2.4. Characterization of the growth

2.4. Characterization of the growth anddevelopment of organoidsTo profile the physiological differences betweenorganoids cultured in a Matrigel dome and onchips with/without the peristalsis, we evaluatedthe expression of Lgr5 and Ki67 in the organoidsmade with each method. Eight days old organoidswere harvested for immunostaining. As shown infigure 4(A), organoids cultured under peristalsisshowed higher and more intensive fluorescence thanthose cultured on the static chip or in the Matrigeldome. Both the bottom and middle layers showedthe same trend. Images at higher magnification areshown in figure 4(B). We further quantified the Lgr5expression with the fluorescence intensity, as shownin figure 4(C), normalized against the results fromthe Matrigel dome organoids. Organoids under peristalsis showed a 1.6-fold up-regulated expression,and organoids without the peristalsis showed similar Lgr5 expression to those from the Matrigel dome.Lgr5 expression of organoids with small lumens alsoshowed the same trend, as shown in figures S8(A)and (B). These results indicate that the peristalsis promoted the proliferation of Lgr5+ cells in the colontumor organoids.