In vitro model of the blood-brain barrier established by co-culture of primary cerebral microvascular endothelial and astrocyte cells

Drugs for the treatment and prevention of nervous system diseases must permeate the bloodbrain barrier to take effect.In vitro models of the blood-brain barrier are therefore important in the investigation of drug permeation mechanisms.However,to date,no unified method has been described for establishing a blood-brain barrier model.Here,we modified an in vitro model of the blood-brain barrier by seeding brain microvascular endothelial cells and astrocytes from newborn rats on a polyester Transwell cell culture membrane with 0.4-μm pores,and conducted transepithelial electrical resistance measurements,leakage tests and assays for specific bloodbrain barrier enzymes.We show that the permeability of our model is as low as that of the bloodbrain barrier in vivo.Our model will be a valuable tool in the study of the mechanisms of action of neuroprotective drugs.

Effect of Tong-Qiao-Huo-Xue decoction on the expressions of related proteins of the blood-brain barrier and analysis of constituents in cerebrospinal fluid of cerebral ischemic rats

OBJECTIVE To evaluate the effects of Tong-Qiao-Huo-Xue decoction(TQHXD)on the bloodbrain barrier(BBB)permeability and the expressions of related proteins on the rats;and to analyse the constituents in the cerebrospinal fluid on the rats with cerebral ischemic injury.METHODS Cerebral ischemia rats were induced by middle cerebral artery occlusion(MCAO).Adult male sprague-dawley(SD)rats were randomly divided into seven groups:sham-group;model group;nimodipine(NMP)-treated group and nao mai tai(NMT)-treated group were set as positive drug control groups;TQHXD-treated group(3,6 and 12g·kg-1body weight);The neurological function of rats was estimated by neurological defect scoring after the 1,7and 15 dafter administration.Histological structure of the brain in rats were observed by hematoxylin and eosin(H&E)staining.Ultramicrostructural features of hippocampus neurons and the opening of tight junction(TJ)of BBB in rats were observed by transmission electron microscope(TEM).Western blotting was performed to detect the expression of ZO-1,occludin,claudin-5,AQP-4 and MMP-9 in BBB after cerebral ischemia injury.Component analysis experiments:adult male SD rats were randomly divided into four groups:Distilled water was administered intragastrically sham-operated rats;Distilled water was administered intragastrically model rats by MCAO;TQHXD was administered intragatrically to rats in sham-operated group;TQHXD was administered intragestrically to rats in model group by MCAO.GC and HPLC was used to detect three compounds,namely,muscone,ligustilide and hydroxysafflor yellow A,in rats cerebrospinal fluid(CSF)after oral administration of TQHXD.Finally,samples of cerebrospinal fluid of rats in each group were compared with single medicine so as to explicit the three compounds come from which herb.RESULTS TQHXD significantly reduced the neurological defect scores.Histological examination indicated that dense neuropil and largely surviving neurons had been seen in TQHXD-treated rats.TEM observation revealed that TQHXD could significantly inhibit the damage of hippocampal neurons and reduce the opening of TJ.The decreased protein expression levels of claudin-5,occludin,ZO-1 and the increased protein expression levels of AQP-4 and MMP-9in cerebral ischemia tissue were significantly prevented by treatment of TQHXD.Analysis of experimental results showed that muscone,ligustilide and hydroxysafflor yellow A could penetrate the BBB into the CSF,and the content of the model group was lower than that of sham group after intragastric administration of TQHXD.CONCLUSION These results demonstrated that TQHXD may act as a potential neuroprotective agent against BBB damage for cerebral ischemia through protecting of hippocampus neurons,reducing the opening of TJ and decreasing the permeability of BBB by up-regulating ZO-1,occludin,claudin-5 expressions,down-regulating AQP-4 and MMP-9 expressions.The effect of TQHXD on the decrease of the opening of TJ also reduced the content of muscone,ligustilide and hydroxysafflor yellow A in cerebrospinal fluid.