Cell culture on ultra-thin membranes provides a model of the blood-brain barrier.

A new model of the blood-brain barrier, which allows a high degree of direct contact between capillary and brain cells, has been developed by US scientists.

Endothelial cells line capillaries in the brain and have extremely tight junctions with other cells, forming an almost impermeable barrier to water soluble molecules between the blood and the brain. This blood-brain barrier (BBB) protects the brain and provides a constant environment for neural processes, and it is thought that direct contact between endothelial cells and astrocytes is at least partially responsible for the development of these tight intercellular junctions.

Although results from several in vitro BBB models suggest that direct contact is necessary for full BBB endothelial cell differentiation, the membranes in most commercially available culture kits do not have the right physical dimensions to allow many interactions between cells grown on different sides. Now, Michael Shuler and co-workers at Cornell University in Ithaca, New York, and the Laboratory of Nervous System Disorders in Albany, New York, have made membranes from silicon nitride that are much thinner and more porous than existing BBB model membranes. Culturing astrocytes and endothelial cells on opposite sides of these membranes allows the potential for high degrees of contact between the cell types.

Synergy between the two cell types has yet to be achieved, possibly because commercially available endothelial cells have lost the ability to respond to astrocyte differentiating signals. However, the authors believe that using nanofabricated silicon nitride membranes will have great potential for BBB models, and may also be useful in other co-culture systems.

Rowena Milan