title: Effect of the size of liposomes on the transfer and uptake of carboxyfluorescein by the perfused human term placenta.
abstract: The effect of the size of liposomes on the uptake and transfer of the low molecular-weight, hydrophilic and polar molecule carboxyfluorescein has been determined across the perfused human term placenta. Carboxyfluorescein-encapsulated neutral liposomes of three different sizes were prepared from equimolar concentrations of lecithin and cholesterol. Size distribution, encapsulation efficiency and stability of liposomes in blood-based media were determined. The concentration of carboxyfluorescein was measured spectrophotometrically. The transplacental transfer and placental uptake of free carboxyfluorescein (control data) were respectively 1.9 +/- 0.2 and 5.0 +/- 0.7% of initial dose. The placental uptake and foetal concentration of carboxyfluorescein were significantly increased by small liposomes (P < 0.05), and reduced by large (0.82 +/- 0.13%; P < 0.05) and multilamellar liposomes (0.32 +/- 0.11%). There was a negative correlation between liposome size and transplacental transfer (y = -0.53 + 0.9x; r = 0.96; P < 0.001; n = 24) and placental uptake of carboxyfluorescein (y = -5.9 + 6.5x; r = 0.84; P < 0.001; n = 24). The study indicates that placental uptake and transfer rate of liposomal carboxyfluorescein were dependant upon the size of liposomes.
authors.affiliation: Department of Obstetrics and Gynaecology, Charing Cross & Westminster Medical School, London, UK.
authors.forename: R
authors.initials: R
authors.lastname: Bajoria
authors.forename: S F
authors.initials: SF
authors.lastname: Contractor
mesh_terms: D000704:Analysis of Variance; D019540:Area Under Curve; D002784:Cholesterol / Q000737:chemistry / Q000378:metabolism; D002850:Chromatography, Gel; D004337:Drug Carriers; D004339:Drug Compounding; D004355:Drug Stability; D005260:Female; D005452:Fluoresceins / Q000008:administration & dosage / Q000493:pharmacokinetics*; D005456:Fluorescent Dyes / Q000008:administration & dosage / Q000493:pharmacokinetics*; D006801:Humans; D066298:In Vitro Techniques; D008081:Liposomes; D010316:Particle Size; D010477:Perfusion; D010713:Phosphatidylcholines / Q000737:chemistry / Q000378:metabolism; D010920:Placenta / Q000378:metabolism*; D011247:Pregnancy; D013050:Spectrometry, Fluorescence; D014018:Tissue Distribution
chemical_list: D004337:Drug Carriers; D005452:Fluoresceins; D005456:Fluorescent Dyes; D008081:Liposomes; D010713:Phosphatidylcholines; C024098:6-carboxyfluorescein; D002784:Cholesterol