Purity of MMEC preparations assessed by FACS, Western blot, and RT-PCR analyses. (A) One representative patient showing by FACS that 96% of ECs express FVIII-RA, and very little CD38 and CD14. At least 10 000 cells were read for each labeling. (B) Western blot shows that MMECs express less FVIII-RA than HUVECs and do not express CD38 by contrast with paired plasma cells. (C) Confirmatory results are obtained by RT-PCR; bp indicates base pair.