Pluripotent Stem Cells And Mouse-Human Chimeras For Modeling The Development And Progression Of Human Cancer In Vivo

Introduction

Neuroblastoma (NB) is the most common pediatric extracranial solid tumor and it is accepted that the cell of origin for NB arises from neural crest lineages during development. Despite the recent successes of cancer immunotherapy, a major impediment to its full realization in the treatment of high-risk NB is the “immune editing” deployed by the tumor, together with the lack of reliable, immune-competent models for studying this evasion tactic in vivo. Our objective is to investigate the cellular and molecular mechanisms governing immune evasion in NB. To pursue these effects in vivo, we developed a mouse-human chimeric NB model from human neural crest cells (hNCCs).

Material and method

Human pluripotent stem cells, which were engineered to express the NB-relevant oncogenes MYCN and ALK^F1174L, were differentiated into hNCCs. These hNCCs were integrated in-utero into immunocompetent mouse embryos to generate mouse-human chimeras, which will provide an experimental platform for studying human NB and immune response interaction in vivo.

Results and discussion

Here we show that hNCCs contribute to mouse development and upon oncogenes activation form human tumors in adult chimeric animals. The tumors, which recapitulate human NB histologically and molecularly, formed in immunocompetent hosts, indicating for tolerance for donor cells during development. However, in adult animals, the tumors showed evidence of host (murine) CD3+ and CD8+ T-cell and macrophages infiltration, supporting a host immune response. Moreover, evasion of this response was observed by recruitment of T-regulatory cells, activating of immune checkpoint signals and T cell exhaustion, within the tumor microenvironment. Finally, we show a direct role of the NB activated oncogenes MYCN and ALK^F1174L, in the immune recognition of NB cells by T cells, and their role in the immune evasion. Overall, our NB-bearing mouse-human chimera provides a unique and highly defined model for studying the initiation and progression of NB, as well as its tumor immune microenvironment and the immune–tumor interactions which govern immune evasion.

Conclusion

Importantly, the ability to grow clinically derived human NB tumor cells in immune-competent host animals will facilitate the study of critical interactions between high-risk NB and the immune system, an advance that contrasts sharply with conventional xenotransplantation assays that rely on immunocompromised host animals and thus preclude meaningful study of the immune response. Ultimately, our unique model may prove to be an optimal platform for studying NB pathogenesis, enabling the evaluation of different combinations of anti-oncogenic and immune-based therapies.