Dual growth factor-loaded in situ gel-forming bulking agent: passive and bioactive effects for the treatment of urinary incontinence.

Stress urinary incontinence (SUI) is one of the major medical problems for adult females and has a devastating effect on their quality of life. The major cause of the development of the SUI is dysfunction of the urethral supporting tissues as a result of aging and childbirth. In this study, in situ gel-forming bulking agent loaded with dual growth factors, nerve growth factor (NGF) and basic fibroblast growth factor (bFGF), was fabricated. The bulking agent consisted of three components; (i) polycaprolactone (PCL) beads, (ii) bFGF-loaded nanogels, and (iii) NGF-loaded in situ gel forming solution. The bulking agent can provide an initial passive bulking effect (from the PCL beads) and regenerate malfunctioning tissues around the urethra (from the sequential and continuous release of growth factors from the hydrogel) for the effective treatment of SUI. The PCL beads were located stably at the applied urethra site (urinary incontinent SD rat) without migration to provide a passive bulking effect. The sequential release of the growth factors (NGF within a week and bFGF for more than 4 weeks) from the bulking agent provided regeneration of damaged nerve and smooth muscle, and thus enhanced biological function around the urethra. From the findings, we suggest that dual growth factor (NGF and bFGF)-loaded in situ gel-forming bulking agent may be a promising injectable bioactive system for the treatment for SUI.