Figure 2. SSEA-4⁺ TICs are Responsible for the Clinical Progression of a Distinct Subtype of High-grade Osteosarcomas.

(a) Overall survival of patients with discrete SSEA-4 staining intensities in osteosarcoma cases, as measured before (left panel) or after (right panel) the first round of chemotherapy. P values: compared with the SSEA-4⁻ subgroup; n: patient number. (b) Oct3/4 expression assayed on primary specimens of osteosarcoma that contained or did not contain SSEA-4⁺ TICs. Percentages of Oct3/4⁺ cells are shown in the upper-right corner. Six representative samples are shown. (c) Cryopreserved sections of SSEA-4⁺ xenografts were co-stained with fluorescent antibodies against Oct3/4 or SSEA-4. Three representative samples are shown. Red arrows indicate SSEA-4⁺ cells. (d) Upper panel, SSEA-4 staining before and after the first round of chemotherapy in one representative case. Bottom panel, SSEA-4-staining intensities of osteosarcoma samples from 19 patients measured before and after chemotherapy. Samples from the same patient are paired with lines. (e) Relative distribution rates of SSEA-4⁻, SSEA-4¹⁺, SSEA-4²⁺, and SSEA-4³⁺ osteosarcoma samples among those obtained from primary or metastatic sites.