Figure 5. Mouse CD200^hiItga6^hi cell location, cell cycle status, and gene expression are similar to those of human CD200^hiITGA6^hi cells.

(A and B) As assessed by immunohistology of mouse skin, CD200 was expressed in bulge and secondary hair germ cells (A), whereas CD34 was expressed in bulge cells, but not secondary hair germ cells (B). (C) FACS identified a CD200^hiItga6^hi population. (D) CD200 versus CD34 identified bulge cells (CD200^hiCD34⁺) and secondary hair germ cells (CD200^hiCD34^–). (E) CD34^hiItga6^hi cells (Supplemental Figure 6E) overlaying CD200^hiItga6^hi cells (as in C) demonstrated that CD200^hiItga6^hi cells extended to a CD34^– population, but CD34^hiItga6^hi cells were entirely CD200⁺. In F, only the CD200^hiItga6^hi population is shown, exhibiting overlap to the secondary hair germ. (G) Cell cycle analysis demonstrated the lowest frequency of G₀/G₁ in CD200^hiItga6^hi cells in the secondary hair germ (CD34^–; n = 3, P = 0.02). (H) Enriched gene lists from microarray expression analysis of human CD200^hiITGA6^hi, mouse bulge (CD200^hiCD34⁺), and mouse secondary hair germ (CD200^hiCD34^–) cells demonstrated that the human CD200^hiITGA6^hi population overlapped with both mouse populations, but more so with murine bulge than with murine secondary hair germ. Scale bars: 100 μm. Numbers within dot plots indicate percent cells in the respective gate or quadrant.