Tiny balloon-like vesicles carry cellular chatter with remarkable specificity, say Stanford researchers

by Krista Conger

Tiny balloon-like vesicles carry cellular chatter with remarkable specificity, say Stanford researchers

“BRUSH YOUR TEETH,” I bellowed up the stairs last night at my (seemingly deaf and clueless) children for what seemed like the one-millionth time since their birth. “Surely there has to be a better way,” I pondered, as I trudged up the stairs to deliver my threatening message in person.

The cells in our bodies don’t have the option to, however reluctantly, leave their metaphorical couch and wag their fingers under the noses of their intended recipients. And yet, without a fail-safe method of communication among distant participants, the orderly workings of our bodies would screech to a halt.

Now biologists Masamitsu Kanada, PhD, and Christopher Contag, PhD, have published in the Proceedings of the National Academy of Sciences an interesting and revealing glimpse into one tool cells can use to do the job: tiny balloon-like vesicles capable of delivering a payload of protein or genetic information from one cell to another. As Contag and Kanada explained to me in an email:

Extracellular vesicles are nanosized little containers of information that are produced by most, if not all, cells in the bodies of plants, animals and humans. From many studies it is apparent that adding vesicles from one cell type to another can affect the behavior of the recipient cells, both in a culture dish and in the living body, even across species from plants to animals and presumably humans.

We wanted to assess, under controlled sets of conditions, which biomolecules within vesicles transfer the most information most efficiently. We learned that the process is complex, and that a biomolecule in one type of vesicle is transferred in a way that affects other cells, but the same molecule in another type of vesicle may not affect cell function.

In other words, Contag, who co-directs Stanford’s Molecular Imaging Program, and his colleagues found that not all these vesicles are created equal. Some, whose outer layer was derived from the cell’s external plasma membrane (these are known as micro-vesicles), handily delivered both protein and DNA to recipient cells. Others, with outer layers derived from internal membranes in the cell (known as exosomes), were less capable and didn’t deliver any functional DNA. Interestingly, neither kind was able to deliver RNA, which was instead swiftly degraded.

The distinction between vesicle type and function is important as researchers increasingly rely on them to eavesdrop on cellular conversations or even to deliver particular biomolecules to be used for therapy or imaging. Understanding more about how they work will allow researchers to both better pick the right type for the job at hand and to learn more about how cells talk with one another. As Contag and Kanada said:

How cells communicate across distances is relevant to mobilization of immune cells to attack pathogens, depression of immune responses by tumor cells, signaling of cancer cells to metastasize, modulation of physiological processes in intestinal cells in response to plant-derived diets and to many other biological process. Understanding this form of cell-to-cell communication will bring us closer to controlling how cells talk to one another inside the body.

Now if only I could find the right kind of vesicle to communicate with my recalcitrant children. Perhaps a helium-filled balloon with a pointed message inside could float up the stairs and pop next to their ears? On second thought, that might not be the best choice.

Kanada M, Bachmann MH, Hardy JW, Frimannson DO, Bronsart L, Wang A, Sylvester MD, Schmidt TL, Kaspar RL, Butte MJ, Matin AC, Contag CH. (2015) Differential fates of biomolecules delivered to target cells via extracellular vesicles. Proc Natl Acad Sci U S A [Epub ahead of print]. [abstract]

Source – Stanford University

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