Artificial Embryo From Stem Cells

Scientists at the University of Cambridge have managed to create a structure resembling a mouse embryo in culture, using two types of stem cells – the body’s ‘master cells’ – and a 3D scaffold on which they can grow. Understanding the very early stages of embryo development is of interest because this knowledge may help explain why a significant number of human pregnancies fail at this time.

Once a mammalian egg has been fertilised by a sperm, it divides multiple times to generate a small, free-floating ball of stem cells. The particular stem cells that will eventually make the future body, the embryonic stem cells (ESCs) cluster together inside the embryo towards one end: this stage of development is known as the blastocyst. The other two types of stem cell in the blastocyst are the extra-embryonic trophoblast stem cells (TSCs), which will form the placenta, and primitive endoderm stem cells that will form the so-called yolk sac, ensuring that the foetus’s organs develop properly and providing essential nutrients.

Using a combination of genetically-modified mouse ESCs and TSCs, together with a 3D scaffold known as an extracellular matrix, Cambridge researchers were able to grow a structure capable of assembling itself and whose development and architecture very closely resembled the natural embryo.  There is a  remarkable degree of communication between the two types of stem cell: in a sense, the cells are telling each other where in the embryo to place themselves.

artificial embryo

We knew that interactions between the different types of stem cell are important for development, but the striking thing that our new work illustrates is that this is a real partnership – these cells truly guide each other,”  says Professor Zernicka-Goetz. “Without this partnership, the correct development of shape and form and the timely activity of key biological mechanisms doesn’t take place properly.”

Comparing their artificial ‘embryo’ to a normally-developing embryo, the team was able to show that its development followed the same pattern of development. The stem cells organise themselves, with ESCs at one end and TSCs at the other.

The study has been published in the journal Science.


How Cancer Cells Invade The Body

Using a nanocomputer that acts as an obstacle course for cells, researchers from the Brown School of Engineering have shed new light on a cellular metamorphosis thought to play a role in tumor cell invasion throughout the body.

The epithelial-mesenchymal transition (EMT) is a process in which epithelial cells, which tend to stick together within a tissue, change into mesenchymal cells, which can disperse and migrate individually. EMT is a beneficial process in developing embryos, allowing cells to travel throughout the embryo and establish specialized tissues. But recently it has been suggested that EMT might also play a role in cancer metastasis, allowing cancer cells to escape from tumor masses and colonize distant organs.

For this study, published in the journal Nature Materials, the researchers were able to image cancer cells that had undergone EMT as they migrated across a device that mimics the tissue surrounding a tumor.
emt pillarsBenign cancer cells that had been induced to become malignant made their way slowly around microscopic obstacles. About 16 percent of the cells moved much more rapidly across the microchip
People are really interested in how EMT works and how it might be associated with tumor spread, but nobody has been able to see how it happens,” said lead author Ian Wong, assistant professor in the Brown School of Engineering and the Center for Biomedical Engineering, who performed the research as a postdoctoral fellow at Massachusetts General Hospital. “We’ve been able to image these cells in a biomimetic system and carefully measure how they move.”


Video Mapping First Stages Of Brain Development

Researchers at the Howard Hughes Medical Institute Janelia Research  campus (Loudun, North Virginia)  are using a new type of computer software to track and image how a nervous system develops in unprecedented detail. The new system is able to track individual cells during embryonic development, giving scientists a powerful tool to create a blueprint of how brains form.

Phillip Keller and his fellow researchers at the Janelia Research Campus in Virginia are tracking each of them as they organize into a working brain.

brain synaptic symphony
Clck the image to enjoy the video of  the first stage of brain development in a fruit fly embryo. It’s an unprecedented view — every single dot represents a single cell

We basically want to understand how development happens. What are the fundamental principles that rule the mechanisms of development? How do you actually get from one cell to a complex multicellular organism in a very robust manner?” Answers to those questions have always eluded scientists“, says Jamelia Research campus group leader Phillip Keller: “But now, thanks to new computer software that can process massive amounts of data in near real time, mapping how cells form into a complex nervous system is possible, he added.

Organizing what amounted to terabytes worth of data into visualizations the scientists could study took weeks. The new software can do it in a matter of minutes. Researcher Fernando Amat says the team have also developed a colour system that allows them to track individual cells during brain development.  “We assign a color, a random color, to each cell at the beginning and then we propagate these colors based on the tracking information. So, what you can see is basically how each single-cell as they divide they go to different parts of the organism. And so, they become kind of colour clusters, so you see basically how each, let’s say, tissue or part of the embryo where it came from. What’s the original cell that it came from“, says Amat.