**Figure 6.** **Intracellular miRNA analysis by NGS identifies early and deep senescence specific miRNAs.** (**A**) Principal component analysis of SIPS versus Q HDF. Principal components were calculated using singular value decomposition (SVD) for imputation. Rows were scaled by applying unit variance scaling. Confidence level of 95% is indicated by ellipses assuming that a new observation from the same group will fall into it. Expression matrix of principal component 1 shows a variance of 34.8% and 24.6% in principal component 2. (**B**) Heatmap and hierarchical clustering of samples and miRNAs of SIPS versus Q human dermal fibroblasts. Clustering was done according to Euclidian distance and Ward linkage method. Samples in columns were clustered using correlation distance and Ward linkage method. (colors in matrix: red = highly transcribed = upregulated, blue = low transcribed = downregulated). (**C**) Volcano plot of differentially transcribed miRNAs in SIPS cells after seven (left D7) and (**D**) 21 days (right D21) post stress treatment. Log2FC are plotted on x-axis against their individual -log10 (p-value) on y-axis. Horizontal dotted lines indicate a separation between miRNA differences of a p-value higher or lower than 0.05. Vertical dotted lines separate transcribed miRNAs with log2FC > 1 or log2FC < 1. MiRNAs reaching a p-value < 0.05 are illustrated with white dots and miRNAs with a p-value > 0.05 are shown in black. (**E**) Venn diagram shows upregulated miRNAs of senescent cells on D7 and on D21. 46 miRNAs are commonly upregulated at both time points of senescence. (**F**) Venn diagram shows downregulated miRNAs of senescent cells on D7 and on D21. 36 miRNAs are commonly downregulated at both time points of senescence. (**A**-**D**) Analysis was performed using three different HDF cell strains (n = 3) each Q and SIPS from two different time points (D7 and D21). Differential expression analysis and statistics, calculated with Edge, was done with 432 miRNAs with normalized TPM signals > 5 in all conditions in at least 1 donor. (**A**-**B**) Each color and symbol represents another annotation defined by data input file. *Green*: Q; *Purple*: SIPS; *light colors and rectangular* D7; *dark colors and circle* D21.