Medical Design Briefs - August 2023 - 22

Drug Delivery
To learn more about how the smart sutures work, watch the video. (Credit: Rajamanickam Antonimuthu)
leaves behind a cell-free material that the researchers call " Degut, "
which contains structural proteins such as collagen, as
well as other biomolecules found in the extracellular matrix
that surrounds cells.
After dehydrating the tissue and twisting it into strands, the
researchers evaluated its tensile strength - a measure of how
much stretching it can withstand before breaking - and
found that it was comparable to commercially available catgut
sutures. They also found that the De-gut sutures induce much
less of an immune response from surrounding tissue than traditional
catgut.
" Decellularized tissues have been extensively used in regenerative
medicine with their superb biofunctionality, " Lee says.
" We now suggest a novel platform for performing sensing and
delivery using decellularized tissue, which will open up new applications
of tissue-derived materials. "
Smart Applications
Next, the researchers set out to enhance the suture material
with additional functions. To do that, they coated the sutures
with a layer of hydrogel. Within the hydrogel, they can embed
several types of cargo - microparticles that can sense inflammation,
various drug molecules, or living cells. For the sensor
application, the researchers designed microparticles coated
with peptides that are released when inflammation- associated
enzymes called MMPs are present in the tissue. Those peptides
can be detected using a simple urine test.
The researchers also showed that they could use the hydrogel
coating to carry drugs that are used to treat inflammatory
bowel disease, including a steroid called dexamethasone and a
monoclonal antibody called adalimumab. These drugs were carried
by microparticles made from FDA-approved polymers
such as PLGA and PLA, which are used to control the release
rate of drugs. This approach could also be adapted to deliver
22
other kinds of drugs such as antibiotics or chemotherapy drugs,
the researchers say.
These smart sutures could also be used to deliver therapeutic
cells such as stem cells. To explore that possibility, the researchers
embedded the sutures with stem cells engineered to express
a fluorescent marker and found that the cells remained viable
for at least seven days when implanted in mice. The cells were
also able to produce vascular endothelial growth factor (VEGF),
a growth factor that stimulates blood cell growth.
The researchers are now working on further testing each of
these possible applications, and on scaling up the manufacturing
process for the sutures. They also hope to explore the possibility
of using the sutures in parts of the body other than the
gastrointestinal tract.
" The decellularized gut suture developed by the MIT team is
an exciting platform for sensing and delivering a wide range of
therapeutics, including small molecules, biologics, and living
cells. The team has done a great job robustly demonstrating
the versatility of this platform, " says Omid Veiseh, an associate
professor of bioengineering at Rice University, who was not involved
in the study.
Other authors of the paper are Gwennyth Carroll, Gary Liu,
Ameya Kirtane, Alison Hayward, Adam Wentworth, Aaron
Lopes, Joy Collins, Siid Tamang, Keiko Ishida, Kaitlyn Hess,
Junwei Li, and Sufeng Zhang. The research was funded by the
Leona M. and Harry B. Helmsley Charitable Trust, the MIT
Department of Mechanical Engineering, the National Research
Foundation of Korea, and a National Institute of Diabetes
and Digestive and Kidney Disease Ruth L. Kirschstein NRSA
Fellowship.
This article was written by Anne Trafton, MIT News Office.
For more information, contact Giovanni Traverso via e-mail at
cgt20@mit.edu or visit https://news.mit.edu.
www.medicaldesignbriefs.com
Medical Design Briefs, August 2023

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Medical Design Briefs - August 2023

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