Objective To investigate the protective effects and mechanisms of sulodexide on renal fibrosis induced by prolonged warm ischemia.

Methods An in vivo ischemia-reperfusion injury (IRI) model was established in rats, which were randomly divided into Sham group, IRI 60 min group (IRI group), and IRI 60 min + sulodexide group (IRI+SDX group), with 20 rats in each group. Pathological examination was used to evaluate renal tissue injury and fibrosis levels in each group. Immunohistochemistry was performed to detect the expression levels of kidney injury molecule (KIM)-1, intercellular adhesion molecule (ICAM)-1, von Willebrand factor (vWF), transforming growth factor (TGF)-β, α-smooth muscle actin (SMA), and type I collagen (COL-1). Immunofluorescence staining was used to detect CD31 expression. Real-time quantitative polymerase chain reaction was employed to measure the expression of KIM-1, ICAM-1, tumor necrosis factor (TNF)-α, interleukin (IL)-1β, and IL-6 in renal tissues. Transmission electron microscopy was used to observe the structure of the renal glycocalyx. Evans blue dye was injected to assess renal vascular permeability. Rat survival was recorded, and serum levels of syndecan (SDC)-1, heparan sulfate (HS) and serum creatinine were measured. An ex vivo perfusion model was also established, with rats randomly assigned to either the hypothermic oxygenated machine perfusion (HOPE) group or the HOPE+SDX group (five rats per group). Perfusion parameters were recorded after 2 hours of ex vivo perfusion.

Results One day after reperfusion, compared with the Sham group, the IRI group exhibited more severe renal tissue injury, higher tubular injury scores, increased expression of KIM-1, ICAM-1 and vWF, decreased CD31 expression, elevated serum levels of SDC-1 and HS, increased vascular permeability, and higher expression of TNF-α, IL-1β and IL-6. Compared with the IRI group, the IRI+SDX group showed reduced renal tissue injury, lower tubular injury scores, decreased expression of KIM-1, ICAM-1 and vWF, increased CD31 expression, lower serum levels of SDC-1 and HS, decreased vascular permeability, and reduced expression of TNF-α, IL-1β and IL-6 (all P < 0.05). Ten days after reperfusion, renal tissue injury was further alleviated in the IRI+SDX group. Twenty-five days after reperfusion, the IRI+SDX group exhibited decreased expression of TGF-β, α-SMA, and COL-1, as well as reduced collagen deposition area (all P < 0.05). Compared with the HOPE group, the HOPE+SDX group showed increased renal perfusion flow and decreased intrarenal vascular resistance (both P < 0.01).

Conclusions Sulodexide may alleviates renal IRI and fibrosis caused by prolonged warm ischemia by inhibiting inflammatory responses and protecting vascular endothelial glycocalyx.