Vascular leakage in chick embryos after expression of a secreted binding protein for fibroblast growth factors

Abstract

Fibroblast growth factors (FGFs) have been implicated in a variety of physiologic and pathologic processes from embryonic development to tumor growth and angiogenesis. FGFs are immobilized in the extracellular matrix of different tissues and require release from this storage site to trigger a response. Secreted FGF-binding proteins (FGF-BPs) can release immobilized FGFs, enhance the activity of locally stored FGFs and can thus serve as an angiogenic switch molecule in cancer. Here, we report on the effect of human FGF-BP transgene expression in chicken embryos. To establish the transgenic model, plasmid-based reporter vectors expressing luciferase, b-galactosidase or green fluorescent protein were introduced through different routes into 4-to 5-day-old embryos grown outside their egg shell on top of the yolk sac. This allows for easy manipulation and continuous observation of phenotypic effects. Expression of human FGF-BP induced dose-dependent vascular permeability, hemorrhage and embryonic lethality. Light and electron microscopic studies indicate that this hemorrhage results from compromised microvascular structure. An FGF-1 expression vector with an added secretory signal mimicked this vascular leakiness phenotype whereas wild-type FGF-1 required coexpression of a threshold amount of FGF-BP. This model is a powerful tool for real-time monitoring of the effects of transient transgene expression during embryogenesis.

The Angiogenic Switch Molecule, Secreted FGF-Binding Protein, an Indicator of Early Stages of Pancreatic and Colorectal Adenocarcinoma

“…Furthermore, FGF-BP was responsible for enhancing FGF-2-mediated angiogenesis in a chick chorioallantoic membrane (CAM) assay (90). Overexpression of FGF-BP in a chicken transgenic model resulted in embryonic lethality due to massive disruption of blood vessel structure and integrity and subsequent hemorrhage (94). FGF-BP is expressed below the level of detection by Northern blotting in normal adult human tissues.…”

Improved growth factor directed vascularization into fibrin constructs through inclusion of additional extracellular molecules

“…The chorioallantoic membrane (CAM) assay, used for more than half a century, has become a mainstay in the study of blood vessel development (Auerbach et al, 2003;Cruz et al, 2000;Cruz et al, 1997;DeFouw and DeFouw, 2000a;DeFouw and DeFouw, 2000b;Djonov et al, 2000a;Djonov et al, 2000b;McDonnell et al, 2005;Rizzo and DeFouw, 1996;Rizzo et al, 1995;Rizzo et al, 1993). The CAM assay has also proved useful for biological devices and in tissue engineering applications, particularly those concerning biocompatibility studies and angiogenic responses to tissue-engineered constructs (Borges et al, 2003a;Borges et al, 2003b;Nguyen et al, 1994;Ribatti et al, 2001;Rickert et al, 2003;Valdes et al, 2003;Valdes et al, 2002;Wong et al, 2003).…”

Stem cell therapy for critical limb ischaemia — a review

“…It was postulated that this would lead to creation of more mature blood vessels which would not "leak". The difference between tumour blood vessels and non-tumour angiogenesis is the ratio between VGF and FGF-1, the increased levels of FGF-1 leading to more mature blood vessel formation in normal healing processes [17]. This process has been the subject of clinical trials which have shown good results, but the principal problem has remained the lack of well controlled, adequately powered doubleblind controlled trials.…”