A Newly Built rAAV-SaCas9 Genome Editing System Enables Muscle-Directed Gene Editing to Improve Muscular Atrophy

Abstract Background At present, genome editing at specific sites in vivo is affected by many factors, including the choice of vector, the efficiency of editing proteins and the influence of the internal environment. These factors make gene editing ineffective and even have adverse effects. Methods Here, we report a single rAAV containing SaCas9 and guide RNAs under the control of subtle EF1a and tRNA promoters. The capacity of rAAV was compressed, and we inserted the sequence of the green fluorescent protein eGFP into rAAV. The efficiency of rAAV gene editing in vivo and in vitro was analyzed by time point and virus titer. In addition, we used the rAAV9-SaCas9 system to knock out the myostatin gene in the thigh muscles of muscle-atrophic mice. Results We demonstrated that the gene editing elements regulated by the rAAV-SaCas9 system can be expressed. By increasing the amount of rAAV and the reaction time, the editing efficiency of myostatin and the expression level of eGFP protein can be improved in vitro and vivo. Furthermore, We demonstrated that muscle cells were improved by knockout partial myostatin gene in a mouse model of muscular dystrophy. Conclusions The rAAV-SaCas9 system can be expressed in a stable and long-term manner. The system has substantial therapeutic potential in treating muscular atrophy.