OC 67.1 - Characterizing the Differences in Adult and Neonatal Biophysical Platelet Function at the Single Cell Level

Background: Neonates undergoing cardiac surgery have a high risk of bleeding after cardiopulmonary bypass (CPB). Both platelet deficiency and impaired platelet function contribute to post-CPB coagulopathy. Current clinical platelet function tests used to predict bleeding risk for adult cardiac surgical patients do not account for morphologic and physiologic differences of neonatal platelets. Previously, our novel quantitative single platelet function test, platelet contraction cytometry (PCC), has shown that low single platelet force correlates strongly with bleeding phenotype in adults. Therefore, we hypothesize that PCC may be more sensitive than the clinically available platelet function tests to predict bleeding risk for neonates undergoing cardiac surgery.

Aims: We sought to characterize differences between neonatal and adult platelet function at the single cell level using PCC and platelet adhesion assays. We aim to establish a reference range for neonatal platelet function that will allow us to predict surgical bleeding in this patient population.

Methods: After IRB approval, we collected whole blood samples from 7 neonates prior to surgery and 7 healthy adults. Platelets were isolated and used for PCC (Fig 1A) and adhesion assays (Fig 1B). Using a mixed effects model, we analyzed differences in platelet contraction forces and adhesion properties between neonatal and adult platelets.

Results: We found that neonatal platelets have significantly greater contraction forces on PCC than adult platelets (Fig 2A). However, we saw no significant differences in adhesion properties between neonatal and adult platelets (Fig 2B).

Conclusion(s): Our study shows that neonates have higher platelet contraction forces than adults. This raises the possibility that there may be mechanistic differences in neonatal platelet contraction compared to adults. Having established a biophysical reference range for neonates, future studies will focus on characterizing how CPB affects neonatal platelet contraction force and adhesion in order to understand post-bypass bleeding risk in this vulnerable population.