Department of Medicine I , Wallenberg Laboratory for Cardiovascular Research , University of Goteborg , Sweden .
Exp Cell Res 176 : 319-35 ( 1988)
Abstract
Human arterial smooth muscle cells ( hASMC ) were cultured from explants of the inner media of uterine arteries obtained at hysterectomy .
The presence of alpha-actin and smooth muscle-specific actin isoforms and the microscopic appearance of the cells in secondary culture established their smooth muscle origin .
The hASMC were diploid and had no signs of transformation .
Plasma-derived serum failed to stimulate their proliferation in vitro .
Their rate of proliferation was , however , proportional to the concentration of whole blood serum in the medium .
Anti-PDGF IgG at high concentrations inhibited the stimulatory effect of whole blood serum on cell proliferation .
This suggests that hASMC depend on exogenous PDGF for their growth .
In PDS or bovine serum albumin cell numbers remained constant for 7 days in culture and the thymidine index was below 1% per 24 h . When reexposed to whole blood serum these cells started to proliferate within 2 days .
This indicates that hASMC when deprived of PDGF enter a quiescent state that is fully reversible upon rexposure to the mitogen .
Heparin is a powerful growth inhibitor for SMC .
In our system , heparin caused a dose-dependent inhibition of cell proliferation despite optimal concentrations of whole blood serum .
This inhibition was reversible upon withdrawal of heparin .
At heparin concentrations which caused a half-maximal inhibition it was also competed for by increasing concentrations of whole blood serum .
Quiescent hASMC expressed the PDGF receptor on their surface as judged from immunofluorescence with a monoclonal antibody .
This was true irrespective of whether growth arrest was achieved by serum depletion or by the addition of heparin to serum-containing medium .
Cells growing in the presence of whole blood serum did not , however , express the receptor antigen .
These observations suggest that heparin may interfere with PDGF or with its binding and further processing at the level of the cell-surface receptor .