the first time ever. This experimental organ  transplant is breaking so many boundaries,  

but let’s start with the fact that  it involves gene editing and…cocaine? 

Let’s start simple. Any transfer of  cells or tissues across species is called  

xenotransplantation. Even though it sounds like  science fiction, this is actually nothing new. Pig  

heart valves have been replacing worn-out  human heart valves for the past 30 years.  

That’s because pig hearts are actually very  similar in structure and size to human hearts. 

But replacing the entire heart with  one from another species…

that’s totally uncharted territory.

See, a major roadblock to xenotransplantation  

is our immune systems. Pig cells are covered in  surface structures that our body recognizes as  

non-human. This can trigger something called graft  rejection, where the human recipient’s immune  

system tries to get rid of the new organ. This  even happens with transplants from other humans. 

But we need whole hearts, and we need them  now. Heart disease is the leading cause of  

death worldwide. Even in places that have enough  resources to provide valve replacements or heart  

transplants, there just aren’t enough organs to go around.

Thousands of people in the U.S. alone are on  

the waitlist for a new heart, and an average of 17  people on organ transplant waitlists die everyday. 

That’s because, until now, we’ve  only had human hearts as our whole  

organ transplant option. Pig hearts fit the  bill and could help us solve this problem,  

but what about that pesky immune response?  The answer just might be…genetic modification! 

The parent company behind Dolly the sheep, 

you know, the world’s first cloned animal,

has also been working on rearing pigs  genetically engineered just for organ  

transplant. In 2021, these pigs were used  to successfully transplant kidneys into two  

legally brain dead people whose bodies were being kept  alive on ventilators. So, we moved on to hearts. 

Scientists used gene-editing technology to make  ten major genetic modifications to these pigs:

‘knocking out’ three pig genes behind those cell  surface molecules that trigger the human immune  

response, removing a tissue proliferation gene,  making sure the pig heart won’t keep growing  

after it’s inside the recipient, and inserting  six human genes that will hopefully help with  

immune acceptance of the heart. There are also several other  

never-before-used techniques at play  here. The doctors are giving the recipient  

an experimental drug to suppress his immune system  for extra protection against graft rejection. They  

also used a brand new machine to pump fluid through  the heart while it was awaiting transplant. 

And that fluid contained relatively  standard cortisol and adrenaline,  

with the nonstandard addition of cocaine. It’s  not clear exactly how or why, but cocaine seems to  

help keep the heart ready for transplant between pig and human.

Getting approval to use the drug apparently caused a bit

of a nightmare, but the team does think it helped. Now, with xenotransplantation, there is also a risk  

of transferring diseases across species.  There are lots of viruses lurking in pig  

genomes. The transplant scientists made  ‘precision alterations’ to remove these in the  

hopes of making disease transfer less likely.  But this is a ‘time will tell’ kind of deal. 

So…who would say yes to all this? 57-year  old David Bennett was the recipient of  

this pig heart. And Bennett’s terminal heart  disease eventually made him too sick for  

any other option—it was this experimental pig heart surgery or death.

The FDA gave emergency approval for just this one  

procedure, making Bennett the only patient allowed  to have this surgery. The scientists will keep  

testing the procedure in baboons, but they really  want to get to clinical trials with even more humans. 

And of course, this breakthrough raises all kinds  of ethical questions. ‘Farming’ hearts like this  

means a reliable supply of these organs could  be available as soon as patients need them,  

but…raising intelligent animals like pigs  just to be slaughtered for organ donation  

has many animal rights activists in uproar. There’s also the medical ethics of it all.  

Is it even ethical to offer a dangerous  procedure with so many unknowns to people who  

are terminally ill and maybe desperate,  essentially making them human guinea pigs? 

As of this writing in February, 2022, Bennett  appears to be doing well, with no signs of  

rejection yet and he's able to breathe and speak on  his own.

It is too early to say if the surgery  

will be a long-term success, but it is an exciting first  step towards a solution to the world’s organ  

shortage. Who knows? Maybe in the future, we could  see genetically modified xenotransplantation of organs

become a norm for other organs too. Want more on how to fix a broken heart?  

Then check out this video on live heart patches  here, and keep coming back to Seeker for all  

your groundbreaking biomedical news. If you have  another topic like this you want us to cover,  

leave us a comment down below, and as always,  thanks for watching. I’ll see you next time.