Reticulated Platelets and Their Relationship with Endothelial Progenitor Cells during the Acute Phase of ST-Elevation Myocardial Infarction

Introduction: Endothelial progenitor cells (EPC) and reticulated platelets (RP) have central roles in the thrombotic and angiogenetic interactions during ST-elevation myocardial infarction (STEMI). The EPC and RP response in patients with STEMI treated by primary percutaneous intervention (PPCI) has not yet been investigated. Methods: We assessed EPC quantification by the expression of CD133⁺ and CD34⁺, and EPC function by the capacity of the cells to form colony-forming units (CFU) and MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide) during the acute phase of STEMI. These measurements were correlated with RP at baseline and after 24 h following PPCI. Results: Our cohort included 89 consecutive STEMI-diagnosed patients enrolled between December 2018 and July 2021. At baseline, there was a strong positive correlation between reticulated platelet quantity and MTT levels (R = 0.766 and R² = 0.586, p < 0.001), CD34⁺ levels (R = 0.602, and R² = 0.362, p < 0.001); CD133⁺ levels (R = 0.666 and R² = 0.443, p < 0.001) and CFU levels (R = 0.437, R² = 0.191, p < 0.001). The multiple linear regression showed that levels of MTT (adjusted R² = 0.793; p < 0.001), CD34⁺ and CD133⁺ (adjusted R² = 0.654; p < 0.001 and adjusted R² = 0.627; p < 0.001, respectively) had strong independent correlations with RP response. At 24 h after PPCI, the correlation between RP quantity and EPC markers was not significant, except for MTT levels (R = 0.465, R² = 0.216, p < 0.001). Conclusions: In patients with STEMI, higher levels of RP at baseline are significantly correlated with a more potent EPC response. The translational significance of these findings needs further investigation.