Cas9

for nearly nine months.

The organ came from eGenesis and carried 69 genomic edits made with CRISPR-Cas9.

The edits were designed to make the organ compatible with the human immune system, and they included inactivation of porcine endogenous retroviruses.

The transplant was performed through the FDA's expanded access pathway as part of a three-patient study.

But that potential is there if you're willing to take the risk.

And I think, you know, like an example of that is, is CRISPR-Cas9-

Mm-hmm

... has absolutely revolutionized science and how we're thinking about treating patients and, and, and disease, but it was discovered just by people trying to understand how do bacteria do something.

Yeah.

Do you...

I feel like a lot of people have also heard of CRISPR, CRISPR-Cas9.

Like, um-

Like what?

One of the most powerful tools in synthetic biology is called CRISPR-Cas9.

Oh,

I've heard of CRISPR.

Another major direction is targeted gene insertion.

The Recruiting B on 9 study in Haemophilia B uses an AV8 vector to deliver the Factor IX donor sequence and a lipid nanoparticle to deliver Cas9 messenger RNA and guide RNA, inserting Factor VIII into the albumin locus.

It is therefore a hybrid rather than a completely AV-free approach.

However, the important difference from conventional AV therapy is that the therapeutic gene is placed into a defined chromosomal site instead of remaining mainly episomal.

CRISPR-like ancient systems in humans represent a fascinating parallel to the bacterial immune system that became famous for gene editing.

Long before CRISPR–Cas9 revolutionized molecular biology, humans had evolved their own systems for silencing genes, including genes derived from invading retroviruses.

Some endogenous retroviruses have been silenced by epigenetic modifications that essentially turn them off without cutting them out of the genome.

The regulatory mechanisms that maintain this silencing are sophisticated and precise.

Right.

When we study genomics, when we utilize CRISPR-Cas9 to edit DNA sequences, when we develop therapies to eradicate hereditary diseases before birth, we are no longer relying on random mutation.

We are swapping out a game of chance for a targeted engineering project.

That's a good way to put it.

Together, they asked the right questions at exactly the right moment.

They wanted to understand how Cas9, a protein that the bacteria used as scissors, could be guided to cut DNA with such precision.

What made it so accurate? Could they program it to target whatever they wanted? Could they combine the tracar RNA with another piece of RNA to create a guide? They worked intensively, conducting experiment after experiment, testing their ideas, refining their understanding.

Some experiments failed, others succeeded.

They collaborated with other researchers who were pursuing similar ideas.

In 2012, they published a paper in Science that demonstrated something revolutionary.

They showed that CRISPR-Cas9 could be programmed to cut DNA at virtually any location you specified.

They had taken a bacterial immune system and transformed it into a general-purpose genetic tool that any researcher could use.

Anyone who's worked in gene editing, uh, in the gene editing field remembers two landmark, uh, science papers that helped, uh, define the modern CRISPR era.

Uh, the first, published in 2012 by Emmanuelle Charpentier and Jennifer Doudna, demonstrated how CRISPR-Cas9 could be programmed for targeted DNA cleavage.

And the second, published in early 2013, uh, from the lab of Feng Zhang, showed how CRISPR-Cas9 could be applied for genome editing, uh, in mammalian cells.

The lead author on that, uh, groundbreaking 2013 paper, uh, was Le Song, and, uh, we're, uh, delighted to have him, uh, with us today.

Uh, Le, welcome to the show, and thank you for joining us today.

... and have low off-target.

But if you do have a, a high off-target, the burden to recreate a new system was so high.

That's why when I saw the, the fundam- the fundamental work that you and others did, and how quickly you could reprogram Cas9 or other CRISPR proteins to other new places in the genome to optimize that on-target versus off-target profile.