Research Projects

Alagille syndrome (ALGS), is a multisystem autosomal rare dominant developmental disorder which is caused by a mutation in JAGGED1 that prevents duct cells from forming in the liver. ALGS is considered a paediatric disorder, where the treatments are available to manage the symptoms, but the disease is incurable, carrying a 75% mortality rate by late adolescence for those without a liver transplant (Mitchell et al., 2018). Large variety of mutations in JAG1 (94%) and NOTCH2 (2%) genes have been identified in specific population that lead to ALGS but the lack of genotype–phenotype correlations, extremely variable clinical presentation from patient to patient even for a same mutation pose a unique challenge for developing targeted treatments (Gilbert et al., 2019; Rajagopalan et al., 2021). To address this unmet need, we propose on developing a vascularized hepato-biliary induced Pluripotent Stem Cells (iPSC) organoid model and explore it for evaluating pathogenicity of various JAG1 variants for understanding the pathophysiology of ALGS using patient-derived samples and data from Indian population. In this proposal, we will use stem cell culture, cell biology assays, clinical data, genomics, and transcriptional profiling based experiments to determine the mechanism of JAG1 regulation by epigenetics and to identify critical targets of JAG1 during bile duct development. Existing iPSC-liver organoid models rarely comment upon the presence of non-parenchymal cells (NPCs) that are important for supporting effective liver and biliary functions (Goulart et al., 2019). Recently, we have developed defined iPSC-liver organoid model (Abbey et al., 2020) and now we aim to take it further by developing vascularized human iPSC-hepato-biliary organoids that overcomes current limitations of lack of NPCs and biliary potential, thereby enabling potential therapies for liver deficiencies associated with bile duct insufficiency, particularly ALGS. To address, the substantial heterogeneity observed in the clinical features from subjects with JAG1 mutations, we would be creating hiPSC lines for couple of known variants in JAG1 that were recently identified in Indian population but need follow-up studies to validate the pathogenicity of the identified variant by phenotyping for ALGS phenotypes (Panwar et al., 2022a; Srivastava et al., 2014). Further, as a proof-of-principle, we aim to identify novel rare variants for ALGS in Indian population and functionally validate them using patient-derived organoids. Overall, the proposed research would develop strategy for futuristic personalized therapies using genetics, clinical and disease-in-dish approaches for understanding pathogenesis of disease and pave the way for precision medicine.