Superiority of poly(l-lactic acid) microspheres as dermal fillers

The chirality of matrix materials and size always affect the properties of polymer microspheres. In this study, the chiral poly(lactic acid) (PLA) microspheres with different sizes were prepared to reveal the biological functions as dermal fillers. The poly(l-lactic acid) microsphere (PLLA MS) were demonstrated to exhibit the slightest inflammatory reaction and the most significant efficacy of promoting the regeneration of skin tissue collagen, while the size did not affect the functions, indicating PLLA MS are promising dermal fillers for clinical application. [Display omitted] The demand for injectable dermal filler has undergone significant growth with the rapid development of the beauty industry. Poly(lactic acid) (PLA) as a benefit of excellent biocompatibility and long-term promotion of collagen regeneration has been favored as a commonly used filler. However, the effects of chirality and particle size of PLA on the efficacy of dermal filler have not been studied. In this study, we prepared three kinds of microspheres (MSs) consisting of poly(d-lactic acid) (PDLA MS), poly(l-lactic acid) (PLLA MS), or meso-PLA (PDLLA MS) at 5, 10 and 20 μm to reveal the different biological functions as dermal filler. Following intradermal injection into guinea pig, it was found that PLLA MS induced the slightest inflammation, and the level of pro-inflammatory cytokine IL-1β induced by PLLA MS is only 0.3 or 0.7-fold of that induced by PDLA or PDLLA MS, respectively. More importantly, PLLA MS significantly stimulated the regeneration of collagen, which was 1.4 or 1.1 times higher than those stimulated by PDLA MS or PDLLA MS, respectively. The size of PLA MSs did not affect the levels of inflammation and collagen regeneration. The results confirmed the superiority of PLLA as a dermal filler.