Bioactive porous beads as an injectable urethral bulking agent: their in vitro evaluation on smooth muscle cell differentiation.

Growth factor (basic fibroblast growth factor or vascular endothelial growth factor)-immobilized polycaprolactone (PCL)/Pluronic F127 porous beads were prepared as an injectable bulking agent for effective treatment of urinary incontinence. The growth factor-immobilized porous beads may stimulate smooth muscle cell (SMC) differentiation of muscle-derived stem cells or defect tissues around urethra to improve the sphincter function (bioactive therapy) as well as to provide a bulking effect (passive therapy). The porous PCL/F127 beads were fabricated by an isolated particle-melting/melt-molding particulate-leaching method. The growth factors were easily immobilized onto the surfaces of the PCL/F127 porous beads via heparin binding and were continuously released for up to 28 days. Both growth factor-immobilized porous beads had a positive effect for the SMC differentiation of muscle-derived stem cells, as were demonstrated by the analyses of quantitative polymerase chain reactions, Western blot using SMC-specific markers, and immunohistochemical staining. In particular, the basic fibroblast growth factor-immobilized porous beads showed desirable SMC differentiation behavior that can be applied as an injectable bulking agent for the treatment of urinary incontinence.