MAY 28, 2014 12:00 AM PDT

Unusual Physical Property of Stem Cell Nuclei

WRITTEN BY: Jen Ellis
Most materials will contract if stretched and will expand if squeezed. Think of the stretching of a rubber band and the way it narrows during the stretching process, and the way the circumference of a tennis ball bows outward when it is squeezed.

If a material shows the opposite effect, contracting when it is squeezed and expanding when it is stretched, it is said to be auxetic. (Think of a sponge).

Man-made items such as shock-absorbing and dampening materials are engineered to have this reaction, but aside from some natural sponges, this effect is fairly rare in nature. However, a research team from the University of Cambridge discovered this property in an unexpected place - in the nucleus of an embryonic stem cell. The team's work was published in a recent edition of Nature Materials.

The property is only observed during the transition period of embryonic stem cells, when they are in the process of evolving into a specific type of cell within the body such as muscle or heart tissue.

During the transition period, the researchers injected a dye into the cytoplasmic fluid around the nuclei and found that when the nucleus was stretched, the dye was absorbed - but without the stretching force, it was not. This suggests that porosity was increased by expansion of the nuclei caused during the stretching process, allowing dye to permeate into the structure.

Perhaps its auxetic properties play a role in the remarkable flexibility of embryonic stem cells to develop into any other type of cell in the body, but if so the mechanism remains to be seen. Physical forces and the surrounding environment within the body may play key roles, and further research into these mechanisms may assist in the understanding of certain disorders.

Outside of the human body, this research could lead to interesting material compositions. Understanding the mechanism of auxetism in the transitional stem cell could lead to development of new industrial materials.

Most auxetic materials have a high degree of order in their structure - a honeycomb would be a classic example. This structure allows for the distribution and dissipation of forces that are applied to the structure. However, some materials can produce this effect with a relatively random orientation, and the nuclei of transitional stem cells appear to be in that category.

Is this an evolutionary process or an inherent property of the transitional stem cell? If it has evolved, was the process originally more ordered, with the evolution providing needed structural changes?

Understanding the difference in the auxetism mechanisms between highly ordered and disordered systems could lead to technological advances, assuming the mechanism found in stem cells can be transferred to man-made materials in the outside world.

It could be the case that disordered or randomly oriented systems that have the same effect of auxetism can produce improved materials for shock absorption - imagine bulletproof vests as an example. We may find improvements in performance, cost, ease of manufacture - or all of those properties.
About the Author
You May Also Like
AUG 08, 2018
Cell & Molecular Biology
AUG 08, 2018
Changing White Fat to Brown Fat
Not all fat is the same. Brown fat is thought to be fat healthier than white fat....
AUG 24, 2018
Cell & Molecular Biology
AUG 24, 2018
Chronic Allergies can Change Cells
Chronic rhinosinusitis is different from allergies; it leads to serious inflammation and swelling in the sinuses that can last for years....
SEP 15, 2018
Videos
SEP 15, 2018
A Hangover Cure in a Pill
A night of drinking can lead to a morning of regret for many people, but science is working on a solution for the physical pain....
OCT 04, 2018
Videos
OCT 04, 2018
Zebrafish as Metastatic Cancer Model
Another Koch Institute Image Award winner from 2018 is presented in this video from MIT....
OCT 06, 2018
Videos
OCT 06, 2018
Explore a Human Cell with an Interactive Website
The Allen Institute is aiming to enhance our understanding of how human cells function....
OCT 09, 2018
Drug Discovery
OCT 09, 2018
'Copper Antibiotic Peptide' Effective in Eradicating Tuberculosis
The bacterium responsible for Tuberculosis has found a way to avoid antibiotics by hiding inside the macrophages which are the specific immune cells that a...
Loading Comments...