Adsorbed BMP-2 in polyelectrolyte multilayer films for enhanced early osteogenic differentiation of mesenchymal stem cells

The present work was focused on the development of multilayer films to adsorb and stabilize growth factors initially for delivery to mesenchymal stem cells (MSCs). The multilayer was constructed by poly(allylamine hydrochloride) (PAH) and poly(sodium 4-styrenesulfonate) (PSS) via layer-by-layer assembly. The adsorption and bioactivity of bone morphogenetic protein 2 (BMP-2) in the films were explored. Then, the response of MSCs to the adsorbed BMP-2 was evaluated. It was demonstrated that the adsorbed BMP-2 could retain its activity toward enhanced early osteogenic differentiation of MSCs. Alkaline phosphatase (ALP) activity of MSCs seeded on the BMP-2 loaded film was even higher than that on the non-loaded film with BMP-2 added to the culture media. The results confirmed that a localized and sustained delivery of BMP-2 was more effective in vivo. It is noteworthy that these films can be deposited on a wide range of substrates with different shapes, sizes and composition, and can load other growth factors for facilitating stem cell differentiation toward specific lineages. Thus, such a system may find diverse applications in local delivery of immobilized growth factors for medical implants and for tissue-engineered constructs.