243
Atherosclerosis, 34 ( 1 9 7 9 ) 2 4 3 - - 2 4 8 9 E l s e v i e r / N o r t h - H o l l a n d Scientific P u b l i s h e r s , Ltd.
CHRONIC R E N A L F A I L U R E AND A T H E R O G E N E S I S Serum Factors Stimulate the Proliferation o f H u m a n Arterial Smooth Muscle Cells
J.D. B A G D A D E
Department o f Medicine, University o f Washington School o f Medicine and Providence Medical Center, 500-17th Avenue C-34008, Seattle, WA 98124 (U.S.A.) (Received 6 March, 1979) (Revised, received 20 J u l y , 1 9 7 9 ) (Accepted 20 July, 1979)
Summary To assess the role of serum factors in the genesis o f accelerated vascular disease in chronic renal failure, human arterial smooth muscle cells (SMC) and dermal fibroblasts were grown in culture and the effects of serum from chronic dialysis patients on cell proliferation was studied. Exposure to serum from these renal failure patients was associated with significantly greater growth of both SMC and fibroblasts than that observed with control serum. A portion of this mitogenic effect appears to be related to the presence of a factor(s) which is heat stable, dialysable, and is contained in the lipoprotein deficient fraction o f plasma of density greater than 1.25 g/dl. These findings suggest that circulating substances which stimulate the proliferation of SMC m a y contribute to accelerated cardiovascular disease in patients undergoing chronic dialysis treatment. Key w o r d s :
Smooth muscle cell -- Atherosclerosis
-
-
Renal failure
Introduction Evidence is increasing to indicate that proliferation o f the multipotential s m o o t h muscle cell (SMC), the predominant cell t y p e in the intima and media o f larger arteries, is a central process in atherogenesis. Indeed, it has been This work was supported by grants No. 5 RO1-HL16219-05 from the National Heart and Lung Institute and the P e m c o I n s u r a n c e Company.
244
shown in b o t h experimental animals [1] and man [2] that this cell proliferates in the intima prior to the accumulation of lipid and other substances in the fully developed atheromatous lesion. Since it is n o w possible to grow SMC from man and animals in tissue c~dture, factors which stimulate their proliferation m a y be identified. The observation that chronic dialysis patients succumb prematurely from an unexplained and accelerated form of cardiovascular disease [3] suggests the possibility that potentially atherogenic substance(s) normally excreted b y the kidney might accumulate in high concentrations in uremia. To determine whether serum from chronic dialysis patients contains factors capable of promoting SMC proliferation and thereby contribute to the genesis of their accelerated vascular disease, the effects o f their serum on cell growth was studied. Methods Human arterial smooth muscle cell cultures were grown from explants of intimal--medial segments of normal-appearing pieces of renal artery obtained at the time of renal transplantation and from the thoracic aorta of young nonuremic sudden death victims using methods of Ross [4]. The explants were grown initially in 30% pooled human serum in a modified Dulbecco--Vogt medium based on that described b y Eagle. Smooth muscle cells from the explants were subcultured in the same medium. Cells from the second to fourth sub-culture were used to test the effect of serum factors upon cell proliferation. Human skin fibroblasts were grown from explants of foreskin obtained at the time of circumcision. Fibroblasts were grown in parallel with smooth muscle cells under similar conditions. Pooled serum for these studies was obtained from equivalent volumes of clotted blood from samples drawn after an overnight fast from t w o different groups of 6 normal human control subjects (3 male and 3 female} and 6 chronic hemodialysis patients with stable chronic uremia immediately prior to their starting morning dialysis (20 h weekly on a two-layer Kiil dialyzer). Lipoprotein
Atherosclerosis, 34 ( 1 9 7 9 ) 2 4 3 - - 2 4 8 9 E l s e v i e r / N o r t h - H o l l a n d Scientific P u b l i s h e r s , Ltd.
CHRONIC R E N A L F A I L U R E AND A T H E R O G E N E S I S Serum Factors Stimulate the Proliferation o f H u m a n Arterial Smooth Muscle Cells
J.D. B A G D A D E
Department o f Medicine, University o f Washington School o f Medicine and Providence Medical Center, 500-17th Avenue C-34008, Seattle, WA 98124 (U.S.A.) (Received 6 March, 1979) (Revised, received 20 J u l y , 1 9 7 9 ) (Accepted 20 July, 1979)
Summary To assess the role of serum factors in the genesis o f accelerated vascular disease in chronic renal failure, human arterial smooth muscle cells (SMC) and dermal fibroblasts were grown in culture and the effects of serum from chronic dialysis patients on cell proliferation was studied. Exposure to serum from these renal failure patients was associated with significantly greater growth of both SMC and fibroblasts than that observed with control serum. A portion of this mitogenic effect appears to be related to the presence of a factor(s) which is heat stable, dialysable, and is contained in the lipoprotein deficient fraction o f plasma of density greater than 1.25 g/dl. These findings suggest that circulating substances which stimulate the proliferation of SMC m a y contribute to accelerated cardiovascular disease in patients undergoing chronic dialysis treatment. Key w o r d s :
Smooth muscle cell -- Atherosclerosis
-
-
Renal failure
Introduction Evidence is increasing to indicate that proliferation o f the multipotential s m o o t h muscle cell (SMC), the predominant cell t y p e in the intima and media o f larger arteries, is a central process in atherogenesis. Indeed, it has been This work was supported by grants No. 5 RO1-HL16219-05 from the National Heart and Lung Institute and the P e m c o I n s u r a n c e Company.
244
shown in b o t h experimental animals [1] and man [2] that this cell proliferates in the intima prior to the accumulation of lipid and other substances in the fully developed atheromatous lesion. Since it is n o w possible to grow SMC from man and animals in tissue c~dture, factors which stimulate their proliferation m a y be identified. The observation that chronic dialysis patients succumb prematurely from an unexplained and accelerated form of cardiovascular disease [3] suggests the possibility that potentially atherogenic substance(s) normally excreted b y the kidney might accumulate in high concentrations in uremia. To determine whether serum from chronic dialysis patients contains factors capable of promoting SMC proliferation and thereby contribute to the genesis of their accelerated vascular disease, the effects o f their serum on cell growth was studied. Methods Human arterial smooth muscle cell cultures were grown from explants of intimal--medial segments of normal-appearing pieces of renal artery obtained at the time of renal transplantation and from the thoracic aorta of young nonuremic sudden death victims using methods of Ross [4]. The explants were grown initially in 30% pooled human serum in a modified Dulbecco--Vogt medium based on that described b y Eagle. Smooth muscle cells from the explants were subcultured in the same medium. Cells from the second to fourth sub-culture were used to test the effect of serum factors upon cell proliferation. Human skin fibroblasts were grown from explants of foreskin obtained at the time of circumcision. Fibroblasts were grown in parallel with smooth muscle cells under similar conditions. Pooled serum for these studies was obtained from equivalent volumes of clotted blood from samples drawn after an overnight fast from t w o different groups of 6 normal human control subjects (3 male and 3 female} and 6 chronic hemodialysis patients with stable chronic uremia immediately prior to their starting morning dialysis (20 h weekly on a two-layer Kiil dialyzer). Lipoprotein
