Microclots - known since 2011, found in 10 diseases + COVID
Microclots: the single blood flaw linking 10+ modern illnesses
Summary by Claude AI
- (00:00) Science ahead of medicine: The research group that found spike-protein-linked microclots in COVID and long COVID has documented the same phenomenon across many diseases for about 15 years. Clinical medicine still doesn't treat it as established, so it isn't used to guide treatment.
- (01:22) Starting point, hereditary fibrinogen amyloidosis: This genetic condition (2007 reference, before the group's own work) shows the core defect. The group's contribution was showing that non-genetic triggers, such as high inflammation, stressors or trauma, can cause the same problem.
- (02:45) Normal clotting: Fibrinogen is cut by an enzyme into fibrin, which links up into strands. Under electron microscopy a normal clot looks like loosely tangled spaghetti, with platelets and red blood cells caught in it.
- (04:24) Why microclots cause harm: They trap red blood cells and take them out of circulation, which reduces oxygen delivery.
- (04:59) The amyloid mechanism: In misfolded fibrin, the normal alpha-helix structure becomes sticky beta-strands. These clump abnormally into dense, wall-like clots full of holes, which also trap other blood components.
- (08:25) Disease timeline, 2010–2014:
- Alzheimer's (2010)
- Stroke and type 2 diabetes (2011)
- Rheumatoid arthritis (2012)
- Hereditary hemochromatosis and hyperferritinemia (2014), which highlight iron dysregulation as a key driver
- Lupus (2014)
- (09:50) Change in methods: Early electron-microscopy work called these clots "dense matted deposits." By 2016 the group confirmed they were amyloid using thioflavin T fluorescence, which let them count and size microclots directly in blood.
- (11:20) 2018–2019:
- Parkinson's was shown in 2018.
- Sepsis, systemic inflammatory response syndrome (SIRS), septic shock and multi-organ dysfunction were proposed but, according to the speaker, never confirmed.
- Migraine with aura was shown in 2019; its neurological symptoms resemble stroke.
- (13:36) COVID era, 2020–2022:
- COVID-19 (2020)
- Long COVID and some vaccinated individuals (2021)
- ME/CFS and idiopathic chronic fatigue (2022)
The speaker never names the group, but the work described (dense matted deposits, thioflavin T, fibrin amyloid microclots) matches Resia Pretorius and Douglas Kell's lab. The speaker twice promises to explain the triggers, including iron, but the transcript ends before that part.
What microclots are
Claude AI - Oct 2026
"Microclots" in current usage means fibrin amyloid microclots, also called fibrinaloids — microscopic, insoluble deposits found in blood plasma rather than normal clots in vessels. The core idea is that fibrinogen, which normally polymerizes into ordinary fibrin, can instead misfold into an amyloid-type β-sheet structure. The resulting deposits persist, trap other proteins, and are strongly present in the platelet-poor plasma of people with long COVID [Kell 2022].
Key features as described by the Pretorius/Kell group:
- Trigger: inflammatory or amyloidogenic stimuli — notably SARS-CoV-2 spike protein, serum amyloid A, bacterial LPS, NETs (neutrophil extracellular traps), cell debris and microparticles.
- Structure: dense, compact, amyloid-like fibrin that resists normal breakdown. Described informally as gummy and tangled rather than the open mesh of a normal clot.
- Persistence: these deposits resist fibrinolysis even after trypsin digestion, requiring a second trypsinization to dissolve [Pretorius 2021]. A key enzyme inhibitor, α2-antiplasmin, is found elevated and entrapped.
- Detection: thioflavin T fluorescence microscopy of platelet-poor plasma; also imaging flow cytometry, thromboelastography, and nailfold capillaroscopy as an indirect measure.
- Companion finding: platelet hyperactivation and clumping almost always accompany them, so the picture is a combined clotting/platelet/endothelial problem rather than microclots alone.
Problems associated with them
Mechanical / circulatory
- Blockage of capillaries and the smallest venules, limiting red-cell passage.
- Reduced O₂ delivery to tissue — the central claimed mechanism. Blocked capillaries inhibiting O₂ transport, plus platelet hyperactivation, are proposed as the explanation for long COVID symptoms [Pretorius 2022].
- Tissue ischemia and ischemia–reperfusion injury on re-exertion.
- Endothelial damage, which in turn generates more clotting — a self-sustaining loop.
Biochemical
- Entrapment of inflammatory molecules inside the clot, shielding them from measurement and from clearance. Proteomics of double-digested microclots from 99 long COVID patients found many entrapped pro-inflammatory molecules plus factors that may block clot breakdown [Proteomics 2022].
- Failed fibrinolysis (elevated antiplasmin, PAI-1), so clots accumulate faster than they clear.
- Possible autoantibody generation against trapped or misfolded proteins.
- Self-templating: like other amyloids, a misfolded seed can propagate the misfolding.
Clinical conditions in which they've been reported
| Condition | Note |
|---|---|
| Long COVID / PASC | Where most of the work has been done |
| Acute severe COVID-19 | Microclots plus overt coagulopathy and DIC |
| ME/CFS | Overlapping symptom profile; actively being studied |
| Type 2 diabetes | Lower burden than COVID in the same assays |
| Alzheimer's, Parkinson's | Amyloid-fibrin deposits reported |
| Rheumatoid arthritis, other inflammatory disease | Reported but less studied |
Symptoms attributed to them — fatigue, post-exertional malaise, brain fog and cognitive impairment, breathlessness, exercise intolerance, orthostatic intolerance/POTS, muscle pain, and peripheral neuropathy-like complaints.
The serious caveat
This is a contested hypothesis, not settled science. The main objections:
- No in-vivo demonstration. Critics point out that nobody has imaged or biopsied these clots actually lodged in the small vessels of long COVID patients — the evidence is from plasma preparations. Beverley Hunt and others argue the hypothesis rests on lab methods that are hard to interpret and reproduce, and that circulation-and-effect has not been shown [Undark].
- Methodological reproducibility. Thioflavin T staining and the microclot scoring system are operator-dependent; independent replication outside the originating labs was slow to appear, though it now exists.
- Artifact concerns. Some argue the deposits may form during sample preparation rather than circulating in vivo.
- Treatment harms. "Triple anticoagulation" (DOAC + dual antiplatelet) and HELP apheresis are being sold to patients at high cost without trial evidence, and both carry real bleeding and procedural risk. This is the practical danger — people spending thousands on unproven and not-harmless therapy.
- Negative trials. Anticoagulant trials have not shown convincing symptom benefit.
That said, newer work has strengthened the observational side: a 2025 study of 50 long COVID patients vs 38 controls found a ~20-fold median increase in microclot burden, larger clots, and correlated NET elevation [NETs study], and work continues on standardizing thromboelastography as a more objective assay.
My read: the observation that long COVID plasma contains abnormal amyloid-fibrin material is now reasonably well supported. The causal claim — that this material blocks capillaries in vivo and causes the symptoms — remains unproven, and the treatment claims built on it are well ahead of the evidence.
Sources
- Kell 2022 review Pretorius 2021 antiplasmin Pretorius 2022 prevalence]
- Microclot proteomics] [Nunes 2026 FMCs]
- Undark critique Kell rebuttal] [NETs + microclots]