Cell division discovery challenges a century of textbook biology

For over a century, biology students have been taught a simple idea about cell division. Before splitting into two identical daughter cells, a parent cell becomes round – like a sphere – and then breaks apart evenly. But what if this isn’t how it usually happens in the body?

Recent research is shaking up this long-held belief, showing that cell division is more dynamic than we’ve been told. The traditional idea of a cell becoming round before dividing doesn’t always hold true, especially in real-life biological systems.

Not all divisions are equal

Scientists from The University of Manchester have discovered that cells often skip the rounding step before division. Instead, they divide without becoming spherical – and this makes a big difference.

These non-round divisions result in daughter cells that are not equal in size or function. This process, known as asymmetric division, turns out to be much more common than previously thought.

Asymmetric cell division is a key way the body creates a variety of cell types needed for different tissues and organs.

Until now, it was mostly linked with rare, specialized cells called stem cells. But this study shows that regular cells can do it too – depending on their shape.

Shape influences cell division

The researchers found that a cell’s original shape can predict how it will divide.

Cells that are short and wide tend to become round before splitting. These rounded cells produce two nearly identical daughter cells. But longer, thinner cells don’t round up. They divide directly into two unequal cells – each with different roles.

This simple difference in shape leads to major changes in what the daughter cells become. And this has big implications for how we understand development, disease, and even cancer.

“The phenomenon of mitosis – or cell division – is one of the fundamentals of life and a basic biological concept which is taught from school age,” said Dr. Shane Herbert.

“Students learn that when a cell divides, it will generate a uniform spherical shape. Our study, however, shows that in real living organisms, it is not as simple as that.”

“Our research suggests that the shape of the cell before it divides can fundamentally direct whether a cell rounds, and importantly, if its daughters are symmetric or asymmetric both in size and function.”

Watching cells divide

To study this process, the scientists used live imaging on transparent 1-day-old zebrafish embryos. These embryos allowed the researchers to watch cells divide in real time.

They looked closely at growing blood vessels, which form from chains of moving cells. A fast-moving “tip” cell leads the way, with slower cells trailing behind.

When that leading cell divided, it didn’t round up. This allowed it to create two new cells: one stayed in front to keep leading, and the other followed behind.

“Using transparent 1-day-old zebrafish embryos allows us to study a dynamic process like cell division inside a living organism,” explained study co-author Dr. Holly Lovegrove.

“We are therefore able to make movies of this fundamental cell behavior, and in doing so, reveal exciting new aspects of how tissues grow.”

Shaping cells in the lab

The team also explored how cell shape affects division using human cells and a technique called micropatterning. This allowed them to control the shape of cells before division.

“Micropatterning allows us to generate specifically shaped microscopic patches of proteins that cells can stick to. The cells will then take the shape of the patch. This therefore allows us to change the shape of the cells and test how these shapes impact on the subsequent cell division,” said study co-author Dr. Georgia Hulmes.

The experts used a system called PRIMO by Alvéole, which lets scientists etch tiny shapes on a surface using a UV laser.

Cells placed on these shapes will spread into that exact form. This let the researchers control the shape of each cell with precision – down to less than a tenth the width of a human hair.

Medicine’s next building block

This new understanding of cell shape and division could have powerful uses. In cancer, for instance, asymmetric divisions might create cells with different behaviors – some that could promote tumor growth or spread.

Knowing how this works could lead to new ways of slowing cancer progression. It could also help regenerative medicine.

By changing the shape of a parent cell, scientists might be able to control what kinds of daughter cells are produced. This could one day help us grow tissues or organs in a more controlled way.

Ultimately, the study may change how biology is taught – and how medicine is practiced.

The full study was published in the journal Science.

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