Sprague Dawley Rag2 null rats created from engineered spermatogonial stem cells are immunodeficient and permissive to human xenografts

The rat is the preferred model for toxicology studies, and it offers distinctive advantages over the mouse as a pre-clinical 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 toxicological testing and PK/PD studies in the same model animal. Here we created an immunodeficient rat with a functional deletion of the Rag2 gene, using genetically modified spermatogonial stem cells (SSCs). 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 27bp 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. Additionally 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.