Research Paper Volume 17, Issue 7 pp 1784—1809

Figure 1. Young or old human serum alone does not have an effect on 3D skin models in static or dynamic culture. (A–C) Human 3D skin models (Phenion^®) were statically cultured with either young (<30 years) or old (>60 years) human serum as depicted in (A) for 7 days before analysis. (B) Heatmap indicating relative gene expression of skin models treated with old vs. young human serum, normalized to treatment with old serum. (C) Cryosections of treated skin models were analyzed by immunofluorescence staining of Ki67 (red). Representative images (scale bar = 100 μm) are shown in the upper panel. Bar graphs show the relative proportion of Ki67+ cells normalized to treatment with old serum. (D–F) Human long life 3D skin models (Phenion^®) were cultured dynamically using the HUMIMIC Chip3plus for 21 days in the presence of young or old human serum as depicted in (D). (E) Heatmap showing relative gene expression of dynamically cultured 3D skin models treated with old vs. young human serum, normalized to the control cultured with old serum. (F) Immunofluorescence staining of Ki67 (red) of dynamic 3D skin models comparing old to young human serum. Representative images (scale bar = 100 μm) are shown. Bar graphs show the relative proportion of Ki67+ cells normalized to treatment with old serum. (G) Determination of the DNA methylation-based biological age using the skin DNA methylation clock [7] and the blood age clock [8], normalized to treatment with old serum. Data are shown as mean values +/− SEM obtained from 1 experiment with 3–5 replicates, unpaired t-test, ns = p > 0.05, Author of HUMIMIC Chip3plus image in (D): TissUse GmbH, licensed under CC BY ND 4.0.