Co-culture with activated ILC2s promoted maturation and proliferation of SPEM cells in Meta1 gastroids. (A) Immunofluorescence staining of Meta1 gastroids cross sections for SPEM-related markers, AQP5 and TFF2. Quantitation of AQP5 and TFF2 double positive cells demonstrated significant increase of proportion of mature SPEM cells in co-cultured condition. Yellow arrowheads point at double positive mature SPEM cells. Scale bar: 100 μm and 50 μm for enlarged. Mean ± SD (N = 3 independent experiments). ∗P < .05. (B) Immunofluorescence staining of Meta1 gastroids cross sections for a proliferation marker, Ki67, and SPEM-related markers, MUC6 and CD44v9. Quantitation of MUC6 and CD44v9 double positive cells demonstrated significant increase of proportion of mature SPEM cells in Meta1 gastroids co-cultured with ILC2s. Quantitation of MUC6, CD44v9, and Ki67 triple positive cells demonstrated significant increase of proportion of proliferative SPEM cells. Yellow arrowheads point at triple positive mature and proliferative SPEM cells. Scale bar: 100 μm and 50 μm for enlarged. Mean ± SD (N = 3 independent experiments). ∗P < .05.