Maternal Exosomes Contribute to the Fetal Cardiac Development Deficiency in Mother with Pre-Existing Diabetes: A Fetal Echocardiography Based Animal Study

Maternal diabetes mellitus induces an increased risk of congenital heart defects (CHD), however, the exact mechanisms are still not fully illustrated. In this study, we explored the possible role of exosomes in the process by combinatory use of fetal echocardiography and cellular biology methods in diabetic mouse model. Diabetic pregnant C57BL/6 mice were induced by injection of streptozotocin (STZ) before mating. Circulating exosomes from the diabetic pregnant mice or the control mice were harvested before purification for further analysis and in vivo delivery. MiRNAs inside the exosomes were analyzed by RNA-seq. Exosomes or the analogue gold nanoparticles were fluorescently labeled before tail vein injection for in vivo distribution analysis. To explore the roles of diabetic maternal exosomes in cardiac development, the exosomes from diabetic pregnant mice were delivered into normal pregnant mice and cardiac development was analyzed by echocardiography or histology. Pre-existing diabetes significantly induces high rate of cardiac developmental deficiency in the mouse model. Compared with the control normal mice, diabetic pregnant mice displayed significant changes of the exosomal contents in the blood, which correlate with the increased cardiac developmental defect. RNA-seq analysis revealed that multiple miRNAs changed more than 10 folds, and bioinformatics revealed their implication in regulating Wnt and other developmental pathways. Moreover, fluorescence labeled exosomes and gold nanoparticles could cross the placenta barrier and infiltrated into the embryonic organs/tissues, including the heart, especially during the early stages of embryonic development. Injection of diabetic maternal exosomes strikingly increased the risk of CHD in the normal recipient pregnant mice. Phenotyping with small animal ultrasound is a powerful strategy for cardiac developmental biology. Maternal exosomes, at least miRNA components, in diabetes could cross the maternal-fetal barrier and the aberrant miRNAs in the exosomes may contribute to the cardiac development deficiency. Our study would provide new insights in CHD prevention and treatment.