Whole human bone marrow aspirates

MDA-MB-231 expressing green fluorescent protein (GFP) was a generous gift from Weinberg lab^{17 (link)}. Normal breast fibroblast (NBF) and cancer-associated fibroblast (CAF) were provided by Orimo lab and previously described by Kojima et al.^{24 (link)} MCF-7 and normal human dermal fibroblast (NHDF) were purchased from ATCC. For in vivo studies, MCF-7 cells were engineered to express firefly luciferase with a lentivirus containing luciferase reporter (MCF-7/Luc) following a previous report^{67 (link)}. Primary human bone marrow mesenchymal stromal/stem cells (BMSCs) were derived from whole human bone marrow aspirates (Lonza)^{68 (link)}. BMSCs were expanded in alpha-modified Minimum Essential Medium Eagle (alpha-MEM), 20 mg L⁻¹ gentamycin, 10% FBS, 2.5 ug L⁻¹ rhFGF-basic (R&D Systems), 100 U ml⁻¹ penicillin, and 100 mg ml⁻¹ streptomycin. All other cells and co-cultures were grown in Dulbecco’s MEM (DMEM) supplemented with 10% FBS, 100 U ml⁻¹ penicillin and 100 μg ml⁻¹ streptomycin.