[Biocompatibility and anti-encrustation effect of IDP_FUS coating-modified ureteral stent materials in SD rat bladder...

Objective: To investigate the biosafety of ureteral stents modified with intrinsically disordered protein family member-fused in sarcoma (IDP_FUS) coating in a rat intravesical stent retention model, and to evaluate its efficacy in preventing encrustation on the stent surface. Methods: An IDP_FUS functional coating was constructed on the surface of polyurethane (PU) stents using a "two-step" method. Eighteen SD rats were randomly assigned to 4 groups: the PU group (n=4), the ethylene-vinyl acetate (EVA) group (n=4), the (PU+polyethylene glycol) (PEG) group (n=5), and the (PU+IDP_FUS) group (n=5). The corresponding stents were implanted into the rat bladders and harvested 14 days postoperatively. The mass of the encrustation on the stent surfaces was measured. Scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) were employed to observe the morphology and chemical composition of the encrustation. Hematoxylin-eosin (HE) staining was performed to evaluate inflammatory cell infiltration in the bladder tissues. Results: There was no statistically significant difference in body weight among the 4 groups (P>0.05), indicating good tolerance to the materials. Significant differences in encrustation mass were observed across the 4 groups (P=0.005). The (PU+IDP_FUS) group exhibited the lowest encrustation mass［M（Q₁，Q₃）］11 (9, 48) mg, which was significantly lower than that of the PU group 124 (115, 146) mg and the EVA group 172 (121, 218) mg (both P<0.05); however, no statistically significant difference was found between the (PU+IDP_FUS) and (PU+PEG) groups 93 (75, 96) mg (P>0.05). SEM analysis showed only sparse, scattered encrustation on the (PU+IDP_FUS) surface, whereas surfaces in the other groups were heavily covered by mineral deposits. EDS analysis confirmed that the primary component of the encrustation was magnesium ammonium phosphate. HE staining revealed diffuse inflammatory cell infiltration accompanied by reactive epithelial hyperplasia in the PU, EVA, and (PU+PEG) groups. In contrast, the (PU+IDP_FUS) group exhibited a significantly attenuated inflammatory response, characterized by only focal, scattered inflammatory cells, intact mucosal structure, and the absence of significant edema or fibrosis. Conclusion: In a rat intravesical stent indwelling model, ureteral stents modified with IDP_FUS coating demonstrate excellent biosafety and effectively reduce the formation of magnesium ammonium phosphate encrustation on the stent surface.