Figure 3.
Human islets produce chemokines and attract BM-MSCs by secreting CXCL12 and CX3CL1. (A) Chemokines/growth factors measured in the supernatant of 100 handpicked human pancreatic islets after 48 hours of culture in the presence or absence of IL-1β (10 ng/mL). Results are expressed as mean ± SD from 3 experiments. (B, left) Release of CXCL12 and CX3CL1 from human pancreatic islet preparation cultured in the presence or absence of IL-1β (10 ng/mL) for up to 8 days. Results are the mean ± SD from 6 islet preparations. (Right) Immunohistochemical detection of CXCL12 and CX3CL1 in human pancreas sections. Anti-CXCL12 and anti-CX3CL1 antibodies stained the cytoplasm of islet cells and small duct cells. (C) Chemotaxis assay showing migration of BM-MSCs to supernatants of human islets cultured with (▦) or without (□) IL-1β (10 ng/mL). The mean ± SE of 8 replicates is shown for each of 4 islet supernatants (Sup. 1 to 4). The effect of supernatant dilution on the chemotactic activity is shown for supernatant 4. Chemotaxis is measured as the number of migrated cells counted in 10 HPFs after subtraction of the basal migration observed in the absence of chemokine. Basal migration was 10 ± 5 cells/10 HPFs. The migration to recombinant CXCL12 and CX3CL1 is shown for comparison. (D) Inhibition studies of BM-MSC migration to islet supernatant. Supernatants were preincubated with 10 μg/mL anti-CX3CL1, BM-MSCs were preincubated with 10 μg/mL anti-CXCR4, or both conditions were observed. Chemotaxis is measured as the number of migrated cells counted in 10 HPFs after subtraction of the basal migration observed in the absence of chemokine. Basal migration was 8 + 4 cells/10 HPFs. Values are the mean ± SE of 8 replicates. *P < .02 versus islet supernatant; **P < .001 versus islet supernatant.

Human islets produce chemokines and attract BM-MSCs by secreting CXCL12 and CX3CL1. (A) Chemokines/growth factors measured in the supernatant of 100 handpicked human pancreatic islets after 48 hours of culture in the presence or absence of IL-1β (10 ng/mL). Results are expressed as mean ± SD from 3 experiments. (B, left) Release of CXCL12 and CX3CL1 from human pancreatic islet preparation cultured in the presence or absence of IL-1β (10 ng/mL) for up to 8 days. Results are the mean ± SD from 6 islet preparations. (Right) Immunohistochemical detection of CXCL12 and CX3CL1 in human pancreas sections. Anti-CXCL12 and anti-CX3CL1 antibodies stained the cytoplasm of islet cells and small duct cells. (C) Chemotaxis assay showing migration of BM-MSCs to supernatants of human islets cultured with (▦) or without (□) IL-1β (10 ng/mL). The mean ± SE of 8 replicates is shown for each of 4 islet supernatants (Sup. 1 to 4). The effect of supernatant dilution on the chemotactic activity is shown for supernatant 4. Chemotaxis is measured as the number of migrated cells counted in 10 HPFs after subtraction of the basal migration observed in the absence of chemokine. Basal migration was 10 ± 5 cells/10 HPFs. The migration to recombinant CXCL12 and CX3CL1 is shown for comparison. (D) Inhibition studies of BM-MSC migration to islet supernatant. Supernatants were preincubated with 10 μg/mL anti-CX3CL1, BM-MSCs were preincubated with 10 μg/mL anti-CXCR4, or both conditions were observed. Chemotaxis is measured as the number of migrated cells counted in 10 HPFs after subtraction of the basal migration observed in the absence of chemokine. Basal migration was 8 + 4 cells/10 HPFs. Values are the mean ± SE of 8 replicates. *P < .02 versus islet supernatant; **P < .001 versus islet supernatant.

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