title: Retro-convection enhanced delivery to increase blood to brain transfer of macromolecules.
abstract: A retro-convection enhanced delivery (R-CED) method has been developed to improve the entry of intravenously administered therapeutics within solid brain tumors. R-CED uses an osmotic gradient to withdraw brain interstitial fluid (ISF) in a controlled manner via an implanted microdialysis catheter. Withdrawal of ISF increases the local tissue specific gravity in normal brain and increases twofold the extravasation of intravenous Evans blue (EB) albumin in normal brain and in an orthotopic 9L tumor. R-CED also increases the extravasation of 70 nm fluorescent liposomes fivefold in the 9L tumor. Thus the transmembrane osmotic gradient induces movement of substances in the blood into the tissue parenchyma. Following probe removal, the magnitude of the R-CED effect on EB-albumin extravasation decreases to control values within 1.5 h in normal brain; however, the effect persists beyond 6 h in the tumor. There was no evidence of histologic damage to the neurons at either 6 h or 2 weeks after R-CED. These studies establish the feasibility of applying R-CED to increase the distribution of systemically administered drugs in both the normal tissue-tumor margin as well as in the central tumor core, holding forth the possibility of improved antitumor drug efficacy.
authors.affiliation: Joint Graduate Group in Bioengineering, University of California, San Francisco and University of California, Berkeley, San Francisco, CA 94143-0446, USA.
authors.forename: Grace H
authors.initials: GH
authors.lastname: Huynh
authors.forename: Tomoko
authors.initials: T
authors.lastname: Ozawa
authors.forename: Dennis F
authors.initials: DF
authors.lastname: Deen
authors.forename: Tarik
authors.initials: T
authors.lastname: Tihan
authors.forename: Francis C
authors.initials: FC
authors.lastname: Szoka
mesh_terms: D000418:Albumins / Q000378:metabolism; D000818:Animals; D001921:Brain / Q000187:drug effects / Q000378:metabolism*; D001932:Brain Neoplasms / Q000188:drug therapy / Q000473:pathology; D045744:Cell Line, Tumor; D018481:Convection; D004333:Drug Administration Routes; D016503:Drug Delivery Systems; D045604:Extracellular Fluid / Q000378:metabolism; D005910:Glioma / Q000188:drug therapy / Q000473:pathology; D008081:Liposomes / Q000378:metabolism; D046911:Macromolecular Substances / Q000378:metabolism* / Q000627:therapeutic use; D017551:Microdialysis / Q000379:methods; D051381:Rats; D013997:Time Factors
chemical_list: D000418:Albumins; D008081:Liposomes; D046911:Macromolecular Substances