20 | New Scientist | 11 June 2022
HealthCarissa WongA HUMAN liver considered
too damaged for transplant has
been repaired inside a machine
over three days and successfully
transplanted into a recipient.
The technology could increase
the number of livers available
for transplant.
Human livers for transplant
are in short supply. In the UK,
an adult waits an average
of 65 days to receive one.
“People are dying on the
waiting list,” says Pierre-Alain
Clavien at the University
Hospital Zurich, Switzerland.
One reason for the shortage
is that the livers that people
donate must pass strict tests
to be considered suitable
for transplant.
Clavien and his colleagues
have built a system that can
take a damaged liver and
repair it over the course of a
few days to make it suitable for
transplantation. This is the first
time a human liver repaired this
way has been tested in people.
The machine contains tubes
that feed oxygen and nutrients,
carried in donated blood, into
the liver. This flow of liquid also
removes waste products such ascarbon dioxide from the liver.
Inside the device, the liver sits
on top of an artificial diaphragm
that simulates movements in
the body. This helps to prevent
a build-up of pressure that could
kill liver cells.
“We give everything to this
liver to keep it happy, in a way
that [we hope means] the liver
doesn’t know it is outside of
the body,” says Clavien.
The team collected the liver
from a 29-year-old donor whohad sepsis that was caused by
their immune system’s reaction
to multiple bacterial infections.
The donor – whose fate after
donating their liver hasn’t
been revealed – couldn’t digest
foods, which damaged their
liver. They also had a small
lesion in their liver, which
meant it was rejected by
transplantation clinics.
“If this organ was not used [in
our study], it would have been
put in the trash,” says Clavien.After inserting tubes
through the organ’s veins and
arteries, the team connected it
to the machine and monitored
its production of proteins and
bile – a fluid that helps with
digestion in the gut. The liver
then repaired itself.
The group was also able to
clear harmful bacteria from
the liver using a high dose of
antibiotics, and took a biopsy
of the lesion that confirmed it
was harmless and so didn’t pose
a threat to a recipient.
Clavien’s team then
transplanted the liver into a
man aged 62, who had cirrhosis
of the liver and liver cancer. He
was unlikely to have survived
long enough to get a transplant
in the standard way.
Samples that the team
took from the liver showed
that it began to regenerate
substantially after just six
days inside the man’s body.
“One week after, we took
a biopsy that showed this
incredible regeneration,
so the liver [cells] were
proliferating like crazy. It
then grew to match the size
of the recipient,” says Clavien.
One year later, the liver
was still functioning normally
and the lesion had halved in
size (Nature Biotechnology,
doi.org/gp8j8g).
Clavien says the team’s
machine can be easily adapted
for the transplantation of
other organs, such as kidneys.
The study “will trigger
new developments that
will change the landscape
of organ preservation”, says
Nazia Selner at the University
of Toronto in Canada. ❚Damaged liver repaired in
machine before transplant
NICO^ WICK,^ UNIVERS
ITYHOSP
ITAL^ ZUR
ICHResearchers connect
a donated liver to
their machine3
days inside the machine was
long enough to repair the liverAnimal behaviourJake BuehlerAFTER hatching on beaches, young
leatherback sea turtles make a dash
for the safety of the waves at night.
But they can find it hard to gauge the
direction of the ocean because their
eyes struggle to sense its dim light,
leading them to crawl in circles.
The circling was already reported
in these animals (Dermochelys
coriacea), but it wasn’t clear why
the turtles have this problem.
Since sea-finding largely relies on
night-time visual cues, Samantha
Trail and Michael Salmon — both
at Florida Atlantic University —
investigated how the soft-shelled
leatherbacks differ in their vision
and beach behaviours from
hard-shelled sea turtles like
loggerheads (Caretta caretta).
The researchers brought
leatherback hatchlings into the
lab and put them in a Y-shaped
maze, with one arm of the maze
illuminated with a specific
wavelength and intensity
of light and the other dark.
Based on how frequently the
turtles crawled into the dark
or illuminated arms, the team
determined the leatherbacks’
sensitivity to a broad spectrum of
light, finding that their vision is, at
best, one-tenth as sensitive as that
of loggerheads. Previous studies on
this comparator species were used
to calculate the figure. The result
means leatherbacks sometimes
fail to discriminate between light
levels in dim conditions.
The leatherbacks’ difficulty
carried over into field experiments
on the beach, where the sea tends
to be brighter than the land at night
as it is more reflective. Under dark,
new-moon conditions, young
leatherbacks wheeled on the sand
far more than loggerheads (Animal
Behaviour, doi.org/gp6g36).
“In trying to distinguish between
a dim direction and a slightly less
dim direction, [leatherbacks] seem
to have trouble,” says Trail. ❚Baby leatherbacks
struggle to find the
sea on dark nightsNews