Surface properties of the substratum affect human mesenchymal stem cell differentiation

Human mesenchymal stem cells (hMSCs) obtained from the adult bone marrow are multipotential cells that are capable of differentiating along several lineages. They are a readily available and an abundant source of cells for tissue engineering applications. For their use in treating certain connective tissue defects or disorders, their success depends at minimum on the use of scaffolds that support differentiation. This study was designed to evaluate the effect of polymeric substratum that exhibit gradual changes in surface properties on the osteogenic differentiation capability of the hMSCs. Tyrosine derived polyarylates and polycarbonates were chosen since structural modifications of their pendant chain and backbone chains modify their physicomechanical, chemical and biological properties. Polymers were coated onto 96-well cell culture plates using the solvent casting technique. Human MSCs isolated from the bone marrow were seeded at 3 × 10⁴ cells/cm². The cells were allowed to grow for 16 days in the presence or absence of osteogenic supplements. Alkaline phosphatase activity, cell number by DNA quantification and the amount of calcium in the extracellular matrix were measured at days 4, 8, 12 and 16. The production of osteocalcin was also determined at day 16. The results indicated that cell proliferation was highest on more hydrophilic surface; however the osteogenic differentiation was greatest on the more hydrophobic polymeric substratum.