Homing of human HSC progeny to liver metastases derived from human breast cancer cells. (A-C) Histology of liver metastases. Two weeks after intraportal MDA-MB435 cell transplantation, liver sections were stained with H&E (A), stained for stroma (black; B), or for laminin (red) and mouse CD31 (green; C). (B-F) Human CD34⁺ cells were transduced with a GFP-expressing lentivirus vectors and transplanted into sublethally irradiated CB17 SCID/beige mice. Six weeks later, mice received MDA-MB435 cells. Liver sections were analyzed 3 weeks later for laminin (red; D), GFP (green; E), and laminin and GFP (F). Notably, there were no specific fluorescence signals on liver/tumor sections of mice that did not receive LV-GFP–transduced bone marrow cells. The scale bar represents 100 μm. (G) Quantification of human donor cells in liver parenchyma and tumor stroma (N = 15; 5 mice, 3 sections per mouse). Error bars represent SD.