Several research groups have used fucoidan, a polysaccharide that has a
high affinity towards P-selectin, functionalised to contrast agents for
visualisation of thrombi via SPECT, PET, MRI and ultrasound imaging
(Rouzet et al., 2011; Saboural et al., 2014; Suzuki et al., 2015; Li et
al., 2019). Using rat models, Rouzet et al. demonstrated the binding of
fucoidan radiolabeled with 99mTc to the intraluminal
thrombus in an elastase rat model of abdominal aortic aneurysm (AAA).
Histologic analysis using Masson trichrome and immunostaining using
P-selectin showed co-registration with the autoradiography of99mTc-fucoidan uptake within the mural thrombi (Figure
2) (Rouzet et al., 2011). Using the same AAA rodent model, Suzuki et al.
investigated the binding of ultrasmall superparamagnetic iron oxide
(USPIO) particles coated in fucoidan to intraluminal thrombi via MRI.
The successful targeting of USPIO-FUCO resulted in hyposignals at the
location of the thrombi, whereas no change of signal was observed using
the non-binding USPIOs control (Figure 3) (Suzuki et al., 2015). Via
SPECT imaging, the group also observed an uptake of99mTc-fucoidan in the intramyocardial vasculature in a
cardiac I/R injury rat model (Figure 4) (Rouzet et al., 2011; Saboural
et al., 2014). The uptake of radioactivity in the mid ventricular
section of the heart (area at risk) also matched their results from
immunohistological staining of P-selectin (Rouzet et al., 2011).
However, P-selectin can be shed from the surface of activated platelets
and is also expressed on other cells such as endothelial cells.
Therefore, it is not specific for platelets, thereby limiting its
suitability as a target epitope of activated platelets.