Abstract
Recently, there has been considerable interest in stem cells which have the potential to differentiate into multiple lineages for cell therapy. Special attention has been paid, in particular, to the use of alternative sources of stem cells with fewer ethical issues. For example, mesenchymal stem cells (MSCs) from bone marrow have been proven to be multipotent for transplantation and tissue engineering. In this study, an integrated microfluidic chip capable of chemically and mechanically stimulating human mesenchymal stem cells (hMSCs) for adipogenic differentiation was presented. It was composed of a dilution module for controlling the insulin concentrations, and pneumatically-modulated membrane structures for precisely applying shear stresses on cells to perform chemical and mechanical stimulation, respectively. With this approach, a long-term culture and differentiation of MSCs were performed in an automatic manner. The accumulation of lipids that represented the results of insulin simulation was evaluated by Oil Red O staining. The measurements including lipid droplet numbers, optical density (OD) values, and expression of the PPARγ2 gene were used to assess the level of differentiation of the MSCs. The experimental result showed that the maximum oil droplets were induced under an optimal insulin concentration of 10 μg/ml. It was also revealed that, under mechanical stimulation, adipogenesis was inhibited under stronger levels of applied shear stresses and at higher pulsation frequencies. This proposed microfluidic chip has great potential as a powerful tool for MSC studies. © Springer-Verlag 2011.