Fluctuations in circulating endothelial progenitor cell levels and acute cardiac graft rejection.

INTRODUCTION:Endothelial progenitor cells (EPCs) in nontransplant settings have reparative properties. However, their role in heart transplantation (HT) is not well defined. OBJECTIVES:The aim of this study was to prospectively evaluate changes in EPC levels in relation to post‑HT rejection. PATIENTS AND METHODS:EPC levels were measured in 27 HT recipients for 6 months after HT. Acute cellular rejection (ACR) or antibody‑mediated rejection (AMR) were assessed by right ventricular endomyocardial biopsy. RESULTS:ACR and AMR were observed in 7 (25.9%) and 6 (22.2%) patients, respectively. The ACR status at 1 month post‑HT did not differ with respect to EPC immediately post‑HT. At 1 month post‑HT in patients without ACR or AMR, EPC levels were significantly reduced compared with the measurements immediately post‑HT (P <0.001). On further follow‑up, EPC levels were similar regardless of the rejection events. Nonetheless, greater changes (coefficient of variation) in EPClog (logarithmic transformation) were associated with the risk of AMR or ACR compared with those without any rejection event (median [lower-upper quartile], 15 [13-18] vs 8 [5-13]; P = 0.02 and 22 [14-26] vs 8 [5-13]; P = 0.01, respectively). The receiver operating characteristic curve showed that the coefficient of variation of EPClog of 12 was the optimal cutoff value for the prediction of rejection (area under the curve = 0.85). Higher levels were associated with greater risk of ACR or AMR (P <0.005). CONCLUSIONS:Early reduction of EPC levels was related to a lower risk of ACR or AMR. Greater changes of EPC‑levels during follow‑up were associated with a significantly higher risk of rejection.