Marine
worms may hold the key to medical breakthroughs including speedier recovery
from surgery and more blood transfusions
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For centuries, the only use humans found for the
lugworm -- dark pink, slimy and inedible -- was on the end of a fish hook.
But the invertebrates' unappreciated status is
about to change.
Their blood, say French researchers, has an
extraordinary ability to load up with life-giving oxygen.
Harnessing it for human needs could transform
medicine, providing a blood substitute that could save lives, speed recovery
after surgery and help transplant patients, they say.
"The haemoglobin of the lugworm can
transport 40 times more oxygen from the lungs to tissues than human
haemoglobin," says Gregory Raymond, a biologist at Aquastream, a
fish-farming facility on the Brittany coastline.
"It also has the advantage of being
compatible with all blood types."
Raymond and his team, which specializes in fish
egg production, joined forces with biotech firm Hemarina in 2015 in the hope of
securing a reliable means of lugworm production.
The facility now churns out more than 1.3 million
of the creatures each year, each providing tiny amounts of the precious
haemoglobin.
"We started basically from zero. Since the
worm had never been studied, all parameters needed inventing from scratch, from
feeding to water temperature," says project researcher Gwen Herault.
Medical interest in the lugworm -- Arenicola
marina -- dates back to 2003, when the outbreak of mad-cow disease in Europe
and the worldwide HIV epidemic began to affect blood supplies.
The problem was that animal haemoglobins, as a
substitute for the human equivalent, can cause allergic reaction, potentially
damaging the kidneys.
In lugworms, though, haemoglobin dissolves in the
blood and is not contained within red blood cells as in humans -- in other
words, blood type is not an issue -- and its structure is almost the same as
human haemoglobin.
In 2006, the worm's potential was validated in a
major study.
Scientists at Roscoff, close to Plomeur,
extracted and purified haemoglobin from local-caught lugworms and tested it on
lab mice. The rodents were fine and showed no sign of the immune response that
dogged other animal substitutes.
If proven safe for humans, the researchers said,
the worms' oxygen-rich blood could tackle septic shock -- a crash in blood
pressure that can cause fatal multiple organ failure -- and help to conserve
organs for transplantation.
Clinical trials of the blood product began in
2015. Lugworm haemoglobin was used last year in 10 human kidney transplants at
a hospital in the western French city of Brest and 60 patients are currently
enrolled in tests of the blood product across France.
Marine
worms are better known as providing bait for fishermen
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- Male or female? -
The secrets of lugworm haemoglobin lie in its
ability to survive in extreme conditions, burrowing into sand at the edges of
the tide.
The worm grows to about 25 centimetres (10
inches) in length and has several bushy external gills along its body.
At high tide, submerged in water, the worm builds
up stocks of oxygen that, astonishingly, allow it to survive more than eight
hours out of the water at low tide.
Anyone who has walked along a sandy beach at low
tide will see evidence of lugworms, from the tiny coiled casts of sand they
throw up from their burrow, 10 cms below the surface.
But, apart from anglers who dig up the creatures
for bait, lugworms are rarely seen -- and breeding them is a novel challenge.
"The main difficulty is working with a small
animal that lives its life hidden," explained Raymond.
Aquastream struggled at first with basic rearing
problems -- including how to tell a male lugworm from a female.
After nine months of testing, "50 percent of
adult worms survived and a good deal of them produced eggs," said Herault.
The larvae start out around 1mm in length and the
worms are transported to Hemarina's testing site once they reach 5mm.
Aquastream director Nathalie Le Rouilly said that
her firm's collaboration with Hemarina could provide the world of medical
science with a sustainable supply of the worms.
"There is nowhere else in France or the
world that has the capacity to produce lugworms in a controlled environment to
ensure a supply of their haemoglobin," she says.
Scientists are excited by the potential of
lugworm haemoglobin -- although they also point to a rigorous testing procedure
before the molecule can be certified as safe and effective for humans.
"The properties of extracellular haemoglobin
extracted from the lugworm could help protect skin grafts, promote bone
regeneration and lead to universal blood," says Raymond.
If this vision turns real, lugworm blood may also
allow donor organs to live longer outside the bodies, potentially helping
thousands of recipients each year.
And, one day, freeze-dried lugworm blood could be a crucial backup for standard blood supplies -- a boon in combat zones or disasters.
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