Plant-produced recombinant Osteopontin-Fc fusion protein enhanced osteogenesis.

Osteopontin (OPN) plays an important role in the bone regeneration process. Previous investigation showed that recombinant human OPN was able to express in Nicotiana benthamiana leaves and induced the osteogenic related genes. Nevertheless, the purification of OPN from plant proteins with Ni affinity chromatography was still not effective enough. To improve the quality of protein expression and purification in plants, we constructed an Fc-based form of OPN. The complete OPN protein was fused to the human IgG1 Fc domain. Here, we showed that the plant-produced OPN-Fc increases the protein expression level and facilitates the purification of the recombinant protein. Our result showed that the plant-produced OPN-Fc can stimulate the expression of osteogenic related genes such as DMP1, OSX, and Wnt3a and also the calcium deposition in hPDL cells. These findings suggest that the plant-produced OPN-Fc has potential application in tissue engineering in the future.