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Abstract: SA-OR093

Urinary Microvesicular Biomarkers for Delayed Graft Function and Overall Outcome after Living Donor Kidney Transplantation

Session Information

Category: Transplantation

  • 1801 Transplantation: Basic

Authors

  • Braun, Fabian, University Medical Center Hamburg-Eppendorf, Hamburg, HH, Germany
  • Rinschen, Markus M., CECAD, Cologne, Germany
  • Buchner, Denise, University Hospital of Cologne, Cologne, Germany
  • Beyer, Andreas, University of Cologne, Köln, Germany
  • Stippel, Dirk L., University of Cologne, Köln, Germany
  • Kurschat, Christine E., University Hospital Cologne, Cologne, Germany
  • Schermer, Bernhard, University Hospital Cologne, Cologne, Germany
  • Benzing, Thomas, University of Cologne, Köln, Germany
  • Mueller, Roman-Ulrich, Dept. 2 of Internal Medicine, University of Cologne, Koeln, Germany
Background

With a cargo of specific proteins and nucleic acids, urinary microvesicles represent a source for cellular material, that can be isolated easily and non-invasively. Despite this, their application in routine diagnostics are still a subject of investigation. Kidney biopsies remain the gold standard procedure in the diagnosis of transplant failure. We hypothesize that the addition of non-invasive biomarkers could benefit this method minimize the risk of a sampling error.

Methods

Via a protocol of differential centrifugation, we isolated urinary microvesicles from living kidney transplant recipients and their donors over the course of 40 kidney transplantations. Urine samples were collected on day -1 (donor sample), 0, 1 and 3 months after transplantation (recipient samples). Microvesicular protein content was measured using quantitative mass spectrometry. We detected proteins, that linearly change their abundance corresponding to clinical parameters, e.g. GFR measured at 6 and 12 Months after transplantation in a set of 20 transplantations, by linear regression models. These results were validated in a cohort of 20 additional transplantations.

Results

We identified >1500 proteins present in at least 50% of the first sample set. In hierarchical clustering analysis, the proteomic profiles depicted a clear clustering by time point of urine collection. Microvesicular proteins of glomerular (e.g. nephrin, podocin) or tubular origin (e.g. V-ATPase and Slc transporters) were regulated over the course of transplantation. Overall, specific proteomic time course patterns were apparent over the course of transplantation. Depending on low statistical error and high stability in a leave-one-out cross-validation of the linear models correlating to GFR values after transplantation, we created a list of 64 candidate proteins. This candidate list was validated in a targeted proteomics analysis in the samples of the follow-up cohort.

Conclusion

With this study, we present the first analysis of the changes in the human urinary microvesicular proteome over the course of kidney transplantation. We believe, the validated biomarkers of all 40 Transplantations to hold the potential to further aid the diagnosis of graft survival and possibly transplant rejection.

Funding

  • Government Support - Non-U.S.