Fibrin monomer and fibrinopeptide B act additively to increase DNA synthesis in smooth muscle cells cultured from human saphenous vein.
OBJECTIVE
We investigated the hypothesis that fibrinogen increased DNA synthesis (and cell proliferation) of smooth muscle cells (SMCs) cultured from human saphenous vein and that the increased DNA synthesis was attenuated when cells were cultured on polymeric collagen.


METHODS
SMCs were cultured from human saphenous vein on plastic, fibronectin, monomeric, and polymeric collagen. Fibrinogen products were prepared by proteolytic digestion. DNA synthesis was measured by bromodeoxyuridine incorporation into DNA, cell proliferation by cell counting, cyclic adenosine monophosphate by enzyme-linked immunosorbent assay, and fibrinopeptide B labeled with iodine 125 used for binding studies.


RESULTS
Fibrin monomer (0.003-0.1 micromol/L) stimulated a concentration-dependent increase in DNA synthesis of up to 10-fold, which could be inhibited by the peptide Bbeta15-42. The stimulation of DNA synthesis was highest for cells cultured on plastic and lowest for cells cultured on type I collagen polymer. Much higher concentrations of fibrinogen (0.3-1 micromol/L) were required to effect similar increases in DNA synthesis. Fibrinogen had a particular effect to augment DNA synthesis, up to 14-fold, when cells were cultured on monomeric type I collagen. This augmented DNA synthesis was inhibited by a neutralizing antibody to urokinase-type plasminogen activator. Incubation of cells cultured on collagen monomer with fibrinogen resulted in production of fibrinopeptide B. Fibrinopeptide B (5 micromol/L) increased DNA synthesis by fourfold and had additive effects with fibrin monomer to increase DNA synthesis. Iodinated tyrosine fibrinopeptide B bound to SMCs (dissociation constant 0.6 micromol/L).


CONCLUSIONS
Cultured human saphenous vein SMCs appear to have high-affinity receptors for fibrin monomer and fibrinopeptide B, the engagement of which stimulates DNA synthesis. These mechanisms may be pertinent to the association between fibrinogen and vein graft stenosis in vivo.
Sturge
J
J
Department of Vascular Surgery, Imperial College School of Science, Technology, and Medicine, London, UK.
Carey
N
N
Davies
A H
AH
Powell
J T
JT
D001973:Bromodeoxyuridine / Q000378:metabolism; D002455:Cell Division / Q000187:drug effects; D002478:Cells, Cultured; D003094:Collagen; D003470:Culture Media; D000242:Cyclic AMP / Q000378:metabolism; D004247:DNA / Q000096:biosynthesis*; D005338:Fibrin Fibrinogen Degradation Products / Q000378:metabolism / Q000494:pharmacology*; D005340:Fibrinogen / Q000494:pharmacology; D005345:Fibrinopeptide B / Q000494:pharmacology*; D006801:Humans; D009131:Muscle, Smooth, Vascular / Q000166:cytology / Q000378:metabolism*; D012501:Saphenous Vein / Q000166:cytology / Q000378:metabolism*; D012710:Serum Albumin, Bovine / Q000494:pharmacology
D003470:Culture Media; D005338:Fibrin Fibrinogen Degradation Products; C011468:fibrinmonomer; D012710:Serum Albumin, Bovine; D005345:Fibrinopeptide B; D005340:Fibrinogen; D003094:Collagen; D004247:DNA; D000242:Cyclic AMP; D001973:Bromodeoxyuridine