Controlled release of BMP-2 from alginate nanohydrogels enhanced osteogenic differentiation of human bone marrow stromal cells

A new controlled release system is proposed for bone morphogenetic proteins (BMP)-induced osteoblastic growth and differentiation of the human bone marrow stromal cells (ABMSCs) using injectable nanohydrogels. Alginate nanohydrogels (ANH) containing BMP-2 (BMP-2@ANH) were prepared using a reverse emulsification- diffusion technique. The mean particle diameter of the BMP-2@ANH measured by dynamic light scattering was 520 nm. The proliferation of ABMSCs was promoted with the BMP-2@ANH. The controlled release of BMP-2 from the BMP-2@ANH enhanced the differentiation of ABMSCs into osteoblasts, which was confirmed by RT-PCR and alkaline phosphate activity. With the BMP-2@ANH, calcification and phosphate deposits on the cells were confirmed by alizarin red-S staining and von-kossa staining, respectively, showing that the differentiation of ABMSCs into osteoblasts was activated by the BMP-2 released from the BMP-2@ANH. Growth factor delivery using a nanohydrogel is a potential method for facilitating the differentiation of stem cells in vivo.