Reacción a "US company Colossal says it has developed artificial egg system to incubate extinct bird embryos"

Colossal Biosciences, a company with a name as spectacular as its ambitions, has just announced a new development – once again via a press release from the company itself, rather than through the usual channel of publishing its findings in a scientific paper. Colossal rose to fame in 2021 with the surprising initial proposal by George Church, the company’s promoter and founder, to de-extinct the woolly mammoth, a pachyderm that went extinct 4,000 years ago, the last of which survived on an island in northern Siberia. Among the many challenges such a de-extinction project would face was that of gestating an embryo, a mammoth foetus. It was impossible to use the species most closely related in evolutionary terms, the Asian elephant, with which they share a common ancestor that lived some 6 million years ago—too distant. It would not work. That is why they have opted for extrauterine gestation, using an artificial womb—a pouch that allows the developing foetus to be nourished and oxygenated—whose initial successes have already been reported in the gestation of lambs, in research aimed at saving premature babies at increasingly earlier gestational ages. Logically, to gestate a mammoth calf, this extrauterine sac will have to be scaled up to the necessary size. This development is not yet available, but Colossal is currently busy incorporating the more than 500,000 genetic variants of the mammoth genome into the genome of Asian elephant cells using CRISPR gene-editing tools. They will likely not need the artificial womb for some time yet.

When it comes to de-extincting birds, the challenge is different. Birds develop externally, inside eggs, and some of the birds they wish to bring back to life, such as the giant moa of the South Island, currently have no similar or compatible species capable of producing eggs of the necessary size (80 times the volume of a hen’s egg, with a length of up to 24 centimetres). The giant moa was a flightless bird that inhabited the South Island of New Zealand; it stood almost 4 metres tall and weighed over 230 kilograms. It became extinct in the mid-15th century, following the arrival of the Maori from Polynesia, who hunted it to extinction. Colossal has set out to de-extinct the giant moa and, to this end, has now announced in a press release the biotechnological breakthrough achieved by its researchers. They have developed an incubation platform – an artificial egg of scalable size – protected by a transparent membrane that allows the embryo’s development to be observed and facilitates the necessary gas exchange and adequate oxygenation of the developing embryo. The tests have been successfully carried out using chicken embryos, which have completed their development until hatching, leaving this artificial egg and being born normally.

Colossal is proving itself to be a unique biotechnology company, tackling challenges that would seem impossible for any other firm. However, at Colossal, they are tackling challenges that require the development of technologies and devices that do not yet exist, such as the artificial womb to gestate a potential woolly mammoth foetus or, now, the artificial egg for the development of bird embryos capable of hatching from species that, like the giant moa, ceased to exist over five centuries ago, or the dodo, also driven to extinction by humans in the 17th century. They have already demonstrated their skill by incorporating multiple genetic edits using CRISPR, including seven modifications discovered in the mammoth genome to create fascinating woolly mice, or up to 14 edited genes to modify the nucleus of a grey wolf cell and produce animals with characteristics similar to those that the giant North American white wolves must have had, which became extinct 13,500 years ago.