Barrier Properties and Transcriptome Expression in Human iPSC-Derived Models of the Blood–Brain Barrier

Abstract

Cell-based models of the blood-brain barrier (BBB) are important for increasing the knowledge of BBB formation, degradation and brain exposure of drug substances. Human models are preferred over animal models because of interspecies differences in BBB structure and function. However, access to human primary BBB tissue is limited and has shown degeneration of BBB functions in vitro. Human induced pluripotent stem cells (iPSCs) can be used to generate relevant cell types to model the BBB with human tissue. We generated a human iPSC-derived model of the BBB that includes endothelial cells in coculture with pericytes, astrocytes and neurons. Evaluation of barrier properties showed that the endothelial cells in our coculture model have high transendothelial electrical resistance, functional efflux and ability to discriminate between CNS permeable and non-permeable substances. Whole genome expression profiling revealed transcriptional changes that occur in coculture, including upregulation of tight junction proteins, such as claudins and neurotransmitter transporters. Pathway analysis implicated changes in the WNT, TNF, and PI3K-Akt pathways upon coculture. Our data suggest that coculture of iPSC-derived endothelial cells promotes barrier formation on a functional and transcriptional level. The information about gene expression changes in coculture can be used to further improve iPSC-derived BBB models through selective pathway manipulation. Stem Cells 2018.

Laminin 221 fragment is suitable for the differentiation of human induced pluripotent stem cells into brain microvascular endothelial-like cells with robust barrier integrity

“…First, the difference in the differentiation processes in vitro versus in vivo and iBMELCs require different factors for differentiation. Infact, iBMELCs expressed low levels of endothelial markers and have characteristics of both endothelial and epithelial cells [17]. In this study, iBMELCs were able to incorporate Dil-Ac-LDL, indicating that iBMELCs have the characteristics of endothelial cells.…”

The pivotal role of micro-environmental cells in a human blood–brain barrier in vitro model of cerebral ischemia: functional and transcriptomic analysis

“…In the last 2 to 3 years some reports with expression data of primary human BCECs and hiPSC-BCECs have been published. These confirmed the expression of almost all claudins in human BBB in vitro models [11,24,47]. However, these data were mostly obtained from RNA-seq analysis and were not validated by a second method, so there is still a need to validate them with e.g.…”

“…Previous studies have in common that they prove the essential role of claudin-5 in all species. However, in vivo tissue and in vitro data from recent publications indicate that the TJ claudin network at the BBB may be much more complex than previously assumed [11,24,47]. To maintain the transport barrier, the BCECs use an array of transporter proteins, most of which belong to either the ABC or the SLC transporter families.…”

Recent advances in human iPSC-derived models of the blood–brain barrier

“…Human iPSC-derived BBB models have been used to understand both BBB development and the impact of other cells of the NVU on barrier formation. Several groups have found that co-culture of iBMECs with primary astrocytes, pericytes, and neural cells significantly enhances barrier formation as measured by TEER and permeability to various molecules [13,24,25]. More recent work has focused on differentiating iPSCs into the additional cells of the NVU and combining these with iBMECs for fully iPSC-derived BBB models.…”