Figure 4.

CD9 mediates PMF megakaryocyte-mesenchymal stromal cell interactions. (A) Analysis of CD9 transcript (QRT-PCR) and membrane expression (flow cytometry) levels in MSC isolated from the bone marrow of PMF patients (BM-MSC). (B) Effect of 2 days of co-culture between PMF megakaryocytes (Mk) derived from CD34⁺ culture (at D6 of Mk culture) and BM-MSC on the number of PMF Mk in suspension. (C) Effect of surface CD9 ligation by anti-CD9 monoclonal antibody (mAb) (clone-SYB; 10 μg/mL) on the proportion of PMF Mk derived from CD34⁺ culture in apoptosis (annexin V⁺ cells) and in the cell cycle phases (S+G2M cells) as well as on the cell count of non-adherent PMF Mk in the co-culture with BM MSC. (D) Effect of surface CD9 ligation by anti-CD9 mAb on the proportion of adherent PMF CD45⁺ hematopoietic cells obtained after co-culture on BM MSC isolated from HD or PMF patients and on adherent PMF Mk in co-culture with MSC isolated from the BM of either HD or PMF patients as shown by Giemsa staining and immunostaining (CD41⁺ Mk, in pink and CD105⁺ MSC, in orange).