Nanotubes in the eye that help us see
Researchers find a new structure by which cells in the retina communicate
with each other, regulating blood supply to keep vision intact

Date:
August 12, 2020
Source:
University of Montreal Hospital Research Centre (CRCHUM)
Summary:
A new mechanism of blood redistribution that is essential for the
proper functioning of the adult retina has just been discovered
in vivo.



FULL STORY ==========================================================================
A new mechanism of blood redistribution that is essential for the proper functioning of the adult retina has just been discovered in vivo by
researchers at the University of Montreal Hospital Research Centre
(CRCHUM).


========================================================================== Their study was published today in Nature.

"For the first time, we have identified a communication structure between
cells that is required to coordinate blood supply in the living retina,"
said Dr.

Adriana Di Polo, a neuroscience professor at Universite' de Montre'al
and holder of a Canada Research Chair in glaucoma and age-related neurodegeneration, who supervised the study.

"We already knew that activated retinal areas receive more blood than
non- activated ones," she said, "but until now no one understood how this essential blood delivery was finely regulated." The study was conducted
on mice by two members of Di Polo's lab: Dr. Luis Alarcon-Martinez, a postdoctoral fellow, and Deborah Villafranca-Baughman, a PhD student. Both
are the first co-authors of this study.

In living animals, as in humans, the retina uses the oxygen and nutrients contained in the blood to fully function. This vital exchange takes
place through capillaries, the thinnest blood vessels in all organs of
the body. When the blood supply is dramatically reduced or cut off --
such as in ischemia or stroke -- the retina does not receive the oxygen
it needs. In this condition, the cells begin to die and the retina stops working as it should.

Tunnelling between cells Wrapped around the capillaries are pericytes,
cells that have the ability to control the amount of blood passing
through a single capillary simply by squeezing and releasing it.

"Using a microscopy technique to visualize vascular changes in
living mice, we showed that pericytes project very thin tubes, called inter-pericyte tunnelling nanotubes, to communicate with other pericytes located in distant capillaries," said Alarcon-Martinez. "Through these nanotubes, the pericytes can talk to each other to deliver blood where it
is most needed." Another important feature, added Villafranca-Baughman,
is that "the capillaries lose their ability to shuttle blood where
it is required when the tunnelling nanotubes are damaged -- after an
ischemic stroke, for example. The lack of blood supply that follows
has a detrimental effect on neurons and the overall tissue function."
The team's findings suggest that microvascular deficits observed
in neurodegenerative diseases like strokes, glaucoma, and Alzheimer's
disease might result from the loss of tunnelling nanotubes and impaired
blood distribution. Strategies that protect these nanostructures should
then be beneficial, but remain to be demonstrated.

This research was supported by the Canadian Institutes of Health Research.


========================================================================== Story Source: Materials provided by University_of_Montreal_Hospital_Research_Centre_(CRCHUM).

Note: Content may be edited for style and length.


========================================================================== Journal Reference:
1. Luis Alarcon-Martinez, Deborah Villafranca-Baughman, Heberto
Quintero, J.

Benjamin Kacerovsky, Florence Dotigny, Keith K. Murai, Alexandre
Prat, Pierre Drapeau, Adriana Di Polo. Interpericyte tunnelling
nanotubes regulate neurovascular coupling. Nature, 2020; DOI:
10.1038/s41586-020- 2589-x ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2020/08/200812115311.htm

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