CRISPR-Cas9 targeting of PCSK9 in human hepatocytes in
vivo. A, Targeting of a sequence in exon 1 of the
human PCSK9 gene. The boxes indicate the 20-bp sequence
matching the protospacer and the 3-bp protospacer-adjacent motif (PAM). The
seven targeted sequences shown below the wild-type sequence reflect the seven
most common mutations (in descending order of frequency) detected by deep
sequencing of the locus in human hepatocytes targeted in vivo
in chimeric liver-humanized mice (see Supplemental Dataset for more
information). B, Surveyor assays performed with genomic DNA from
liver samples taken from mice 4 days after receiving an adenovirus expressing
Cas9 and the PCSK9 guide RNA (CRISPR-PCSK9) or
a control adenovirus (CRISPR-control). Arrows show the cleavage products
resulting from the Surveyor assays; the intensity of the cleavage product bands
relative to the uncleaved product band corresponds to the mutagenesis rate.
C, Relative changes in blood human PCSK9 protein levels, blood
mouse PCSK9 protein levels, and blood human albumin levels (post-treatment
divided by pre-treatment levels) in chimeric liver-humanized mice receiving
CRISPR-control virus (n = 6 mice) or
CRISPR-PCSK9 virus (n = 5 mice).
The bars indicate the median values for the relative changes within the groups.
The Mann–Whitney U test was performed to compare the
relative changes in the two groups. D, Indel rates at on-target and
off-target sites from next-generation DNA sequencing of liver samples from
post-treatment mice.