A Transgenic Mouse Model for Reticulated Platelet Detection Reveals Expansion After Myocardial Ischemia/Reperfusion Open Access

• A genetic RiboTag-based murine model allows identification of reticulated platelets in mice without RNA-binding dyes.

• Reticulated platelets increase after myocardial ischemia/reperfusion injury with enhanced activation and distinct transcriptional profile.

Reticulated platelets are newly formed, RNA-rich platelets with heightened reactivity. Although elevated levels are observed in patients after myocardial ischemia/reperfusion injury, their functional contributions to post-ischemia pathology remain unclear. Our goal was to determine if reticulated platelets actively contribute to inflammation and repair following myocardial ischemia and reperfusion, rather than serving solely as biomarkers of platelet turnover. We generated Pf4-Cre:RiboTag mice, in which hemagglutinin tagged ribosomal proteins are selectively expressed in megakaryocytes and platelets. Using hemagglutinin-based flow cytometry, we identified reticulated platelets without relying on nucleic acid dyes. Surface marker expression and agonist responsiveness were evaluated ex vivo. Bulk RNA sequencing was performed on sorted reticulated and non-reticulated platelets 48 hours after ischemia/reperfusion injury. Hemagglutinin-based detection revealed a time-dependent increase in circulating reticulated platelets after myocardial ischemia/reperfusion injury, confirmed by conventional dye-based methods. These platelets exhibited higher baseline expression of glycoprotein Ibα, and agonist-induced increase in activated glycoprotein IIb/IIIa and P-selectin. Transcriptomic profiling demonstrated enrichment in genes associated with platelet activation, cytoskeletal reorganization, and wound healing. Ligand–receptor analysis suggested communication between reticulated platelets and cardiac endothelial cells, fibroblasts, and macrophages. In conclusion, reticulated platelets comprise a transcriptionally distinct, hyperreactive subset of platelets that may modulate post-myocardial ischemia/reperfusion inflammation and tissue remodeling. This genetic model offers a robust platform for mechanistic studies and may inform therapeutic strategies targeting platelet-mediated responses in cardiovascular disease.