Background: In solid-organ transplantation, the allograft vasculature, in particular the endothelium, is prone to injury inflicted by peritransplantational and posttransplantational factors. Previously, we have shown that circulating endothelial cells (cEC) can be detected in the peripheral blood of kidney allograft recipients and are often associated with acute rejection and active infections with human cytomegalovirus. In the present study we hypothesized that cEC after kidney transplantation are of donor origin, thus reflecting transplantation-related damage to the allograft endothelium.
Methods: Using hydraulic micromanipulation equipment, we isolated single cEC (n=153) from the peripheral blood of nine kidney allograft recipients at various time points after transplantation. We demonstrated the origin of these cells (donor or recipient) by typing their HLA-DRB alleles by single-cell, genomic, nested polymerase chain reaction.
Results: The majority (71.8%) of cEC were of donor origin and could be detected up to 141 days after onset of acute rejection episodes. Although less frequent (28.2%), recipient-type cEC were detected in the same time course as donor-type cEC.
Conclusion: We conclude that posttransplantational injury to the allograft endothelium is reflected by the presence of donor-derived cEC in the blood.