Optimizing embryo collection for application of CRISPR/Cas9 system and generation of fukutin knockout rat using this method

Abstract

Rat animal models are widely used owing to their relatively superior cognitive abilities and higher similarity compared with mouse models to human physiological characteristics. However, their use is limited because of difficulties in establishing embryonic stem cells and performing genetic modifications, and insufficient embryological research. In this study, we established optimal superovulation and fertilized-egg transfer conditions, including optimal hormone injection concentration (≥150 IU/kg of PMSG and hCG) and culture medium (mR1ECM), to obtain high-quality zygotes and establish in vitro fertilization conditions for rats. Next, sgRNA with optimal targeting activity was selected by performing PCR analysis and the T7E1 assay, and the CRISPR/Cas9 system was used to construct a rat model for muscular dystrophy by inducing a deficiency in the fukutin gene without any off-target effect detected. The production of fukutin knockout rats was phenotypically confirmed by observing a drop-in body weight to one-third of that of the control group. In summary, we succeeded in constructing the first muscular dystrophy disease rat model using the CRISPR/CAS9 system for increasing future prospects of producing various animal disease models and encouraging disease research using rats.