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This week, I published a story about the results of a study on Parkinson’s disease in which a biotech company transplanted dopamine-making neurons into people’s brains. (You can read the full story here.)

The reason I am following this experiment, and others like it, is that they are long-awaited tests of transplant tissue made from embryonic stem cells. Those are the sometimes controversial cells first plucked from human embryos left over from in vitro fertilization procedures 25 years ago. Their medical promise is they can turn into any other kind of cell.

In some ways, stem cells are a huge disappointment. Despite their potential, scientists still haven’t crafted any approved medical treatment from them after all this time. The Parkinson’s study, run by the biotech company BlueRock, a division of Bayer, just passed phase 1, the earliest stage of safety testing. The researchers still don’t know whether the transplant works.

I’m not sure how much money has been plowed into embryonic stem cells so far, but it’s definitely in the billions. And in many cases, the original proof of principle that cell transplants might work is actually decades old—like experiments from the 1990s showing that pancreas cells from cadavers, if transplanted, could treat diabetes.

Cells derived from human cadavers, and sometimes from abortion tissue, make for an uneven product that’s hard to obtain. Today’s stem-cell companies aim instead to manufacture cells to precise specifications, increasing the chance they’ll succeed as real products. 

That actually isn’t so easy—and it’s a big part of the reason for the delay. “I can tell you why there’s nothing: it’s a manufacturing issue,” says Mark Kotter. He’s the founder of a startup company, Bit Bio, that is among those developing new ways to make stem cells do researchers’ bidding. 

While there aren’t any treatments built from embryonic stem cells yet,  when I look around biology labs, these cells are everywhere. This summer, when I visited the busy cell culture room at the Whitehead Institute, on MIT’s campus, a postdoc named Julia Juong pulled out a plate of them and let me see their silvery outlines through a microscope. 

Juong, a promising young scientist, is also working on new ways to control embryonic stem cells. Incredibly, the cells I was looking at were descendants of the earliest supplies, dating back to 1998. One curious property of embryonic stem cells is that they are immortal; they keep dividing forever.

“These are the originals,” Juong said.

That reproducibility is part of why stem cells are technology, not just a science project. And what a cool technology it is. The internet has all the world’s information. A one-cell embryo has the information to make the whole human body. 

It’s what I have started to think of as “embryo tech.” I don’t mean what we do to embryos (like gene testing or even gene editing) but, instead, the powerful technology researchers can extract by studying them. Embryo tech includes stem cells and new ways of reproducing through IVF. It could even hold clues to real rejuvenation science.

For instance, one lab in San Diego is using stem cells to grow brain organoids, a bundle of fetal-stage brain cells living in a petri dish. Scientists there plan to attach the organoid to  a robot and learn to guide it through a maze. It sounds wild, but some researchers imagine that cell phones of the future could have biological components, even bits of brain, in them.

Another recent example of embryo tech is in longevity science. Researchers now know how to turn any cell into a stem cell, by exposing it to what are called transcription factors. It means they don’t need embryos (with their ethical drawbacks) as the starting point.

One hot idea in biotech is to give people controlled doses of these factors in order to actually rejuvenate body parts. Until recently, scientific dogma said human lives could only run in one direction: forward. But now the idea is to turn back the clock—by pushing your cells just a little way back in the direction of the embryo you once were.

One company working on the idea is Turn Bio, which thinks it can inject the factors into people’s skin to get rid of wrinkles. Another company, called Altos Labs, has raised  $3 billion to pursue the deep scientific questions around this phenomenon. 

Finally, another cool discovery is that given the right cues, stem cells will try to self-organize into shapes that look like embryos. These entities, called synthetic embryos, or embryo models, are going to be useful in research, including studies aimed at developing new contraceptives. They are also a dazzling demonstration that any cell, even a bit of skin, may have the intrinsic capacity to create an entirely new person. 

All these, to my mind, are examples of embryo tech. But by its nature, this type of technology can shock our sensibilities. It’s the old story: reproduction is something secret, even divine. And toying with the spark of life in the lab—well, that’s playing at Frankenstein, isn’t it?  When reporting about the Parkinson’s treatment, I learned that Bayer is still anxious about embryo tech. Those at the company have been tripping over themselves to avoid saying “embryo” at all.  That’s because Germany has a very strict law that forbids destruction of embryos for research within its borders.

So what will embryo tech lead to next? I’m going to be tracking the progress of human embryonic stem cells, and I am working on a few big stories from the frontiers that I hope will shock, awe, and inspire. So stay tuned to MIT Technology Review.

Read more from MIT Technology Review’s archive

Earlier this month, we published a look back over 25 years since human embryonic stem cells were first captured. While there are no treatments yet, the number of experiments on patients is growing. That has some researchers predicting that the technology could deliver soon. It’s about time! And check out the ethics issue of our magazine, where we resurfaced our pathbreaking scoop on the topic, from way back in 1998.

Stem cells come from embryos, but surprisingly, the reverse also seems to be the case: given a few nudges, these potent cells will spontaneously form structures that look, and act, a lot like real embryos. I first reported on the appearance of “synthetic human embryos” in 2017 and the topic has only heated up since, as we recounted this June in this story about the wild race to improve the technology. 

Stem cells aren’t the only approach to regrowing organs. In fact, some of our body parts have the ability to regenerate on their own. Jessica Hamzelou reported on a biotech company that’s trying to make mini livers inside people’s lymph nodes.

From around the web

The overdose reversal drug Narcan is going over-the-counter. A two-pack of the nasal spray will cost $49.99 and should be at US pharmacies next week. The move comes as overdoses from the opioid fentanyl spiral out of control. (NBC News)

If you’re having surgery, you’ll probably be looking for the best surgeon you can get. That might be a woman, according to a study finding that patients of female surgeons are a lot less likely to die in the months following an operation than those operated on by men. The reasons for the effect are unknown. (STAT News)

New weight-loss drugs don’t just cause people to shed pounds. One of them, Wegovy, could also protect against heart failure. New England Journal of Medicine.

I stopped worrying about covid-19 after my second vaccine shot and never looked back. But a new variant has some people asking, “How bad could BA.2.86 get?” (The Atlantic)