Login to Access Video or Poster Abstract: MP12-20
Sources of Funding: the NIH K12-DK-07-006 and P20-DK-100863, JSPS KAKENHI Grant #16K11054

Introduction

Endoscopic tools have provided versatile examination and treatment for kidney stones. Desptie endourologists performing translational research in urinary stone disease using endoscopes to collect tissue, the genomic basis for lithogenesis remains unknown. One challenge is the limited tissue that can be endoscopically removed from the papilla. We investigated a new method of renal papilla biopsy and RNA extraction to establish a genomic research methodology for kidney stone disease.

Methods

We conducted a prospective multi-institutional study between Japan and the United States and collected renal papilla specimens from consecutive percutaneous nephrolithotomy (PCNL) and ureteroscopy (URS) cases performed for removal of upper urinary tract stones. Renal papilla tissue was extracted using ureteroscopic biopsy forceps after stone removal. The biopsied tissues were immediately stored in RNAlater^® for prevention of RNA degeneration. RNA was then extracted using 3 different extraction kits. The quantity and quality of RNA were examined by NanoDrop^TM for comparison. The impact of biopsy on surgical complications was also compared between cases performed with and without papillary biopsy extraction.

Results

A total of 87 biopsies from 44 patients were performed at 5 institutions between September 2014 and August 2016. Forty-four specimens were biopsied from normal papilla tissue whereas 43 were from Randall&[prime]s plaque lesions. The mean patient age was 52.4 ± 14.8 years old, 28 patients were males and 16 females, and mean duration between specimen collection and RNA extraction was 106 ± 113 days. One third of biopsies were performed during URS. Univariate analysis showed biopsy from PCNL had larger total yield of RNA compared to URS: 1117 ng and 415 ng, respectively (p=0.023). Both univariate and multivariate analyses revealed that usage of the RNeasy Micro Kit^® and BIGopsy^® forceps significantly increased total yield and improved A260/230 ratio of extracted RNA (p<0.01), enabling ideal quantities and quality of RNA purified. There were no associations between specimen storage duration prior to RNA extraction and total yield or A260/230 ratio. Moreover, comparing 18 patients who received a biopsy to 113 who received a procedure with no biopsy, there were no differences in peri- and postoperative parameters, including procedure time (p=0.139), stone free rate (p=0.061), and complications (p=0.353).

Conclusions

We established a methodology for optimal RNA extraction of renal papilla tissue during URS and PCNL. We believe this will accelerate genomic studies for kidney stone formers.

Funding

the NIH K12-DK-07-006 and P20-DK-100863, JSPS KAKENHI Grant #16K11054