, unlike MCF-7 cells, depended on the content of trastuzumab.
  
  
  CONCLUSIONS
  Cholesterol and PEG-PE in the liposome composition are prerequisites for a successful lipid mixing due to their ability to facilitate fusion. The higher lipid mixing results in higher antibody incorporation and consequently higher targeted cell binding.
  
  
  CONCLUSIONS
  The lipid mixing depends on the liposome composition, which reflects targeted cell binding of the immunoliposomes.
authors.affiliation: a Center for Nanotechnology in Drug Delivery, Shiraz University of Medical Sciences , Shiraz , Iran and.|b Department of Pharmaceutics , School of Pharmacy, Shiraz University of Medical Sciences , Shiraz , Iran.
authors.forename: Nasim
authors.initials: N
authors.lastname: Golkar
authors.affiliation: a Center for Nanotechnology in Drug Delivery, Shiraz University of Medical Sciences , Shiraz , Iran and.|b Department of Pharmaceutics , School of Pharmacy, Shiraz University of Medical Sciences , Shiraz , Iran.
authors.forename: Ali Mohammad
authors.initials: AM
authors.lastname: Tamaddon
authors.affiliation: a Center for Nanotechnology in Drug Delivery, Shiraz University of Medical Sciences , Shiraz , Iran and.|b Department of Pharmaceutics , School of Pharmacy, Shiraz University of Medical Sciences , Shiraz , Iran.
authors.forename: Soliman Mohammadi
authors.initials: SM
authors.lastname: Samani
mesh_terms: D000970:Antineoplastic Agents / Q000008:administration & dosage* / Q000737:chemistry / Q000494:pharmacology*; D049109:Cell Proliferation / Q000187:drug effects; D002627:Chemistry, Physical; D004354:Drug Screening Assays, Antitumor; D006801:Humans; D008055:Lipids / Q000737:chemistry / Q000494:pharmacology*; D008081:Liposomes / Q000138:chemical synthesis / Q000737:chemistry* / Q000494:pharmacology; D061986:MCF-7 Cells; D008823:Micelles; D053758:Nanoparticles / Q000737:chemistry*; D011092:Polyethylene Glycols / Q000737:chemistry / Q000494:pharmacology*; D000068878:Trastuzumab / Q000008:administration & dosage* / Q000737:chemistry / Q000494:pharmacology*; D014407:Tumor Cells, Cultured
chemical_list: D000970:Antineoplastic Agents; D008055:Lipids; D008081:Liposomes; D008823:Micelles; D011092:Polyethylene Glycols; D000068878:Trastuzumab
keywords: HER2; immunoliposomes; lipid mixing; specific cell binding