Lytic Effects of Water on Bladder Cancer Cell Lines – Implications for Clinical Use of Water Irrigation to Reduce Recurrence

Abstract

Recurrence of bladder cancer (BC) following initial management with transurethral resection of bladder tumour (TURBT) is observed in 15-60% of patients. Intraoperative tumour spillage can be a concern during TURBT, given that it can lead to tumour cell re-implantation and local recurrence. Immediate post-TURBT instillation of chemotherapy is effective at reducing recurrence, but remains underutilised. There is evidence that mechanically washing out free-floating tumour cells with bladder irrigation may be a comparable but less expensive or toxic alternative. Irrigating with sterile water may be more effective compared to iso-osmotic irrigants (such as saline) by virtue of causing additional osmotic cytolysis, but this has not been well characterised. This in vitro study aimed to ascertain the time-course of osmotic effects of water on BC cell lines to guide its meaningful clinical usage. In-vitro studies were conducted on HT1197 and HT1376 BC cell lines, red blood cells, and white blood cells. Each cell line was exposed to either water, 0.9% saline or 1.5% glycine. Cell counts (in triplicate) were performed at 10, 20, and 40 minutes, and then hourly for up to 5 hours using a haemocytometer. Cell viability was determined using Trypan blue. In both BC cell lines, saline and glycine caused respectively ∼50% and 65% reduction in the number of viable cells after a minimum of 1 hour of exposure (p<0.0001 vs time 0). Conversely, the effect of water was rapid, inducing 100% cell lysis in under 20 minutes (p = 0.0001 vs time 0), while saline and glycine had no measurable effect in this timeframe (p = 0.9255 and 0.0662 vs time 0, respectively). For red blood cells and white blood cells, water also precipitated cell lysis within 10 minutes, whilst saline and glycine had minimal effect. These results suggest that water has a rapid osmolytic effect upon BC cells. If confirmed using ex vivo samples from patients, this suggests that a short period of irrigation with water may potentially be effective in reducing BC recurrence.