Monolayer culture of human fetal and adult pancreas. Static and dynamic studies of insulin release in vitro.

Abstract

Insulin release from pancreata of human fetuses aged 4 to 9 months and from adult pancreata were studied in monolayer cell culture by static incubation and perifusion technique. Fetal pancreata at the midterm of gestation (4 to 6 months) showed no response of insulin release to glucose. In a case of 9 months-old fetus, in which a small but significant increase of insulin release was observed with glucose (300 mg/ml). Tolbutamide (100 microgram/ml) had no effect on insulin release from all the pancreata of fetuses tested. Caffeine (5 and 10 mM), a phosphodiesterase inhibitor, potentiated insulin release by itself and also induced the glucose-stimulated insulin release from the fetal pancreata in the dose related manner. Glucagon (2 microgram/ml), L-isoproterenol (2 microgram/ml), L-arginine (10 mM) and L-leucine (10 mM) failed to induce any increase of insulin release from fetal pancreata. In the presence of caffeine, the significant increase of insulin release from fetal pancreata was observed with L-leucine, but not with L-arginine. There was no evidence of the maturation of B-cells during the culture periods (4 to 8 days), probably lacking the key steps of stimulus-secretion couplings in relation to adenylate cyclase-cyclic AMP system. By contrast, glucose (100 and 300 mg/100 ml), tolbutamide (100 microgram/ml), L-arginine (10 mM) and caffeine (5 mM) caused a significant increase of insulin release from adult pancreata. Thus, the development of human pancreatic B-cells seems to depend substantially on gestational age, being ready to equip most machinary of insulin release before delivery.