Platelets are crucial for the closure of a blood vessel that, if left open after birth, can lead to disease, according to a report online this week in Nature Medicine. The finding helps to advance our understanding of an important disorder which is seen in newborns.

The ductus arteriosus is a fetal blood vessel that is essential during embryonic development and closes promptly after birth. If it doesn’t close, patients develop pulmonary hypertension and heart failure. How the ductus arteriosus manages to close has remained unclear, but Steffen Massberg and his colleagues show that platelets ― the cells responsible for blood clotting ― play an essential role in its closure in mice.

The team found that platelets are recruited to the ductus arteriosus during closure, promoting the formation of a clot as this blood vessel contracts. In mice with defective platelet function, the ductus arteriosus failed to close, resulting in a condition similar to that found in the human disease: increased blood flow in the lung and excessive growth of the right ventricle of the heart. They also showed, in a clinical study in premature babies, that not having enough platelets in the blood was associated with a failure of the ductus arteriosus to close.