Binding and interstitial penetration of liposomes within avascular tumor spheroids Journal Article


Authors: Kostarelos, K.; Emfietzoglou, D.; Papakostas, A.; Yang, W. H.; Ballangrud, A.; Sgouros, G.
Article Title: Binding and interstitial penetration of liposomes within avascular tumor spheroids
Abstract: The liposomal delivery of cancer therapeutics, including gene therapy vectors, is an area of intense study. Poor penetration of liposomes into interstitial tumor spaces remains a problem, however. In this work, the penetration of different liposomal formulations into prostate carcinoma spheroids was examined. Spheroid penetration was assessed by confocal microscopy of fluorescently labeled liposomes. The impact of liposomal surface charge, mean diameter, lipid bilayer fluidity and fusogenicity on spheroid penetration was examined. A variety of different liposome systems relevant to clinical or preclinical protocols have been studied, including classical zwitterionic (DMPC:chol) and sterically stabilized liposomes (DMPC:chol:DOPE-PEG 2000), both used clinically, and cationic liposomes (DMPC:DOPE:DC-chol and DOTAP), forming the basis of the vast majority of nonviral gene transfer vectors tested in various cancer trials. Surface interactions between strongly cationic vesicles and the tumor cells led to an electrostatically derived binding-site barrier effect, inhibiting further association of the delivery systems with the tumor spheroids (DMPC:DC-chol). However, inclusion of the fusogenic lipid DOPE and use of a cationic lipid of lower surface charge density (DOTAP instead of DC-chol) led to improvements in the observed intratumoral distribution characteristics. Sterically stabilized liposomes did not interact with the tumor spheroids, whereas small unilamellar classical liposomes exhibit extensive distribution deeper into the tumor volume. Engineering liposomal delivery systems with a relatively low charge molar ratio and enhanced fusogenicity, or electrostatically neutral liposomes with fluid bilayers, offered enhanced intratumoral penetration. This study shows that a delicate balance exists between the strong affinity of delivery systems for the tumor cells and the efficient penetration and distribution within the tumor mass, similar to previous work studying targeted delivery by ligand-receptor interactions of monoclonal antibodies. Structure-function relationships from the interaction of different liposome systems with 3-dimensional tumor spheroids can lead to construction of delivery systems able to target efficiently and penetrate deeper within the tumor interstitium and act as a screening tool for a variety of therapeutics against cancer. © 2004 Wiley-Liss, Inc.
Keywords: controlled study; human cell; drug penetration; drug targeting; binding affinity; metastasis; confocal microscopy; tumor volume; fluorescent dye; lipid; tumor cells, cultured; drug design; structure activity relation; gene transfer; gene vector; monoclonal antibody; drug delivery systems; prostatic neoplasms; antibodies, monoclonal; drug distribution; tumor cell; ligand; neoplasm metastasis; ligands; binding site; receptor; density; tumor vascularization; liposome; drug delivery system; liposomes; lipid bilayer; electricity; drug formulation; engineering; cation; spheroids, cellular; chemical interaction; surface property; penetration; leydig cell tumor; targeting; tumor spheroids; tumor spheroid; 1,2 dioleoyl 3 trimethylammoniopropane; humans; human; male; priority journal; article; interstitial transport; ampholyte; macrogol 2000; interstitium
Journal Title: International Journal of Cancer
Volume: 112
Issue: 4
ISSN: 0020-7136
Publisher: John Wiley & Sons  
Date Published: 2004-11-20
Start Page: 713
End Page: 721
Language: English
DOI: 10.1002/ijc.20457
PROVIDER: scopus
PUBMED: 15382056
DOI/URL:
Notes: Int. J. Cancer -- Cited By (since 1996):45 -- Export Date: 16 June 2014 -- CODEN: IJCNA -- Source: Scopus
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  1. George Sgouros
    146 Sgouros
  2. Wei Hong Yang
    19 Yang