Scientists Just Engineered Human Cells With a Squid-Like Power of Invisibility.

June 5, 2020
Engineered Human cell

Researchers at the University of California, Irvine have engineered human cells to have similar transparent abilities to that of an octups or squid.

The Squids, Octopuses and other sea animals can pull up a disappearing act by using dedicated tissues in their bodies to manipulate the transmission and reflection of light, and now some researchers at the University of California, Irvine have been able to engineer the human cells to have similar transparent abilities.

The prismatic squid has a unique superpower. It can change the colour of its skin and can also turn parts of itself invisible. So the fact that scientists have found a way to used this ability on human cells is just fascinating.

"Our project centres on designing and engineering cellular systems and tissues with controllable properties for transmitting, reflecting and absorbing light," Atrouli Chatterjee, biomolecular engineer from the University of California (UCI) explained.

Squids are not the only animals with the ability to make use of trasperent skin. Gliding lizards, called the Draco sumatranus can also make there skinf traslucent, but they only do it to draw attention, while on the other hand, prismatic inshore squids (Doryteuthis opalescens) use this ability to avoid unwanted attention.

The Females squids can turn a white stripe along their backs from opaque white to nearly transparent. They are able to do this using specialised cells called leucophores, which have membrane-bound particles made of reflectin proteins.

The way these proteins are arranged, determines how light is transmitted or reflected around them. And it's actually not a random process: Squids are able to alter the arrangement of these highly deflective proteins within their cells, using an organic chemical called acetylcholine.

Now for them to try this trick in human tissue, the scientist genetically engineered the human kidney cells to produce reflectins, which clustered together as disordered particles in the cell's cytoplasm. With the use of quantitative phase microscopy, the scientist brought to light that these proteins changed the way light was scattering through the engineered cells, compared to the normal kidney cells without reflectin.

"We were amazed to find that the cells not only expressed reflectin but also packaged the protein in spheroidal nanostructures and distributed them throughout the cells' bodies," said UCI biomedical engineer Alon Gorodetsky.

They went on to expose the reflectin-expressing cells to different levels of sodium chloride and discovered that they could adjust the levels of light being transmitted through them, as the salt made the reflectin particles swell in size, and change how they arranged themselves. The more salt, the more light scattered, and the more opaque the cells became. The kidney cells now had tunable light-transmitting and light-reflecting capabilities - essentially an opacity dial of sorts.

Experimental setup

Experimental setup. The cells became more opaque after exposure to salt (bottom). (Chatterjee et al, Nat. Commun, 2020)

The reflectin's reaction to salt "bore a superficial resemblance to the acetylcholine-triggered switching of the opacity and broadband reflectance for female D. opalescens squids' leucophore-containing layers", the scientist wrote in their paper. The team says their success lays the groundwork for incorporating other squid tricks into mammalian cells, like for instance, changing colour patterns and iridescence.

Thier success will also allow researchers to go into further exploration of the mechanisms responsible for these abilities, as so far, culturing cephalopod skin cells in a lab has proved very challenging. Possible future applications could include the ability to image entire living tissues with improved clarity which will allow us to discover things that weren't apparent before. The team pointed out how similar studies on jellyfish's green fluorescent proteins led to their now popular use in fluorescence microscopy.

"Our findings may afford a variety of exciting opportunities and possibilities within the fields of biology, materials science, and bioengineering," the team concluded.

This research was published in Nature Communications.


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