Fig. 2

PCa migration potential in Transwell co-cultures with bone marrow stromal cells. a Schematic illustration of the Transwell assay. PCa cell suspensions were seeded in Transwell inserts with 8 μm pore size membrane. The co-cultures were performed over 18 h to allow PCa cell migration towards 2D monolayers or 3D microtissues of stromal cells (BMSC, osteoblasts or adipocytes). Prior to co-culture establishment, the osteoblasts and adipocytes were differentiated for 14 days using osteogenic or adipogenic induction media; and undifferentiated BMSC controls were assembled 1 day prior to initiation of the Transwell co-culture. b PCa cells that had migrated to the bottom surface of the Transwell membrane were stained with 0.5% crystal violet, and this was extracted and quantified. Results are represented as the mean optical densities of crystal violet extracts normalized to the control mono-cultures. Similar results were obtained in three independent experiments with two different BMSC donors, each having four replicate cultures n = 4. Statistical significance was performed using two-way ANOVA (* P < 0.05, *** P < 0.001 and n.s = non-significant)