Angiotensin II and basic fibroblast growth factor induce neonatal bladder stromal cell mitogenesis

Purpose: Our aims were to establish primary stromal cell cultures from the neonatal rabbit bladder and investigate the potential mitogenic effects of angiotensin II and basic fibroblast growth factor on these cells. Materials and Methods: Primary bladder stromal cell cultures were obtained from 3-day-old rabbits, plated at a density of 3 × 10⁴ cells per ml. and allowed to grow for 24 hours. Subconfluent cells were growth arrested in serum deficient (0.25% newborn calf serum) or serum-free media for 24 hours and then stimulated with 10^-7 M. angiotensin II or 10 ng./ml. basic fibroblast growth factor for an additional 48 hours. Cell counts and [³H] thymidine incorporation were done to measure cellular proliferation and deoxyribonucleic acid synthesis. Results: Angiotensin II and basic fibroblast growth factor each stimulated neonatal bladder stromal cell proliferation and [³H] thymidine incorporation under serum deficient conditions. Angiotensin II provoked an average 26% increase in cell number (p <0.01) and 35% increase in [³H] thymidine incorporation (p <0.01) compared to control values. Basic fibroblast growth factor was an even more potent mitogen with a 47% increase in cell number (p <0.01) and 180% increase in [³H] thymidine incorporation (p <0.01) compared to controls. In contrast, angiotensin II and basic fibroblast growth factor each failed to have significant stimulatory effects under serum-free conditions. Conclusions: Angiotensin II and basic fibroblast growth factor induce a mitogenic response to neonatal bladder stromal cells in vitro. These mitogenic effects require the presence of serum factors. Whether angiotensin II and basic fibroblast growth factor are involved in the in vivo regulation of bladder growth associated with obstructive uropathy requires further investigation.