Jarvi, J., Tewodros, M., Wang, M. et al. 2016. Refining the PDX mouse model: Development of a less invasive and disposable tumor engraftment process. Laboratory Animal Science Professional 4(1) (March), 47-51.

Patient-derived xenograft (PDX) models are created using fragments of human tumors subcutaneously implanted into immunodeficient mice. Solid tumor engraftment of mice is commonly performed with a 10-13 gauge trocar needle under general anesthesia. In this study, three different engraftment methods were compared. With each method, we evaluated tumor growth rate, tumor symmetry, and procedural efficiency while considering the most benevolent approaches for animal welfare. Method 1 uses a larger stainless steel, 13 gauge trocar needle and plunger and is a common method for PDX engraftment. Methods 2 and 3 use a disposable 1cc syringe and a smaller 14 gauge disposable needle. In 21 days post engraftment, 100% of tumors in Method 3 and 90% in Method 2 were palpable compared to only 60% of tumors in Method 1. Tumors engrafted with Methods 2 and 3 were more symmetrical. Overall, the less invasive and disposable method of tumor engraftment was a success. The smaller gauge needle, with a reliably sharp tip, offers a less traumatic procedure for mice compared to the standard method.