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In vivo effects of vascular endothelial growth factor on the chicken chorioallantoic membrane
J Wilting1, B Christ, M Bokeloh
1Anatomisches Institut II, Albert-Ludwigs-Universität, Freiburg, Germany.
Abstract:
The effect of vascular endothelial growth factor (VEGF165) on the chorioallantoic membrane (CAM) of 13-day-old chick embryos was studied. The factor was applied in doses of 0.5-4 micrograms for a period of up to 4 days. Macroscopical, histological and immunohistological studies were carried out. The localization of the factor was examined with an anti-VEGF antibody. The mitogenicity of VEGF165 and basic fibroblast growth factor (bFGF) were studied by means of the BrdU-anti-BrdU method. Furthermore, the effect of heparin alone and in combination with VEGF165 was investigated. VEGF165 specifically induces angiogenesis in doses of 0.5 microgram and more. A brush-like formation of blood vessels can be seen in the region of the precapillary vessels. Angiogenesis also takes place in the region of the capillaries and the venules. Histologically we found indications of sprouting as well as of intussusceptive capillary growth. The presence of the factor in the application area could be demonstrated with the anti-VEGF antibody for a period of 3 days. The factor is located in the chorionic epithelium and the intraepithelial capillaries. The BrdU-studies show that VEGF165 induces strong endothelial cell proliferation, whereas bFGF elicits fibrocyte proliferation and minor endothelial cell proliferation. Heparin induces squamous metaplasia of the chorionic and allantoic epithelium in combination with an aggregation of fibrocytes. We could not detect any enhancement of VEGF165 by heparin.
Insights
Vascular endothelial growth factor (VEGF165) stimulates new blood vessel formation (angiogenesis) in chick embryos. VEGF165 promotes endothelial cell proliferation, while heparin does not enhance its effects.
Area of Science:
- Developmental Biology
- Angiogenesis Research
- Vascular Biology
Background:
- Vascular endothelial growth factor (VEGF165) is a key regulator of angiogenesis.
- Understanding VEGF165's role in vascular development is crucial for regenerative medicine.
Purpose of the Study:
- To investigate the effects of VEGF165 on the chorioallantoic membrane (CAM) of chick embryos.
- To determine the localization and duration of VEGF165 activity.
- To compare the mitogenic effects of VEGF165 and basic fibroblast growth factor (bFGF).
Main Methods:
- Application of VEGF165 to the CAM of 13-day-old chick embryos.
- Macroscopical, histological, and immunohistological analyses.
- Detection of VEGF165 using anti-VEGF antibodies.
- BrdU incorporation assay to assess cell proliferation.
- Investigation of heparin's effects alone and with VEGF165.
Main Results:
- VEGF165 induced significant angiogenesis at doses of 0.5 µg and higher, characterized by brush-like vascular formations.
- Histological examination revealed both sprouting and intussusceptive capillary growth.
- VEGF165 was detectable for 3 days, localized in the chorionic epithelium and intraepithelial capillaries.
- VEGF165 strongly stimulated endothelial cell proliferation, whereas bFGF primarily induced fibrocyte proliferation.
- Heparin induced squamous metaplasia and fibrocyte aggregation, without enhancing VEGF165 activity.
Conclusions:
- VEGF165 is a potent inducer of angiogenesis and endothelial cell proliferation in vivo.
- The study elucidates the mechanisms of VEGF165-mediated vascular development in the CAM model.
- Heparin does not potentiate VEGF165-induced angiogenesis and has distinct effects on epithelial and connective tissues.