Curing hemophilia A by NHEJ-mediated ectopic F8 insertion in the mouse

• Main Authors: Jian-Ping Zhang, Xin-Xin Cheng, Mei Zhao, Guo-Hua Li, Jing Xu, Feng Zhang, Meng-Di Yin, Fei-Ying Meng, Xin-Yue Dai, Ya-Wen Fu, Zhi-Xue Yang, Cameron Arakaki, Ruijun Jeanna Su, Wei Wen, Wen-Tian Wang, Wanqiu Chen, Hannah Choi, Charles Wang, Guangping Gao, Lei Zhang, Tao Cheng, Xiao-Bing Zhang
• Format: Article
• Language: English
• Published: BMC 2019-12-01
• Series: Genome Biology
• Subjects: Hemophilia A; CRISPR-Cas9; Genome editing; Knock-in; NHEJ
• Online Access: https://doi.org/10.1186/s13059-019-1907-9

Abstract Background Hemophilia A, a bleeding disorder resulting from F8 mutations, can only be cured by gene therapy. A promising strategy is CRISPR-Cas9-mediated precise insertion of F8 in hepatocytes at highly expressed gene loci, such as albumin (Alb). Unfortunately, the precise in vivo integration efficiency of a long insert is very low (~ 0.1%). Results We report that the use of a double-cut donor leads to a 10- to 20-fold increase in liver editing efficiency, thereby completely reconstituting serum F8 activity in a mouse model of hemophilia A after hydrodynamic injection of Cas9-sgAlb and B domain-deleted (BDD) F8 donor plasmids. We find that the integration of a double-cut donor at the Alb locus in mouse liver is mainly through non-homologous end joining (NHEJ)-mediated knock-in. We then target BDDF8 to multiple sites on introns 11 and 13 and find that NHEJ-mediated insertion of BDDF8 restores hemostasis. Finally, using 3 AAV8 vectors to deliver genome editing components, including Cas9, sgRNA, and BDDF8 donor, we observe the same therapeutic effects. A follow-up of 100 mice over 1 year shows no adverse effects. Conclusions These findings lay the foundation for curing hemophilia A by NHEJ knock-in of BDDF8 at Alb introns after AAV-mediated delivery of editing components.