Immunoelectron microscopic localization of growth factors and other markers in human long-term bone marrow cultures

Ultrastructural immunocytochemical characterization of human long-term bone marrow cultures has shown positive localization for growth factors on cell surface and on extracellular matrix (ECM). In some cases double-labelling indicated co-localization of growth factors and specific cell surface labels. Specific markers for endothelial cells and fibroblasts showed that growth factor (GM-CSF, G-CSF and b-FGF) were present at the surface of these cell types. Both scanning and transmissiorr electron microscopy indicated intense labelling for growth factors on the extracellular matrix. Double-labelling of heparan sulphate proteoglycans and GM-CSF showed a co-localization of the labelling, which indicated the binding of growth factor to the extracellular matrix.