Circulating microRNAs are not eliminated by hemodialysis.
BACKGROUND
Circulating microRNAs are stably detectable in serum/plasma and other body fluids. In patients with acute kidney injury on dialysis therapy changes of miRNA patterns had been detected. It remains unclear if and how the dialysis procedure itself affects circulating microRNA level.


METHODS
We quantified miR-21 and miR-210 by quantitative RT-PCR in plasma of patients with acute kidney injury requiring dialysis and measured pre- and post-dialyser miRNA levels as well as their amount in the collected spent dialysate. Single treatments using the following filters were studied: F60 S (1.3 m(2), Molecular Weight Cut Off (MWCO): 30 kDa, n = 8), AV 1000 S (1.8 m(2), MWCO: 30 kDa, n = 6) and EMiC 2 (1.8 m(2), MWCO: 40 kDa, n = 6).


RESULTS
Circulating levels of miR-21 or -210 do not differ between pre- and post-dialyzer blood samples independently of the used filter surface and pore size: miR-21: F60S: p = 0.35, AV 1000 S p = 1.0, EMiC2 p = 1.0; miR-210: F60S: p = 0.91, AV 1000 S p = 0.09, EMiC2 p = 0.31. Correspondingly, only traces of both miRNAs could be found in the collected spent dialysate and ultrafiltrate.


CONCLUSIONS
In patients with acute kidney injury circulating microRNAs are not removed by dialysis. As only traces of miR-21 and -210 are detected in dialysate and ultrafiltrate, microRNAs in the circulation are likely to be transported by larger structures such as proteins and/or microvesicles. As miRNAs are not affected by dialysis they might be more robust biomarkers of acute kidney injury.
Institute for Molecular and Translational Treatment Strategies (IMTTS), Hannover Medical School, Hannover, Germany.
Filippo
F
Martino
Johan
J
Lorenzen
Julius
J
Schmidt
Mascha
M
Schmidt
Michael
M
Broll
Yvonne
Y
Görzig
Jan T
JT
Kielstein
Thomas
T
Thum
D058186:Acute Kidney Injury / Q000097:blood* / Q000628:therapy*; D000328:Adult; D001692:Biological Transport; D015415:Biomarkers / Q000097:blood; D005260:Female; D006801:Humans; D008297:Male; D035683:MicroRNAs / Q000097:blood*; D008875:Middle Aged; D006435:Renal Dialysis
D015415:Biomarkers; C524940:MIRN21 microRNA, human; C543800:MIRN210 microRNA, human; D035683:MicroRNAs