Abstract 2580: Potential Role of Circulating Progenitor Cells in Coronary Microvascular Dysfunction of Heart Transplant Patients with Normal Coronary Angiograms
Peripheral blood progenitor cells (PCs) may play a role in the early stages of cardiac allograft vasculopathy (CAV). We assessed the relationship between PCs and coronary microvascular function in heart transplant (HT) patients (pts) with normal coronary angiograms.
Methods: We studied 41 pts with (36 M, aged 50 ± 12 years) at 6 ± 3 years from HT and 40 age and sex matched healthy subjects. Six subpopulations of PCs were determined by flow cytometry as follows: uncommitted (CD34+, CD133+, CD34+CD133+) and endothelial PCs (EPCs, CD34+KDR+, CD133+KDR+, CD34+CD133+KDR+). Coronary flow velocity in the LAD was detected at rest and during i.v. adenosine by transthoracic echocardiography. Coronary flow reserve (CFR) was the ratio of hyperemic diastolic mean velocity (DMV) to resting DMV. CFR <2.5 was considered abnormal. CFR was measured in 10 pts (8 M, aged 50 ± 12 years) and was abnormal in 3 (group A) and normal in 7 (group B).
Results: EPCs were lower in pts than in controls (p<0.05). CD34+ cell count was higher in group A than in group B (583 ± 100 vs 282 ± 185 cells/10^6 cytometric events, p=0.01). CD34+ cell count was also inversely correlated with CFR as shown in the figure⇓. At multivariable analysis, adjusted for time from HT, diabetes, hypertension and hypertrophy, CD34+ cell count was the only independent predictor of CFR (β=-0.773, p=0.006).
Conclusion: EPCs were reduced in HT pts with normal angiograms, in keeping with their immunosuppressed status. Levels of CD34+ cells were inversely related with CFR. Mobilization of uncommitted PCs may be involved in the pathogenesis of CAV, possibly by PCs capacity of differentiation into neointimal and medial cells.