Inhibition of pressure induced bladder smooth muscle cell hyperplasia using CRM197

Purpose: In vivo the effects of sustained hydrostatic pressure on the bladd er wall and its components are evident under physiological and pathological conditions. We previously reported that exposure of bladder smooth muscle cells to 20 and 40 cm, H2O hydrostatic pressure for as little as 1 hour res ulted in the up-regulation of heparin binding epidermal growth factor messe nger RNA in a time dependent fashion as well as in activation of the hepari n binding epidermal growth factor growth factor gene. In our current study we investigated the use of CRM197 as an agent for blocking undesirable cell ular level events, such as smooth muscle cell hyperplasia, eliminating the irreversible alterations in bladder and kidney function that result from ch ronic and/or severe bladder outlet obstruction. Materials and Methods: Control and experimental neonatal ovine smooth muscl e cells were exposed to 0.3 pressure and 8.5 cm. H2O, respectively, for 7 d ays. We evaluated the mitogenic activity of the supernatant medium from bla dder smooth muscle cells exposed to 8.5 cm. H2O for 5 days (conditioned med ium) before and after the addition of 0.1 mg./ml, CRM197. Bladder smooth mu scle cell apoptosis was also assessed after CRM197 exposure. Statistical an alysis was performed using the Student t test with p <0.05 considered signi ficant. Results: Exposing bladder smooth muscle cells to sustained 8.5 cm. H2O hydr ostatic pressure for 7 days resulted in increased cell proliferation. Condi tioned medium contained mitogenic activity, which was ablated after CRM197 was added. No direct toxic effect of CRM197 on bladder smooth muscle cell g rowth was appreciated (no apoptosis). Conclusions: We demonstrated a proliferative response of neonatal bladder s mooth muscle cells after exposure to sustained hydrostatic pressure. This r esponse was partially due to the release of heparin binding epidermal growt h factor and was blocked by adding CRM197. These data support the potential use of CRM197 in drug targeted therapy for diseases involving bladder outl et obstruction.