Cells of primarily extravalvular origin in degenerative aortic valves and bioprostheses

Aims We assessed aortic valves from patients with non-rheumatic aortic valve stenosis (AS) and with degenerative aortic valve bioprostheses (BP) for the presence of progenitor cell and leukocyte subtype-specific markers. Methods and results Diseased valve probes from a total of 87 patients (60 AS and 27 BP) were studied. We assessed presence and localization of endothelial progenitor cells (EPCs: CD34, CD133), dendritic cells (DCs: S100), T-lymphocytes (CD3), and macrophages (CD68) by immunohistochemical and morphometric analyses. In the majority of valves, we detected cell-bound signals of CD34 (48% of AS, 74% of BP, respectively), CD133 (58%/81%), S100 (58%/93%), CD3 (62%/81%), and CD68 (78%/93%). Labelled cells were predominantly localized within the valvular fibrosa. As key results, frequency of EPCs, DCs, macrophages, and lymphocytes was found significantly higher in BP when compared with AS (CD34: 19.2 +/- 23.2 vs. 5.7 +/- 13.0%; CD133: 13.7 +/- 12.4 vs. 5.5 +/- 8.3%; S100: 15.2 +/- 12.2 vs. 5.7 +/- 8.9%; CD3: 3.3 +/- 2.7 vs. 1.1 +/- 1.4%; CD68: 35.3 +/- 26.6 vs. 3.4 +/- 4.1%; each P <= 0.001). Conclusion EPCs and DCs were detected in a large collective of degenerative aortic valves, more frequently in bioprostheses than in native cusps. Aortoluminal presence of these primarily extravalvular cells co-localized with inflammatory cells is a novel key feature involved in aortic valve degeneration.