Activation of RARα, RARγ, or RXRα Increases Barrier Tightness in Human Induced Pluripotent Stem Cell-Derived Brain Endothelial Cells

Biotechnol J. 2018 Feb;13(2):10.1002/biot.201700093. doi: 10.1002/biot.201700093. Epub 2017 Sep 28.

Abstract

The blood-brain barrier (BBB) is critical to central nervous system (CNS) health. Brain microvascular endothelial cells (BMECs) are often used as in vitro BBB models for studying BBB dysfunction and therapeutic screening applications. Human pluripotent stem cells (hPSCs) can be differentiated to cells having key BMEC barrier and transporter properties, offering a renewable, scalable source of human BMECs. hPSC-derived BMECs have previously been shown to respond to all-trans retinoic acid (RA), and the goal of this study was to identify the stages at which differentiating human induced pluripotent stem cells (iPSCs) respond to activation of RA receptors (RARs) to impart BBB phenotypes. Here the authors identified that RA application to iPSC-derived BMECs at days 6-8 of differentiation led to a substantial elevation in transendothelial electrical resistance and induction of VE-cadherin expression. Specific RAR agonists identified RARα, RARγ, and RXRα as receptors capable of inducing barrier phenotypes. Moreover, RAR/RXRα costimulation elevated VE-cadherin expression and improved barrier fidelity to levels that recapitulated the effects of RA. This study elucidates the roles of RA signaling in iPSC-derived BMEC differentiation, and identifies directed agonist approaches that can improve BMEC fidelity for drug screening studies while also distinguishing potential nuclear receptor targets to explore in BBB dysfunction and therapy.

Keywords: blood-brain barrier; brain microvascular endothelial cells; human pluripotent stem cells; nuclear hormone receptors; retinoic acid.

MeSH terms

  • Antigens, CD / metabolism
  • Blood-Brain Barrier / cytology*
  • Blood-Brain Barrier / drug effects
  • Brain / cytology
  • Brain / drug effects
  • Brain / metabolism
  • Cadherins / metabolism
  • Cell Differentiation / drug effects
  • Cells, Cultured
  • Endothelial Cells / cytology
  • Endothelial Cells / drug effects
  • Gene Expression Regulation
  • Humans
  • Induced Pluripotent Stem Cells / cytology*
  • Induced Pluripotent Stem Cells / drug effects
  • Neurons / cytology
  • Neurons / drug effects
  • Receptors, Retinoic Acid / agonists
  • Receptors, Retinoic Acid / metabolism*
  • Retinoic Acid Receptor alpha / agonists
  • Retinoic Acid Receptor alpha / metabolism*
  • Tretinoin / pharmacology

Substances

  • Antigens, CD
  • Cadherins
  • Receptors, Retinoic Acid
  • Retinoic Acid Receptor alpha
  • cadherin 5
  • retinoic acid receptor gamma
  • Tretinoin