RNA profiling identifies miR-125a-5p association with platelet count. (A) Wright-Giemsa stain of BM aspirate. Scale bar, 30 μm. Same field (i) before and (ii) after laser-capture microdissection (LCM). Red arrow indicates mature MK. (B) Plot of Spearman rank correlation (ρ) of miRs from platelets and LCM BM MKs isolated from the same healthy donors (n = 2). (C) Plot of Spearman rank correlation (ρ) of miRs from CD61-purified, day 13–cultured, cord blood (CB)-derived MKs (n = 3 independent cords) and LCM BM MKs (n = 2 healthy donors). (D) Heat map shows miRs differentially expressed between day 6 (D6) and day 13 (D13) cultured cord blood–derived MKs (n = 3). (E) Variation in platelet count in 154 healthy donors. (F) Volcano plot shows platelet miR association with human platelet count. Green dots indicate negative correlation and red dots shows positive correlation of platelet miRs with platelet count in healthy donors; P < .05. (G) Venn diagram showing intersection of candidate miRs from panels A through F. (H-J) Plots of Pearson correlations (R) of (H) platelet count, (I) WBC, and (J) Hb level against miR-125a-5p levels (n = 154 healthy donors). Dotted lines, 95% confidence intervals. Plt # assoc., platelet number association.