Presence of Donor- and Recipient-derived DNA in Cell-free Urine Samples of Renal Transplantation Recipients: Urinary DNA Chimerism

Abstract

Background: Previous studies have indicated that microchimerism is present in body tissues, peripheral blood, and plasma of recipients after organ transplantation. We hypothesize that donor-derived DNA may also be present in cell-free urine of renal transplant recipients and that the concentrations of urine DNA may be correlated with graft rejection. Methods: Thirty-one female patients who had renal transplantation were enrolled in the study. In women with male organ donors, the SRY gene on the Y chromosome was used as a marker for donor-derived DNA. Real-time quantitative PCR for the SRY and β-globin genes was carried out on cell-free urinary DNA from these patients. Serial urine samples from a female renal transplant recipient undergoing an acute rejection episode were also collected and analyzed with the β-globin quantitative PCR system. Results: SRY sequences were detected in the urine of 14 of 17 female patients with male organ donors. None of the 14 patients with female organ donors had detectable SRY sequences in urinary DNA. The median fractional concentration of donor-derived DNA was 8.7% (interquartile range, 1.9–26.4%). During the acute rejection episode, urinary concentrations of the β-globin gene were markedly increased, with the concentrations returning rapidly to normal following antirejection treatment. Conclusions: Our results demonstrate that urinary DNA chimerism is present following renal transplantation. The measurement of urinary DNA using quantitative PCR may be useful for the diagnosis and monitoring of graft rejection.

Circulating DNA

“…36 Organ rejection also caused an increase in the amount of circulating DNA, in the urine in this case, and after treatment the amount of free DNA rapidly decreased. 41 When comparing plasma DNA concentrations in healthy individuals to those in patients having received bone marrow transplants, no significant difference could be found, but when the total circulating DNA was split into two factions-originating either from the bone marrow or from the rest of the body-it was found that a significantly higher concentration originated from the bone marrow. 45 Chang et al 46 observed a 10-fold increase relative to controls in the amount of circulating DNA in patients suffering from myocardial infarction.…”

“…Regardless of the rapid clearance rate, with a mean half-life estimated to be at only 16.3 minutes, 41 it is known that fetal DNA is present in large amounts in the maternal circulation during pregnancy. This means that fetal DNA must be released in large quantities to maintain the high concentration which is continuously detectable in the maternal circulation during pregnancy.…”

“…40 Although the mechanism of clearance has not been elucidated, a few possibilities can be proposed. Many reports state that free DNA can be detected in urine, 18,41 and thus it can be expected that the kidneys may play a role in clearance. Animal studies also suggested that the liver, spleen, and kidneys may be responsible for removal of circulating DNA.…”

Structure and diversity of urinary cell-free DNA informative of host-pathogen interactions in human urinary tract infection

“…shotgun sequencing to assay cfDNA isolated from 141 urine samples collected from a 23 cohort of 82 kidney transplant recipients, including patients diagnosed with bacterial UTI 24 and BK polyomavirus nephropathy (BKVN). We implemented a single-stranded DNA 25 (ssDNA) library preparation, optimized for the analysis of short, highly fragmented 26 DNA [17][18][19] , and were able to perform sequence analyses for cfDNA isolated from 27 relatively small volumes of urine supernatant (1 mL or less).…”

Detection of SNPs in the Plasma of Pregnant Women and in the Urine of Kidney Transplant Recipients by Mass Spectrometry

“…7 Quantitative analysis indicated that the urinary donor-derived cell-free DNA may be useful for the monitoring of kidney transplant engraftment because increased cell-free DNA is associated with acute graft rejection. 7,8 However, these studies frequently relied on the detection of Y chromosome-specific sequences in sex-disparate donor-recipient pairs, in which the female recipient received male kidneys. We previously reported that the PCR analysis of STR loci can be used for the detection of donor-specific urinary cell-free DNA.…”