RESUMO
OBJECTIVE To improve the poor water solubility and evaluating poor acitivity of etoposide (VP-16) by preparing VP-16 nanoparticle suspension (VP-16 NP) and its penetration through the blood-brain barrier (BBB).METHODS VP-16 NP was prepared with the anti-solution exchange method.The shape structure and diameter were observed with transmission electron microscopy (TEM) and scanning electron microscopy (SEM) and dynamic light scattering (DLS), respectively. The drug release profiles of the VP-16 powder and VP-16 NP were measured.The effect of VP-16 NP on the growth of KB cells was observed via MTT assay. In addition, primary brain microvascular endothelial cells from 1stto 2nd generation of SD rats at two weeks of age were used to construct an in vitro BBB model.The classic 4 h leak test,trans-epithelial electrical resistance (TEER) test and fluorescein disodium salt(FLU)perme?ability test were conducted to verify whether the in vitro BBB model was successfully established.RESULTS VP-16 NP was a solid sphere with a size of 140 nm detected by TEM,SEM and DLS.The cumulative release rate of VP-16 NP was 3 times that of VP-16 powder. The results of MTT colorimetric assay showed that VP-16 powder had no inhibitory effect on KB cells,while VP-16 NP could effectively inhibit KB cells. In the 4 h leakage experiment, the top and bottom chambers of the Transwell cell model could maintain a liquid surface distance of >0.5 cm,indicating that the in vitro BBB model was initially formed.The effective resistance value of the TEER experiment was 223 Ω·cm2,indicating that the in vitro BBB model was basically established. In FLU permeability experiments, the permeability coefficients were respectively (0.33±0.04)×10-3,(0.42±0.07)×10-3,and (0.52±0.06)×10-3cm·min-1at 15,30 and 60 min, indicating that the model had low permeability.The above three experiments suggested that the BBB in vitro model was successfully constructed. On this basis, the in vitro BBB model was used to evaluate the penetration of VP-16 NP at a permeability coefficient of (1.87±0.03)×10-3cm·min-1at 30 min,showing high permeability.VP-16 NP showed better penetration of BBB.CONCLUSION VP-16 NP is success?fully prepared,which increases the release rate of the drug,enhances the killing effect of the cells,and shows good penetration through the in vitro BBB model evaluation.