These mice have been used to study regenerative medicine such as allograft, organ regeneration, and drug evaluation. Immunodeficient mice deficient in T, B and natural killer (NK) cells are accepted as recipients for human cell transplant and have been widely used in human disease studies, including human-specific infections such as viral infections (HIV, EBV, dengue virus, HBV, HCV) and bacterial infections. Recently, humanized mice have been developed and used to replace primates. Non-human primates are the best alternative model of human disease, but extremely high costs and ethical concerns have limited their widespread use. However, translation of these studies is limited due to species differences between rodents and humans. The rodent model is a useful tool for in vivo studies related to gene functions, mechanisms of disease, and new therapeutic agents. Taken together, our data indicates that small deletions by genome editing is sufficient to generate null mutant mice. These results suggest that the NOD/SCID mice with deletion of 2 bp in the IL2 receptor γ gene shows same phenotype as NSG mice. In addition, tumor growth was exceedingly increased in the mutant mice transplanted with HepG2, Raji and A549 cells, but not in nude and NOD/SCID mice. T and B cells in the mutant mice were severely deficient, and NK cells were almost absent. Our results show that the thymus weight of mutant mice is significantly less than that of NOD/SCID mice, whereas the spleen weight was marginally less. In this study, we generated a mutant by microinjecting sgRNAs targeting the IL2 receptor γ gene and Cas9 protein, into the cytoplasm of IVF-derived NOD.CB17/Prkdcscid/JKrb (NOD/SCID) mice embryos, and further investigated whether a 2 bp deletion of the IL2 receptor γ gene affects severe deficiency of immune cells as seen in NOD/LtSz-scid IL2 receptor γ −/− (NSG) mice. However, there are very few reports analyzing the phenotypes in small deleted mutant mice generated by CRISPR/Cas9.
Small deletions of nucleotides in the target genes are frequently found in CRISPR/Cas9 mediated mutant mice. Genome editing has recently emerged as a powerful tool for generating mutant mice.