FIG. 1.

Confocal microscopy images of cells encapsulated in PEG hydrogels with entrapped collagen (PEGCol) on culture days 0 (a–d), 7 (e–h), and 10 (i–k). Images are of hydrogel sections incubated with antibodies directed against insulin and PDX-1 costained (a, e, i), insulin alone (b, f, j), glucagon (c, g, k), and vimentin (d, h). On day 0, 65 ± 5% of encapsulated cells stained positive for PDX-1 (a), including cell clusters (inset); however, no PDX-1+ cells were found to costain with insulin at this time. Insulin (b) and glucagon (c) staining was seen in only scattered single cells on day 0 and was not detected in cell clusters. On day 0, 25 ± 3% of the encapsulated cells were vimentin+ (d). Strong insulin and PDX-1 costaining was seen on both days 7 and 10 (e, i), where upper and lower insets show separated insulin and PDX-1 staining, respectively. Insulin staining was seen throughout the islet-like clusters present in PEGCol hydrogels at days 7 and 10 (f, j), while glucagon+ cells are predominantly found on the periphery of the clusters (g, k). By day 7 only a few scattered vimentin+ cells were present in PEGCol hydrogels (h) and none was found on day 10 (not shown). A 4′,6-diamidino-2-phenylindole (DAPI) nuclear counterstain was used in all images. Scale bar, 10 μm for all images. Color images available online at www.liebertonline.com/ten.