Degradation of Mg-6Zn alloy stents does not influence the healing of the common bile duct in vivo

To investigate the effects of Mg-6Zn alloy on the healing of the common bile duct (CBD), Mg-6Zn alloy stents were implanted into the CBDs of rabbits. Stainless steel stents were transplanted into a second group of rabbits to serve as a control. Computed tomography (CT) scanning was performed and weight loss was recorded to evaluate the in vivo degradation process. Hematoxylin and eosin staining and immunohistochemical analyses were performed to determine the expressions of transforming growth factor (TGF)-β, vascular endothelial growth factor (VEGF) and basic fibroblast growth factor (bFGF) and evaluate CBD healing. The Mg-6Zn stents maintained ~82 and ~50% of the original length, and ~90 and ~43% of the original CT value at 1 and 2 weeks post-operatively, respectively. The residual weights of the Mg-6Zn stents were ~89, ~42 and ~9% of the original weights at 1, 2 and 3 weeks post-operatively, respectively. At 3 weeks post-surgery, the CBD was completely healed, with no wounds observed in the 3 groups. VEGF expression in the Mg-6Zn stent group was lower than that in the stainless steel stent group at 3 weeks post-surgery (P=0.002). No significant differences were observed between the mean expressions of the TGF-β1 and bFGF genes at 1 and 2 weeks post-surgery. The results of the present study suggest that degradation of the Mg-6Zn alloy may not affect healing of the CBD.