The pathology of depopulated bovine ureter xenografts utilized for vascular access in haemodialysis patients.

Aims: Vascular access for long-term haemodialysis is obtained through the surgical fashioning of arteriovenous fistulae, utilizing the patients' native blood vessels, or by insertion of synthetic grafts or non-synthetic gluteraldehyde cross-linked biological xenografts. These non-native grafts have high complication rates and a depopulated bovine ureter xenograft has recently been developed as an alternative. The aim was to undertake the first systematic review of the histopathology of bovine ureter xenografts (n = 25) utilized for haemodialysis vascular access in humans.

Methods And Results: Pre-insertion specimens (n = 7) showed preservation of some cellular architecture and histological antigenicity. Uncomplicated segments of post-insertion specimens (n = 18) showed myofibroblastic in-growth but no luminal endothelialization and no vascularization of the wall, other than at sites of needle puncture. Post-insertion, 50% showed a severe adventitial host inflammatory response with a dominant granulomatous and eosinophil-rich infiltrate. Inflammation was present in grafts with various complications (stenosis, thrombosis, aneurysm), but there was no clear pathogenic link.

Conclusions: We conclude that repopulation of bovine ureter xenografts by host cells is limited and that, in specimens removed for complications, an inflammatory reaction to the xenograft is common. This could reflect retention of some antigenicity following pre-insertion 'depopulation' of the grafts.