Localized transfection
method for 3D MDCK culture. (a) MDCK cells
seeded into collagen grow into hollow spherical cysts (∼200
cells) over a period of 6 days. (b) Schematic view showing two collagen
layers in a 35 mm diameter dish. A second layer, comprising collagen
mixed with the seeding cells, allows cysts to develop at the interface
between the layers. The top layer is peeled away to allow transfection
of one face of the cysts. A new collagen layer is then poured on top.
(c) A typical MDCK cyst, locally transfected with EGFP under a constitutive
CMV promoter. (d) Local transfection with HGF under a CMV promoter,
followed by an internal ribosome entry site (IRES) and the EGFP gene.
A schematic view (below) shows the transfected region (green) secreting
functional HGF, which diffuses around the cyst to induce tubulation.
Phase contrast light microscopy images are superimposed with the GFP
fluorescence channel. Scale bars: 50 μm.