ASN's Mission

To create a world without kidney diseases, the ASN Alliance for Kidney Health elevates care by educating and informing, driving breakthroughs and innovation, and advocating for policies that create transformative changes in kidney medicine throughout the world.

learn more

Contact ASN

1401 H St, NW, Ste 900, Washington, DC 20005

email@asn-online.org

202-640-4660

The Latest on Twitter

Kidney Week

Abstract: TH-PO650

DNA of Urinary Extracellular Vesicles Reflects Kidney Allograft Injury

Session Information

  • Transplantation: Basic
    November 03, 2022 | Location: Exhibit Hall, Orange County Convention Center‚ West Building
    Abstract Time: 10:00 AM - 12:00 PM

Category: Transplantation

  • 2001 Transplantation: Basic

Authors

  • Sedej, Ivana, Department of Nephrology, Division of Internal Medicine, University Medical Center Ljubljana, Ljubljana, Slovenia
  • Stalekar, Maja, Department of Biotechnology and Systems Biology, National Institute of Biology, Ljubljana, Slovenia
  • Tusek Znidaric, Magda, Department of Biotechnology and Systems Biology, National Institute of Biology, Ljubljana, Slovenia
  • Goricar, Katja, Institute of Biochemistry and Molecular Genetics, Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia
  • Kojc, Nika, Institute of Pathology, Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia
  • Kogovšek, Polona, Department of Biotechnology and Systems Biology, National Institute of Biology, Ljubljana, Slovenia
  • Dolzan, Vita, Institute of Biochemistry and Molecular Genetics, Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia
  • Lenassi, Metka, Institute of Biochemistry and Molecular Genetics, Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia
  • Arnol, Miha, Department of Nephrology, Division of Internal Medicine, University Medical Center Ljubljana, Ljubljana, Slovenia
Background

When allograft injury (AI) occurs, levels of donor-derived cell-free DNA (dd-cfDNA) increase in kidney transplant (TX) recipients' body fluids, including urine. Within this are extracellular vesicles (uEVs), membranous particles released by virtually all cell types carrying biomolecules reflecting the state of the original cell. DNA is an important, unexplored uEV cargo (evDNA) that may be a relevant noninvasive biomarker for AI. The rationale of our study was to investigate the evDNA characteristics of kidney TX recipients to reveal possible association with AI and finally to evaluate the biomarker potential of dd-evDNA.

Methods

We isolated uEVs, ev-, and cfDNA from 2nd morning spot urine of 41 kidney TX recipients undergoing protocol or for-cause biopsy. We used Nanoparticle Tracking Analysis to determine the size and concentration of uEVs. We measured DNA yield, copy number, integrity index, and dd-fraction using fluorometry, donor-recipient genotyping and digital droplet PCR, respectively. We associated DNA characteristics to histological phenotype, by comparing data from normal histology (NH), rejection injury (RI; combination of antibody- (ABMR) and T-cell mediated rejection (TCMR)) and non-rejection injury (NRI) group.

Results

The uEVs concentration was similar in all patient groups, whereas uEVs were significantly larger in the RI and NRI groups (mean P=0.045; median P=0.031). We detected higher evDNA yields and higher evDNA copy number in the RI and NRI groups than in the NH group (P=0.018 and P=0.007, respectively). In particular, the number of dd-evDNA copies was significantly increased in ABMR patients (Figure 1). In addition, we report significantly lesser fragmentation of dd-evDNA vs. dd-cfDNA (P<0.001). evDNA characteristics were related to the degree of interstitial inflammation, microvascular inflammation, and inflammation in the areas of fibrosis (all P<0.050).

Conclusion

evDNA reflects AI, particularly allograft rejection and could be used as a biomarker for monitoring kidney allograft injury status.

Funding

  • Government Support – Non-U.S.