A lot of hay has been made about CRISPR Cas9,
the gene editing technique so precise, so
easy, so versatile it’s opened the possibility
of chopping and swapping DNA around like a
molecular level Dr. Frankenstein.
The implications are huge for humans and our
genome.
We could alter the genes of embryos, or treat
genetic maladies in those already born.
Now in 2018 clinical trials on humans are
scheduled to start for the first time.
But just as they’re getting underway, there
may be a problem thanks to our immune system.
To understand why our immune system is being
a jerk and preventing us from treating disorders
like sickle-cell anemia, it helps to step
back and remember exactly what CRISPR Cas9
is.
It’s actually an immune response bacteria
use to protect themselves from viruses.
Cas9 is a protein the bacteria make that act
as molecular scissors, cutting virus DNA to
ribbons, and two of the most commonly used
types of Cas9 come from bacteria that can
cause staph infections or strep throat.
These are bacteria we want our immune systems
to have a defense against.
And to defend against them, our immune system
has to be able to recognize the bacteria and
the various proteins they make, so they can
track them down and destroy them.
Sorry I called you a jerk earlier, immune
system, you’re just doing what comes naturally.
<3
To see if these two versions of Cas9 were
on our immune system’s hit list, researchers
tested the blood of 34 donors for antibodies.
They found 65 percent had a defense against
the strep version while 79 percent fought
the staph variety.
In another experiment with 13 blood donors,
6 of them had t-cells that attacked staph’s
Cas9.
The findings are yet to be peer reviewed,
but one of the authors is the scientific founder
of a leading CRISPR human therapy company,
so he’s got some credibility.
And if our immune systems respond to CRISPR,
it could mean more that just rendering the
therapy ineffective.
It could make our immune systems go haywire
and kill us, which has happened in a previous
attempt at human genetic therapy.
The next question is: is this the end of the
line for CRISPR?
Good game, well played, but our bodies are
just too vigilant for this revolutionary gene
editing?
Hahaha, no, we’re going to science our way
around this conundrum!
There are already a few solutions to this
possible problem, like modifying Cas9 into
a form our immune system can’t recognize,
or using a different protein from the oodles
of other bacteria that have their own versions
of Cas9.
Or if the protein gets attacked when it’s
in our bodies, then perhaps we could put it
to work outside our bodies, modifying extracted
cells before returning them to the body.
Or Cas9 could be used in places where the
immune system is locked out, like inside our
eyes where it could treat hereditary blindness.
CRISPR has way too much potential to let a
little thing like our bodies stop progress.
The findings of these recent experiments are
more of a speed bump than a brick wall.
Medical advances occasionally have to overcome
biological defenses.
For example our blood vessels in our brains
make it really hard to deliver medicine to
our old noodle.
To learn why the blood brain barrier is overall
a good thing, check out this video here.
We could talk CRISPR all day here at Seeker
so if you have any questions about it go ahead
and drop them in the comments.
Be sure to subscribe, and thanks for watching
Seeker!
