Figure 2

Amniotic fluid stem cells (AFSs) form spheres and tubular structures in 3D cultures. AFSs alone or equal numbers of AFSs and MECs derived from GFP transgenic C57/B6-TG (ACTB-EGFP) mice were subjected to 3D differentiation and monitored for up to 10 days after plating. (a) AFS-derived progeny form spherical structures 5 days after plating and extend to a branched tubular network in 3D Matrigel culture. (b) These structures are positive for α-SMA and vimentin. Inset shows a section through a spherical structure. (c) We observed the emergence of tubular structures formed by AFSs surrounding GFP⁺ MECs (upper panel) or spheroids formed from GFP⁺ MECs with a hollow central lumen surrounded by a layer of cells contributed by AFSs (middle panel) and side branches surrounding GFP⁺ MECs (lower panel). (d) AFSs closely associated with GFP⁺ MECs express α-SMA. Scale bars, 50 μm, and for inset, 30 μm.