The horseshoe crab...it’s a living fossil that has called Earth its home for almost
half a billion years.
It’s outlived dinosaurs and survived mass extinctions and ice ages, but today it’s
facing a new threat.
Their adaptations have worked with the way the Earth has changed and it’s only in recent
years with humans bringing impacts to their population that they've started to have declines.
Rising sea levels, habitat loss and overharvesting all threaten the population.
But if you’ve ever had a vaccine, injection or a medical implant, then you might not know
that you’ve been relying on this prehistoric creature’s blood to save your life.
Now, after decades of waiting, a new synthetic solution could change all of that.
Here on our beaches on the Delaware Bay, it is a place that people are witnessing a phenomena
that they cannot see anywhere else.
It is the equivalent of the wildebeests crossing the Serengeti.
In May and June here on the Delaware Bay where we are right now, millions of crabs come out
on a high tide to lay their eggs about six inches deep in the sand, and they will stay
in the sand and hatch in about a month.
And horseshoe crab eggs are a really critical part of the ecosystem here.
If a single crab is laying almost 100,000 eggs, that is providing a food source for
shorebirds, for gulls, for fish, for terrapins and then all up the food chain for that.
And then what happens with the horseshoe crabs then trickles down to the whole ecosystem here.
They just have managed to evolve with the changing oceans and the changing land.
The reason this crab has been able to evolve for so long?
Its blue blood.
This copper-based blood contains special cells called amebocytes, which are extremely sensitive
to endotoxins.
These are contaminants released from the cell walls of harmful bacteria and they can cause
life-threatening fever or toxic shock.
As soon as the amebocytes detect any of these endotoxins, the blood clots around the intruder,
immobilizing it and protecting the crab from infection.
In the 1960s scientists found a way to harness this unique superpower to make sure our medical
supplies were free from contamination.
And it replaced slower, more unpredictable tests involving rabbits.
The formula is called limulus amebocyte lysate, or LAL, and relies on amebocytes taken from
horseshoe crab blood.
And so every year half a million crabs are collected along the Atlantic coast, as well
as across the eastern shores of Mexico and China.
A third of the crab’s blood is drawn before they're released back into the ocean.
It’s estimated that 15% of crabs collected die as a result of this bleeding process,
which could mean the loss of 75,000 crabs in the US every year.
An alternative was found, however, almost 20 years ago here in Singapore.
In the past say 20 to 30 years ago we managed to collect 30 pieces in one afternoon, but
now it is difficult to find even a few.
In the mid-'80s Professor Ding Jeak Ling needed LAL for work involving IVF embryos, but there
was a problem.
Singapore research was not very well funded.
So because the LAL was so expensive, we had to find a good way to understand how the horseshoe
crab blood works.
So, my research collaborator, also my husband, together with our research students, went
to the Kranji mudflats to look for horseshoe crabs, and to bring a few samples back to the lab.
We cleaned them, we tagged them, and we took only a small volume of the blood, isolating
the blood cells from the horseshoe crab and we could produce our own equivalent of LAL.
This synthetic equivalent is called recombinant factor C, and it’s a clone of the main gene
in a horseshoe crab’s blood, which is sensitive to bacterial endotoxins.
It was a moment of realization that it is going to change the biomedical industry, and
it's going to save a very, very highly threatened species.
But the pharmaceutical companies didn’t come around as quickly as Professor Ding had hoped.
And so years and then decades passed.
We're a highly regulated industry.
And to say we would like to market a new medicine... a lot of people are reluctant to take a chance
on trying something new.
That’s until a scientist at pharmaceutical company Eli Lilly with a particular hobby
came along.
Birding is a hobby of mine, so to go to Delaware Bay and see the horseshoe crab spawning, it
kind of put it all together for me.
So the horseshoe crab is a keystone species in its ecology obviously for its own sake
but then for a lot of other animals that depend on it.
If we use RFC then there aren't any crabs that are affected, whether it's mortality
or whether there's some behavioural effect by taking the blood.
Studies have shown that the RFC test is a more effective and a potentially cheaper solution
than LAL.
Changing minds, however, remained the biggest challenge.
There's been several times I was ready to throw in the towel.
So it's been a difficult journey: to fight internally, to fight externally.
Nobody likes change but we think we're doing it for the right reasons.
We have had success and we have the data at the end of the day.
Persistence paid off, and in 2018, the first drug to use the recombinant factor C test
was approved by the FDA, and Eli Lilly is planning to transition 90% of its tests to
the synthetic by the end of 2020.
I think the consequence, if industry carries on with bleeding crabs, is at some point there
won't be any.
So there are real impacts to what we're doing and the longer we say, you know, they'll be
available forever...
It's likely not true.
It is important that we as humans are playing a role in protecting biodiversity and not
impacting biodiversity.
The synthetic version of the horseshoe crab lysate used by pharmaceutical industry is
going to have a major impact on horseshoe crab conservation.
It's not the only factor that we need.
We also need to continue with harvest limits and with beach restoration.
But reducing the need to harvest crabs for the use of their blood will have a major impact.