Serum-free culturing of human mesenchymal stem cells with immobilized growth factors

In vitro expansion of human mesenchymal stem cells (hMSCs) using serum-free culture medium is important for basic research and clinical applications. It is known that some growth factors are required for developing a defined medium for hMSC culture. However, growth factors usually show poor stability, short circulating half-life and a rapid rate of cellular internalization when they are in a diffusible state. A potential way to overcome these problems is to immobilize growth factors on materials. Here, three different types of growth factors, basic fibroblast growth factor, transforming growth factor-beta, and platelet-derived growth factor, were co-immobilized on cell culture dish surfaces by photo-reactive gelatin and used for serum-free hMSC cultures. The results showed that the immobilized growth factors supported cell proliferation similarly to the serum-containing medium. More importantly, the immobilization of growth factors significantly improved their thermal stability and efficiently prolonged their shelf life at 4 degrees C and 37 degrees C. Furthermore, the immobilized growth factors could be reused at least three times without losing their stimulation effect on cell proliferation. This photo-reactive gelatin-based immobilization of growth factors appears to be a promising method for serum-free hMSC culturing.