Insulin secretion and DNA synthesis of cultured islets of Langerhans are influenced by the matrix.

To compare the effect of matrix on glucose-stimulated insulin release, we cultured neonatal (3- to 5-day-old) rat islets of Langerhans, devoid of mesenchymal cell, on fibronectin, Cell-Tak, or endothelial basement membranes, free-floating, or dispersed into single cells. We also examined the rate of DNA synthesis during the culture period. Compared to free-floating islets [0.386 +/- 0.03 (SEM) ng per 24 h/ng total], single-cell cultures had the lowest basal insulin release (0.159 +/- 0.03 ng per 24 h/ng total; p < 0.0001), which was also low in islets attached to endothelial basement membrane (0.294 +/- 0.02 ng per 24 h/ng total; p = 0.01). The spontaneous insulin release (1 h in medium with 2.7 mM glucose) was lowest in islets attached to endothelial basement membrane (0.003 +/- 0.00023 ng per h/ng total; p < 0.0001 vs. free-floating) and highest in single-cell cultures (0.01153 +/- 0.00259 ng per h/ng total; p = 0.039 vs. free-floating). The ability to increase insulin release following a glucose challenge (16.1 mM for 1 h) was highest in islets grown on endothelial basement membranes (16.4-fold) and fibronectin (12.6-fold) compared to free-floating islets (8.7-fold), Cell-Tak (7.9-fold), and single-cell cultures (5.4-fold).(ABSTRACT TRUNCATED AT 250 WORDS)