Aqueous two-phase system to isolate extracellular vesicles from urine for prostate cancer diagnosis.

Hyunwoo Shin,Yong-Goo Kim,Ji Youl Lee,Yong Hyun Park,Jaesung Park,Aamir Ahmad

doi:10.1371/journal.pone.0194818

Abstract

Analyzing extracellular vesicles (EVs) is an attractive approach to diagnosis of prostate diagnosis. However, existing methods of EVs isolation have low efficiency, purity, and long process time, and therefore have low diagnostic ability. To solve these the problems, a two-phase system is adapted to isolate EVs from a patient’s urine. Urine from 20 prostate cancer (PCA) patients and 10 benign prostate hyperplasia patients was used to quantify the EVs-isolation ability of an aqueous two-phase system (ATPS) and to compare the diagnostic ability of ATPS with that of the conventional diagnosis method. An optimized ATPS isolates EVs with ~100% efficiency within ~30 min, with 14 times as high as achieved by ultracentrifugation. Afterward, PCR and ELISA are used to detect EVs derived from PCA cells in urine. The results demonstrate that diagnostic ability based on ATPS is better than other conventional diagnostic methods. ATPS can obtain a high quality and quantity of EVs from patients’ urine. EVs contain cancer-related protein and genes, so these abundant sources enable diagnosis with high specificity and sensitivity. Therefore, ATPS is a useful tool to increase the specificity and sensitivity of diagnosis.

Highlights

Serum prostate-specific antigen (PSA) is a marker that is widely used to detect incipient cancer, and to provide a post-treatment prognosis
Prostate cancer (PCA) cells secrete proteins into urine in a way similar to circulating tumour cells (CTCs) passing barriers between tumour and body vessels, and the sediments can contain PCA cells originated from tumour tissues, as well [5, 6]
During aqueous two-phase system (ATPS), most of the extracellular vesicles (EVs) and ~15% of the proteins from the urine migrated into the DEX phase (Fig 2A)

Summary

Introduction

Serum prostate-specific antigen (PSA) is a marker that is widely used to detect incipient cancer, and to provide a post-treatment prognosis. PSA can increase during benign hyperplasic conditions, so PSA does not exhibit sufficient diagnostic specificity [1]. To overcome this limitation of PSA as a disease marker, approaches that analyse urinary sediments or extracellular vesicles (EVs) have been introduced [2,3,4]. Urinary sediments may contain a few red blood cells, white blood cells, epithelial cells, and microorganisms. Prostate cancer (PCA) cells secrete proteins into urine in a way similar to circulating tumour cells (CTCs) passing barriers between tumour and body vessels, and the sediments can contain PCA cells originated from tumour tissues, as well [5, 6].

Methods

Results

Conclusion