Integrin α4 impacts on differential adhesion of preadipocytes and stem cells on synthetic polymers.

Stem cells represent an ideal cell source for tissue engineering and regenerative medicine, because they can be readily isolated, expanded, differentiated and transplanted. For stem cell-based therapies, biomaterials are required to allow for a spatial distribution of the stem cells within a defined area in the body. In our recent studies, we analysed the interaction of a large panel of stem cell types with an array of biomaterials and demonstrated that a rational prediction of stem cell behaviour on a specific biomaterial is so far not possible. Interestingly, even ontogenetically related stem cell types, such as mesenchymal stem cells (MSCs), preadipocytes and dental pulp stem cells (DPSCs), exhibit distinct adhesion properties on the very same biomaterial surface. Therefore, we investigated integrin and extracellular matrix (ECM) protein expression of stem cells to relate gene expression to adhesion behaviour. MSCs, preadipocytes and DPSCs were cultured on selected synthetic polymers, such as Texin, a thermoplastic polyurethane, poly(dimethyl siloxane) (PDMS), poly-d,l-lactic acid (PDLLA) and l-lactic acid-trimehylene carbonate (Resomer® LT706). Integrins and ECM proteins were analysed by RT-PCR, real-time PCR and immunohistochemistry. Analysis of several adhesion molecules yielded that only one molecule, integrin α4, might play a significant role in differential adhesion on polymers for preadipocytes compared to DPSCs and MSCs. Thus, our studies on the molecular interactions of stem cells and polymers are expected to lead to a more profound understanding of the stem cell-biomaterial interactions to eventually allow for a rational biomaterial design.