Specifically, RA FLSs (F Unit), which were isolated from the synovial tissue of RA patients and characterized as Vimentin+CD68− by flow cytometry (Figure S1A, Supporting Information), were positioned in the central channel, whereas M1 macrophages (M Unit) and HUVECs (E Unit) were seeded in the lateral channels (Figure 1B). Here, CD68 is linked to rheumatoid arthritis.