Figure 2. Aged LT-HSCs show increased transcriptional priming of platelet- and myeloid-lineage genes.

(a) Bars show the frequency of cells in which Vwf expression was detected within the indicated LT-HSC populations by single-cell PCR. Number of cells analysed: young Vwf⁻, 123; old Vwf⁻, 167; young Vwf⁺, 111; old Vwf⁺, 163. ***P<0.001 (Student's t-test). Data are from five independent experiments (young mice N=3, old mice N=2) and a total of 16 BioMark 48.48 Dynamic Arrays. (b) Vwf expression level in single LT-HSCs from a. Dots represent individual expressing cells. Bars indicate the average expression level for positive cells in each population. E–, Vwf-EGFP⁻; E+, Vwf-EGFP⁺. ***P<0.001 (Student's t-test). (c) Bars show the frequency of expression of genes associated with HSC function and platelet, myeloid and lymphoid differentiation in single HSCs from a. The frequencies of co-expression were compared between old and young Vwf⁻ LT-HSCs (O– versus Y–), and between old and young Vwf⁺ LT-HSCs (O+ versus Y+) using the Kolmogorov–Smirnov test, and the level of significance is indicated. Data on individual genes are shown in Supplementary Fig. 2. (d) Diagram showing changes during ageing to the average expression level of the indicated HSC-associated genes in single Vwf⁺ and Vwf⁻ LT-HSCs from a. Detailed data in Supplementary Fig. 3. (e) Diagram showing changes during ageing to the average expression level of the indicated platelet-lineage-specific genes in single Vwf⁺ and Vwf⁻ LT-HSCs from a. Detailed data in Supplementary Fig. 4. (f) Diagram showing changes during ageing to the average expression level of the indicated myeloid lineage-specific genes in single Vwf⁺ and Vwf⁻ LT-HSCs from a. Data from Supplementary Fig. 5.