Production of platelet-derived growth factor-like molecules by cultured arterial smooth muscle cells accompanies proliferation after arterial injury.

The migration and proliferation of smooth muscle cells (SMCs) within the intima of arteries following mechanical injury is thought to be initiated by vessel wall injury and release of growth factors, in particular the platelet-derived growth factor (PDGF). However, the mechanism by which SMC proliferation is regulated after platelet interaction with the vessel wall has ceased is unknown. Here we show that SMCs derived from the intima of injured rat arteries (intimal SMCs) are phenotypically distinct from SMCs from unmanipulated vessels (medial SMCs). Intimal SMCs secrete 5-fold greater amounts of PDGF-like activity into conditioned medium in culture, have fewer receptors for 125I-labeled PDGF, and are not mitogenically stimulated by exogenous purified PDGF. This study demonstrates that two SMC phenotypes can develop in the adult rat artery and suggests that SMC proliferation in vivo may be controlled, in part, by SMCs that produce PDGF-like molecules.     

Analysis of platelet-derived growth factor receptor A and oligodendrocyte transcription factor 2 markers following Hydroxychloroquine administration in animal induced multiple sclerosis model

Metabolic Brain Disease - It has been shown that following demyelination, Oligodendrocyte Progenitor Cells (OPCs) migrate to the lesion site and begin to proliferate, and differentiate. This study...     

Identification of a c-fos-induced gene that is related to the platelet-derived growth factor/vascular endothelial growth factor family.

Using a mRNA differential screening of fibroblasts differing for the expression of c-fos we isolated a c-fos-induced growth factor (FIGF). The deduced protein sequence predicts that the cDNA codes for a new member of the platelet-derived growth factor/vascular endothelial growth factor (PDGF/VEGF) family. Northern blot analysis shows that FIGF expression is strongly reduced in c-fos-deficient cells. Transfection of exogenous c-fos driven by a constitutive promoter restores the FIGF expression in these cells. In contrast, both PDGF and VEGF expression is unaffected by c-fos. FIGF is a secreted dimeric protein able to stimulate mitogenic activity in fibroblasts. FIGF overexpression induces morphological alterations in fibroblasts. The cells acquire a spindle-shaped morphology, become more refractive, disorganized, and detach from the plate. These results imply that FIGF is a downstream growth and morphogenic effector of c-fos. These results also suggest that the expression of FIGF in response to c-fos activation induces specific differentiation patterns and its aberrant activation contributes to the malignant phenotype of tumors.     

Dual control of cell growth by somatomedins and platelet-derived growth factor.

Quiescent BALB/c 3T3 cells exposed briefly to a platelet-derived growth factor (PDGF) become "competent" to replicate their DNA but do not "progress" into S phase unless incubated with growth factors contained in platelet-poor plasma. Plasma from hypophysectomized rats is deficient in progression activity; it does not stimulate PDGF-treated competent cells to synthesize DNA, demonstrating that somatomedin C is required for progression. Various growth factors were tested for progression activity and competence activity by using BALB/c 3T3 tissue culture assays. Multiplication stimulating activity and other members of the somatomedin family of growth factors are (like somatomedin C) potent mediators of progression. Other mitogenic agents, such as fibroblast growth factor, are (like PDGF) potent inducers of competence. Growth factors with potent progression activity have little or no competence activity and vice versa. In contrast, simian virus 40 provides both competence and progression activity. Coordinate control of BALB/c 3T3 cell growth in vitro by competence factors and somatomedins may be a specific example of a common pattern of growth regulation in animal tissues.     

A histologically distinctive interstitial pneumonia induced by overexpression of the interleukin 6, transforming growth factor beta 1, or platelet-derived growth factor B gene.

Interstitial pneumonia is characterized by alveolitis with resulting fibrosis of the interstitium. To determine the relevance of humoral factors in the pathogenesis of interstitial pneumonia, we introduced expression vectors into Wistar rats via the trachea to locally overexpress humoral factors in the lungs. Human interleukin (IL) 6 and IL-6 receptor genes induced lymphocytic alveolitis without marked fibroblast proliferation. In contrast, overexpression of human transforming growth factor beta 1 or human platelet-derived growth factor B gene induced only mild or apparent cellular infiltration in the alveoli, respectively. However, both factors induced significant proliferation of fibroblasts and deposition of collagen fibrils. These histopathologic changes induced by the transforming growth factor beta 1 and platelet-derived growth factor B gene are partly akin to those changes seen in lung tissues from patients with pulmonary fibrosis and markedly contrast with the changes induced by overexpression of the IL-6 and IL-6 receptor genes that mimics lymphocytic interstitial pneumonia.     

Inhibition of vascular smooth muscle cell proliferation by DNA-RNA chimeric hammerhead ribozyme targeting to rat platelet-derived growth factor A-chain mRNA

BACKGROUND: Spontaneously hypertensive rats (SHR)-derived vascular smooth muscle cells (VSMC) show exaggerated growth and increasingly express platelet-derived growth factor (PDGF) A-chain mRNA compared to VSMC from normotensive Wistar-Kyoto (WKY) rats. OBJECTIVE: To investigate the effects of designed DNA-RNA chimeric hammerhead ribozyme to rat PDGF A-chain on exaggerated growth of VSMC from SHR. DESIGN AND METHODS: We designed and synthesized a 38-base DNA-RNA chimeric hammerhead ribozyme with two phosphorothioate linkages at the 3' terminal to cleave rat PDGF A-chain mRNA at the GUC sequence at nucleotide 921. We confirmed the cleavage activity of designed ribozyme by in vitro cleavage reaction and by lipofectin-mediated transfection of ribozyme into VSMC. RESULTS: Doses of 0.1 and 1 micromol/l DNA-RNA chimeric ribozyme dose-dependently inhibited basal DNA synthesis in VSMC from SHR. A dose of 1 micromol/l DNA-RNA chimeric ribozyme time-dependently inhibited basal DNA synthesis in VSMC from SHR. However, the same doses of all-RNA ribozyme had no effects on DNA synthesis in VSMC from SHR. Fluorescein isothiocyanate-labeled DNA-RNA chimeric ribozyme was recognized in cytosol at 30 min, and in nucleus at 60 min after lipofectin transfection. A dose of 1 micromol/l DNA-RNA chimeric ribozyme significantly inhibited expressions of both PDGF A-chain mRNA and PDGF-AA protein in VSMC from SHR, but not from WKY rats. CONCLUSION: These results indicated that the designed DNA-RNA chimeric ribozyme to PDGF A-chain mRNA effectively and specifically inhibited the exaggerated growth of VSMC from SHR at low concentrations, which were mediated by the reduction of PDGF A-chain mRNA and PDGF-AA protein expressions.     

Hirulog-1 reduces expression of platelet-derived growth factor in neointima of rat carotid artery induced by balloon catheter injury

Vascular restenosis is one of the major concerns for the treatment of atherosclerotic cardiovascular diseases using therapeutic vascular procedures. Hirulog-1, a synthetic thrombin inhibitor, effectively reduced ischemic events in coronary heart disease patients and caused less hemorrhagic complications compared to heparin. Thrombin stimulated the expression of platelet-derived growth factor (PDGF) in vascular cells. PDGF receptor blockers reduced angioplasty-induced restenosis in the swine model. The present study examined the effects of hirulog-1 on vascular stenosis, platelet deposition and the expression of PDGF in rat carotid arteries injured by balloon catheter. Multiple intravenous infusions of hirulog-1 (1 mg/kg/h for 4 h for 6 times), but not bolus injection or 1-2 times of infusion, reduced neointima/media ratio by 50% in balloon-injured carotid arteries compared to injured animals receiving saline alone. Activated partial thromboplastin time in hirulog-1-treated rats was significantly prolonged compared to saline controls but shorter than that in animals receiving heparin (50 U/kg/h). One of heparin-treated rat, but none of hirulog-1-treated, died from bleeding complication. Hirulog-1 injection transiently reduced platelet deposition on denuded intima visualized by scanning electron microscopy. Abundance of PDGF in neointima of injured carotid arteries detected by immunohistochemistry was significantly decreased following infusions of hirulog-1. The results suggest that balloon catheter injury induced neointima formation and the overexpression of PDGF in the neointima of rat carotid artery may be effectively suppressed by infusions with hirulog-1, a thrombin-specific inhibitor.     

Betaxolol inhibits extracellular signal-regulated kinase and P70S6 kinase activities and gene expressions of platelet-derived growth factor A-chain and transforming growth factor-beta1 in Dahl salt-sensitive hypertensive rats.

We evaluated the protective effects of long-term treatment with betaxolol, a specific beta-antagonist, on platelet-derived growth factor (PDGF) A-chain and transforming growth factor (TGF)-beta1 gene expression in the left ventricle of Dahl salt-sensitive hypertensive rats fed a high-salt diet. In addition, we evaluated the relations between these effects and coronary microvascular remodeling, expression of extracellular signal-regulated kinases (ERK) belonging to one subfamily of mitogen-activated protein kinases, and expression of p70S6 kinase belonging to one subfamily of ribosomal S6 kinases. Betaxolol (0.9 mg/kg/day, subdepressor dose) was administered for 5 weeks, from 6 weeks of age to the left ventricular hypertrophy stage at 11 weeks of age. Increased PDGF A-chain and TGF-beta1 mRNA and protein expression were suppressed by betaxolol. Upregulated activities of ERK1/2 and p70S6 kinase phosphorylations were decreased by betaxolol. Betaxolol administration resulted in significant improvements in the wall-to-lumen ratio, perivascular fibrosis and myocardial fibrosis. Thus, we conclude that ERK1/2 and p70S6 kinase activities may play a key role in coronary microvascular remodeling of Dahl salt-sensitive hypertensive rats, and that beneficial effects of betaxolol on cardiovascular remodeling may be at least partially mediated by decreased PDGF A-chain and TGF-beta1 expression in the left ventricle.     

Smooth muscle cell migration induced by shear-loaded platelets and endothelial cells. Enhanced platelet-derived growth factor production by shear-loaded platelets.

BACKGROUND: Uncontrolled migration and proliferation of smooth muscle cells (SMC) are the main mechanisms of development of atherosclerotic neointima. However, it has not yet been elucidated how mechanical stress is involved in this process. We investigated smooth muscle cell mitogenic activity induced by shear-loaded platelets and endothelial cells. METHODS: Experimental design: in vitro experimental study. We devised four types of conditioned media; supernatant of mixed culture of platelets and endothelial cell (ST), supernatant of shear-loaded mixed culture of platelets and endothelial cell (SH), ST medium neutralised with anti-PDGF antibody (ST+), and SH medium neutralised with anti-PDGF antibody (SH+). Smooth muscle cells were cultured in each conditioned medium, and their spreading activity was determined under a microscope. RESULTS: Smooth muscle cells spreading activity in the SH group was significantly greater than that in the ST group. Their spreading activity was suppressed by anti-PDGF antibody under shear conditions (SH+), but it was not by anti-PDGF antibody under static conditions (ST+). CONCLUSIONS: Our results demonstrate that platelet-derived growth factor is produced by shear-loaded platelets and endothelial cells, and local mechanical forces may play an important role in cardiovascular disease.