A angiogênese é um processo de múltiplos degraus que conduz a formação de novos vasos sangüíneos a partir de capilares preexistentes e que participa em diversos processos fisiológicos e patológicos incluindo o crescimento tumoral e de metástases. Vários métodos têm sido desenvolvidos para estudar a angiogênese. A técnica de indução de vascularização na córnea do coelho foi uma das primeiras a serem desenvolvidas pelo grupo de Gimbrone e colaboradores. O principal objetivo deste trabalho foi descrever a técnica de indução de angiogênese na córnea do coelho, através do implante cirúrgico de "pellets" de polimetilmetacrilato (PMMA) contendo fator básico de crescimento fibroblástico (FCFb). Um "pellet" contendo 0.1 mig de FCFb foi implantado em uma das córneas e outro, sem FCFb, na córnea contralateral, como controle. A atividade angiogênica foi expressa por um índice, resultado da contagem do número de vasos e da medição de seu comprimento em milímetros. Os resultados mostraram que o FCFb induz crescimento vascular significativo a partir do sexto dia após o implante do "pellet" com atividade máxima no 15º dia. O PMMA sem FCFb não estimulou significativamente a vascularização. Esta técnica fornece uma nova opção de modelo para o estudo da biologia da angiogênese e para avaliação de drogas antiangiogênicas, usando "pellets" de polimetilmetacrilato (PMMA).

Angiogenesis is a multistep and redundant process crucial in several physiological events and pathophysiological developments such as cancer. Since the early findings by Folkman et al. that tumor growth is dependent on new vascularization, it is now broadly accepted that solid tumors cannot grow beyond 1-2 mm without a vascular supply of oxygen and nutrients.1) Further, there is a substantial body of evidence indicating that attacking tumor neovascularization is a promising approach in the treatment of cancer.2)The acquisition of an angiogenic phenotype in endothelial cells requires that angiogenic factors be overexpressed and released by cancer cells and host cells. These factors include fibroblastic growth factors and vascular endothelial growth factors that bind to specific receptors on the endothelial cell surface stimulating their migration and proliferation.3,4) On the other hand, the migration and organization of endothelial cells in capillary structures depend on the activity of the pericellular fibrinolytic system and the overexpression of different cellular adhesion molecules.5) All these events in the angiogenic process afford potential targets for an antiangiogenic therapy.Many compounds derived from various natural sources have been found to have antiangiogenic effects using both in vitro and in vivo models. 6) These compounds include extracts and fractions from cartilage. 7) Cartilage is an avascular tissue, and for this reason was believed to contain compounds with antiangiogenic activity. This hypothesis was first tested in 1973 by Eisenstein et al., who reported that cartilage extracted with guanidine 1 M did not resist to becoming vascularized when placed on the chick chorioallantoic membrane (CAM).8) It was later demonstrated by Folkman and Ingber that cartilage could inhibit tumor-induced angiogenesis in the CAM model. 9) Based on those works, recent studies have shown that substances isolated from shark cartilage, for example U-995 and AE-941, inhibit angiogenesis and tumor growth in vivo. 10,11) Fontenele et al. recently described analgesic and antiinflammatory properties of a water soluble fraction (WSF) of shark cartilage that was attributed principally to a small peptide with a molecular weight of 2.3 KDa.12) In the latter work these in vivo pharmacological effects were observed with oral as well as intraperitoneally administration.The aims of the present study were a) to demonstrate the ability of oral shark cartilage to exert an inhibitory effect on rabbit cornea neovascularization induced by basic fibroblast growth factor (bFGF), and b) to examine in the same model a newly described bioactive fraction of shark cartilage for antiangiogenic activity. Several angiogenic inhibitors have been obtained from shark cartilage, some of these are currently in clinical trials for assessment of safety and therapeutic efficacy in humans. Still, shark cartilage taken orally is commonly used in alternative and complimentary medicine for various ailments including serious diseases such as cancer. Howe...