165 - Single Cell Atlas Reveals Subpopulation of Platelets with Hyporeactive Traits in Preterm Blood

Publication Number: 2159.165

Carson Shalaby, Children’s Hospital of Philadelphia, Philadelphia, PA, United States; Weihong Gu, Yale School of Medicine, New Haven, CT, United States; Oluwabunmi Olaloye, Yale School of Medicine, New Haven, CT, United States; Liza Konnikova, Yale School of Medicine, New Haven, CT, United States; Christopher Thom, CHOP/UPenn, Philadelphia, PA, United States

Background: Transfusions of adult platelets harm preterm neonates, likely because adult platelets are hyper-reactive and contain inflammatory molecules absent in neonatal platelets (Thom et al, JTH 2023). Past work has examined bulk platelets from individual donors. Key open questions are 1) if subpopulations of platelets have different protein content and/or reactivity profiles, and 2) how platelets change in temporal relation to gestational age and birth. Recent studies identified megakaryocyte (Mk) subsets, including ‘platelet-producing’ Mks, Mks that nurture hematopoietic stem cells, and ‘immune’ Mks with immunoregulatory signatures (CD53, LSP1, and CD14; Sun et al, Blood 2021). We hypothesized that circulating platelets would show diversity based on the type of Mk that produced them, and that variation in platelets would explain functional changes during perinatal life.

Objective: Our goals were to identify platelet populations and transcriptional changes using a single cell atlas of umbilical cord blood or peripheral blood cells from term neonates, preterm neonates, and healthy adults (Olaloye et al, STM 2025).

Design/Methods: We conducted analyses using the established pipelines for Seurat, CellChat, and SCENIC.

Results: We identified platelets based on expression of the canonical platelet genes PF4, ITGA2B, and GP9. Targeted analysis revealed platelet heterogeneity, including ‘immune’ platelets (IPs) with gene expression patterns that suggested immune Mks as their precursor (CD53, LSP1, and CD14). Compared to ‘standard’ platelets (SPs), IPs had reduced SELP, GP6, GP1BA/GP1BB, and TXA2R expression, suggesting hyporeactivity.

Pathway analyses suggested IPs have different functions from SPs. Gene set enrichment analysis revealed elevated interferon, inflammation, and immune signaling pathways in IPs. IPs also showed enrichment of heat shock and oxidative stress responses. Conversely, SPs were enriched for coagulation pathway genes. We also noted temporal enrichment of inflammation in peripheral blood from premature infants and a relative deficiency in cord blood.

Conclusion(s): We identify 2 platelet populations in circulating blood cells, including IPs enriched for immunoregulatory genes and an expression profile suggesting agonist hyporeactivity. Our findings motivate lineage tracing experiments to confirm Mk origins for platelet subtypes. Analyses on larger data sets will better classify platelet changes during fetal and neonatal life. These results highlight developmental changes in platelet content that will guide improved blood banking practices and transfusion product development for pediatric patients.