Effect of Maternal Hyperglycemia on Fetal Pancreatic Islet Development

Hyperglycemia during fetal development disturbs extracellular matrix (ECM) synthesis and deposition patterns, which disrupts organogenesis and adult organ function. Although the ECM cooperates in pancreas development, little is known about the effects of hyperglycemia on the pancreatic ECM during development. This study investigates the effect of severe maternal hyperglycemia on ECM composition and endocrine pancreas development in E19.0 mouse fetuses. Deposition patterns of pan-laminin, laminin (alpha 1 and gamma 1 chains) and integrin alpha 3 were evaluated by immunostaining. The proliferative index of islet cells and alpha and beta cell distribution were evaluated by PCNA, glucagon and insulin immunostaining, respectively. <i>Pdx1</i> and <i>Pax4</i> expressions were analyzed by RT-qPCR. While for pan-laminin and laminin (alpha1 and gamma1 chains) deposition was weaker in the endocrine pancreas of hyperglycemic mothers' fetuses, integrin alpha 3 deposition in the basement membrane was increased. The proliferative index of endocrine cells was lower in the hyperglycemic group, while the beta-cell area was increased. In addition, there was a tendency towards lower <i>Pdx1</i> and increased <i>Pdx4</i> expression. These data suggest that maternal hyperglycemia alters fetal endocrine pancreas morphogenesis by modifying peri-islet basement membrane molecule patterns, promoting a decrease in endocrine cell proliferation associated with changes in the expression of important growth factors for the beta cells differentiated and the proliferative state.