Fig. 4

In vivo heterotopic bone formation. hMSC-LUC2 (a, d, g, j, m), hMSC-CD146⁺ (b, e, h, k), and hMSC-CD146⁻ (c, f, i, l) were implanted subcutaneously (n = 4) mixed with hydroxyapatite tricalcium phosphate/Triosite (HA/TCP) into immune-compromised mice for 8 weeks. Analysis was performed on three serial sections at three depths with 100 μm between each depth. Hematoxylin and eosin (H&E) staining of bone formation demonstrating distribution of bone within the implants (a-i, m). d-f Blood vessel formation within the implants. g-i Establishment of bone marrow within the implants. j-l Human-specific vimentin staining of developing bone demonstrating the human origin. o, p Quantification of total bone or bone marrow volume. Scale bar on all H&E and vimentin staining = 100 μm