Fig. 4

Cell sheets were obtained 14 days after the in vitro culture of BMSCs (passage 3). The cell sheets were translucent with a certain thickness and had a certain mechanical strength and elasticity (a). Alkaline phosphatase (ALP) staining of BMSCs after osteogenic induction showed positive staining, with the cytoplasm presenting blue and black staining (b), Alizarin Red staining showed typical mineralized nodules with orange red staining (c), and lipid droplets stained with Oil Red O showed orange red staining under a microscope (d)