Immunophenotyping of the SDR rat. Analysis of SDR whole blood demonstrates greatly diminished T and B cells compared to the wild-type rat. A, The wild-type rat has a significant population of circulating CD4+, CD8+, and CD4/CD8 double positive T cell populations compared to the SDR rat. B, The wild-type rat has over 20% B220/IgM double positive mature B cells, compared to 3.5% in the SDR rat. C, The SDR rat has slightly less circulating NK cells, unlike what is observed in the spleen. Panels are representative of 3 wild-type and 3 SDR rats. Left panels: wild-type rat. Right panels: SDR rat.
ARTICLE ABSTRACTThe rat is the preferred model for toxicology studies, and it offers distinctive advantages over the mouse as a preclinical research model including larger sample size collection, lower rates of drug clearance, and relative ease of surgical manipulation. An immunodeficient rat would allow for larger tumor size development, prolonged dosing and drug efficacy studies, and preliminary toxicologic testing and pharmacokinetic/pharmacodynamic studies in the same model animal. Here, we created an immunodeficient rat with a functional deletion of the Recombination Activating Gene 2 (Rag2) gene, using genetically modified spermatogonial stem cells (SSC). We targeted the Rag2 gene in rat SSCs with TALENs and transplanted these Rag2-deficient SSCs into sterile recipients. Offspring were genotyped, and a founder with a 27 bp deletion mutation was identified and bred to homozygosity to produce the Sprague-Dawley Rag2 - Rag2tm1Hera (SDR) knockout rat. We demonstrated that SDR rat lacks mature B and T cells. Furthermore, the SDR rat model was permissive to growth of human glioblastoma cell line subcutaneously resulting in successful growth of tumors. In addition, a human KRAS-mutant non–small cell lung cancer cell line (H358), a patient-derived high-grade serous ovarian cancer cell line (OV81), and a patient-derived recurrent endometrial cancer cell line (OV185) were transplanted subcutaneously to test the ability of the SDR rat to accommodate human xenografts from multiple tissue types. All human cancer cell lines showed efficient tumor uptake and growth kinetics indicating that the SDR rat is a viable host for a range of xenograft studies. Mol Cancer Ther; 17(11); 2481–9. ©2018 AACR.