Preparation of Polystyrene Microspheres/PEG-PCL-PEG Hydrogel Composite for Soft Tissue Augmentation

The use of injectable dermal fillers for soft tissue augmentation has increased greatly in recent years, as patients seek nonsurgical and less invasive options for facial rejuvenation. All biological materials for soft tissue augmentation are resorbed within a certain time. Therefore, a lasting effect can be achieved only with non-resorbable synthetic substances. In this study, non-biodegradable polystyrene (PS) microspheres of approximately 60 mu m were incorporated into poly(ethylene glycol)-poly(epsilon-caprolactone)-poly(ethylene glycol) (PEG-PCL-PEG, PECE) hydrogel to prepare as permanent dermal filler. The PECE hydrogel with great thermosensitivity contributed to the injection of PS microspheres and prevented microspheres getting away from the injection site. Within 44 days, PECE hydrogel was metabolized. In the same period of time, PS microspheres with exceptional smooth surface served merely as a stimulus for connective tissue formation. Biocompatibility of PS microspheres was good in Sprague-Dawley (SD) rats up to 4 weeks. It was demonstrated that the PS microspheres/PECE hydrogel composite had excellent biocompatibility in the in vivo study. Furthermore, the initial volume of PECE hydrogel was almost totally replaced by connective tissue within 12 weeks. All results suggested that PS microspheres/PECE hydrogel composite might have prospective application in facial rejuvenation.