Structural differences in the umbilical vein wall after full-term and pre-term delivery

Area of Science:

• Obstetrics and Gynecology
• Developmental Biology
• Vascular Biology

Background:

• The human umbilical cord, largely devoid of innervation, suggests paracrine signaling is crucial for regulating fetoplacental circulation.
• Direct cell-to-cell contact between smooth muscle cells and endothelium may play a vital role in this regulation.

Purpose of the Study:

• To investigate the ultrastructure and cellular characteristics of umbilical veins in full-term and pre-term neonates.
• To examine the role of smooth muscle cell processes and endothelial cell apoptosis in umbilical cord function.

Main Methods:

• Electron microscopy was used to analyze the ultrastructure of umbilical vein smooth muscle cells.
• Immunohistochemistry was employed to assess c-kit and Bax immunoreactivity in umbilical vein tissues.
• Samples were obtained immediately following full-term and pre-term deliveries.

Main Results:

• Smooth muscle cells in the tunica media possess c-kit immunoreactive, foot-like processes.
• In full-term neonates, over 50% of these processes showed normal ultrastructure, closely associated with the lamina elastica interna.
• In pre-term infants, over 60% of processes were shrunken and detached, with increased endothelial Bax expression indicating apoptosis.

Conclusions:

• Umbilical vein smooth muscle cell processes undergo significant ultrastructural changes in pre-term infants.
• Enhanced endothelial apoptosis in pre-term umbilical veins suggests a compromised fetoplacental circulation mechanism.
• These findings highlight potential cellular mechanisms underlying circulatory issues in pre-term neonates.