Figure 6. Released PDGF-BB induces chemotaxis of MSCs in a stringent migration assay. A) .

Schematic showing experimental set-up (not drawn to scale). GFP-MSCs were seeded in 8-well rectangular plates. After cell confluence was established, cells were completely removed from the top half of the well by scraping along a pre-drawn central line. Subsequently, a PDGF-BB-adsorbed PCL/col/HA/scaffold, placed on a steel wire mesh, was placed 1.5 cm away from the cell front. As a control, some chambers were set up with PCL/col/HA scaffolds lacking PDGF-BB. B) After a 72 hr-incubation in the chambers described, MSCs were stained with DAPI and visualized by fluorescence microscopy. The original cell front created is denoted by a white line. C) GFP-images showing change in cell morphology of MSCs exposed to PDGF-BB. D) Significantly greater cell number was observed migrating toward PDGF-BB coated scaffolds compared to uncoated scaffolds. E) DAPI-stained images were further analyzed by counting the number of cells in three defined regions of distance beyond the original cell front. The distribution of cells in the wells with PDGF-BB-coated scaffolds showed that a greater percentage of the total cells that had migrated beyond the cell front had localized to the region beyond 400 µm. In comparison, the greatest percentage of cells in the control wells localized to the region below 150 µm. A total of six samples were analyzed for each condition. An asterisk (*) denotes significant differences observed with p<.01, whereas (**) denotes p<.0001.