Shorter daily dwelling time in peritoneal dialysis attenuates the epithelial-to-mesenchymal transition of mesothelial cells.

BACKGROUND: Peritoneal dialysis (PD) therapy is known to induce morphological and functional changes in the peritoneal membrane. Long-term exposure to conventional bio-incompatible dialysate and peritonitis is the main etiology of inflammation. Consequently, the peritoneal membrane undergoes structural changes, including angiogenesis, fibrosis, and hyalinizing vasculopathy, which ultimately results in technique failure. The epithelial-to-mesenchymal transition (EMT) of mesothelial cells (MCs) plays an important role during the above process; however, the clinical parameters associated with the EMT process of MCs remain to be explored. METHODS: To investigate the parameters impacting EMT during PD therapy, 53 clinical stable PD patients were enrolled. EMT assessments were conducted through human peritoneal MCs cultured from dialysate effluent with one consistent standard criterion (MC morphology and the expression of an epithelial marker, cytokeratin 18). The factors potentially associated with EMT were analyzed using logistic regression analysis. Primary MCs derived from the omentum were isolated for the in vitro study. RESULTS: Forty-seven percent of the patients presented with EMT, 28% with non-EMT, and 15% with a mixed presentation. Logistic regression analysis showed that patients who received persistent PD therapy (dwelling time of 24 h/day) had significantly higher EMT tendency. These results were consistent in vitro. CONCLUSIONS: Dwelling time had a significant effect on the occurrence of EMT on MCs.

An in vitro short time-high dose drug exposure assay for predicting 5FU-resistance of colorectal cancer.

The goal of this study was to develop a simple and rapid in vitro drug resistance assay to ascertain the effectiveness of 5-fluorouracil (5-FU) for the individual therapy of colorectal cancer. Colorectal cancer cells were isolated from tumor specimens and, after 4h exposure to high doses of 5-FU cell viability was measured with an ATP assay. The average IC50 concentration for 5-FU was calculated as 4000 microg/ml from 35 patients' tumors. The tumor cells were defined as extreme drug resistance with a survival rate 1 standard deviation (SD) over IC50, low drug resistance (LDR) with a survival rate 1 SD below IC50, and intermediate drug resistance (IDR) with survival rate between these two. The drug resistant assay for 102 patients' cancer cells showed that the proportion of patients with LDR to 5-fluorouracil was 19%. The in vitro drug resistance of the cancer cells was not correlated with cancer stages or by patient sex or age. However, most mucinous and poor differentiated cancer cells showed extreme or IDR. The in vitro ATP assay values for 25 Duke's D patients receiving postoperative 5-FU chemotherapy were comparable with clinical postchemotherapy responses. The sensitivity and specificity of the assay were 100 and 95%, respectively. This short time-high dose drug exposure assay may serve as an aid to improve 5-FU treatment for individual chemotherapy.