Credit: Business Insider (video)
- Horseshoe crabs' blue blood is so valuable that a quart of it can be sold for $15,000.
- This is because it contains a molecule that is crucial to the medical research community.
- Today, however, new innovations have resulted in a synthetic substitute that may end the practice of farming horseshoe crabs for their blood.
One of humanity's strangest and most macabre activities is slowly coming to an end, a trend that every horseshoe crab should celebrate. For the time being, however, hundreds of thousands of horseshoe crabs are being harvested from the ocean off the US's east coast and drained of their valuable blue blood.
It's a surreal practice, but there's good reason for it. Limulus Polyphemus—the Atlantic horseshoe crab—has extremely valuable blood. Unlike the blood of vertebrates, horseshoe crabs do not use hemoglobin to transport oxygen throughout their body. Instead, they use hemocyanin, a chemical that gives their blood that distinctive blue color – but this isn't what makes their blood so valuable. Instead, it's the kind of immune cells they carry.
Life-saving blue blood
Vertebrates carry white blood cells in their blood streams; invertebrates like the horseshoe crab carry amebocytes instead. When an amebocyte comes into contact with a pathogen, it releases a chemical that causes the local blood to clot, which researchers believe is a mechanism for isolating dangerous pathogens. Specifically, the amebocytes in horseshoe crab blood solidifies when it comes into contact with endotoxins, a pervasive and sometimes deadly product of bacteria that kicks immune systems into gear, sometimes resulting in fever, organ failure, or septic shock.
The presence of endotoxins in drugs, needles, or anything that comes into contact with human blood is a serious problem. Researchers used to give rabbits a sample of whatever material or substance they were interested in and observe them for hours to see if their immune system reacted, implying the presence of endotoxins. But the amebocytes in horseshoe blood were a game changer—instead of conducting time-consuming tests on rabbits, horseshoe crab amebocytes could be added to a sample of a substance. If the sample started to clot, then endotoxins were there.
The substance derived from horseshoe blood is called Limulus Amebocyte Lysate, or LAL, and it quickly became nearly as valuable as gold. Thanks to the ubiquity of endotoxins and the dire need to test for their presence, a quart of horseshoe crab blood could fetch $15,000. To cash in, companies harvest as many as 600,000 crabs a year. Up to 30% of their blood is drained before they are returned to the ocean, although a procedure this traumatic obviously entails some mortality. Estimates vary wildly. Some official sources put the mortality estimate at around 3 or 4%, but these figures typically represent mortality directly resulting from transportation and handling. Other organizations put the mortality rate as high as 30%.
A new substitute
A horseshoe crab heading for the ocean.
Photo: Shutterstock.
Fortunately for horseshoe crabs, this practice may be dying out. Researchers discovered that a molecule in LAL called factor C was responsible for its clotting action. Researchers genetically modified the guts of insects—who belong to the same phylum as horseshoe crabs, Arthropoda—to produce factor C. As a result, the insects began pumping out factor C, which could then be sold as recombinant factor C (rFC) on the market as a viable substitute to horseshoe crab blood.
Though rFC has been on the market since 2003, it's been slow to gain traction. Initially, it was only being produced by one manufacturer, the Lonza Group. Pharmaceutical companies are wary to rely on a single manufacturer in case an emergency occurs, and their supply is cut off. The Food and Drug Administration's (FDA's) regulatory process was quite slow as well. But these obstacles are gradually being overcome. Hyglos GmbH, another pharmaceutical manufacturer, began producing rFC in 2013. European regulatory bodies have approved its use, which lays the groundwork for future approval by the FDA. Major pharmaceutical companies who have used rFC have confirmed that it works just as well as LAL. Today, experts believe that rFC will become the dominant method of detecting endotoxins, letting horseshoe crabs off the hook.
Image source: camillo jimenez/Unsplash
Technology & Innovation
- 10-15% of people visiting emergency rooms eventually develop symptoms of long-lasting PTSD.
- Early treatment is available but there's been no way to tell who needs it.
- Using clinical data already being collected, machine learning can identify who's at risk.
The psychological scars a traumatic experience can leave behind may have a more profound effect on a person than the original traumatic experience. Long after an acute emergency is resolved, victims of post-traumatic stress disorder (PTSD) continue to suffer its consequences.
In the U.S. some 30 million patients are annually treated in emergency departments (EDs) for a range of traumatic injuries. Add to that urgent admissions to the ED with the onset of COVID-19 symptoms. Health experts predict that some 10 percent to 15 percent of these people will develop long-lasting PTSD within a year of the initial incident. While there are interventions that can help individuals avoid PTSD, there's been no reliable way to identify those most likely to need it.
That may now have changed. A multi-disciplinary team of researchers has developed a method for predicting who is most likely to develop PTSD after a traumatic emergency-room experience. Their study is published in the journal Nature Medicine.
70 data points and machine learning
Image source: Creators Collective/Unsplash
Study lead author Katharina Schultebraucks of Columbia University's Department Vagelos College of Physicians and Surgeons says:
"For many trauma patients, the ED visit is often their sole contact with the health care system. The time immediately after a traumatic injury is a critical window for identifying people at risk for PTSD and arranging appropriate follow-up treatment. The earlier we can treat those at risk, the better the likely outcomes."
The new PTSD test uses machine learning and 70 clinical data points plus a clinical stress-level assessment to develop a PTSD score for an individual that identifies their risk of acquiring the condition.
Among the 70 data points are stress hormone levels, inflammatory signals, high blood pressure, and an anxiety-level assessment. Says Schultebraucks, "We selected measures that are routinely collected in the ED and logged in the electronic medical record, plus answers to a few short questions about the psychological stress response. The idea was to create a tool that would be universally available and would add little burden to ED personnel."
Researchers used data from adult trauma survivors in Atlanta, Georgia (377 individuals) and New York City (221 individuals) to test their system.
Of this cohort, 90 percent of those predicted to be at high risk developed long-lasting PTSD symptoms within a year of the initial traumatic event — just 5 percent of people who never developed PTSD symptoms had been erroneously identified as being at risk.
On the other side of the coin, 29 percent of individuals were 'false negatives," tagged by the algorithm as not being at risk of PTSD, but then developing symptoms.
Going forward
Image source: Külli Kittus/Unsplash
Schultebraucks looks forward to more testing as the researchers continue to refine their algorithm and to instill confidence in the approach among ED clinicians: "Because previous models for predicting PTSD risk have not been validated in independent samples like our model, they haven't been adopted in clinical practice." She expects that, "Testing and validation of our model in larger samples will be necessary for the algorithm to be ready-to-use in the general population."
"Currently only 7% of level-1 trauma centers routinely screen for PTSD," notes Schultebraucks. "We hope that the algorithm will provide ED clinicians with a rapid, automatic readout that they could use for discharge planning and the prevention of PTSD." She envisions the algorithm being implemented in the future as a feature of electronic medical records.
The researchers also plan to test their algorithm at predicting PTSD in people whose traumatic experiences come in the form of health events such as heart attacks and strokes, as opposed to visits to the emergency department.
