“I understand the difficulties. I understand. You are entering the field of abortions, ”says Hanna. However, he says he can streamline such experiments because researchers are already studying five-day-old human embryos from IVF clinics, which are also destroyed in the process.
“So I would recommend growing it until day 40 and then getting rid of it,” Hanna says. “Instead of getting tissue from abortions, let’s take a blastocyst and grow it.”
The research is part of an explosion of new techniques and ideas for studying early development. Today, in the same issue of Nature, two other research groups report a leap forward in the creation of “artificial” human embryos.
These teams have been successful in persuading ordinary skin cells and stem cells to self-assemble into early human embryos resembling themselves they call “blastoids,” which they cultured for about 10 days in the lab. Several types of artificial embryo models have already been described, but those described today are among the most complete, since they have the cells necessary for the formation of a placenta. This means that they are one step closer to viable human embryos that could develop further, even until birth.
Scientists say they would never try to establish a pregnancy with artificial embryos – an act that is now reportedly banned in most countries.
Instead, Hanna says, an obvious next step would be to add these embryo models to her rotating pot system and see how far they can grow. “It took six years of very intense work to get this system to where it is,” says Hanna. “We aim to do this with synthetic embryos as well.”
For now, the technology of the artificial uterus remains “complex and expensive”, explains Martinez Arias. He doesn’t think many other labs will be able to use it, limiting its short-term impact, and he’s not conducive to growing human embryos like this: “It’s expensive and complicated, it will take so see how useful this is. “
Mouse-in-a-pot technology needs further improvement, Hanna says. He was unable to grow the mice from a fertilized egg until day 12. Instead, he collected 5-day-old embryos from pregnant mice and transferred them to the system. ‘incubation, where they lived another week.
The problem is that currently mouse embryos only develop properly if they can be attached to an actual mouse uterus, at least for a short time. Hanna’s team is working on adapting the procedure so that they can develop the mice entirely in vitro.
Hanna says he’s not interested in bringing full-term mice into the lab. Its objective is to observe and manipulate the first developments. “I want to see how the program is going,” he says. “I have a lot to study.”
Long-term studies of live human embryos developing in the laboratory are currently banned under the so-called 14-day rule, a directive (and law in some countries) that prohibits embryologists from growing human embryos longer. two weeks. .
However, a key scientific organization, the International Society for Stem Cell Research, or ISSCR, intends to recommend lifting the ban and allowing some embryos to develop longer.
Hanna says that means he could grow human embryos in his incubator – as long as Israeli ethics boards approve, which he thinks they would do.
“Once the guidelines are updated, I can apply, and they will be approved. It’s a very important experience, ”says Hanna. “We have to see human embryos gastriculate and form organs and start to disrupt them. The benefits of growing human embryos up to the third week, the fourth week, the fifth week are invaluable. I think these experiences should at least be considered. If we can come up with an advanced human embryo, we can learn a lot. “
Hanna says that to make these experiences more acceptable, human embryos could be modified to limit their potential to develop fully. One possibility would be to install genetic mutations in a calcium channel that would prevent the heart from beating.
I asked Hanna if he had sought the advice of ethicists or religious figures. He said no. Instead, he waits for advice from his professional body and ethical clearance from his university.
“The ISSCR is my rabbi,” he said.
There may be unexpected practical applications of the culture of human embryos in pots. William Hurlbut, a doctor and bioethicist at Stanford University, says the system suggests a way for him to obtain primitive organs, like livers or pancreatic cells, from first trimester human embryos, which could then be further cultivated and used in transplant medicine. Hanna agrees that this is a potential direction for the technology.
“The scientific frontier is from molecules and test tubes to living organisms,” says Hurlbut. “I don’t think organ harvesting is that exaggerated. He could possibly get there. But it is very difficult, because the limit of one person is not the limit of another person.