Long-term FVIII production by ECs. Endothelial cells (A, HCMECs; B, HDMECs; C, HIMECs, and D, HAECs) were plated in microculture wells. The culture medium was completely removed 3 times a week. FVIII concentrations (left y-axis; ●) and VWF:Ag (right y-axis; ○) were measured in culture supernatant collected 48 hours after replacement of the medium. Results are expressed in logarithmic scale as the mean ± SD of 5 or 10 microcultures.