Abstract
BackgroundSomatic cells differentiated from patient-specific human induced pluripotent stem cells (iPSCs) could be a useful tool in human cell-based disease research. Hermansky–Pudlak syndrome (HPS) is an autosomal recessive genetic disorder characterized by oculocutaneous albinism and a platelet dysfunction. HPS patients often suffer from lethal HPS associated interstitial pneumonia (HPSIP). Lung transplantation has been the only treatment for HPSIP. Lysosome-related organelles are impaired in HPS, thereby disrupting alveolar type 2 (AT2) cells with lamellar bodies. HPSIP lungs are characterized by enlarged lamellar bodies. Despite species differences between human and mouse in HPSIP, most studies have been conducted in mice since culturing human AT2 cells is difficult.MethodsWe generated patient-specific iPSCs from patient-derived fibroblasts with the most common bi-allelic variant, c.1472_1487dup16, in HPS1 for modeling severe phenotypes of HPSIP. We then corrected the variant of patient-specific iPSCs using CRISPR-based microhomology-mediated end joining to obtain isogenic controls. The iPSCs were then differentiated into lung epithelial cells using two different lung organoid models, lung bud organoids (LBOs) and alveolar organoids (AOs), and explored the phenotypes contributing to the pathogenesis of HPSIP using transcriptomic and proteomic analyses.ResultsThe LBOs derived from patient-specific iPSCs successfully recapitulated the abnormalities in morphology and size. Proteomic analysis of AOs involving iPSC-derived AT2 cells and primary lung fibroblasts revealed mitochondrial dysfunction in HPS1 patient-specific alveolar epithelial cells. Further, giant lamellar bodies were recapitulated in patient-specific AT2 cells.ConclusionsThe HPS1 patient-specific iPSCs and their gene-corrected counterparts generated in this study could be a new research tool for understanding the pathogenesis of HPSIP caused by HPS1 deficiency in humans.
Highlights
Somatic cells differentiated from patient-specific human induced pluripotent stem cells could be a useful tool in human cell-based disease research
By maintaining and maturing iPSCderived alveolar type 2 (AT2) cells using SPC-GFP reporter or NaPi2B, an AT2 cell surface antigen, we established human iPSCbased disease models related to abnormalities in lamellar bodies caused by amiodarone, an antiarrhythmic agent notorious for inducing pulmonary fibrosis, and AP3B1 deficiency, which is observed in HPS2 patients [3, 20, 21]
Since TGFβ was reported to be able to function as an upstream regulator of IL11 [31], we evaluated whether TGFβ signaling could be involved in the epithelial abnormalities of HPS1 patient-specific C-lung bud organoids (LBOs)
Summary
Somatic cells differentiated from patient-specific human induced pluripotent stem cells (iPSCs) could be a useful tool in human cell-based disease research. Out of the 11 HPS causative genes, mutations in HPS1, AP3B1, and HPS4 can induce lethal HPS-associated interstitial pneumonia (HPSIP), for which lung transplantation is the only treatment available [5, 7, 8]. By maintaining and maturing iPSCderived AT2 cells using SPC-GFP reporter or NaPi2B, an AT2 cell surface antigen, we established human iPSCbased disease models related to abnormalities in lamellar bodies caused by amiodarone, an antiarrhythmic agent notorious for inducing pulmonary fibrosis, and AP3B1 deficiency, which is observed in HPS2 patients [3, 20, 21]. We generated iPSCs from HPS1 patientderived fibroblasts with bi-allelic c.1472_1487dup variant in HPS1 gene and their gene-corrected counterparts and differentiated them into lung epithelial cells in organoids to model HPSIP
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