title: Establishment of coculture model of blood-brain barrier in vitro for nanoparticle's transcytosis and toxicity evaluation.
abstract: OBJECTIVE
  A method of coculture of brain capillary endothelial cells (BCECs) and astrocytes of rats was used to evaluate nanoparticle's blood-brain barrier (BBB) transcytosis and toxicity at the endothelial tight junction.
  
  
  METHODS
  A lipophilic fluorescent probe, 6-coumarin, was incorporated in poly (ethyleneglycol)-poly (lactide) nanoparticle using double emulsion/solvent evaporation method. BCECs and astrocytes were firstly isolated from brain of newborn rats and characterized by their morphology and immunocytochemistry staining, separately. Subsequently, a coculture model with BCECs on the top of micro-porous membrane of cell culture insert and astrocytes on the bottom side was established. The permeability of 14C-labeled sucrose and nanoparticle were determined, separately.
  
  
  RESULTS
  The mean weight-based diameter of 6-coumarin loaded nanoparticles was (102.4 +/- 6.8) nm, with zeta potential of (-16.81 +/- 1.05) mV. BCECs were positive for factor VIII staining and glial fibrillary acidic protein was expressed in astrocytes. The transendothelial electrical resistance reached up to (313 +/- 23) omega x cm2. The tight junction between BCECs in the coculture model could be visualized by both scanning electron microscopy and transmission electron microscopy. The unchanged paracellular transport of sucrose proved that nanoparticle with concentration lower than 200 microg x mL(-1) did not impact the integrity of BBB endothelial tight junctions. The permeability of 10 microg x mL(-1) 6-coumarin labeled nanoparticle was 0.29 x 10(-3) cm x min(-1).
  
  
  CONCLUSIONS
  This in vitro experimental model of rat BBB was close to resemble the in vivo situation for examination of the permeability of nanoparticle and toxicity evaluation.
authors.affiliation: Department of Pharmaceutics, School of Pharmacy, Shanghai Medical School, Fudan University, China.
authors.forename: Wei
authors.initials: W
authors.lastname: Lu
authors.forename: Yu-zhen
authors.initials: YZ
authors.lastname: Tan
authors.forename: Xin-guo
authors.initials: XG
authors.lastname: Jiang
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D001253:Astrocytes / Q000378:metabolism* / Q000648:ultrastructure; D001692:Biological Transport; D001812:Blood-Brain Barrier; D001921:Brain / Q000098:blood supply / Q000166:cytology; D002196:Capillaries / Q000166:cytology; D002463:Cell Membrane Permeability; D018920:Coculture Techniques; D003374:Coumarins / Q000008:administration & dosage / Q000493:pharmacokinetics* / Q000633:toxicity; D042783:Endothelial Cells / Q000378:metabolism* / Q000648:ultrastructure; D005169:Factor VIII / Q000378:metabolism; D005904:Glial Fibrillary Acidic Protein / Q000378:metabolism; D053758:Nanoparticles; D011091:Polyesters; D011092:Polyethylene Glycols; D051381:Rats; D017207:Rats, Sprague-Dawley; D013395:Sucrose / Q000493:pharmacokinetics
chemical_list: D003374:Coumarins; D005904:Glial Fibrillary Acidic Protein; D011091:Polyesters; C492425:methoxy poly(ethylene glycol)-poly(lactide); D011092:Polyethylene Glycols; D013395:Sucrose; D005169:Factor VIII