Progeny of single HSCs participate in neovascularization. (A) Mice that received a transplant of GFP⁺ BM cells from primary donors initially engrafted with single HSCs demonstrate multilineage engraftment. Shown are representative flow cytometry plots demonstrating both myeloid (CD11b) and lymphoid (CD4 and B220) cell populations in engrafted secondary mice. Also shown is a representative isotype control. (B) In these mice, LLC tumors showed substantial HSC-derived GFP⁺ cell contribution throughout the tumor mass (n = 9; scale bar represents 100 μm). (C) Confocal micrograph of HSC-derived GFP⁺ cell in blood vessel wall coexpressing CD31. Orthogonal views created from confocal sections verify luminal expression of CD31 on HSC-derived cells.