Figure 7.

MSC-mediated inhibition of proliferation, but not cytokine secretion requires close cellular contact. (A) 5 × 10⁴ MSC (PVG.7B) were cultured together with ConA (3 μg mL^-1)-stimulated LNC (5 × 10⁵, i.e., a cell ratio of 1:10) either separate from LNC (PVG.7B) in transwell membrane inserts (no contact) or co-localized (cell contact) for 3 days. Relative inhibition of proliferation measured as ³H-TTP incorporation is shown as the mean and the SD of triplicates. Cell proliferation was inhibited by MSC only when in proximity to target cells (P = 0.001). (B) In the same set-up as shown in (A) increasing numbers of MSC [log] were co-cultured with ConA–LNC in transwell plates either separately (crossed squares) or co-localized (unfilled squares). Cytokine concentrations were assayed in the culture supernatants after 3 days (shown as the average of duplicates). IL18, IFNγ, and TNFα were significantly reduced in a MSC dose-dependent, contact-independent manner. OR, data point out of range.