Katalin Karikó: This regenerated RNA coding for urokinase receptor. And that was important not to let the blood clot inside the blood vessel. So that has a role in it. And so, that – We just could make this – I made the mRNA, working with Elliot Barnathan, who was a cardiologist, and we delivered to the cell. And this receptor had to be very decorated with sugars and had to be processed to be functional. And we delivered the RNA. And voila, inside the cell, I knew what to do, how to formulate, how to decorate, and we could see that this receptor was functional.

We knew at that point and it was in the mid-1990s, like ’95, ’96 we did this experiment. We knew that the RNA would be good for something. That’s what we said. And I remember it was about the same time, before Christmas we were standing there in this gamma counter, because the light gun for this receptor was labeled with iodine, and then we want to see that could it bind, could it function on this receptor? Which we encoded by the RNA, and if it could bind then we could see radioactive material and measuring this gamma counter. And then we stand there and we could see that oh my God, we get high numbers. It could bind. And it was like all of this joy. I remember exactly how we stand there and one colleague, Alice Kuo, Elliot Barnathan, and me, the three of us we were watching. We did this experiment together. And of course I moved on to neurosurgery and we did more and more experiments. I did not realize that the RNA is inflammatory.

It’s not until I met Drew Weissman, started to work together, and in 2000 we realized that the RNA, what I was making, ten years I was working in, that caused inflammation in human cells. And that was the reason I said I wanted to use for therapy, for stroke, for blood clot inhibition and what not, and this is all for nothing because this is useless. And then the question that we asked with Drew, why, why it is? In our cells we have RNA, why? I think that the RNA I am making is very similar what is inside the cell. Is it because it’s coming from outside and sees our immune system as an invader, which turned out like that? And then it was the question, can we at all do anything and make it non-immunogenic? Because we didn’t know that. And so that’s what we started to work on with Drew Weissman. And we did a lot of studies and many, many things that, as a scientist, we don’t know that is it doable or not?