Figure 1.

Cumulative cell counts of proliferating progenitors in direct contact, non-contact and supernatant cultures. Cell counts were determined by demi-depopulation after 7, 14 and 21 days and summarized. Culture conditions were as follows: A) HPC in direct contact with IL1-β stimulated EC (Direct Contact, open squares), on a 0.4 μm microporous transmembrane above the IL-1β stimulated EC (Indirect Contact, open circles), in the supernatant of IL-1β stimulated EC (Supernatant, closed circles), B) in direct contact with IL-3 stimulated EC (Direct Contact), on a 0.4 μm microporous transmembrane above IL-3 stimulated EC (Indirect Contact) and in the supernatant of IL-3 stimulated EC (closed circles). Significant differences to contact cultures (*), to indirect contact cultures (#) and to bone marrow (§ were only found in IL-1β and IL-3 dependent conditions. C) No significant differences were determined among the IL-6 stimulated EC culture conditions or among bone marrow fibroblast cultures. The HPC cell count at the beginning was 5.5 × 10⁴ per 3 ml. Each point represents the average of at least three independent measurements. Bone marrow (BM) fibroblast cocultures consisted of direct contact (open triangles), indirect contact (crosses) and supernatant cultures (closed triangles). Dotted lines: HPC cultured in endothelial supernatants, to which IL-1β, IL-3 or IL-6 was added.