Fig. 1
Effect of MSC on insulin secretion by islets. The insulin secretion assay was performed by incubating islets (150 IEQ) or pseudoislets (105 islet cells) at basal glucose (2.8 mM, white bars), high glucose concentration (16.7 mM, striped bars), and high glucose plus theophylline (16.7 and 5 mM, respectively, black bars) for 1 h. a Islets alone (islets), together with 15 × 103 MSC (ratio 1 IEQ:100 MSC) in direct cell–cell contact (islets-MSC contact), and islets–MSC without cell–cell contact separated in a transwell chamber (islets-MSC no contact) after 3-day culture. b Pseudoislets (p-islets), pseudoislets cultured in direct cell–cell contact with 3 × 104 MSC (ratio 3:1) (p-islets MSC contact), and pseudoislets cultured in MSC-conditioned medium (p-islets MSC cond.medium) after 6-day culture. Values are normalized to the total amount of insulin, and insulin secretion expressed as fold increase where the basal level is set at 1. Data presented as arithmetic mean ± SEM of four or five independent islet donors respectively, and for each donor the assays were performed in triplicate. Mann–Whitney test: *p < 0.05, **p < 0.01