Fucoidan preserves endothelial glycocalyx and reduces microvascular obstruction after myocardial ischemia-reperfusion

Introduction Ischemia–reperfusion (I/R) injury induces microvascular obstruction (MVO). The endothelial glycocalyx (eGC) is crucial for maintaining microvascular homeostasis. Fucoidan (FCD), a heparan sulfate mimetic, may protect the eGC. This study investigated whether FCD preserves the eGC and attenuates MVO following myocardial I/R. Methods Isolated rat hearts were perfused using a Langendorff apparatus and allocated to four groups: Sham (S), perfused with Krebs–Henseleit (KH) solution for 80 min (min); Sham + FCD (S + F), with FCD added during the final 40 min; I/R, consisting of 10 min perfusion, 30 min global no-flow ischemia, and 40 min reperfusion; and I/R + FCD (I/R + F), treated as I/R with FCD administered throughout reperfusion. Results FCD administration during reperfusion significantly reduced MVO compared with I/R alone. Transmission electron microscopy revealed preservation of the eGC in the I/R + F group. Pericapillary edema was significantly decreased with FCD treatment. Additionally, nitrite levels were significantly higher in the I/R + F group during both early and late reperfusion. Conclusion FCD attenuates MVO after myocardial I/R injury by preserving the eGC, reducing pericapillary edema, and restoring nitric oxide bioavailability.