Oligonucleotide transport in rat and human intestine ussing chamber models.
Cellular and intestinal absorption of naked oligonucleotides (ONs) is limited and still remains a developmental challenge. A previous report in the literature suggests that ON absorption occurs via a paracellular mechanism. The aim of this study was to test this hypothesis using rat and human intestine in a Ussing chamber and in Caco-2 cells. Transport of a (35)S-labelled mixed backbone ON (MBO) across human or rat intestinal tissue or across Caco-2 cells was measured after a 2-h incubation in the presence or absence of increasing MBO concentrations or with uptake inhibitors and enhancers. MBO intestinal absorption was compared with an internal standard, mannitol. (35)S-MBO demonstrated very little absorption (<1%) across rat and human intestinal tissues. Transport appeared to be unsaturable up to 500 microM, and relatively insensitive to compounds that opened tight junctions or inhibited P-glycoprotein. However, preliminary studies with Caco-2 cells suggest a possible saturable mechanism at higher ON concentrations. Confocal fluorescence microscopy studies show that fluorescein isothiocyanate (FITC)-MBO was internalized into intestinal cells. Although some differences in ON transport were observed as a function of the transport model, MBO transport was mostly consistent with a transcellular, rather than a paracellular, absorption mechanism.
Wu-Pong
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Department of Pharmaceutics, Virginia Commonwealth University, Richmond, VA 23298-0581, USA. swupong@vcu.edu
Livesay
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Dvorchik
B
B
Barr
W H
WH
D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1 / Q000037:antagonists & inhibitors; D000465:Algorithms; D000818:Animals; D001693:Biological Transport, Active; D003106:Colon / Q000378:metabolism; D006801:Humans; D007082:Ileum / Q000378:metabolism; D066298:In Vitro Techniques; D007408:Intestinal Absorption; D007413:Intestinal Mucosa / Q000378:metabolism*; D007583:Jejunum / Q000378:metabolism; D008297:Male; D008353:Mannitol / Q000493:pharmacokinetics; D018613:Microscopy, Confocal; D009841:Oligonucleotides / Q000493:pharmacokinetics*; D010539:Permeability; D051381:Rats; D017208:Rats, Wistar
D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D009841:Oligonucleotides; D008353:Mannitol