The ultimate purpose of this study was to develop a bioactive filler system that would allow volume restoration (passive property) and continuous release of signaling molecules to recruit soft tissues (bioactive property) and thus effectively correct facial aging. To achieve this, we prepared porous particles with a leaf-stacked structure throughout the entire particle volume (LSS particles) using a simple heating-cooling technique. LSS particles were loaded with insulin-like growth factor-1 (IGF-1) and vascular endothelial growth factor (VEGF) separately, by immersing the particles in signaling molecule-containing solutions for target tissue recruitment (adipose by IGF-1 and blood vessels by VEGF). IGF-1 and VEGF were continuously released from LSS particles for 28 and 21 days in vitro, respectively, even without additional chemical/physical modifications, because of the unique morphology of the particles. Signaling molecules preserved their bioactivity in vitro (induction of adipogenic and angiogenic differentiation) and in vivo (recruitment of fat and blood vessels) for a sufficient period. Moreover, it was observed that the LSS particles themselves have stable volume retention characteristics in the body. Thus, we suggest that the signaling molecule-loaded LSS particles can function as a bioactive filler system for volume retention and target tissue regeneration.
Keywords: cosmetic filler; delivery system; insulin-like growth factor-1 (IGF-1); leaf-stacked structure; vascular endothelial growth factor (VEGF).