Horseshoe crabs are ancient creatures that emerged before the dinosaurs and have proven extremely successful in surviving various environmental stressors, such as mass extinctions and several ice ages, during their 450 years-long history. However, conservationists warn that these crustaceans may soon become extinct due to the fact that humans are using them to test a large variety of drugs and vaccines.
One of their most amazing and unique features is how their bright blue blood coagulates when exposed to harmful bacterial endotoxins which usually induce inflammation and fever, often causing anaphylactic shock and death. These toxins are responsible for venereal diseases, bacterial meningitis, cholera, bubonic plague, and many other diseases. The immune cells in the horseshoe crabs’ blood, containing immune cells called Limulus amebosyte lysates (LALs), trap and immobilize these endotoxins, rendering them inert.
Ironically, the same feature that helped them survive over the ages, may now bring the crabs to extinction. Since the 1960s, when scientists discovered this extraordinary defensive system, the crabs’ blood has been extensively used to test medications, vaccines (including the recent coronavirus ones), needles, and biomedical devices to ensure they are not contaminated.
To do this, scientists drain the crabs of their blood and, although they return them to the ocean afterwards, up to 30 percent of the creatures die.
“As it is now, the entire supply chain for endotoxin testing of drugs rests upon the harvest of a vulnerable or near extinct sea creature,” said Kevin Williams, a researcher at bioMérieux, a French multinational biotechnology firm.
According to a recent study published in the journal Frontiers in Marine Science, “in the US, 525,000 horseshoe crabs per year were captured during 2013 to 2017 and the Atlantic States Marine Fisheries Commission estimates short-term bleeding-induced mortality to be 15 percent (4 percent to 30 percent), resulting in mortality of approximately 78,750 horseshoe crabs annually in recent years comprising a minor portion.”
Fortunately, many pharmaceutical companies in Europe and Asia have recently switched to a synthetic product called recombinant Factor C assay (rFC), which appears to be able to detect bacterial endotoxins as reliably as LAL. However, due to the fact that using this alternative is more costly and time consuming, in the United States the only major company that has switched to rFCs is Ely Lily. Only if many more companies take this road, will this magnificent ancestral creature have a chance to survive.
By Andrei Ionescu, Earth.com Staff Writer