Vacuolar H(+)-ATPase plays a crucial role in growth and phenotypic modulation of myofibroblasts in cultured human saphenous vein.
BACKGROUND
The molecular mechanism of neointimal hyperplasia after vein graft surgery remains elusive. Vacuolar H(+)-ATPase (V-ATPase) is involved in intracellular trafficking and may play a crucial role in neointimal cell growth.


RESULTS
Cultured human saphenous vein segments developed neointimal formation within 10 days. Neointimal cells were positive for vimentin and alpha-smooth muscle actin but negative for desmin, which is indicative of myofibroblasts. Those myofibroblasts were found to have originated from periadventitial fibroblasts, which upregulated the expression of 16-kDa proteolipid of V-ATPase before proliferation and phenotypic modulation. Neointimal myofibroblast growth and survival were highly sensitive to inhibition of V-ATPase by bafilomycin A(1) (BA(1)), because the incorporation of [(3)H]thymidine into the myofibroblasts was significantly inhibited by nanomolar concentrations of BA(1) and apoptotic cell death was induced by a similar concentration range of BA(1). In contrast, endothelial cells and differentiated smooth muscle cells were resistant to apoptosis by BA(1).


CONCLUSIONS
These results suggest that V-ATPase plays a crucial role in growth and phenotypic modulation of myofibroblasts that contributes to neointimal formation in cultured human saphenous vein.
Otani
H
H
Department of Thoracic and Cardiovascular Surgery, Kansai Medical University, Moriguchi, Japan. otanih@takii.kmu.ac.jp
Yamamura
T
T
Nakao
Y
Y
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
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D000943:Antigens, Differentiation / Q000096:biosynthesis; D017209:Apoptosis / Q000187:drug effects; D001973:Bromodeoxyuridine; D002455:Cell Division / Q000187:drug effects; D002465:Cell Movement; D002478:Cells, Cultured; D004305:Dose-Response Relationship, Drug; D005260:Female; D005347:Fibroblasts / Q000166:cytology / Q000187:drug effects / Q000201:enzymology*; D006801:Humans; D066298:In Vitro Techniques; D018942:Macrolides; D008297:Male; D008875:Middle Aged; D009131:Muscle, Smooth, Vascular / Q000166:cytology / Q000187:drug effects / Q000201:enzymology*; D010641:Phenotype; D021122:Protein Subunits; D011510:Proteolipids / Q000096:biosynthesis; D006180:Proton-Translocating ATPases / Q000378:metabolism*; D012501:Saphenous Vein / Q000166:cytology / Q000201:enzymology*; D013936:Thymidine / Q000378:metabolism; D017539:Tunica Intima / Q000166:cytology / Q000378:metabolism*; D025262:Vacuolar Proton-Translocating ATPases
D000900:Anti-Bacterial Agents; D000943:Antigens, Differentiation; D018942:Macrolides; D021122:Protein Subunits; D011510:Proteolipids; C040929:bafilomycin A1; D025262:Vacuolar Proton-Translocating ATPases; D006180:Proton-Translocating ATPases; D001973:Bromodeoxyuridine; D013936:Thymidine