Embryological cellular origins and hypoxia-mediated mechanisms in PIK3CA-driven refractory vascular malformations

Congenital vascular malformations, affecting 0.5% of the population, frequently occur in the head and neck, complicating treatment due to their vital functions. Our previous research identified distinct developmental origins for blood and lymphatic vessels in these regions in both mouse and human embryos. In this study, we expressed Pik3caH1047R in the cardiopharyngeal mesoderm (CPM) to investigate the pathogenesis of these malformations. Mice expressing Pik3caH1047R in the CPM developed abnormal vasculature restricted to the head and neck. Single-cell RNA sequencing revealed that Pik3caH1047R promotes Vegf-a expression in endothelial cells via Hif-driven hypoxia signaling. Human samples corroborated these findings, showing elevated HIF-1a and VEGF-A in malformed vessels. Notably, treatment with Hif-1a and Vegf-a inhibitors significantly reduced abnormal vasculature in the mouse model. Our findings highlight the role of developmental origins and hypoxia-driven mechanisms in vascular malformations, providing a basis for developing targeted therapies for these refractory conditions. Overall design: Cardiopharyngeal mesoderm (CPM) cells were isolated from the pharyngeal arch of Isl1-Cre;R26R-eYFP (control) or Isl1-Cre;R26R-eYFP;Pik3caH1047R mice using Fluorescence-activated cell sorting (FACS) and analyzed using scRNA-seq.