Studying the Permeation of FITC and FITC-Ferritin through an In Vitro Blood-Brain Barrier Model

Begin with a multiwell plate containing an in vitro blood-brain barrier or BBB model.

This model consists of endothelial cells adhered to the upper or blood side and astrocytes on the lower or brain side of a matrix-coated membrane insert.

Add fluorescein isothiocyanate or FITC, a fluorescent dye, to the upper chamber of a control well.

Conversely, add FITC-loaded ferritin, or FITC-ferritin, to the upper chamber of a sample well and then incubate.

In the control well, free FITC remains confined to the upper chamber, with minimal crossing through the BBB.

Meanwhile, in the sample well, FITC-ferritin complexes bind to receptors on the endothelial cells.

This allows receptor-mediated internalization and transport into the lower chamber.

Next, regularly collect medium from the lower chambers of both wells and measure fluorescence intensity.

The control exhibits lower fluorescence, while the sample displays higher fluorescence, confirming the differential BBB permeability for FITC and FITC-ferritin.