RESUMO
Connective tissue growth factor (CTGF) is a member of the CCN family of growth factors. CTGF is important in scarring, wound healing, and fibrosis. It has also been implicated to play a role in angiogenesis, in addition to vascular endothelial growth factor (VEGF). In the eye, angiogenesis and subsequent fibrosis are the main causes of blindness in conditions such as diabetic retinopathy. We have applied three different models of angiogenesis to homozygous CTGF(-/-) and heterozygous CTGF(+/-) mice to establish involvement of CTGF in neovascularization. CTGF(-/-) mice die around birth. Therefore, embryonic CTGF(-/-), CTGF(+/-), and CTGF(+/+) bone explants were used to study in vitro angiogenesis, and neonatal and mature CTGF(+/-) and CTGF(+/+) mice were used in models of oxygen-induced retinopathy and laser-induced choroidal neovascularization. Angiogenesis in vitro was independent of the CTGF genotype in both the presence and the absence of VEGF. Oxygen-induced vascular pathology in the retina, as determined semi-quantitatively, and laser-induced choroidal neovascularization, as determined quantitatively, were also not affected by the CTGF genotype. Our data show that downregulation of CTGF levels does not affect neovascularization, indicating distinct roles of VEGF and CTGF in angiogenesis and fibrosis in eye conditions.
Assuntos
Proteínas Imediatamente Precoces/fisiologia , Peptídeos e Proteínas de Sinalização Intercelular/fisiologia , Neovascularização Patológica/metabolismo , Animais , Animais Recém-Nascidos , Osso e Ossos/irrigação sanguínea , Neovascularização de Coroide/etiologia , Neovascularização de Coroide/genética , Neovascularização de Coroide/fisiopatologia , Fator de Crescimento do Tecido Conjuntivo , Embrião de Mamíferos/irrigação sanguínea , Proteínas Imediatamente Precoces/biossíntese , Proteínas Imediatamente Precoces/genética , Técnicas In Vitro , Peptídeos e Proteínas de Sinalização Intercelular/biossíntese , Peptídeos e Proteínas de Sinalização Intercelular/genética , Lasers , Camundongos , Camundongos Knockout , Neovascularização Patológica/genética , Neovascularização Patológica/fisiopatologia , Oxigênio , Doenças Retinianas/induzido quimicamente , Doenças Retinianas/genética , Doenças Retinianas/fisiopatologia , Fator A de Crescimento do Endotélio Vascular/farmacologiaRESUMO
A major obstacle in the study of angiogenesis and the testing of new agents with anti-angiogenic potential has been the lack of experimental models with predictive in vivo value. We describe here the combined use of in vitro and in vivo angiogenesis models that are based on endochondral bone development. This approach led to the identification of a new inhibitor of matrix metalloprotease (MMP) activity that inhibits neovascularization in vitro and in vivo while osteoclast invasion, which occurs simultaneously during bone development, remained unaffected. In contrast, the broad-spectrum MMP-inhibitor marimastat inhibited both in vitro angiogenesis and osteoclastogenesis dose-dependently but displayed severe toxic side effects in vivo. The combined use of these experimental models may, therefore, facilitate the discovery of mechanisms underlying angiogenesis and lead to identification of new pharmacological compounds with clinical efficacy and appropriate selectivity in the treatment of angiogenesis-dependent disorders like arthritis and cancer.