Scientists Develop Human Embryo Model Without Sperm Or Eggs

11:58 minutes

3d rendered illustration of a human embryo - week 2
Credit: Shutterstock

This week, research published in the journal Nature detailed a model of a 14-day old human embryo created without using sperm or eggs. The hope is to shine a light into a previously unavailable window of an embryo’s development, potentially helping to better understand miscarriages and side effects of medications taken during pregnancy. 

Ira talks with Casey Crownhart, climate and energy reporter at MIT Technology Review to talk about that and other top science news of the week including Japan’s rocket launch to the moon, zinc batteries, and newly discovered toxic bird species.

Segment Guests

Casey Crownhart

Casey Crownhart is a climate reporter for MIT Technology Review in New York, New York.

Segment Transcript

IRA FLATOW: This is Science Friday. I’m Ira Flatow. If you’ve done nothing else this summer, I’m betting you’ve been sweating a lot, and as we all know, sweat helps us cool off as it evaporates. But what do animals that don’t sweat– what do they do to cool off? Some unexpected things, as we’ll find out as we talk about the science of sweat a little bit later.

But first what do embryos, a moon landing, and arm joints all have in common? Well, they’re all part of our news roundup this week. Here with her selected short subjects in science is Casey Crownhart, climate and energy reporter at MIT Technology Review, reporting from New York City. Casey, welcome back.

CASEY CROWNHART: Thanks so much for having me back, Ira.

IRA FLATOW: You’re quite welcome. Big news this week in the world of STEM cell research– scientists at the Weizmann Institute in Israel have successfully created a 14-day-old human embryo model without sperm or eggs. The findings were published in the prestigious journal Nature. Casey, why is this such a big deal?

CASEY CROWNHART: These synthetic embryos, or embryo models as we might call them, could be a really big deal for understanding the earliest stages of our development, creating new drugs and treatments, and it’s kind of a wild bit of science that these researchers had to do to make it happen.

Like you said, instead of a sperm and an egg, this embryo model is made with stem cells, those cells in your body that can turn into a lot of different kinds of things. By reprogramming them, scientists were able to make a small fraction of them spontaneously come together and assemble into something that looks a lot like a human embryo.

IRA FLATOW: Tell us why it’s like a human embryo. It’s a model and not an embryo itself, which could become a person.

CASEY CROWNHART: So a natural embryo really means that it’s a sperm and an egg that come together and then divide and turn into eventually a fetus and then a person. Because these were made with stem cells, it’s not quite the same thing, but it starts to get a little bit fuzzy because this model was a really good one. This model even secreted some hormones that were able to turn a pregnancy test positive in the lab. It’s really kind of wild.

IRA FLATOW: So what kind of knowledge then is there to be gained from embryo models like these?

CASEY CROWNHART: So we could understand a lot more about the earliest stages of human development, and it could also help scientists understand a little bit more stuff like really early miscarriages. Why do some early pregnancies work and some don’t? So there’s a lot of potential knowledge to be gained, but there’s also a lot of controversy around this sort of research.

IRA FLATOW: Yeah, because we all know, at least here in this country, embryonic research has a history of controversy, and I’m imagining this should be no exception.

CASEY CROWNHART: Absolutely. I mean, there are really strict rules around researching natural embryos, but as these models start to look more and more like the natural, real thing, it’s not totally clear what rules should apply. Right now, a lot of researchers are kind of following the same rules that they would for natural embryo research, but it’s definitely this really early developing field.

IRA FLATOW: As you said, this embryo was taken to 14 days. Could it actually go past 14 days?

CASEY CROWNHART: There’s no kind of technical reason why these couldn’t keep developing. Like I said, right now in the US and the UK for a natural embryo, 14 days is pretty much the cutoff for when it’s legal to do research. So that’s why that 14 day mark is what researchers are sticking with, but there’s no reason that this kind of thing couldn’t keep developing further on.

IRA FLATOW: All right. Let’s go on to our next story, which takes us to the moon, which is getting to be a pretty busy place. I mean, last week it was an Indian moon rover on its South Pole, and this week Japan launched a rocket with a moon lander on board. What’s the goal of this mission?

CASEY CROWNHART: This mission is kind of a similar one. The goal here is to test out what’s called a soft lunar landing. So that’s a controlled, targeted touchdown, and if it is successful, in a couple of months or so– like you said, this rocket just took off. But if it is able to land on the moon, that would make Japan the fifth country to do that.

IRA FLATOW: And what kind of stuff are they going to be studying there?

CASEY CROWNHART: So a lot of it is about how to carefully touch down on the moon– kind of learning that so that as we start to go more and more places, we can land very carefully and precisely, which might be really important as we start to go places that are really resource limited.

IRA FLATOW: There’s a telescope on board too, right?

CASEY CROWNHART: Yeah. A lot of people have been talking a lot about the moon lander, but the X-ray telescope that’s on board this rocket is actually kind of the main payload. This X-ray telescope is going to look into space using X-rays instead of visible light. It’ll try to help us figure out how galaxies are shaped, how the universe formed– just the small stuff.

IRA FLATOW: Back here on terra firma, you have a story about a New Jersey based company Eos, which developed a zinc battery. Now what’s so great about a zinc battery?

CASEY CROWNHART: We’ve got a lot more solar panels and wind turbines on the grid now generating electricity, but as you know, the sun doesn’t always shine. The wind doesn’t always blow, so a lot of people are trying to make batteries to store energy. The problem is the ones that we have for grid-based storage are pretty expensive.

A lot of people use the same kind of batteries that are in electric vehicles, but we’re looking for much cheaper ways to do that. And that’s what Eos Energy is trying to do with this zinc-based battery– is to make a way to store a lot of energy for a really, really low price.

IRA FLATOW: What’s the shortcoming here? What’s the trade off?

CASEY CROWNHART: They’re not able to store as much energy in a small space. So for example, a zinc-based battery would not work on a car. It would be way too heavy, way too big, but if you’re trying to just build gigantic buildings to store energy to power homes, that’s not as big of a deal. So that’s why these kinds of batteries have kind of specialized application.

IRA FLATOW: Yeah, Tesla’s been doing them with lithium ions, but this would be zinc. Scaling up production, though, is the challenge all the time, and it is here too, right?

CASEY CROWNHART: Absolutely, and so the big news this week is that Eos got this big loan commitment from the US Department of Energy. It’s about $400 million. It’s a conditional commitment, so they have to check some boxes. But this kind of funding is exactly what’s so important with batteries. It’s tough to make a battery in the lab, but a lot of people would say it’s a lot tougher to take that battery, make a whole bunch of them, and then actually get them out into the world to store energy. So this funding could help with that.

IRA FLATOW: Yeah, technology has this problem all the time. More news on the energy front– the Biden administration announced that they will be canceling oil drilling leases in the Arctic. What’s the latest on that? How did this all come about?

CASEY CROWNHART: These leases were sold in January 2021 just as Trump was leaving office, but recently the current interior secretary said that these sales were kind of legally flawed. The environmental review didn’t really hold up. So just recently they canceled seven of these oil and gas leases in the Arctic National Wildlife Refuge.

A lot of groups are celebrating this. We can’t have any more oil and gas development and expect to meet our climate targets, according to the UN Climate report, but it’s not totally clear what’s going to happen going forward because this sale of these leases was mandated in a 2017 law to help pay for tax cuts. So it might not be over yet.

IRA FLATOW: Yeah, we’ll have those legal battles, I’m sure. Let’s move on to a story about climbing chimps, and from what I understand, scientists studied how chimpanzees climbing down from trees– how human shoulders and elbows may have evolved.

CASEY CROWNHART: Yes. Our arms look different from other primates– our shoulders and our elbow joints– but they look pretty similar to those of chimpanzees. Scientists weren’t really sure how this evolution happened, but like you said, researchers were watching chimpanzees and another type of monkey called sooty mangabeys go up and down trees.

And they noticed that when both primates were going down trees, they did it pretty differently. The chimpanzees were extending their shoulders and elbows a lot more going down. So they were able to come down very quickly in this– they called it a controlled fall.

IRA FLATOW: Sort of like a brake– they were like good brakes.

CASEY CROWNHART: Yes, they’re like little brakes to climb down trees. So scientists put together that this must be why our shoulders and elbows evolved the way we did is to be able to climb down trees better.

IRA FLATOW: Yeah. Did anybody ever think of looking at the chimps climbing down versus up? I understand that an undergraduate student discovered this.

CASEY CROWNHART: It’s one of those wild things that they just weren’t looking at it. Climbing up the tree seems to be the more important part, but I guess coming down is just as crucial.

IRA FLATOW: Yeah you’re not burdened with all that graduate knowledge. Let’s stay in the animal kingdom a bit. You’ve got some bad bee news for us involving invasive hornets, which are bees’ natural enemies. Tell us about that.

CASEY CROWNHART: There were 22 confirmed sightings in England this year of Asian hornets. I’ll just say, these are not the Asian giant hornets you may have heard about in the US a couple of years ago. These are smaller, so less maybe scary to humans but really, really a big deal for bees.

So these hornets are native to Asia. They’ve spread to some other places, and they prey on wild insects. Bees outside of this typical range don’t really have any defenses against them. So this could be a big threat to local bee populations, other local pollinators, which there’s all sorts of bad news– habitat destruction, climate change, pesticides, all this stuff. So this is kind of just another thing facing bees in England.

IRA FLATOW: Let’s wrap up with some news that I dare to say is a little dangerous, and I’m talking about researchers finding two new toxic bird species in Papua New Guinea. Now I approach this very ignorantly. I don’t know that it ever heard of a toxic bird. Is there such a thing?

CASEY CROWNHART: I had not heard of these either, but apparently researchers have known since the ’90s that there are some species of toxic birds. You might be more familiar with poison dart frogs from South America.

IRA FLATOW: Yeah, that I’ve heard about.

CASEY CROWNHART: It’s kind of a similar sort of thing where these birds have this sort of neurotoxin that they carry in their skin and in their feathers, and it can be kind of irritating and itchy at low doses. At high doses, it can cause paralysis or even be fatal. Scientists think that these birds use these toxins as a sort of defense against parasites and that they get them by eating poisonous beetles and then storing it. But they’re not totally sure how these birds became toxic in the first place.

IRA FLATOW: So the poison doesn’t attack the bird itself. It’s sort of immune, but anything that wants to eat it is going to get hit?

CASEY CROWNHART: Yep, they’ve evolved some sort of defenses against this toxin, and again, we’re not 100% sure exactly how that happened. But they’ve kind of pulled the Uno reverse card and used it to their own advantage.

IRA FLATOW: Well, let’s say this is adding to my ever-growing list of reasons not to touch unknown wildlife, no matter how cute they look. Thank you for taking time to be with us today.

CASEY CROWNHART: Thanks so much for having me.

IRA FLATOW: You’re welcome. Casey Crownhart, climate and energy reporter at MIT Technology Review here in New York.

Copyright © 2023 Science Friday Initiative. All rights reserved. Science Friday transcripts are produced on a tight deadline by 3Play Media. Fidelity to the original aired/published audio or video file might vary, and text might be updated or amended in the future. For the authoritative record of Science Friday’s programming, please visit the original aired/published recording. For terms of use and more information, visit our policies pages at http://www.sciencefriday.com/about/policies/

Meet the Producers and Host

About Shoshannah Buxbaum

Shoshannah Buxbaum is a producer for Science Friday. She’s particularly drawn to stories about health, psychology, and the environment. She’s a proud New Jersey native and will happily share her opinions on why the state is deserving of a little more love.

About Ira Flatow

Ira Flatow is the host and executive producer of Science FridayHis green thumb has revived many an office plant at death’s door.

Explore More

The Hidden Beauty Of The Human Placenta

Though discarded after birth, the placenta builds the first vital connection between mother and fetus.

Read More