Generation and Characterization of Human Blood-Brain Barrier Models for Investigating Neuropsychiatric Disorders and Tumor Metastasis
The blood–brain barrier (BBB) is important in the normal function of the central nervous system (CNS). An altered BBB has been described in various neuropsychiatric disorders. The brain-specific microvascular endothelial cell (BMEC) is an essential structural component of the BBB. To test if integrity of the BBB formed by BMECs is compromised in 22q11.2 deletion syndrome (also called DiGeorge syndrome), which is one of the validated genetic risk factors for schizophrenia, a 2D iBBB (induced BBB) on a Transwell filter was generated from human microvascular endothelial cells (HBMECs) derived from the induced pluripotent stem cells (iPSCs) out of patients with 22q11.2DS and age and gender matched healthy controls. It was found that the solute permeability of the iBBB formed from patient HBMECs increases by ~1.3-1.4 folds, while the trans-endothelial electrical resistance (TEER) decreases to ~62% of the control values. Correspondingly, tight junction proteins and the endothelial glycocalyx that determine the integrity of the BBB are significantly disrupted. It was also found that CRKL, a gene within the 22q11.2 DS deletion region, contributes to the deficit. The CRKL is a major substrate of the Abl tyrosine kinase, and the Abl/CRKL signaling pathway is critical for endothelial barrier functions. Imatinib, an FDA-approved drug, inhibits Abl kinase and has been used to treat various disorders involving vascular leakages. To test if imatinib can restore the compromised iBBB, the patient’s iBBB was treated with imatinib. After treatment, both TEER and solute permeability returned to comparable levels of the healthy control iBBB. Correspondingly, changes in tight junctions and endothelial glycocalyx of the iBBB were also restored. The disruption of endothelial glycocalyx is an early event in tumor cell (TC) adhesion and transmigration across vascular barriers. But how glycocalyx of TC affects TC adhesion and transmigration is unclear. Whether or not glycocalyx can be a target for tumor metastasis is also understudied. Therefore, the 2D BBB generated from HCMECs was employed to investigate the role of glycocalyx in breast cancer cell (MDA-MB-231) adhesion to and transmigration across the BBB. It was found that the reduced/enhanced BBB glycocalyx and enhanced/reduced breast cancer cell glycocalyx increase/decrease breast cancer cell adhesion to and transmigration across the BBB. Because the 2D BBB generated on the Transwell filter under static conditions may not completely represent the real BBB under physiological conditions, a 3D microchannel-BBB in PDMS-hydrogel was generated under flow. The solute permeability of the 3D BBB was quantified as well as the glycocalyx after the treatment with a variety of glycocalyx-modulating agents. Breast cancer cell adhesion in this 3D BBB was also quantified under physiological flows and after pretreatment with those glycocalyx-modulating agents.
Blood-brain barrier, In vitro medol, Microfluidic device, Neuropsychiatric disorders, Tumor metastasis, Bioimaging and Biomedical Optics, Biological Engineering, Biomechanics and Biotransport, Molecular, Cellular, and Tissue Engineering
City University of New York - City College
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