Adult human aortic smooth muscle cells in culture produce active TGF-beta.
Vascular smooth muscle cells (VSMC) from adult human aortas proliferated in culture in response to fetal calf serum (FCS) with a population doubling time of 70-85 h compared with 35 +/- 5 h for VSMC derived from adult rat aortas. Medium conditioned on cultures prepared from aortas from three different donors and mixed 1:1 with fresh Dulbecco's modified Eagle's medium plus 20% FCS [human conditioned medium (HCM)] reduced the rate of proliferation of rat VSMC by 46 +/- 6% (n = 3) after 48 h compared with cells in fresh medium. HCM did not reduce the proportion (> 65%) of rat VSMC that entered DNA synthesis but delayed entry into mitosis by at least 18 h. This effect was similar to previous observations of the action of transforming growth factor-beta (TGF-beta) on rat VSMC (G. K. Owens, A. A. Geisterfer, Y. W. Yang, and A. Komoriya. J. Cell Biol. 107: 771-780, 1988). A TGF-beta assay using DNA synthesis in mink lung epithelial cells confirmed that human, but not rat, VSMC in culture secrete active TGF-beta. Addition of a neutralizing antibody to TGF-beta to human VSMC in the presence of 20% FCS decreased the population doubling time from 74 +/- 3 to 46 +/- 6 h (n = 3). These observations demonstrate that the long population doubling time of human VSMC is due to the production of active TGF-beta and to an inhibitory autocrine loop.
Kirschenlohr
H L
HL
Department of Biochemistry, University of Cambridge, United Kingdom.
Metcalfe
J C
JC
Weissberg
P L
PL
Grainger
D J
DJ
D000818:Animals; D000906:Antibodies / Q000276:immunology; D001011:Aorta / Q000166:cytology / Q000378:metabolism*; D002455:Cell Division / Q000187:drug effects; D002478:Cells, Cultured; D017077:Culture Media, Conditioned; D006801:Humans; D009131:Muscle, Smooth, Vascular / Q000166:cytology / Q000378:metabolism*; D051381:Rats; D016212:Transforming Growth Factor beta / Q000276:immunology / Q000378:metabolism* / Q000494:pharmacology
D000906:Antibodies; D017077:Culture Media, Conditioned; D016212:Transforming Growth Factor beta