Development of a vestibular schwannoma xenograft zebrafish model for in vivo antitumor drug screening

Objectives/Hypothesis The development of a simple, reliable, and cost‐effective animal model greatly facilitates disease treatment. We aimed to establish a rapid, simple, and reproducible live zebrafish vestibular schwannoma xenograft model for antitumor drug screening. Methods We optimized each of the following conditions for tumor cell xenografts in zebrafish larvae: larval stage, incubation temperature, and injected cell number. We used NF2‐/‐mouse Schwann (SC4) cells and generated mCherry fluorescent protein‐expressing cells prior to injection into zebrafish larvae. SC4 cells were counted using a fluorescence microscope, suspended in 10% fetal bovine serum, and injected into the center of the yolk sac using a microinjection system. The injected embryos were transferred to E3 medium (for zebrafish embryos), and subsequent tumor formation was observed by fluorescence microscopy over a 5‐day period. To validate our model, xenografted embryos were transferred into 6‐well plates (5 embryos per well) and treated with everolimus, a known antitumor drug. Results mCherry fluorescent protein‐expressing SC4 cells were successfully grafted into the yolk sacs of zebrafish embryos without any immunosuppressant treatment. At 2 days postinjection, the xenografted cells had grown into tumor masses. The optimal speed of tumor formation depended on the larval stage (30 hpf), incubation temperature (31°C), and injected cell number (200 cells). In preliminary tests, everolimus treatment yielded a > 20% reduction in the number of SC4 cells in the yolk. Conclusion Our in vivo model has the potential to greatly facilitate vestibular schwannoma treatment because of its speed, simplicity, reproducibility, and amenability to live imaging. Level of Evidence NA Laryngoscope , 126:E409–E415, 2016