The transport of substances from blood to brain is regulated by the blood-brain barrier (BBB), i.e. the barrier properties of the brain endothelium. The endothelium restricts the transport into the brain of the majority of new drug candidates. Cultured monolayers of brain endothelial cells can be used to investigate drug transport in vitro, and screen candidates for permeation properties. One recent approach is to develop in vitro models of the BBB using human induced pluripotent stem cells (hIPSCs) as described by Stebbins et al. (2015).The aim of the present study was to investigate whether the published protocols were generically applicable and thus to develop and characterize in vitro models of the BBB using hIPSCs from different sources. Two stem cell lines, Bioni010-C and WTSli024-A, were seeded and maintained on Matrigel in mTesR1 media. Cells were then seeded as single cells at different densities and when the cells reached 80 % confluence the media was changed to undifferentiated media. Endothelial cell media (w. PDS and bFGF) w/o retinoic acid (RA) were added after six days followed by seeding on permeable supports. Media were changed to endothelial cell media (w. PDS) after 24h, and used for experiments the following day. The model was monitored by measuring the trans-endothelial electrical resistance (TEER).
RA had an inductive effect on the model, shown by an elevation in barrier tightness which correlated with the presence of tight junction proteins, shown by confocal microscopy images which also showed presence of efflux pumps. This indicates that it is possible to generate in vitro BBB models derived from hIPSCs from different sources.