Background:
In vitro blood-brain barrier (BBB) models are valuable for studying neurovascular biology and testing drug permiablity. Induced pluripotent stem cells (iPSCs)-derived brain microvascular endothelial cell (BMEC) models demonstrate superior barrier properties compared to immortalised cell lines. This project compares two differentiation protocols (Bertucci and Qian et al.)1.2 to identify strategies for generating robust, biologically relevant BBB models with stronger barrier integrity.
Methods:
Transwell-based BBB models were established using iPSC-derived endothelial cells differentiated through two types of protocols. Endothelial characteristics were evaluated via detecting of VE-cadherin, tube formation, and membrane transporters. Barrier integrity was assessed by sodium fluorescein permeability, transendothelial electrical resistance (TEER), and tight junction formation (claudin-5, occludin, and ZO-1). In addition, transferrin uptake assay and rhodamine accumulation assay were also performed to exam endocytic and P-glycoprotein (Pgp) efflux transport function, respectively.
Results:
iPSCs derived using Bertucci’s protocol exhibited well-defined endothelial phenotype, characterized by expression of VE-cadherin and CD31, successful tube formation in 3D extracellular matrix, and intact endocytosis and efflux transport function. However, despite of tight junctions formation, those cells yielded low barrier integrity with TEER measurement around 20 Ω·cm2. In contrast, iPSCs derived from Qian’s protocol displayed mixed endothelial/epithelial features, including the ability to form tubes and high epithelial markers expression (E-cadherin and CD326). Despite this, it showed robust transport functions and superior barrier integrity with higher TEER measurements (~3000 Ω·cm2).
Conclusions:
The two BBB models performed distinctly due to different iPSC-derived cell phenotypes and functional properties. The Bertucci’s iPSC-derived BBB model is appropriate for mechanistic studies and neurovascular biology study because of its well-defined endothelial phenotype, whereas the Qian’s BBB model with superior barrier integrity is better suited for drug delivery screening applications.