FIG. 5.

Glucose-stimulated insulin secretion of encapsulated islets. (A) Stimulation indices (ratio of high glucose insulin secretion to low glucose secretion) were measured at days 3, 7, 14, 21, and 28 in vitro for encapsulated islets in HA-COL and alginate-RGD hydrogels and for unencapsulated controls. The stimulation index for control cells in media did not change significantly over time, which was also true for islets encapsulated in HA-COL and alginate (n = 3 donor animals). (B) Actual secreted insulin concentrations in response to low and high glucose incubations normalized to IEQ are summarized. Data shown are the mean values from three separate donors measured in triplicate for each group at 3, 7, 14, 21, and 28 days. Significant differences were denoted with an asterisk (p < 0.05). Incubation periods were 90 min for both low and high glucose conditions. IEQ, islet equivalents.