Limitations of the hCMEC/D3 Cell Line as a Model for Aβ Clearance by the Human Blood-brain Barrier

Alzheimer's disease and cerebral amyloid angiopathy are characterized by accumulation of amyloid-beta (A beta) at the cerebrovasculature due to decreased clearance at the blood-brain barrier (BBB). However, the exact mechanism of A beta clearance across this barrier has not been fully elucidated. The hCMEC/D3 cell line has been characterized as a valid model for the BBB. In this study we evaluated the use of this model to study A beta clearance across the BBB, with an emphasis on brain-to-blood directional permeability. Barrier integrity of hCMEC/D3 monolayers was confirmed for large molecules in both the apical to basolateral and the reverse direction. However, permeability for smaller molecules was substantially higher, especially in basolateral to apical direction, and barrier formation for A beta was completely absent in this direction. In addition, hCMEC/D3 cells failed to develop a high TEER, possibly caused by incomplete formation of tight junctions. We conclude that the hCMEC/D3 model has several limitations to study the cerebral clearance of A beta. Therefore, the model needs further characterization before this cell system can be generally applied as a model to study cerebral A beta clearance. (C) 2016 The Authors Journal of Neuroscience Research Published by Wiley Periodicals, Inc.