A biotechnology company that aims to resurrect extinct creatures announced that it has managed to hatch live chicks in an artificial environment, an achievement that was met with mixed opinions from scientists and critics of its de-extinction mission.

23 chicks – ranging in age from a few days to several months – were hatched from a 3D-printed lattice structure that mimics the shell of an egg, Colossal Biosciences reported.

Colossal had previously announced that it had genetically modified living animals to resemble extinct species, including mice with long hair similar to that of the woolly mammoth and wolf pups inspired by the dire wolf.

The giant moa, on the horizon

Colossal CEO Ben Lamm said the artificial egg technology could one day scale up to genetically modifying living birds to make them look like the extinct New Zealand South Island giant moa, whose eggs are 80 times larger than a chicken's and would be difficult for any modern bird to lay.

“We wanted to build something that nature has developed quite successfully and make it better, more scalable and even more efficient,” Lamm said.

Independent scientists point out that the technology, while impressive, lacks some components to truly be considered an artificial egg. And they maintain that the idea of ​​reviving extinct beasts is probably impossible.

"They may be able to use this technology to create a genetically modified bird, but that's just a genetically modified bird. It's not a moa," said evolutionary biologist Vincent Lynch of the University at Buffalo.

How the artificial incubation system works

To hatch the chicks, Colossal scientists poured fertilized eggs into the artificial system and placed them in an incubator. They also added calcium, which is normally absorbed from the eggshell, and monitored the development and growth of the embryos in real time using imaging.

Scientists point out that Colossal has designed an artificial shell with a membrane that allows the correct amount of oxygen to pass through, just like a real egg. However, other components of the egg – such as the temporary organs that form to nourish and stabilize the growing chick and remove waste – were not included.

"That's not an artificial egg, because you've put in all the other parts that make it an egg. It's an artificial shell," Lynch said.

In past decades, researchers have used more rudimentary technologies to create transparent eggshells that allowed chicks to be hatched from plastic films or bags. These technologies are useful for studying chicken development and obtaining knowledge that can also be applied to other mammals and even humans.

“Producing a chick from an artificial container is not necessarily new,” said Nicola Hemmings, who studies the reproductive biology of birds at the University of Sheffield. Hemmings is not part of the Colossal team.

There's still a long way to go before Colossal attempts a moa resurrection via this artificial egg system. Scientists must first compare ancient DNA extracted from well-preserved moa bones with the genomes of extant bird species. And they need a bigger shell.

"We didn't want to wait until we were ready to give birth to a giant moa. We actually wanted to start working now on the engineering challenges related to surrogacy and birth," Lamm said.

The ethical dilemma of de-extinction

Even if Colossal managed to create a large moa-like bird, some scientists are concerned about what would happen next, including how it would survive in a landscape that looks nothing like that of the past.

“The big challenge is: What environment is this animal going to live in?” said bioethicist Arthur Caplan of New York University's Grossman School of Medicine.

These de-extinction efforts might make more sense applied to currently endangered species, where scientists could preserve sperm and eggs from living specimens to try to bring more into the world, Hemmings said.

“My personal interest leans more towards preserving what we have than trying to recover what has already been lost,” Hemmings said.