Investigating the effect of hyperglycemia on embryonic heart development using the chick embryo model

Abstract

Congenital heart defects (CHDs) represent the most common form of human birth defects. Maternal diabetes increases the risk of CHD by 3-5 folds. During heart development, little is known about the effects of high blood glucose on the fetal development of CHDs. Chick embryo is a widely used animal model to investigate CHDs. Heart development in this specie closely resembles humans with four chambers/four-valve configuration. In this project, the mechanisms that contribute to heart defects during gestational diabetes were investigated using chick embryo model. Fertilized chicken eggs were injected with glucose to induce hyperglycemia in embryos. Blood glucose level was measured using a glucometer. Cardiac function was assessed via echocardiography. Heart tissues were extracted for histological assessment and for measurement of gene expression of cardiac markers via RT-PCR. Hyperglycemia resulted in increasing the blood flow velocities in the atrioventricular (AV) valve and reduced the ejection fraction at AV and outflow track (OFT) canals. It altered the structure of the hearts and the gene expression of sheer stress markers. Results of this study showed that chick embryo is a good model for investigating the effect of hyperglycemia on the heart function during the development. Hyperglycemia affects the function of the heart valves as well as heart ventricles. These results could identify alterations in the early developmental process that contribute to the increased cardiac malformations risk in babies of diabetic mothers.