Molecular Detection of Venous Thrombosis in Mouse Models Using SPECT/CT.

Area of Science:

• Biomedical Imaging
• Molecular Biology
• Cardiovascular Research

Background:

• Thrombolysis efficacy decreases with clot age.
• Activated factor XIII (FXIIIa) protects early fibrin clots from lysis by cross-linking α2-AP.
• Early clot detection is crucial for effective thrombolysis treatment.

Purpose of the Study:

• To improve and validate an α2-macroglobulin-AP (α2-AP)-based imaging probe for detecting early thrombosis.
• To assess the probe's specificity and binding affinity to fibrin in vitro and in vivo.
• To evaluate the potential of fibrin-targeting probes for non-invasive imaging of active thrombosis.

Main Methods:

• Development and in vitro validation of 111In-labeled imaging probe (111In-DTPA-A16) with fibrin cross-linking assays.
• Establishment of mouse models for deep vein thrombosis (DVT) using FeCl3-induced endothelial damage and IVC ligation (stenosis).
• In vivo imaging using 111In SPECT/CT and ex vivo analysis including autoradiography and histochemistry.

Main Results:

• The A16 imaging probe demonstrated efficient in vitro cross-linking to fibrin.
• In vivo models produced distinct thrombi: platelet-rich (FeCl3) and red cell-rich (stenosis).
• SPECT/CT imaging revealed a hotspot in the vena cava stenosis model, correlating with clot formation and specific A16 probe binding.

Conclusions:

• The fibrin-targeting A16 probe specifically binds to thrombi in vitro and in a DVT mouse model.
• This molecular tracer shows promise for non-invasive imaging of early, active thrombosis.
• Covalent fibrin-binding probes could advance clinical diagnosis and treatment of thrombotic events.