Poly-l-lactic acid microspheres delay aging of epidermal stem cells in rat skin.

Objective: Injectable skin fillers offer a wider range of options for cutaneous anti-aging and facial rejuvenation. PLLA microspheres are increasingly favored as degradable and long-lasting fillers. The present study focused solely on the effect of PLLA on dermal collagen, without investigating its impact on the epidermis. In this study, we investigated the effects of PLLA microspheres on epidermal stem cells (EpiSCs). Methods: Different concentrations of PLLA microspheres on epidermal stem cells (EpiSCs) in vitro through culture, and identification of primary rat EpiSCs. CCK-8 detection, apoptosis staining, flow cytometry, Transwell assay, wound healing assay, q-PCR analysis, and immunofluorescence staining were used to detect the effects of PLLA on EpiSCs. Furthermore, we observed the effect on the epidermis by injecting PLLA into the dermis of the rat skin in vivo. Results: PLLA microspheres promote cell proliferation and migration while delaying cell senescence and maintaining its stemness. In vitro, Intradermal injection of PLLA microspheres in the rat back skin resulted in delayed aging, as evidenced by histological and immunohistochemical staining of the skin at 2, 4, and 12 weeks of follow-up. Conclusion: This study showed the positive effects of PLLA on rat epidermis and EpiSCs, while providing novel insights into the anti-aging mechanism of PLLA.

In situ formed anti-inflammatory hydrogel loading plasmid DNA encoding VEGF for burn wound healing.

Excessive inflammation and reduced angiogenesis are two major obstacles in burn wound healing and skin regeneration. Here we report the fabrication and application of a sophisticated hydrogel from chemically modified hyaluronic acid (HA), dextran (Dex), and ß-cyclodextrin (ß-CD) integrating resveratrol (Res) and vascular endothelial growth factor (VEGF) plasmid as the anti-inflammatory and pro-angiogenic components for burn wounds. Firstly, covalent alterations were conducted to obtain methacrylic acid anhydride modified HA (HAMA), N-hydroxyethylacrylamide (HEAA) modified Dex (Dex-HEAA), and poly(ethylene glycol) methyl acrylate (526) modified ß-CD (526-ß-CD), respectively. Secondly, anti-inflammatory substance Res was embedded into the lipophilic central cavity of 526-ß-CD to achieve a complex of 526-ß-CD-Res. Then hydrogels with different HAMA, Dex-HEAA, and 526-ß-CD-Res ratios were generated via UV irradiation. Lastly, plasmid DNA encoded with vascular endothelial growth factor (pDNA-VEGF) conjugating with polyethylenimine was loaded into the hydrogel scaffold. Combining the benefits of all components of the scaffold, the hydrogel embedded with Res and VEGF (Gel-Res/pDNA-VEGF) accelerated the splinted excisional burn wound healing, particularly by inhibiting inflammation response and promoting microvascular formation while being biocompatible. The Res and VEGF gene loaded hydrogel system can be considered as a promising wound dressing for the treatment of various types of wounds. STATEMENT OF SIGNIFICANCE: Combining the benefits of all components of the scaffold, the hydrogel embedded with Res and VEGF (Gel-Res/pDNA-VEGF) accelerated the splinted excisional burn wound healing, particularly by inhibiting inflammation response and promoting microvascular formation while being biocompatible. The Res and VEGF gene loaded hydrogel system can be considered as a promising wound dressing for the treatment of various types of wounds.