Figure 2.

Stroma is required for multiple myeloma (MM) cell permanence inside scaffolds. β1-integrin and α4 chain expression by flow cytometric (FACS) analysis (A) and in vitro adhesion to HS-5 cells and VCAM1 transfectant (B) of MM1.S and RPMI.8226 cells. Gray histograms represent the isotype controls. (C) Number of MM cells recovered from nude or pre-seeded scaffolds after 24 hours (input number =500×10³/scaffold). Data are mean±Standard Error of Mean (SEM) of three independent experiments. (D) Immunohistochemistry (IHC) showing proliferating (Ki67⁺) CD138⁺ MM cells over a layer of HS-5 cells or CD31⁺HUVEC. CD138 staining of MM1.S in the presence of bone-differentiated bone marrow stromal cells is also shown. Insert represents alizarin staining of the osteoblasts-coated scaffold. Bar=100 mm. (E) Scanning electron microscopy analysis shows RPMI.8226 cells without (left panel and insert, bar=2 mm) and with HS-5 cells (middle panel) or endothelial cells (HUVEC) (right panel). Bar=20 mm.