Modeling iPSC-derived human neurofibroma-like tumors in mice uncovers the heterogeneity of Schwann cells within plexiform neurofibromas

Fibroblast; Neural crest; SpheroidsFibroblasto; Cresta neural; EsferoidesFibroblast; Cresta neural; EsferoidesPlexiform neurofibromas (pNFs) are developmental tumors that appear in neurofibromatosis type 1 individuals, constituting a major source of morbidity and potentially transforming into a highly metastatic sarcoma (MPNST). pNFs arise after NF1 inactivation in a cell of the neural crest (NC)-Schwann cell (SC) lineage. Here, we develop an iPSC-based NC-SC in vitro differentiation system and construct a lineage expression roadmap for the analysis of different 2D and 3D NF models. The best model consists of generating heterotypic spheroids (neurofibromaspheres) composed of iPSC-derived differentiating NF1(−/−) SCs and NF1(+/−) pNF-derived fibroblasts (Fbs). Neurofibromaspheres form by maintaining highly proliferative NF1(−/−) cells committed to the NC-SC axis due to SC-SC and SC-Fb interactions, resulting in SC linage cells at different maturation points. Upon engraftment on the mouse sciatic nerve, neurofibromaspheres consistently generate human NF-like tumors. Analysis of expression roadmap genes in human pNF single-cell RNA-seq data uncovers the presence of SC subpopulations at distinct differentiation states.This work has mainly been supported by an agreement from the Johns Hopkins University School of Medicine and the Neurofibromatosis Therapeutic Acceleration Program (NTAP). Its contents are solely the responsibility of the authors and do not necessarily represent the official views of the Johns Hopkins University School of Medicine. The work has also been partially supported by the Spanish Ministry of Science and Innovation, Carlos III Health Institute (ISCIII) (PI17/00524; PI20/00228) Plan Estatal de I + D + I 2013–2016, co-financed by the FEDER program – a way to build Europe, the Fundación PROYECTO NEUROFIBROMATOSIS, and by the Government of Catalonia (2017-SGR-496) and CERCA Program/Generalitat de Catalunya. M.M.-L. is supported by Fundación PROYECTO NEUROFIBROMATOSIS