Fig. 1

Isolation, cultivation and characterization of SCB-SPCs. a Representative images showing the protocols. The marked subchondral bone region of the lateral tibia plateau was cut into bone pieces, rinsed, mildly digested, and then incubated in a culture flask. SCB-SPCs outgrew from bone chips after approximately 10 days of cultivation. The P0 cells were passaged successively to P3 (n = 10 donors). b Stem/progenitor cell surface immunophenotype expression (CD29, CD31, CD44, CD45, CD73, CD90, CD105, CD166, and CD271) was identified via flow cytometric analysis (n = 5). c The multiple differentiation potency of SCB-SPCs was examined by induction assay and staining. HE, safranin O, toluidine blue staining, and collagen II and Sox9 immunohistochemical staining to detect chondrogenesis after micropellet culture. ALP staining for osteogenesis. Oil Red O staining for adipogenesis. Scale bars represent 500 μm (ALP staining), 100 μm (Oil Red O staining), and 200 μm (chondrogenic-related staining). SCB-SPCs, subchondral bone stem/progenitor cells