MC culture improves MK ploidy and proplatelet formation. (A) Expression of MK markers (αIIbβ3, GPIbβ, and GPV) on Lin⁻ cells after 2, 3, or 4 days in liquid or 2% MC culture (% of total viable cells). Bar graphs represent 3 different flow cytometric analyses of 3 independent cultures, and results are expressed as the mean ± SEM. No significant difference observed between both culture conditions at each time point (2-way ANOVA). (B) Flow cytometric analysis of the percentage of MKs in each ploidy class at day 4 of differentiation, considering only cells of ploidy > 4 N. Bar graphs are representative of 6 independent experiments. *P < .05 using Student t test. Mean ploidy ± SEM: 33.18 ± 3.55 N for MC cultures vs 25.58 ± 2.20 N for liquid cultures (n = 6, P = .09). (C) Bar graphs represent the percentages of cells extending proplatelets in liquid and 2% MC cultures after 4, 6, 8, 10, or 24 hours following resuspension in liquid medium. A total of at least 300 MKs were examined in each kinetic. Results are the mean ± SEM in 4 independent experiments; *P < .05 using Student t test. (D) Images of MKs bearing proplatelets after 3 days in liquid or 2% MC medium followed by 1 day resuspension in liquid medium.