ECM adhesion
is required in wide channels but not in narrow channels.
(A) Collagen immunofluorescence staining in channels that have been
functionalized with collagen (left), exposed to 10% FBS in cell culture
media for 24 h (center), and exposed to serum free cell culture media
for 24 h (right). Scale bars = 10 μm. (B) The number of cells
observed permeating channels functionalized with collagen, FBS, or
no protein. Permeation was not observed in protein-free 10 μm
channels. Error bars represent 95% confidence intervals. N = 28, 21, 10, 16, 9, and 8 from left to right. (* p < 0.05, ANOVA, F = 13.71, DF = 141). (C) Average
cell speed during channel permeation. N = 32, 12,
7, 22, 0, and 1 from left to right. Error bars represent 95% confidence
intervals. (*** p < 0.001, ANOVA, F = 6.602, DF = 69). (D) Phase contrast, background subtracted images
of a cell permeating a serum-free channel (cell moves from left to
right).