Large platelets but not putative endothelial progenitor cells are associated with low strut coverage after drug-eluting stent implantation

Objectives: This study assessed whether different subsets of circulating endothelial and putative endothelial progenitor cells (CEC and EPC) correlate with stent strut coverage (SSC) using second generation optical coherence tomography (OCT).Background: Due to the lack of imaging modalities with a resolution down to the magnitude of a few cells, the influence of EPC on endothelialisation of drug-eluting stents has not been assessed in patients.Methods: In 37 patients, SSC of everolimus-eluting stents was assessed by OCT 5–7 months after stent implantation. Different subsets of EPC (CD34+KDR+, CD34+KDR+CD45dim, CD133+, CD3+CD31+), CEC (CD31+CD45−CD146+), and CD31+CD45−CD146− representing large platelets were analysed by flow cytometry, including viability analyses with 7-AAD. Statistical analysis comprised univariate regression analysis and multivariable models integrating OCT and flow cytometry data as well as clinical variables.Results: SSC and frequency of different cell types were highly comparable with previously published data. EPC defined in part by KDR expression were mostly non-viable. On univariate and in multivariable models, no association between EPC counts and strut coverage was detected. For CD31+CD45−CD146− counts, representing large platelets, an inverse relationship with strut coverage was identified by a multivariable regression model adjusting for age, sex, diabetes mellitus, NYHA and CCS class, CRP, serum triglycerides, glucose and creatinine (beta = − 9.42, p = 0.006).Conclusions: There was no significant association between EPC or CEC and healing after drug-eluting stent implantation. Yet, CD31+CD45−CD146− cells were associated with low SSC. These data suggest that large platelets may represent a more important mediator of late stent endothelialisation than EPC.