Neural crest cells (NCC) are stem cells that generate different lineages, including neuroendocrine, melanocytic, cartilage, and bone. The differentiation potential of NCC varies according to the level from which cells emerge along the neural tube. For example, only anterior “cranial” NCC form craniofacial bone, whereas solely posterior “trunk” NCC contribute to sympathoadrenal cells. Importantly, the isolation of human fetal NCC carries ethical and scientific challenges, as NCC induction typically occur before pregnancy is detectable. As a result, current knowledge of NCC biology derives primarily from non-human organisms. Important differences between human and non-human NCC, such as expression of HNK1 in human but not mouse NCC, suggest a need to study human NCC directly. Here, we demonstrate that current protocols to differentiate human pluripotent stem cells (PSC) to NCC are biased toward cranial NCC. Addition of retinoic acid drove trunk-related markers and HOX genes characteristic of a posterior identity. Subsequent treatment with bone morphogenetic proteins (BMPs) enhanced differentiation to sympathoadrenal cells. Our approach provides methodology for detailed studies of human NCC, and clarifies roles for retinoids and BMPs in the differentiation of human PSC to trunk NCC and to sympathoadrenal lineages.

Highlights d MYCN drives SHH medulloblastoma tumorigenesis in human iPSC-derived NES cells d NES cells from Gorlin syndrome (PTCH1 +/À) iPSCs generate SHH medulloblastoma d Mutation of DDX3X or GSE1 accelerates tumorigenesis in Gorlin NES cells

NEURO-ONCOLOGY • NOVEMBER 2017 accurately predict drug responses in human patients. In order to address this issue, our lab has established a large panel (>80) of orthotopic xenograft mouse models of brain tumors that have been shown to replicate the histopathological features, invasive growth phenotypes and gene expression profiles of the original primary tumors. In addition, treatment information and clinical outcomes are available for the patients from which these models were derived. To test whether these patient tumor-derived orthotopic xenograft tumor respond to anti-cancer therapies similarly to the corresponding human primary tumors, we designed modified treatment schedules based on original patient treatment data for > 10 models of pediatric glioblastoma and 7 models of medulloblastoma and treated them accordingly. We are able to demonstrate the feasibility of combining radiation and multiagent cytotoxic chemotherapy our mouse models. Furthermore, our results correlate with what has been seen in large scale human clinical trials with glioblastoma models showing little benefit from standard treatments while medullblastoma models show a significant increase in survival time.