Effect of human astrocytes on the characteristics of human brain-microvascular endothelial cells in the blood–brain barrier

A blood–brain barrier (BBB) model in vitro was established by cultivating human brain-microvascular endothelial cells (HBMECs) with the regulation of human astrocytes (HAs) (HBMEC/HA). Astrocyte-conditioned medium (ACM) was employed to constitute a confluent monolayer of HBMECs without directly conjugated HAs. HBMECs exhibited an orientated multiplication on the supporting membrane; while HAs grew in an overlapping fashion. In addition, HBMECs could propagate over the membrane pore, and the end-feet of HAs extended into the membrane pore to improve the integral feature of the BBB. HBMEC/HA demonstrated a high transendothelial electrical resistance (TEER) about 230 Ω cm2 and low permeability of propidium iodide (PI) about 4 × 10−6 cm/s. The order in TEER was HBMEC/HA > HBMECs with 100% ACM > HBMECs with 50% ACM > HBMECs. The reverse order was valid for the permeability of PI and uptake of calcein-AM by HBMECs. The tranwell culture of HBMECs and HAs displays appropriate characteristics of the BBB and can be applied to estimate the delivery efficiency of therapeutic chemicals for the brain-related disease.