Artificial Womb for Growing Mammals Is at 'One-Yard Line', Says Colossal CEO

By Jason Nelson

Biotech company Colossal Biosciences claims it has nearly completed an artificial womb system designed to grow mammals entirely outside another animal’s body—a breakthrough the de-extinction startup says could eventually support its long-term goal of reviving the woolly mammoth.

In a blog post on Tuesday, the Dallas-based company said the remaining obstacle is chemistry.

“We are on the one-yard line of this, which is insane,” CEO Ben Lamm said in a statement.

In an interview with Rolling Stone in February, Lamm said the company has already solved the hardware and software side of the artificial womb system, leaving chemical signaling between developmental stages as the final major hurdle.

“We designed the system so you just have to tweak all the chemical cueing,” Lamm said. “This is now a chemical cueing thing. It’s not a hardware or software problem.”

An artificial womb, also known as an ectogenesis system, is designed to replicate the functions of a uterus by supplying oxygen, nutrients, hormones, and waste removal to a developing embryo or fetus outside the body. Until this point, most artificial womb research has focused on keeping premature animals alive after early birth rather than supporting full gestation from embryo to delivery.

Colossal says its platform is designed to support development across the full gestational process, a technology that the company believes could eventually reshape both conservation biology and reproductive medicine.

The platform, developed at Colossal Biosciences’ Australian laboratory under Chief Biology Officer Andrew Pask, uses a dialysis-like system paired with AI models and proprietary algorithms that monitor embryo development and adjust nutrients, gases, and chemical signals in real time.

“We have been testing and perfecting the artificial egg system, so we have been optimizing it as we go along and stopping development at various stages to ensure correct body patterning and health of the embryos,” Pask told Decrypt. “We very carefully monitor development to make sure we have the biologically closest natural development to [being] in the egg as possible.”

Colossal said researchers tested the platform using the fat-tailed dunnart, a small Australian marsupial with a 13-day gestation period, one of the shortest among mammals. The company said the team successfully guided embryos through all three major developmental stages while using AI and physiological monitoring to track development against normal biological patterns.

“Now we have perfected it, we see very high rates of development—100%,” Pask told Decrypt. “But around 25% of fertilized eggs will fail even under normal conditions inside the egg. Using our system, we have hatched 26 chicks, and we are now actively monitoring these birds as they grow up.”

Despite the breakthrough, Colossal said the artificial womb is not currently part of its plan to produce a woolly mammoth calf by late 2028, despite earlier comments positioning the technology as a potential alternative to using endangered Asian elephants as surrogates.

Colossal has spent the past year expanding its reproductive engineering work across multiple species. In April 2025, Colossal announced the birth of three dire wolf pups—Romulus, Remus, and Khaleesi—created using ancient DNA recovered from a 13,000-year-old tooth and a 72,000-year-old inner ear bone, engineered into gray wolf cells. This was followed in November with the company saying it had cloned seven-time Super Bowl Champion Tom Brady’s dog, Lua.

“A few years ago, I worked with Colossal and leveraged their non-invasive cloning technology through a simple blood draw of our family's elderly dog before she passed," Brady told ABC News. "In a few short months, Colossal gave my family a second chance with a clone of our beloved dog."

Colossal said it owns the intellectual property behind the artificial womb system, and defended the project’s ethical framework, arguing that controlled ex-utero development could improve survival outcomes compared to conventional breeding attempts—and that the artificial womb work could eventually have implications beyond de-extinction.

“Our goal is to leverage our technologies to help save endangered species, and we open source all of our technologies for conservation,” a company spokesperson said.

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