title: Short-term exposure to thapsigargin inhibits neointima formation in human saphenous vein.
abstract: Vascular smooth muscle cell (VSMC) migration and proliferation are involved in the intimal thickening responsible for late vein graft failure. In addition to growth and chemotactic factors, VSMCs require expression of matrix-degrading enzymes, e.g., metalloproteinases (MMP), to relieve the antiproliferative and antimigratory constraints of the extra-cellular matrix. Thapsigargin irreversibly inhibits Ca(2+)-ATPase, eliciting an increase in intracellular Ca2- and depletion of the intracellular calcium pools that are thought to be involved in the control of VSMC migration, VSMC proliferation, and MMP activity. We therefore studied the effect of thapsigargin on VSMC migration, VSMC proliferation, and MMP expression in human saphenous vein organ cultures. Vein segments were cultured for 14 days, and VSMC proliferation and migration were determined by autoradiography. Cell death was assessed using in situ end-labeling and lactate dehydrogenase release. Using Western blotting, we examined MMP-2 and MMP-9 and tissue inhibitor of metalloproteinases (TIMP)-1 and TIMP-2 expression. Exposure to thapsigargin at 10 nmol/L for 60 minutes before culture significantly inhibited neointimal thickening (60%, P < .05), intimal and medial VSMC proliferation (32%, P < .05 and 37%, P < .05, respectively), and VSMC migration (36%, P < .05). Thapsigargin at 10 nmol/L did not significantly increase cell death or MMP-2, MMP-9, TIMP-1, and TIMP-2 expression. These results suggest that blockade of Ca(2+)-ATPase by thapsigargin inhibits VSMC migration and proliferation involved in neointimal formation without affecting MMP-2 and MMP-9 expression. Because short-term exposure to thapsigargin was sufficient to inhibit neointima formation, this drug may prove useful in the treatment of intimal thickening after arterial bypass graft surgery.
authors.affiliation: Bristol Heart Institute, University of Bristol, Bristol Royal Infirmary, UK. s.j.george@bristol.ac.uk
authors.forename: S J
authors.initials: SJ
authors.lastname: George
authors.forename: J L
authors.initials: JL
authors.lastname: Johnson
authors.forename: G D
authors.initials: GD
authors.lastname: Angelini
authors.forename: J Y
authors.initials: JY
authors.lastname: Jeremy
mesh_terms: D017209:Apoptosis / Q000187:drug effects; D002118:Calcium / Q000378:metabolism; D000252:Calcium-Transporting ATPases / Q000037:antagonists & inhibitors*; D002455:Cell Division / Q000187:drug effects; D002465:Cell Movement / Q000187:drug effects; D017364:Collagenases / Q000096:biosynthesis / Q000235:genetics; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D018093:Gelatinases / Q000096:biosynthesis / Q000235:genetics; D005786:Gene Expression Regulation / Q000187:drug effects; D006801:Humans; D020778:Matrix Metalloproteinase 2; D020780:Matrix Metalloproteinase 9; D008666:Metalloendopeptidases / Q000096:biosynthesis / Q000235:genetics; D009924:Organ Culture Techniques; D012501:Saphenous Vein / Q000187:drug effects* / Q000293:injuries / Q000473:pathology; D015290:Second Messenger Systems / Q000187:drug effects; D019284:Thapsigargin / Q000494:pharmacology*; D019715:Tissue Inhibitor of Metalloproteinase-1 / Q000096:biosynthesis / Q000235:genetics; D019716:Tissue Inhibitor of Metalloproteinase-2 / Q000096:biosynthesis / Q000235:genetics; D017539:Tunica Intima / Q000187:drug effects* / Q000293:injuries / Q000473:pathology; D014945:Wound Healing / Q000187:drug effects
chemical_list: D004791:Enzyme Inhibitors; D019715:Tissue Inhibitor of Metalloproteinase-1; D019716:Tissue Inhibitor of Metalloproteinase-2; D019284:Thapsigargin; D017364:Collagenases; D018093:Gelatinases; D008666:Metalloendopeptidases; D020778:Matrix Metalloproteinase 2; D020780:Matrix Metalloproteinase 9; D000252:Calcium-Transporting ATPases; D002118:Calcium