Brain microvascular endothelial cell dysfunction in an isogenic juvenile iPSC model of Huntington's disease

• Published in: Fluids and barriers of the CNS 2022-06, Vol.19 (1), p.54-16, Article 54
• Main Authors: Linville, Raleigh M, Nerenberg, Renée F, Grifno, Gabrielle, Arevalo, Diego, Guo, Zhaobin, Searson, Peter C
• Format: Article
• Language: English
• Subjects: Analysis; Angiogenesis; Animal models; Animals; Blood flow; Blood-brain barrier; Brain - metabolism; Brain microvascular endothelial cells; Cell adhesion; Cell culture; Cell differentiation; Cerebral blood flow; Cognitive ability; Collagen; CRISPR; Cytosine; Electrical resistivity; Endothelial cells; Endothelial Cells - metabolism; Endothelium; Genetic aspects; Genotype & phenotype; Guanine; High-definition television; Huntingtin; Huntington Disease - metabolism; Huntington's disease; Huntingtons disease; Induced pluripotent stem cells; Induced Pluripotent Stem Cells - physiology; Inhibitory postsynaptic potentials; Medical research; Medicine, Experimental; Microvasculature; Nervous system diseases; Neurodegenerative disease; Neurodegenerative diseases; Neurodegenerative Diseases - metabolism; Osmotic stress; Oxidative stress; Pathogenesis; Permeability; Phenotypes; Plasma; Polyglutamine; Proteins; Pyrimidines; Stem cell transplantation; Stem cells; Tissue engineering
• ISSN: 2045-8118; 2045-8118
• DOI: 10.1186/s12987-022-00347-7

Huntington's disease (HD) is an inherited neurodegenerative disease caused by expansion of cytosine-adenine-guanine (CAG) repeats in the huntingtin gene, which leads to neuronal loss and decline in cognitive and motor function. Increasing evidence suggests that blood-brain barrier (BBB) dysfunction may contribute to progression of the disease. Studies in animal models, in vitro models, and post-mortem tissue find that disease progression is associated with increased microvascular density, altered cerebral blood flow, and loss of paracellular and transcellular barrier function. Here, we report on changes in BBB phenotype due to expansion of CAG repeats using an isogenic pair of induced pluripotent stem cells (iPSCs) differentiated into brain microvascular endothelial-like cells (iBMECs). We show that CAG expansion associated with juvenile HD alters the trajectory of iBMEC differentiation, producing cells with ~ two-fold lower percentage of adherent endothelial cells. CAG expansion is associated with diminished transendothelial electrical resistance and reduced tight junction protein expression, but no significant changes in paracellular permeability. While mutant huntingtin protein (mHTT) aggregates were not observed in HD iBMECs, widespread transcriptional dysregulation was observed in iBMECs compared to iPSCs. In addition, CAG expansion in iBMECs results in distinct responses to pathological and therapeutic perturbations including angiogenic factors, oxidative stress, and osmotic stress. In a tissue-engineered BBB model, iBMECs show subtle changes in phenotype, including differences in cell turnover and immune cell adhesion. Our results further support that CAG expansion in BMECs contributes to BBB dysfunction during HD.