Oxidative stress can damage cellular components including DNA, proteins or lipids, and may cause several skin diseases. To protect from this damage and addressing consumer's appeal to natural products, antioxidants obtained from algal and vegetal extracts are being proposed as antioxidants to be incorporated into formulations. Thus, the development of reliable, quick and economic in vitro methods to study the cytoactivity of these products is a meaningful requirement.A combination of erythrocyte and cell line-based assays was performed on two extracts from Sargassum muticum, one from Ulva lactuca, and one from Castanea sativa. Antioxidant properties were assessed in erythrocytes by the TBARS and AAPH assays, and cytotoxicity and antioxidant cytoprotection were assessed in HaCaT and 3T3 cells by the MTT assay. The extracts showed no antioxidant activity on the TBARS assay, whereas their antioxidant capacity in the AAPH assay was demonstrated. On the cytotoxicity assays, extracts showed low toxicity, with IC50 values higher than 200 µg/mL. C. sativa extract showed the most favourable antioxidant properties on the antioxidant cytoprotection assays; while S. muticum and U. lactuca extracts showed a low antioxidant activity. This battery of methods was useful to characterize the biological antioxidant properties of these natural extracts.
Blood and lymphatic vessels provide nutrients for the skin and fulfill important homeostatic functions, such as the regulation of immunologic processes. In this study, we investigated the development of blood and lymphatic endothelial cells in prenatal human skin in situ using multicolor immunofluorescence and analyzed angiogenic molecules by protein arrays of lysates and cell culture supernatants. We found that at 8 to 10 weeks of estimated gestational age, CD144(+) vessels predominantly express the venous endothelial cell marker PAL-E, whereas CD144(+)PAL-E(-) vessels compatible with arteries only appear at the end of the first trimester. Lymphatic progenitor cells at 8 weeks of estimated gestational age express CD31, CD144, Prox1, and temporary PAL-E. At that developmental stage not all lymphatic progenitor cells express podoplanin or Lyve-1, which are acquired with advancing gestational age in a stepwise fashion. Already in second-trimester human skin, the phenotype of blood and lymphatic vessels roughly resembles the one in adult skin. The expression pattern of angiogenic molecules in lysates and cell culture supernatants of prenatal skin did not reveal the expected bent to proangiogenic molecules, indicating a complex regulation of angiogenesis during ontogeny. In summary, this study provides enticing new insights into the development and phenotypic characteristics of the vascular system in human prenatal skin.
The skin is the first barrier against foreign pathogens and the prenatal formation of a strong network of various innate and adaptive cells is required to protect the newborn from perinatal infections. While many studies about the immune system in healthy and diseased adult human skin exist, our knowledge about the cutaneous prenatal/developing immune system and especially about the phenotype and function of antigen-presenting cells such as epidermal Langerhans cells (LCs) in human skin is still scarce. It has been shown previously that LCs in healthy adult human skin express receptor activator of NF-κB (RANK), an important molecule prolonging their survival. In this study, we investigated at which developmental stage LCs acquire this important molecule. Immunofluorescence double-labeling of cryostat sections revealed that LC precursors in prenatal human skin either do not yet [10–11 weeks of estimated gestational age (EGA)] or only faintly (13–15 weeks EGA) express RANK. LCs express RANK at levels comparable to adult LCs by the end of the second trimester. Comparable with adult skin, dermal antigen-presenting cells at no gestational age express this marker. These findings indicate that epidermal leukocytes gradually acquire RANK during gestation – a phenomenon previously observed also for other markers on LCs in prenatal human skin.
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