ACTIN CYTOSKELETON ORGANIZATION AND SPREADING OF BONE MARROW STROMAL CELLS AND CARTILAGE CELLS DURING THEIR COMBINED AND INDEPENDENT CULTIVATION ON DIFFERENT EXTRACELLULAR MATRIX PROTEINS
To clarify the mutual influence of bone marrow stromal cells (BMSCs) and cartilage cells we studied the organization of their actin cytoskeleton and cell spreading on different extracellular matrix proteins - laminin 2/4, collagen type I or fibronectin. It has been shown that the most pronounced difference in morphological characteristics of the cells such as their form, size and actin cytoskeleton organization occur in the case of interaction with fibronectin. So, after separate brief incubation of both cell types on fibronectin, the average area of BMSCs spreading was about 4 times greater than the area of the cartilage cell spreading. However, in the co-culture of these cells in a ratio of 1:1,the average jointed spreading area on fibronctin was nearly 1.5 times less than the theoretically calculated. To determine the nature of exposure of the cells to each other we have studied spreading of these cells in the media conditioned by another cell type. We have found that the area of BMSC's spreading in the medium conditioned by cartilage cells is markedly smaller than the area of spreading of the same cells in the control medium. These data suggest that the cartilage cells secrete factors that reduce BMSC's spreading.