Figure 4.

SSPCs failed to develop osteogenic tissue in vitro and in vivo. (a) Osteogenic differentiation of SSPCs and BMMSCs. The Alizarin red S staining showed that SSPCs (top left) could not be induced to form red mineralizing areas in comparison with BMMSCs (lower left). RT-PCR (right) showed that the osteogenic gene expression profile was far less in osteogenic SSPCs compared to BMMSCs. (b) Multipotential differentiation of mouse SSPCs in vivo. Bar, 50 μm. H&E-stained sections of transplant (left) showed sclera-like connective tissue around the carrier (HA/TCP). The tissue was positively stained for Sox9 (top middle, positive nuclear stained) and aggrecan (bottom middle) along the margin of HA/TCP and some cartilage lacuna-like tissue (arrow) was found in the aggrecan-positive area. Alcian blue–positive staining showed that this tissue contained proteoglycans (top right). Collagen II-expressing tissue may be found in the HT/TCP area. The immunostaining showed that fibrocartilage had formed.