Researchers from the Massachusetts Institute of Technology (MIT) and Boston Children's Hospital have found that physically crowding cells, or "squeezing" them, affects the rate at which they grow and develop.
Likening the phenomenon to people sharing ideas or infection the more they remain in close proximity with each other, a cell in its microscopic environment can also enjoy increased interactions that have an effect on its development. The details of their discovery are published in the journal Cell Stem Cell Tuesday, October 13.
Limiting Space and Increasing Intracellular Interactions
While limiting the space within an organism seems to cause adverse effects, it is actually the opposite in cells. Squeezing, or subjecting them to volumetric compression, actually expels water from a cell. With less fluid for parts of the cell and proteins to move around in, they are basically packed together more tightly, increasing the likelihood of interactions as well as reducing the distance that has to be traveled in certain cellular processes. Furthermore, with these constituents being kept in close proximity from one another, certain cell signals are sent and activate intracellular genetic materials.
Specifically, in this study, researchers squeezed intestinal cells and observed that proteins compressed together in a certain signaling part of the cell. This behavior helped the cell to maintain its stem cell state - pluripotent progenitor cells that soon grow and divide to create specialized cells.
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In a press release from MIT, mechanical engineering associate professor Ming Guo explains that if squeezing cells help promote its "stemness," or keeping its stem cell state, cells can also be "directed" to quickly build mini-organs like intestines or colons. Guo added that this can serve as a platform to gain new insights for organ function - having wide applications in the fields of pharmacology, medicine, and even for testing potential transplant materials in regenerative medicine.
Squeezing Cells With a Pressing Method
To simulate "squeezing" cells, researchers introduced different types of cells in a solution that hardened as "rubbery slabs of the hydrogel," according to MIT. They then placed weights on top of the hydrogel, using coins like quarters or dimes to introduce a pressing weight.
Guo explains that to achieve their targeted volumetric compression from the cells, they used coins as weights as these can compress their sample cells by up to 30 percent of the total volume.
They then used a confocal microscope to precisely measure the change in the cells' shapes as these were subjected to compression. While it definitely showed that the cells shrunk with the weights, they also inquired on whether this process also affected the contents of the cell. Researchers posited that if squeezing wrings water out, the cells will be less hydrated and become stiffer as a result.
Using optical tweezers - devices that use a highly focused laser beam to "pick up" and move microscopic objects - they were able to confirm that the cells become stiffer. Additionally, researchers were also able to observe that there was significantly less activity in the cell constituents - leading them to believe that its contents were packed more tightly together.
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