Potential role of vacuolar H-adenosine triphosphatase in neointimal formation in cultured human saphenous vein.
OBJECTIVE
Vacuolar H(+)-adenosine triphosphatase plays a pivotal role in pH regulation and molecular transport across the vacuolar membranes and is involved in cell proliferation and transformation. In the present study, possible involvement of vacuolar H(+)-adenosine triphosphatase in neointimal formation was investigated in an organ culture model of human saphenous vein.


RESULTS
Cultured saphenous vein segments developed neointimal formation and marked thickening of the media within 14 days. Neointimal formation and medial thickening were completely inhibited by 10 nmol/L bafilomycin A(1), a selective inhibitor of vacuolar H(+)-adenosine triphosphatase, although structurally related macrolide antibiotics FK-506 and erythromycin were without an effect. The neointimal cells were positive for alpha-smooth muscle actin and vimentin but negative for desmin, indicative of myofibroblasts. The emergence of myofibroblasts was inhibited, and endothelial cells were preserved in the saphenous vein segments treated with bafilomycin A(1). Uptake of bromodeoxyuridine, a proliferation marker, by myofibroblasts was abrogated in the saphenous vein segments treated with 10 nmol/L bafilomycin A(1). Detection of apoptotic cells by terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling concomitant with identification of desmin-expressing smooth muscle cells demonstrated that neointimal myofibroblasts, but not medial smooth muscle cells, that expressed desmin underwent apoptosis by treatment with bafilomycin A(1).


CONCLUSIONS
These results suggest that vacuolar H(+)-adenosine triphosphatase may be involved in myofibroblast growth that contributes to neointimal formation and medial thickening in cultured human saphenous vein. Increased sensitivity of myofibroblasts, but not endothelial cells, and differentiated smooth muscle cells to bafilomycin A(1) may have potential therapeutic implications in the treatment for vein graft disease.
Otani
H
H
Department of Thoracic and Cardiovascular Surgery, Kansai Medical University, Department of Surgery (II), School of Medicine, Kanazawa University, Kanazawa, Japan.
Ohmiya
H
H
Hattori
R
R
Fujii
H
H
Ninomiya
H
H
Kido
M
M
Kawaguchi
H
H
Osako
M
M
Imamura
H
H
Ohta
T
T
Ohkuma
S
S
D000199:Actins / Q000378:metabolism; D000368:Aged; D000369:Aged, 80 and over; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D017209:Apoptosis; D001692:Biological Transport / Q000187:drug effects; D015415:Biomarkers; D002455:Cell Division; D003893:Desmin / Q000378:metabolism; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005260:Female; D005347:Fibroblasts / Q000187:drug effects / Q000378:metabolism; D005455:Fluorescent Antibody Technique; D006801:Humans; D007124:Immunoenzyme Techniques; D007166:Immunosuppressive Agents / Q000494:pharmacology; D020287:In Situ Nick-End Labeling; D018942:Macrolides; D008297:Male; D008875:Middle Aged; D009924:Organ Culture Techniques; D006180:Proton-Translocating ATPases / Q000037:antagonists & inhibitors / Q000502:physiology*; D012501:Saphenous Vein / Q000187:drug effects / Q000201:enzymology*; D017539:Tunica Intima / Q000187:drug effects / Q000201:enzymology*; D014617:Vacuoles / Q000187:drug effects / Q000201:enzymology*; D014746:Vimentin / Q000378:metabolism
D000199:Actins; D000900:Anti-Bacterial Agents; D015415:Biomarkers; D003893:Desmin; D004791:Enzyme Inhibitors; D007166:Immunosuppressive Agents; D018942:Macrolides; D014746:Vimentin; D006180:Proton-Translocating ATPases