Thanks to Linode Cloud Computing for supporting this episode of SciShow.

You can go to linode.com/scishow to learn more and get a $100 60-day credit on a new Linode account. [♪ INTRO] Organ donation saves lives – but it’s not easy. It’s extremely time sensitive, especially when dealing with vital organs like the heart, because organs don’t last long when they’re deprived of oxygen.

And even if the organ makes it to the recipient quickly, there’s still a risk that the organ won’t be accepted by the recipient's body. But new research published in the journal Nature this week may have come up with a new method of helping organ donations become more successful in the future. When blood stops moving through a body, the red blood cells which carry oxygen throughout the body are no longer being moved around.

These cells have a finite supply of oxygen contained in them, transported by the molecule hemoglobin. Now, cells and organs can survive for a while without circulation on the red blood cell reserves, but the clock is ticking. Because eventually, of course, those cells are deprived of fresh oxygen for long enough, that they start to break down and can even die.

On the flip side, though, if cells receive oxygen after they’ve been deprived of it for some time, that can also cause damage or death, in a phenomenon known as reoxygenation injury. Like, if blood stops circulating through a body, like when someone suffers a heart attack or stroke, their cells are quickly deprived of oxygen and begin to show signs of damage. If circulation restarts, whether because the body recovers or is put on life support, the sudden influx of oxygen can lead to damaging chemical reactions.

The longer the oxygen deprivation, the more severe the damage can be. Technologies already exist to move blood through a body that has lost its circulatory abilities. One such technique is to pump the blood out of the body, into an artificial lung that adds fresh oxygen, and then putting it back into the body.

But this method isn’t always successful at restoring organ function without causing cell damage in the process. And this is due in part to reoxygenation injury. In addition, smaller blood vessels can collapse and not rebound when the blood tries to pass through them again.

Which means that organs from donors who are put on circulatory support may not perform at full capacity, or may be rejected, upon transplantation. With that in mind, in this week’s paper in Nature, researchers have unveiled a new strategy that they hope will perform much better. Their system, called OrganEx, uses a synthetic form of hemoglobin that is mixed with the body’s blood and then pumped throughout the body.

It also mimics the body’s natural way of pumping blood more closely. And this synthetic hemoglobin not only delivers oxygen to the cells that need it, it also contains additives that help protect cells and prevent blood clots. OrganEx builds on previous work restoring oxygen flow specifically in the brains of model organisms.

And the researchers were confident enough in that technology to expand it to the whole body in this preliminary research. In the new study, they used pigs, a great stand-in for humans due to their similar size, body functions, and even genetics. They induced heart attacks in the pigs and then they left the bodies alone at 36 to 37 degrees Celsius for an hour, to deprive the cells of oxygen and cause cell damage.

That’s pretty warm – just under normal body temperature for healthy pigs. They did this on purpose because all other things being equal, more damage occurs to oxygen-deprived cells at higher temperatures, which is why donated organs are put on ice. After an hour had passed, the researchers jump-started the pigs’ circulatory process using both the traditional approach of circulating the blood outside the body, as well as this new method.

The more traditional approach failed to preserve all of the organs, and they found that smaller blood vessels had collapsed. In contrast, OrganEx preserved all of the pigs’ organs and there was no blood vessel collapse within the body. And when they analyzed critical organs, like the brain, heart, lungs, liver and kidneys, they found that those preserved using OrganEx showed evidence of cell repair rather than damage.

While this technology is still a ways off from human trials, the new findings show potential for improving the success of organ donations and transplants. In other donation-related news, sterile mice are successful donors… of rat sperm! Researchers have successfully produced rat sperm cells inside sterile mice and published their findings in a recent issue of the journal Stem Cell Reports.

And believe it or not, these findings could one day become an important tool in conservation research. They created a mouse-rat chimera, a hybrid containing both creatures’ DNA, using a mouse embryo and rat stem cells. The researchers ensured this mashup had a genetic mutation on the mouse side that would make the males sterile.

But the rat side wasn’t sterile. The stem cells became rat sperm-producing cells, setting up shop in the testes of the mouse. The sperm cells produced were able to successfully fertilize rat egg cells, with help from the researchers.

But the cells weren’t mobile on their own, and couldn’t produce live embryos or offspring. Which means the researchers still need to improve this technique beyond proof-of-concept, to produce live offspring. They would also like to try it with other animals outside of rats and mice.

They wanted to see if they could use sterile animals, like the mice in this study, as hosts for reproductive cells from other animals. That’s where the conservation part comes in. See, they hope to be able to use this technique for the production of reproductive cells from endangered animal species, by using more prevalent animal species as hosts.

We’re a lot better at manipulating rats and mice in the lab than most endangered species, so the researchers don’t really say who they’d try to save with this approach. It’s too early. Still, imagine if we could breed northern white rhinos, which are effectively extinct, by giving them rhino sperm from other species.

So the hope is that this admittedly weird approach could help with conservation efforts of critically endangered species. Scientists, if you're watching, I'm sorry I called your research a little weird. But you have to admit that when you go to a cocktail party and tell people what you do, it's a little weird.

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