RETRACTED: Paracrine cytokine interaction between UVB-exposed epidermal keratinocytes and dermal fibroblasts in stimulating expression of skin fibroblast-derived elastase

Protective roles of mesenchymal stem cells on skin photoaging: A narrative review

Skin is a natural barrier of human body and a visual indicator of aging process. Exposure to ultraviolet (UV) radiation in the sunlight may injure the skin tissues and cause local damage. Besides, it is reported that repetitive or long-term exposure to UV radiation may reduce the collagen production, change the normal skin structure and cause premature skin aging. This is termed "photoaging". The classical symptoms of photoaging include increased roughness, wrinkle formation, mottled pigmentation or even precancerous changes. Mesenchymal stem cells (MSCs) are a kind of cells with the ability of self-renewal and multidirectional differentiation into many types of cells, like adipocytes, osteoblasts and chondrocytes. Researchers have explored diverse pharmacological actions of MSCs because of their migratory activity, paracrine actions and immunoregulation effects. In recent years, the huge potential of MSCs in preventing skin from photoaging has gained wide attention. MSCs exert their beneficial effects on skin photoaging via antioxidant effect, anti-apoptotic/anti-inflammatory effect, reduction of matrix metalloproteinases (MMPs) and activation of dermal fibroblasts proliferation. MSCs and MSC related products have demonstrated huge potential in the treatment of skin photoaging. This narrative review concisely sums up the recent research developments on the roles of MSCs in protection against photoaging and highlights the enormous potential of MSCs in skin photoaging treatment.

Effect of TNFα blockade on UVB-induced inflammatory cell migration and collagen loss in mice

UVB irradiation induces pro-inflammatory cytokines including interleukin-1 (IL-1) and tumor necrosis factor-α (TNFα) in the skin. TNFα stimulates the chemotaxis of inflammatory cells to the skin. These cells secrete metalloproteinases (MMPs) and other enzymes that damage the cutaneous matrix. Therefore, blocking TNFα activity could be effective in preventing the influx of inflammatory cells and subsequent collagen degradation in the skin. In addition, TNFα downregulates procollagen mRNA, and thus blockade may be beneficial to production of type I collagen. Female C57BL/6 J mice were treated with etanercept (TNFα blocker, 4 mg/kg/day) for 4 days 1 h prior to UVB irradiation (100 mJ/cm²/day for 5 days). On the 5th day mice were sacrificed 3 h after UVB exposure. Blocking TNFα significantly inhibited UVB-induced recruitment of macrophages, mast cells, and neutrophils. UVB-irradiated mice skin contained more mature collagen compared to etanercept and UVB + etanercept-treated mice. Skin from UVB + etanercept-treated mice had more collagen fragments relative to UVB-irradiated mice. Procollagen protein was lower in UVB-irradiated and UVB + etanercept-treated mice. TNFα blockade decreased decorin and TGF-β1 in UVB-irradiated mice compared to UVB alone. MMP13 was inhibited by etanercept in UVB-irradiated mice (p < 0.01). In conclusion, blockade of TNFα significantly decreased mature collagen in UVB-irradiated mice, while increasing collagen fragmentation and decreasing procollagen.

Conditioned medium from human bone marrow-derived mesenchymal stem cells promotes skin moisturization and effacement of wrinkles in UVB-irradiated SKH-1 hairless mice

BACKGROUND

Mesenchymal stem cells (MSCs) are promising therapeutic agents for various diseases.

AIMS

To investigate the effects of conditioned medium from human bone marrow-derived mesenchymal stem cells (MSC-CdM) on pro-collagen production and wrinkle formation, we performed in vitro and in vivo experiments.

METHODS

We assessed the effects of MSC-CdM on proliferation and photo-aging in human dermal fibroblasts after UVB exposure using enzyme activity assays for collagen type I secretion and MMP-1. To determine the effect of topically applied MSC-CdM on wrinkle formation, MSC-CdM (1% and 10%) and vehicle (propylene glycol: ethanol, 7 : 3) were applied to the dorsal skin of UVB-irradiated hairless mice for 8 weeks. We examined the effects on wrinkle formation by assessing visual skin grading, replica, tape stripping, transepidermal water loss (TEWL), and skin hydration measurement. We also examined histology of the lesions using hematoxylin-eosin, Masson's trichrome, and immunohistochemical staining.

RESULTS

MSC-CdM markedly reduced UV-induced matrix metalloproteinase-1 expression and increased pro-collagen synthesis in a dose-dependent manner. Our findings suggest that MSC-CdM induces repair of dermal damage and effacement of wrinkles on UVB-irradiated hairless mice through protective effect of hydration.

CONCLUSION

These results support an anti-wrinkle effect of MSC-CdM that involves increased collagen synthesis and suggest that MSC-CdM might be a potential candidate for preventing UV-induced skin damage.