Figure 3. TNAP blockade inhibits new bony appositions induced by AS MSCs in NOD-SCID mice.

(A, C, and D) Representative images of lumbar spine micro-CT of NOD-SCID mice implanted with AS MSCs (derived from A1, A2, and A3 with triplicates in each group) or control MSCs (derived from C1, C2, and C3 with triplicates in each group) in the artificial cortical defect of the right lamina of lumbar spine segment L4–5 (A); with AS MSCs (derived from A1, A2, and A3 with triplicates in each group) transduced with shCtrl or shTNAP (C); or with AS MSCs (derived from A1, A2, and A3 with triplicates in each group) plus daily oral administration of H₂O (n = 9), levamisole (10 mg/kg) (n = 9), beryllium sulfate (7.5 mg/kg) (n = 9), or pamidronate (0.3 mg/kg) (n = 9) (D). Images were taken 3 weeks after implantation. Longitudinal view over L4–6 (left), longitudinal view at high magnification over L4 (middle), and cross-sectional view over L4 (right) are shown. New bony appositions are highlighted by a red rectangle (middle) and white arrow (right). (B) Representative H&E staining images showing MSC-implanted sites (arrowhead-dotted areas) in the spinal tissues. AS MSCs (A1) formed new woven bone apposition (asterisks) bridging with host bone (HB), with some osteochondral-like tissues surrounding the newly formed bone (white arrow), while control MSCs (C3) formed fibrous-like tissues (black arrow) in direct contact with host bone. Higher-magnification views of areas in red rectangles in upper panels are shown in lower panels (scale bars: 200 μm). (E) The quantitative volumes of new bony appositions (mm³) between groups (A, C, and D). Data are the mean ± SEM (n = 9 in E). ****P < 0.0001 by 2-tailed Student’s t test (2 groups) or 1-way ANOVA, followed by Tukey’s HSD test.