This thesis considered aspects of cells and biomaterials required for effective tissue engineering of bone. Along these lines, we investigated cell characteristics decisive for the control of cell-biomaterial interactions and adhesion to three-dimensional carriers. We focused on cell characteristics required for selective cell adhesion.
Bone marrow stromal cells are a promising source of osteoprogenitor cells and can easily be obtained by bone marrow aspiration in humans or by bone centrifugation in rodents followed by cell selection based on adherence to tissue culture plastic. We characterized the populations found in the adherent cell fraction of the rat bone marrow. We found that adherent cells included marrow stromal cells (MSC), which are a source of the progenitors of mesenchymal cell types, and hematopoietic cells (HC). To determine if the HC fraction had positive or negative effects on osteogenic differentiation, we separated MSC and HC immunomagnetically and combined them in controlled and varied proportions. Because we found that co-culturing the MSC with HC hindered MSC differentiation, we focused on enrichment strategies for MSC. We first varied the adhesion time of bone marrow cells after isolation. In the second step we focused on selective adhesion of MSC to the extracellular matrix (ECM) proteins in the presence of HC. A rational approach to selective cell adhesion is the characterization of the ECM receptor expression pattern, i.e. integrin expression on the cell surface. We therefore investigated the integrin expression on MSC and HC depending on the time in culture. Moreover, we initiated investigations into the induced modification of integrin expression following the addition of growth factors
