Tech Briefs Magazine - February 2024 - 38

Health & Biotech
Using 3D Bioprinting to Create Eye Tissue
Technique provides model for studying genesis of age-related macular degeneration
and other eye diseases.
National Institutes of Health, Bethesda, MD
S
cientists used patient stem cells and 3D
bioprinting to produce eye tissue that
will advance understanding of the mechanisms
of blinding diseases. The research
team from the National Eye Institute
(NEI), part of the National Institutes of
Health, printed a combination of cells that
form the outer blood-retina barrier - eye
tissue that supports the retina's light-sensing
photoreceptors. The technique provides
a theoretically unlimited supply of
patient-derived tissue to study degenerative
retinal diseases such as age-related
macular degeneration (AMD).
" We know that AMD starts in the outer
blood-retina barrier, " said Kapil Bharti,
Ph.D., who heads the NEI Section on
Ocular and Stem Cell Translational Research.
" However, mechanisms of AMD
initiation and progression to advanced
dry and wet stages remain poorly understood
due to the lack of physiologically
relevant human models. "
The outer blood-retina barrier consists
of the retinal pigment epithelium
(RPE), separated by Bruch's membrane
from the blood-vessel rich choriocapillaris.
Bruch's membrane regulates the
exchange of nutrients and waste between
the choriocapillaris and the RPE.
In AMD, lipoprotein deposits called drusen
form outside Bruch's membrane, impeding
its function. Over time, the RPE
break down leading to photoreceptor
degeneration and vision loss.
Bharti and colleagues combined three
immature choroidal cell types in a hydrogel:
pericytes and endothelial cells,
which are key components of capillaries;
and fibroblasts, which give tissues structure.
The scientists then printed the gel
on a biodegradable scaffold. Within
days, the cells began to mature into a
dense capillary network.
On day nine, the scientists seeded retinal
pigment epithelial cells on the flip
side of the scaffold. The printed tissue
reached full maturity on day 42. Tissue
analyses and genetic and functional testing
showed that the printed tissue looked
and behaved similarly to native outer
blood-retina barrier.
Under induced stress, printed tissue exhibited
patterns of early AMD such as drusen
deposits underneath the RPE and progression
to late dry stage AMD, where
tissue degradation was observed. Low oxygen
induced wet AMD-like appearance,
with hyperproliferation of choroidal vessels
that migrated into the sub-RPE zone.
Anti-VEGF drugs, used to treat AMD suppressed
this vessel overgrowth and migration
and restored tissue morphology.
" By printing cells, we're facilitating the
exchange of cellular cues that are necessary
for normal outer blood-retina barrier
anatomy, " said Bharti. " For example, presence
of RPE cells induces gene expression
changes in fibroblasts that contribute to
the formation of Bruch's membrane -
something that was suggested many years
ago but wasn't proven until our model. "
Bharti and collaborators are using
printed blood-retina barrier models to
study AMD, and they are experimenting
with adding additional cell types to the
printing process, such as immune cells,
to better recapitulate native tissue. Such
tissue models have many potential uses
in translational applications, including
therapeutics development.
For more information, contact Dustin
Hays at dustin.hays@nih.gov; 301-4965248.
Stretchable
Micro-Supercapacitors to Self-Power
Wearable Devices
The system harvests energy from human breathing and motion.
Penn State University, University Park, PA
A
stretchable system that can harvest
energy from human breathing and
mo tion for use in wearable health-monitoring
devices may be possible, according
to an international team of researchers,
led by Huanyu " Larry " Cheng, the
Dorothy Quiggle Career Development
Professor in Penn State's department of
engineering science and mechanics. The
research team, with members from Penn
State and Minjiang University and Nanjing
Uni versity, both in China, recently
published its results in Nano Energy.
38
According to Cheng, current versions
of batteries and supercapacitors powering
wearable and stretchable health-monitoring
and diagnostic devices have many
shortcomings, including low energy density
and limited stretchability.
" This is something quite different than
what we have worked on before, but it is
a vital part of the equation, " Cheng said,
noting that his research group and collaborators
tend to focus on developing
the sensors in wearable devices. " While
working on gas sensors and other wearwww.techbriefs.com
able
devices, we always need to combine
these devices with a battery for powering.
Using micro-supercapacitors gives us the
ability to self-power the sensor without
the need for a battery. "
An alternative to batteries, micro-supercapacitors
are energy storage de vices
that can complement or replace lithium-ion
batteries in wearable de vices.
Micro-supercapacitors have a small
footprint, high power density, and the
ability to charge and discharge quickly.
How ever, according to Cheng, when
Tech Briefs, February 2024
http://www.techbriefs.com
Tech Briefs Magazine - February 2024

Table of Contents for the Digital Edition of Tech Briefs Magazine - February 2024
