FIG. 2.

An Epo pulse stimulates differentiation of CD36⁺/Epo⁻ EPCs toward CD36⁺/Epo⁺ EPCs. Purified CD36⁺/Epo⁻ EPCs were pulsed with Epo (3 U/ml) for different lengths of time and were analyzed after 8 days in culture. CD36⁺/Epo⁺ EPCs expanded in Wong medium were used as controls. (A) Expression of the indicated surface markers. (B) Expression of CD34 and CD36. (C) Annexin V/PI staining for assessment of cell death and DAPI staining for cell cycle analysis. For annexin V/PI staining, the numbers shown in the lower left quadrants represent the percentages of live cells, and the numbers in the upper and lower right quadrants represent the percentages of later and early stage apoptotic cells, respectively. In the case of DAPI staining, the three sets of numbers represent the percentages of cells in each phase of the cell cycle (G₀/G₁, S, and G₂/M). o/n, overnight.