Hemocompatible coating of expanded polytetrafluoroethylene vascular graft based on cross-linked alginate/recombinant hirudin multilayer

Chang JIANG; Xiuli YUE; Fang MA; Meng LIU; Lei XING; Nanqi REN

ABSTRACT

BACKGROUND:

Thrombus formation and neointimal hyperplasia limit its use for revascularization of small-caliber vessels (<6mm diameter) in the coronary or peripheral circulation.

OBJECTIVE:

To improve hemocompatibility, the luminal surface of a small diameter expanded polytetrafluoroethylene (Eptfe) vascular prosthesis was modified with alginate and recombinant hirudin.

DESIGN:

Observational experiment.

SETTING:

This study was performed in Nanomedicine and Biosensor Laboratory, Bio-X Center, Harbin Institute of Technology from Marcy 2006 to June 2007.MATERIALS The GORE-TEX Epife vascular grafts (W. L Gore & Associates, Inc., Flagstaff, AZ) used in this study were 4mm in internal diameter. rHir was obtained from Calbiochem, Germany. Sodium alginate (also called alginic acid sodium salt; medium viscosity) was purchased from Sigma.

METHODS:

A p-diazonium diphenyl amine polymer (PA) was used as an interlayer between alginate and recombinant hirudin (rHir). The diazonium moieties were capable of covalently coupling with electron-rich aromatic systems such as histidine and tyrosine residues of hirudin. No need for chemical pretreatment took all advantage by preserving the bulk properties with almost no effect on stability and elasticity of the Eptfe vascular graft. rHir amount on Epife surface Was determined by the Micro BCA (Bicinchoninic acid) Protein Assay kit.MAIN OUTCOME

MEASURES:

① Determination rHir amount on Eptfe surface; ② Static water contact angles; ③ Attenuated total reflectance fourier transform infrared spectroscopy (ATR-FTIR) was employed to confirm the change taking place in the Eptfe graft surface modification process; ④ Characterization of the surface morphology and platelet adhesion by SEM; ⑤ APTT and PT; ⑥ Percent hemolysis.

RESULTS:

① The amount of rHir adsorbed onto the Eptfe vascular was deduced to be 16.35 μg/cm2. ② Surface analysis ATR-FTTR revealed the presence of new functional groups on the modified graft surfaces. ③ The water contact angle of the modified graft surface decreased. ④ The longer APTT and PT value lower than 5% hemolysis level and dramatically decrease of platelet adhesion assay showed that rHir modified graft had great improved blood compatibility.CONCLUS10N Cross-linked Alg/rHir onto Eptfe can improve luminal surface and hemocompatibility.