Phospholipid content, expression and support of thrombin generation of neonatal platelets

Newborns have, despite low clotting factors and poor in vitro platelet function, a well functioning haemostasis. We investigated whether phospholipids (PL) in neonatal platelets differ from those in adult platelets in their exposure on the platelet surface, and their effect on thrombin generation.

The effect of newborn and adult platelets on thrombin generation (TG) was measured by means of calibrated automated thrombography (CAT), and in a purified system. In addition, clotting times were measured. Phosphatidylserine (PS)-exposure was measured by flow cytometry. The amount of PL was determined by means of mass-spectrometry (Materials and Methods section in Supporting Information online).

In comparison with adults the clotting times in platelet-rich plasma of newborns were less shortened by adding calciumionophore. No differences in the support of TG between neonatal and adult platelets were found by means of CAT. In the purified system, TG was increased by ionophor-stimulated platelets but no difference was evident between newborn and adult platelets. Flow cytometric analysis showed no difference between adult and newborn platelets. Results of mass-spectrometry showed a very similar pattern of phospholipid-content of adult and newborn platelets.

Our results do not provide any evidence that a different phospholipid-expression of neonatal platelets may alter TG in neonates.