Hippo and Wnt pathways are impaired in Port Wine Birthmark-derived induced pluripotent stem cells and endothelial cells

Background: Port Wine Birthmark (PWB) is a congenital vascular malformation resulting from developmentally defective endothelial cells (ECs). Developing clinically relevant disease models is an unmet need for PWB studies. Objective: This study aims to generate PWB-derived induced pluripotent stem cells (iPSCs) and those-iPSC-derived ECs that preserve disease-related phenotypes. Method: PWB iPSCs were generated by reprogramming lesional dermal fibroblasts and were differentiated into ECs. Bulk RNA-seq and ATAC-seq were performed to identify enriched pathways. The functional phenotypes of iPSC-derived ECs were characterized using capillary-like structure (CLS) formation in vitro and Geltrex plug-in assay in vivo. Result: Human PWB and normal iPSC lines were generated through reprogramming of dermal fibroblasts by introducing the Yamanaka factors (Oct3/4, Sox2, Klf4, c-Myc) into them; The iPSCs were differentiated into ECs. These iPSCs and their-derived ECs were validated by expression of series of stem cell and EC biomarkers, respectively. PWB EC showed impaired CLS in vitro with larger perimeters and thicker branches comparing with control iPSC-derived ECs. In plug-in assay, perfused human vasculature formed by PWB iPSC-derived ECs showed bigger perimeters and greater densities than those formed by control iPSC-derived ECs in SCID mice. The transcriptome analysis showed that the impaired pathways of stem cell differentiation, Hippo, Wnt, and focal adhersion persisted through PWB iPSCs to ECs during differentiation. Interactive networks showed that the Hippo and Wnt pathway-related differentially expressed genes (DEGs) significantly function in vasculature development, tube morphology, endothelium development, and EC differentiation. Members of zinc-finger (ZNF) gene family were among the top changed DEGs in both PWB iPSCs and ECs. The ZNF DEGs confer significant functions in transcriptional regulation, chromatin remodeling, protein ubiquitination, and retinol acid pathway. In addition, NF-kappa B, TNF, MAPK, and cholesterol metabolism pathways were upregulated in PWB ECs as readouts of impaired differentiation. Conclusion: PWB iPSC-derived ECs can be served as novel and clinically relevant disease models by retaining pathological phenotypes. Our data suggests the impaired Hippo and Wnt pathways underlie the development of differentiation-defective ECs in PWB lesions. ### Competing Interest Statement The authors have declared no competing interest.