A snail sugar stops dangerous blood clots without causing bleeding - at least in mice
Heparin stops dangerous blood clots. It also makes you bleed. For more than a century, that tradeoff has defined anticoagulant therapy - preventing the clots that cause strokes, pulmonary embolisms, and deep vein thrombosis while accepting the risk that a minor cut could become a serious problem.
A team led by Mingyi Wu at the Chinese Academy of Sciences may have found a way around that tradeoff, and it came from an unlikely source: a land snail.
Two kinds of clots, one blunt instrument
The body makes two fundamentally different types of clots. Hemostatic clots are the helpful kind - they seal wounds, stop bleeding, and dissolve once healing is underway. Thrombi are the dangerous kind - they form inside blood vessels and the heart, blocking blood flow and potentially breaking loose to cause strokes or pulmonary embolisms.
Heparin does not distinguish between the two. It interferes with the coagulation cascade broadly enough to prevent thrombus formation, but broadly enough to impair normal wound healing too. Every patient on heparin carries elevated bleeding risk. The drug saves lives, but it does so with a margin of danger that clinicians have spent decades trying to narrow.
Screening mollusks for a selective blocker
Wu's team reasoned that nature might have produced anticoagulant molecules with more selectivity than heparin. They screened numerous mollusk compounds and identified CCG, a glycosaminoglycan (a type of complex sugar molecule) extracted from the snail Camaena cicatricosa.
Structurally, CCG shares some features with heparin - both are glycosaminoglycans. But a critical difference emerged at the molecular level: the specific sugar sequence that heparin uses to bind one of its key partner proteins is absent in CCG. The researchers hypothesized that this structural gap might make CCG selective - able to block thrombus formation through a different mechanism while leaving hemostasis alone.
Results in plasma and in mice
The hypothesis held up in testing. In human blood plasma, CCG inhibited thrombus formation. It had no measurable effect on hemostasis - the normal clotting process that stops bleeding from wounds.
In mouse models of deep vein thrombosis, CCG administered by injection reduced the incidence of thrombi. Heparin, tested in parallel, also reduced thrombi - but increased bleeding risk, as expected. CCG did not.
The mechanistic investigation revealed why. CCG prevents the assembly of intrinsic factor Xase (iFXase), an enzyme complex active in thrombus formation but not in hemostasis. By targeting this specific step in the coagulation cascade - rather than the broader set of interactions heparin disrupts - CCG appears to leave wound-healing pathways intact while still blocking pathological clot formation.
From snail to pharmacy: a long road
The results are promising in the narrow sense that they demonstrate a proof of principle: a naturally derived molecule can separate the anti-thrombotic effect from the anti-hemostatic effect. That separation is what heparin cannot achieve and what the field has been chasing for years.
But the distance from mouse model to human medicine is vast, and several caveats apply. The study tested CCG in mouse models only. Mice and humans differ in their coagulation systems in ways that have tripped up anticoagulant candidates before. Mouse bleeding assays, while standard, do not perfectly predict human bleeding risk.
The compound was administered by injection, raising questions about bioavailability, dosing, half-life, and whether an oral form could be developed. Sourcing CCG from snails also presents scalability challenges - any clinical candidate would likely need to be synthesized or produced through fermentation rather than harvested from animals.
No toxicology data were reported in the press release, and long-term safety studies - essential for any anticoagulant intended for chronic use - have not been conducted. The study represents early-stage preclinical work, not a drug candidate ready for trials.
Still, the specificity of CCG's mechanism - blocking iFXase assembly while sparing hemostasis - provides a concrete molecular target for future drug design, regardless of whether CCG itself becomes a therapeutic.
The study was published in ACS Central Science and was supported by the Strategic Priority Research Program of the Chinese Academy of Sciences, the National Natural Science Foundation of China, and several Yunnan provincial funding programs.