Quantum dots shine bright to help scientists see inflammatory cells in
fat

Date:
March 22, 2022
Source:
University of Illinois College of Agricultural, Consumer and
Environmental Sciences
Summary:
To accurately diagnose and treat diseases, doctors and researchers
need to see inside bodies. Medical imaging tools have come a long
way since the humble x-ray, but most existing tools remain too
coarse to quantify numbers or specific types of cells inside deep
tissues of the body.

Quantum dots can do that, according to new research in mice.



FULL STORY ==========================================================================
To accurately diagnose and treat diseases, doctors and researchers need
to see inside bodies. Medical imaging tools have come a long way since
the humble x- ray, but most existing tools remain too coarse to quantify numbers or specific types of cells inside deep tissues of the body.


========================================================================== Quantum dots can do that, according to new research in mice from the
University of Illinois.

"Quantum dots can measure things in the body that are very, very dynamic
and complicated and that we can't see currently. They give us the ability
to count cells, detect their exact locations, and observe changes over
time. I think it is really a huge advance," says Andrew Smith, professor
in the Department of Bioengineering at U of I and co-author on the ACS
Nano study.

Quantum dots are lab-grown nanoparticles -- just a few hundred atoms
in size - - with special optical properties detectable by standard
microscopy, tomography (e.g., PET/CT scanners), and fluorescence
imaging. Depending on their size and composition, bioengineers like
Smith can make them glow in specific colors and emit light in the
infrared spectrum.

"Emitting light in the infrared is rare. Very little light is emitted by tissues in the infrared, so if you put them in the body, they appear very bright. We can see deeply into the body and can more accurately measure
things than we could using technology in the visible range," Smith says.

In the ACS Nano study, Smith and colleagues let quantum dots loose
on macrophages.



==========================================================================
When our bodies need to gobble up pathogens or clean up cellular debris, macrophages go to work. One of their jobs is to initiate inflammation,
making the environment inhospitable to harmful microbes. But sometimes
they do that job too well. Depending on the tissue they're in,
chronic inflammation due to macrophage activity can lead to diabetes, cardiovascular issues, cancers, and more.

The U of I team was particularly interested in macrophages in fat,
or adipose tissue.

"With weight gain and obesity, macrophage numbers are known to increase
in adipose tissue and tend to shift towards an inflammatory phenotype,
which contributes to the development of insulin resistance and metabolic syndrome.

The number and location of macrophages in adipose tissue are poorly
described, especially in vivo," says Kelly Swanson, Kraft Heinz Company
Endowed Professor in Human Nutrition in the Department of Animal Sciences
at U of I and study co- author.

"The quantum dots our group developed allow for better quantification
and characterization of the cells present in adipose tissue and their
spatial distribution," he adds.

The team created quantum dots coated with dextran, a sugar molecule that
also targets macrophages in adipose tissue. As a proof-of-concept, they injected these quantum dots into obese mice and compared imaging results against dextran alone, the current standard for imaging macrophages.



========================================================================== Quantum dots outperformed dextran alone across all imaging platforms,
including simple optical techniques.

"Quantum dots put out a huge amount of light, giving us the ability
to measure specific cell types to a greater degree and identify where
they are," Smith says. "That degree of light output allows the use of
optical techniques, which are much more accessible than other imaging technologies. Compared with MRI and PET scanners, they're cheap
instruments that can be put into a small clinic.

Everybody could have one." Although quantum dots haven't been used yet
in humans, Swanson sees a future in which a simple optical technology
like ultrasound could be used to non- invasively diagnose and track inflammatory macrophages in overweight patients.

"There could be a device like an ultrasound where you scan somebody, and
even if a patient's weight hasn't changed, a doctor could tell if the
cell types are changing. More inflammatory cells could predict insulin resistance and other issues," he says. "That's why I'm interested in
it, for its diagnostic properties." Quantum dots aren't used in humans
because they are typically made with heavy metals such as cadmium and
mercury, and scientists still haven't figured out how they're metabolized
and removed from the body. Smith and his team are working on quantum
dots made with safer elements, but until then, they remain an invaluable research tool. For example, their long circulation time -- nine times
as long as dextran in the current study -- could give diagnosticians a
way to go beyond a snapshot in time.

"There's a huge level of variability of macrophages even across a
day. Adipose tissue may have a very high number in the middle of the
day, and then it drops way down," Smith says. "In animal studies, we
can sacrifice animals at the start and end of a day to study the trend,
but with quantum dots, we might not have to do that. You could track
one animal over time to see its progression.

"Quantum dots offer a huge amount of value in animal studies. So even
if quantum dots don't make it to humans, if we never find a way to make
them non- toxic, the value is still really great." Smith, Swanson,
and other colleagues were recently awarded a National Institutes of
Health grant to expand their work with quantum dots to target dozens of different cell types.

The Department of Animal Sciences is in the College of Agricultural,
Consumer and Environmental Sciences at the University of Illinois Urbana-Champaign.


========================================================================== Story Source: Materials provided by University_of_Illinois_College_of_Agricultural,_Consumer and_Environmental_Sciences. Original written by Lauren Quinn. Note:
Content may be edited for style and length.


========================================================================== Journal Reference:
1. Hongping Deng, Christian J. Konopka, Suma Prabhu, Suresh Sarkar,
Natalia
Gonzalez Medina, Muhammad Fayyaz, Opeyemi H. Arogundade, Hashni
Epa Vidana Gamage, Sayyed Hamed Shahoei, Duncan Nall, Yeoan Youn,
Iwona T.

Dobrucka, Christopher O. Audu, Amrita Joshi, William J. Melvin,
Katherine A. Gallagher, Paul R. Selvin, Erik R. Nelson, Lawrence
W. Dobrucki, Kelly S. Swanson, Andrew M. Smith. Dextran-Mimetic
Quantum Dots for Multimodal Macrophage Imaging In Vivo, Ex Vivo, and
In Situ. ACS Nano, 2022; 16 (2): 1999 DOI: 10.1021/acsnano.1c07010 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2022/03/220322130028.htm

--- up 3 weeks, 1 day, 10 hours, 51 minutes
* Origin: -=> Castle Rock BBS <=- Now Husky HPT Powered! (1:317/3)