Extended Data Fig. 1: Removal of periosteum reduces bone formation and callus vascularization.

a, Histological characterization of the mouse bone-autograft healing model. At the host–graft junction cartilage (safranin O⁺) is formed at PFD7. Note absence of CD31⁺ blood vessels in these regions. Near the graft centre new woven bone (bright pink on H&E staining) is deposited, cartilage is absent and blood vessels are abundant. By PFD14, the cartilage at the host–graft junction is gradually being replaced by bone, while the woven bone near the graft centre appears mature (representative images of four mice). Scale bars, 200 μm in host–graft junction images, 100 μm in graft-centre images, 50 μm in magnifications. b, MicroCT-based visualization and quantification of newly formed bone around control autografts, autografts from which the periosteum was removed or devitalized allografts (no living cells) at PFD28 (n = 3 mice). Coverage ratio represents percentage of graft surface covered by new bone. c, Dual-energy microCT-based visualization and quantification of vascularization in a 250-μm-wide region around autografts and allografts at PFD14 (n = 5 mice for autograft, n = 6 mice for devitalized allograft). d, CD31 immunohistochemical visualization and quantification of vascularization in a 250 μm-wide region around autografts and allografts at PFD14 (n = 3 mice). Scale bars, 500 μm. b, bone; c, cartilage; ft, fibrous tissue; g, graft; h, host; m, muscle; p, periosteum. Data are mean ± s.e.m.; one-way ANOVA with Bonferroni post hoc test (b), two-tailed Student’s t-test (c, d).

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