Biliary Atresia Relevant Human iPSCs Recapitulate Key Disease Features in a Dish

Biliary atresia (BA) is the most common cause of pediatric end-stage liver disease and the etiology is poorly understood. There is no effective therapy for BA partly due to lack of human BA models. Towards developing in vitro human models of BA, disease-specific iPSCs from 6 BA patients were generated using non-integrating episomal plasmids. In addition, to determine the functional significance of BA-susceptibility genes identified by genome wide association studies (GWAS) in biliary development, a genome-editing approach was used to create iPSCs with defined mutations in these GWAS BA loci. Using the Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR)/Cas9 system, isogenic iPSCs deficient in BA-associated genes (GPC1 and ADD3) were created from healthy iPSCs. Both the BA patient-iPSCs and the knockout (KO) iPSCs were studied for their in vitro biliary differentiation potential. These BA-specific iPSCs demonstrated significantly decreased formation of ductal structures, decreased expression of biliary markers including CK7, EpCAM, SOX9, CK19, AE2 and CFTR and increased fibrosis markers such as alpha SMA, Loxl2 and Collagen1 compared to controls. Both the patient- and the KO- iPSCs also showed increased yes-associated protein (YAP, a marker of bile duct proliferation/fibrosis). Collagen and YAP were reduced by treatment with the anti-fibrogenic drug pentoxifylline. In summary, these BA-specific human iPSCs showed deficiency in biliary differentiation along with increased fibrosis, the two key disease features of BA. These iPSCs can provide new human BA models for understanding the molecular basis of abnormal biliary development and opportunities to identify drugs that have therapeutic effects on BA. This is an open access article distributed under the terms of the Creative Commons Attribution-Non Commercial-No Derivatives License 4.0 (CCBY-NC-ND), where it is permissible to download and share the work provided it is properly cited. The work cannot be changed in any way or used commercially without permission from the journal. https://ift.tt/OBJ4xP Address correspondence and reprint requests to Kathleen B. Schwarz, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA (e-mail: kschwarz@jhmi.edu), Yoon-Young Jang, MD, PhD, 1550 Orleans Street, CRB2 Rm552, Baltimore, MD 21231 (e-mail: yjang3@jhmi.edu). Received 2 August, 2018 Accepted 3 October, 2018 Supplemental digital content is available for this article. Direct URL citations appear in the printed text, and links to the digital files are provided in the HTML text of this article on the journal's Web site (www.jpgn.org). Author contribution: Lipeng Tian: Collection and/or assembly of data, Data analysis and interpretation Zhaohui Ye: Collection and/or assembly of data, Conception and design Kim Kafka: Collection of data, Administrative support Dylan Stewart: Provision of study material or patients Robert Anders: Provision of study material or patients Kathleen B. Schwarz: Provision of study material or patients, Conception and design, Manuscript writing Yoon-Young Jang: Data analysis and interpretation, Conception and design, Manuscript writing Financial support: Maryland Stem Cell Research Foundation, NIBIB (R01EB023812), NICHD (R03HD091264), Colleen Mitchel BA 5K; Zachary Meehan Memorial Fund for BA Research; Johns Hopkins Pediatric Liver Center, Johns Hopkins Children's Center There are no conflicts of interest. © 2018 by European Society for Pediatric Gastroenterology, Hepatology, and Nutrition and North American Society for Pediatric Gastroenterology,

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