摘要：Aim The gene encoding neurotrophic factor was transfected into brain capillary endothelial cells with the aim of delivering the gene product extensively into the brain parenchyma by making use of the secretory function of BCECs. Methods Plasmid DNA encoding mouse glial cell-derived neurotrophic factor (mGDNF gene) was constructed and prepared. Then, mGDNF gene was transfected into cultured mouse brain capillary endothelial cells (BCECs) in vitro. The amount of mGDNF protein in the transfected cells and secreted from the transfected cells were determined by ELISA. The polarity of the secretion of mGDNF protein from BCECs was investigated in a bicameral culture system. Results The mGDNF protein was detected out not only from the transfected cells but also the cultured media. And mGDNF protein was mainly found in the brain side of the culture compartment. Conclusion It has been demonstrated that a secretory protein can be successfully delivered into brain parenchyma by utilizing the secretory pathway of BCECs.