Effect of heat exposure on viability and contractility of cultured prostatic stromal cells

Objectives: Different thermotherapeutic modalities such as transurethral mi crowave therapy or transurethral needle ablation have been developed to pro vide effective alternatives to surgical management of benign prostate hyper plasia (BPH). The mechanisms of thermotherapy, however, are not completely understood. We developed a model to investigate the effects of heat applica tion on stromal cell viability and contractility. Methods: Cells isolated from prostatectomy and cystoprostatectomy specimens were cultured in a selective medium. Temperatures ranging from 37 to 50 de grees C were applied for 1 h. Cell contraction was visualized by means of a cell culture microscope equipped with a time-lapse video system. For quant itative analysis, the percentage of contracting cells was evaluated; 10 mu M of phenylepherine were applied for adrenergic stimulation of the eel Is. Results: On immunohistochemistry and phase-contrast microscopy, these cells were identified as prostatic myofibroblasts. Incubation at 50 degrees C fo r 1 h in vitro induced immediate death of all cells, whereas at 45 degrees C a II cells survived. At 37 degrees C 55% of the cells were seen to contra ct after addition of phenylephrine. Immediately after incubation at 45 degr ees C contraction rate decreased to 29%, but returned to 46% 1 day later. Conclusions: With this model, it is possible to study the mechanisms of the rmotherapy in vitro. The results suggest that the effects of thermotherapy are due to the induction of cell death rather than to reduced stromal cell contractility. Furthermore, the data show that treatment is probably only s uccessful if temperatures in excess of 50 degrees C are maintained. Copyrig ht (C) 2000 S. Karger AG, Basel.