Biological cells can be all kinds of shapes and sizes, even though they don’t have skeletons or other rigid structures to maintain that shape. Different forms help different types of cells accomplish different functions. How do they do that? Scientists at the Swiss Federal Institute of Technology in Zürich discovered internal forces that form the shape of lipid membranes from within.
Human epithelial tissue sample – you can see individual cells. Image credit: Berkshire Community College Bioscience Image Library via Wikimedia
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Biological cells are typically very soft. They are like bags of water and stuff in a soft lipid membrane. And yet they maintain their shape throughout their life cycle. How? We already mentioned that cells don’t have skeletons, but that’s not entirely accurate – there are cytoskeleton, consisting of such materials like actin filaments and microtubules, that exert forces from within the cell in order to form the shape of it. Scientists have been using large vesicles surrounded by a double lipid membrane to investigate this process and now researchers in Switzerland might have achieved a breakthrough.
Scientists at the ETH Zürich filled the vesicle with freely-moving micrometre-sized particles. When these particles collide, they exert forces that lead to the formation of tethers, antennae and other structures. Scientists have never been able to observe this process. By colliding with the membrane of the vesicle, these particles are forming curvatures that attract more particles.
Rao Vutukuri, one of the authors of the study, said: “Not only have we succeeded in creating an artificial, greatly simplified system that imitates cells very well. but, thanks to this approach, we’ve also been able to clarify the material physics and mechanics of membranes made of double lipid layers.”
This research shows how self-propelled particles produce a variety of unusual shapes in biological cells. Experiments performed with big cell models match up with direct observations, which means that similar processes probably actually control the shape of different cells. However, on the other hand, scientists admit that their vesicles don’t fully represent the complexity of a real cell. In future studies they would like to develop new artificial membrane systems that would both improve understanding of biological cells and serve as a basis for various soft robots.
Biological processes commonly inspire technological innovations. Knowing how different types of cells get their shape could lead to knowledge that would pave the way for soft nano robots. Cells need their different shapes to form tissues and perform their functions. Hopefully, robots could maintain their shapes to accomplish amazing things in medicine.
Source: ETH Zürich