A man-made embryo shows how a stem cell finds its role

A unique 3D model allows researchers to explore embryonic development.

Image source: Mijo Simunovic/Rockefeller University
  • Researchers observe the beginning of embryonic stem cells dividing into upper and lower body sections.
  • An interdisciplinary team invents an impressively accurate 10-day-old "embryoid."
  • The team's model may be important to other future research on pregnancy.

What makes stem cells so attractive for research is that they start off in an undifferentiated state — they're capable of becoming anything in the human body. Working with them, scientists can construct organoids: limited-function, synthetic versions of organs or other biological structures for study. (Organoids can't grow into independent living organisms.) However, the natural mechanism that causes embryonic stem cells to become different cell types remains an area about which not a lot is known.

Now a study identifies a particular growth factor — bone morphogenetic protein 4, or "BMP4"— that appears to be the trigger for a critical event, "symmetry breaking." It occurs about two weeks after conception via a process called gastrulation, taking place just after an embryo attaches to its mother's uterus. It's a pivotal moment at which a clump of cells first begins to separate into upper and lower body regions. "Symmetry breaking drives almost everything that happens during embryonic development," says Mijo Simunovic, a junior Fellow in the lab that conducted the research. "Our heads don't look like our feet, and that's because, at some point, the embryo breaks into two parts, anterior and posterior."

The researchers' conclusion regarding BMP4 is just part of what they've achieved — the study also validates the unique 3D model, or "embryoid," they developed as being accurate enough to use in laboratory investigations of other developmental processes.

The research is published in Nature Cell Biology.

Breaking symmetry

Artist's rendering of stem cells

Image source: Giovanni Cancemi/Shutterstock

Earlier research using mouse embryoids demonstrated symmetry breaking, and it was observed in human embryonic stem cells a few years ago, leading to the hope that symmetry breaking might also occur in an experimental embryoid if the model emulated the real thing well enough.

By combining bioengineering, physics, and developmental biology, the researchers — Simunovic, Ali H. Brivanlou and Eric D. Siggia — were able to create a new type of 3D model from human embryonic stem cells. It mimics the genetics, shape, and size of a roughly 10-day-old human embryo. (Researchers are prohibited from creating embryoids whose development goes beyond that of a natural 14-day-old.)

To test their embryoid, the researchers exposed it to a range of chemical signals the placenta releases during pregnancy until they got to bone morphogenetic protein. Simunovic recalls, "We added BMP4, and two days later one part of the three-dimensional culture became the future posterior, and the opposite part became the future anterior."

A model embryoid

Image source: ValentinaKru/Shutterstock

The teams' work results in the introduction of a new type of 3D model that may lead to better understanding of pregnancy complications, such as why some embryos fail to attach to the uterus successfully. "About 50 to 75 percent of embryos do not attach, creating a huge bottleneck to pregnancy," says Simunovic. "We don't know why that is, but using this model we may be able to find out."

Simunovic says that the model may also be useful in exploring developmentally incurred diseases. He says, "We can create 3D embryonic models of genetic conditions, and follow the developmental process in real time. These models can finally advance the understanding of a wide range of diseases for which we currently have no idea where and when things begin to go wrong."

Higher ed isn’t immune to COVID-19, but the crisis will make it stronger

The pandemic reminds us that our higher education system, with all its flaws, remains a key part of our strategic reserve.

Sponsored by Charles Koch Foundation
  • America's higher education system is under great scrutiny as it adapts to a remote-learning world. These criticisms will only make higher ed more innovative.
  • While there are flaws in the system and great challenges ahead, higher education has adapted quickly to allow students to continue learning. John Katzman, CEO of online learning organization Noodle Partners, believes this is cause for optimism not negativity.
  • Universities are pillars of scientific research on the COVID-19 frontlines, they bring facts in times of uncertainty and fake news, and, in a bad economy, education is a personal floatation device.
Keep reading Show less

An ancient device too advanced to be real gives up its secrets at last

Researchers present what they’ve learned now that they can read the tiny text inside the Antikythera mechanism.

Exploded view of Antikythera mechanism (Peulle/Wikimedia)
Surprising Science

Though it it seemed to be just a corroded lump of some sort when it was found in a shipwreck off the coast of Greece near Antikythera in 1900, in 1902 archaeologist Valerios Stais, looking at the gear embedded in it, guessed that what we now call the “Antikythera mechanism" was some kind of astronomy-based clock. He was in the minority—most agreed that something so sophisticated must have entered the wreck long after its other 2,000-year-old artifacts. Nothing like it was believed to have existed until 1,500 years later.

Keep reading Show less

Hyper-innovation: COVID-19 will forever change the way we teach kids

The institutional barriers that have often held creative teaching back are being knocked down by the coronavirus era.

Future of Learning
  • Long-held structures in the education system, like classroom confines and schedules, have held back innovation for a long time, says education leader Richard Culatta.
  • In the coronavirus era, we have been able to shake some of those rigid structures loose, making way for creativity and, ultimately, a more open mindset.
  • When creativity and technology combine, learning can become so much more than delivering content to a student. Culatta gives two stunning examples: one of a biotech class, and another involving a student discovering a star.
Keep reading Show less

Algorithms associating appearance and criminality have a dark past

We'd like to think that judging people's worth based on the shape of their head is a practice that's behind us.

PATRICK KOVARIK/AFP via Getty Images
Culture & Religion

'Phrenology' has an old-fashioned ring to it. It sounds like it belongs in a history book, filed somewhere between bloodletting and velocipedes.

Keep reading Show less
Scroll down to load more…