Exogenous expression of interferon-beta in cultured brain microvessel endothelial cells.

Brain microvessel endothelial cells (BMECs) make up the blood-brain barrier (BBB) and regulate the passage of therapeutic proteins as well as drugs from the cerebrovasucular circulation to the brain. In the present study, we transferred mouse or human interferon-beta (IFN-beta) gene via cationic liposomes into primary cultures of bovine BMECs developed as an in vitro model of the BBB. The gene-transferred BMECs secreted transiently a substantial amount of IFN activity more efficiently during the growth phase than at confluence. This was suggested to be due to a difference in the potential for plasmid incorporation between growing and confluent BMECs in a series of cell association experiments with (32)P-labelled plasmid DNA. Furthermore, when BMEC monolayers in Transwell plates were transfected with the IFN-beta-expression vectors from the upper side, IFN-beta was predominantly detected in the upper compartments, suggesting polarized secretion of the transgene products in BMEC monolayers. These findings provide important basic information about therapeutic secretory protein gene delivery to BMECs.