• Renewal Bio, a biotech company, wants to create embryo-stage versions of people.
• They've done it before with mouse embryos.
• The company views the embryo as the "best 3D bio-printer."

Last week, we reported on scientists in Israel making mouse embryos without using sperm or egg cells; but only stem cells taken from the skin. The same researchers are now creating embryo-stage versions of people to harvest tissues for use in transplant treatments.

Their company, Renewal Bio, wants to be at the forefront of stem-cell technology and artificial wombs – demonstrated by Jacob Hanna, a biologist at the Weizmann Institute of Science in Rehovot and Renewal's scientific founder. Hanna's research was published in the journal Cell on Monday.

But, Hanna is already working on replicating the technology with human cells. He told MIT Technology Review that he hopes to eventually produce artificial models of human embryos equivalent to a 40- to 50-day-old pregnancy.

"We view the embryo as the best 3D bioprinter," said Hanna. "It’s the best entity to make organs and proper tissue."

A 'universal starting point'

For now, researchers can print or grow simple tissues like cartilage or bone. Printing complex cell types and organs have proved to be difficult. However, an embryo starts building the body naturally.

"The vision of the company is ‘Can we use these organized embryo entities that have early organs to get cells that can be used for transplantation?’ We view it as perhaps a universal starting point," said Hanna.

Renewal Bio’s technical plan has not been disclosed yet, and the company’s website is just a calling card for now. "It’s very low on details for a reason. We don’t want to overpromise, and we don’t want to freak people out," Omri Amirav-Drory, a partner at NFX who is acting as CEO of the new company, told MIT Technology Review. "The imagery is sensitive here."

We don’t want to overpromise, and we don’t want to freak people out

Not all scientists await the development. According to some, it will be difficult to grow human embryo models to an advanced stage, and it's best to avoid the controversy raised by imitating real embryos too closely.

"It’s absolutely not necessary, so why would you do it?" said Nicolas Rivron, a stem-cell scientist at the Institute of Molecular Biotechnology in Vienna. He argues that scientists should only create "the minimal embryonic structure necessary" to yield cells of interest.

Synthetic embryos with the start of a brain and tail

A year ago, Hanna first showed off a "mechanical womb" in which he managed to grow natural mouse embryos outside of a female mouse for several days. The embryos were kept in spinning jars and bathed in nutritious blood serum and oxygen.

In the new research, Hanna used the same mechanical womb, but this time to grow look-alike embryos created from stem cells. When stem cells are grown together in specially shaped containers, they will join and try to assemble an embryo, producing structures called embryoids, blastoids, or synthetic embryo models.

Many researchers insist that these structures have limited relation to real embryos and zero potential to develop completely.

However, Hanna added these synthetic mouse embryos to his mechanical womb, growing them further than ever before – to a point where the hearts started beating, blood began moving, and "there was the start of a brain and a tail."

Hanna's report stunned scientists. "The embryos really look great. They are really, really similar to natural embryos," he said.

Still, techniques for growing synthetic embryos remain inefficient. Attempts to mimic a mouse embryo have not been very successful. Even the model embryos eventually suffered abnormalities.

Next step: Using human blood and skin cells

In the next stage, Hanna is using his blood or skin cells, including those of a few other volunteers, as the starting point for making synthetic human embryos. His lab could soon be filled with thousands of genetic clones of himself.

Hanna is not troubled by the idea. He views these as entities without a future. Right now, there is no way to graduate from jar life to real life, he said.

"We are not trying to make human beings. That is not what we are trying to do," said Hanna. "To call a day-40 embryo a mini-me is just not true."

It's a gray area. There could be debates as to whether synthetic embryos have any rights. In the US, the National Institutes of Health has, in some cases, declined to fund studies on synthetic embryos that it believes would be too close to the real thing.

Hanna doesn’t think an artificial embryo made from stem cells and kept in a lab will ever count as a human being, but he has a contingency plan to make sure there is no confusion. Restricting the potential of an embryo could help avoid ethical dilemmas. "We think this is important and have invested a lot in this," said Hanna. "Genetic changes can be made that lead to "no lungs, no heart, or no brain."

Amirav-Drory and Hanna have been approaching other scientists and doctors to learn what they would do if they had access to large numbers of synthetic embryos developed for days or even weeks.

"We’ve been asking people, 'Imagine if we can get to this or that milestone. What does it unlock?' And people’s eyes light up," said Amirav-Drory.

Originally published on Interesting Engineering : Original article