Cell composition of the human pulmonary valve: A comparative study with the aortic valve - The VESALIO* project

Background. Cell populations present in human semilunar valves have not bee n investigated thoroughly. The aim of this study was to characterize the ce ll phenotypes in pulmonary valve leaflets (PVL) in comparison with aortic ( AVL) valve leaflets. Methods. AVL and PVL were dissected from hearts (n = 4) harvested from tran splanted patients. Leaflets were processed for immunocytochemistry analysis and Western blotting procedures using a panel of monoclonal antibodies spe cific for cytoskeletal/contractile antigens. Results. The fibrosa and the ventricularis layers of AVL had a higher cellu larity than PVL. In PVL and AVL most cells were reactive for vimentin and n onmuscle (NM) myosin, though vimentin-positive cells were more abundant in AVL than in PVL. Sparse cells positive to antismooth muscle (SM) alpha -act in, calponin, and anti-SM myosin antibodies were found only at the outer ed ge of fibrosa. In Western blotting, AVL and PVL extracts were shown to be e qually reactive for vimentin, SM alpha -actin, and NM myosin, whereas both valves were negative for SM myosin and SM22. Conclusions. Three distinct cell phenotypes have been identified in both va lves: fibroblasts, myofibroblasts, and fetal-type SM cells whose distributi on is specifically related to the valve layers. Although PVL and AVL cell p opulations differ quantitatively, some minor qualitative differences exist for vimentin and NM myosin distribution. These data are essential for studi es aimed at repopulating valve scaffolds by using tissue engineering techno logy. (Ann Thorac Surg 2000;70:1594-600) (C) 2000 by The Society of Thoraci c Surgeons.