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Proliferation pattern of capillary endothelial cells in chorioallantoic membrane development indicates local growth
1Anatomisches Institut II, Albert-Ludwigs-Universität Freiburg, Germany.
Insights
Endothelial cell proliferation in chick chorioallantoic membrane (CAM) decreases after day 10, shifting to focal patterns. Vascular endothelial growth factor (VEGF) stimulates proliferation and randomizes cell distribution.
Area of Science:
- Angiogenesis research
- Developmental biology
- Vascular biology
Background:
- Endothelial cell proliferation and distribution are crucial for vascular development.
- The chick chorioallantoic membrane (CAM) is a widely used model for studying angiogenesis.
- Understanding the regulation of endothelial cell behavior is key to controlling vascular growth.
Purpose of the Study:
- To analyze the density and distribution of endothelial cells in the CAM during development.
- To investigate the effect of vascular endothelial growth factor (VEGF) on CAM angiogenesis.
- To elucidate the regulatory mechanisms of endothelial cell proliferation and differentiation in the CAM.
Main Methods:
- Computer-assisted microscopy was used to quantify BrdU-labeled endothelial cells in whole-mount CAMs.
- Analysis of endothelial cell density and distribution at different developmental stages (days 6-15).
- Assessment of precapillary vessel length density and the impact of VEGF application.
Main Results:
- Endothelial cell proliferation significantly decreased after day 10, with a shift from random to focal distribution patterns.
- Vessel length density increased until day 14 and then stabilized.
- VEGF application on day 13 increased proliferative activity and induced a random distribution of endothelial cells by day 15.
Conclusions:
- A local regulatory mechanism normally controls endothelial cell proliferation and differentiation in the CAM, maintaining a stable vascular pattern.
- Despite overall regulation, proliferative foci persist, and precapillary vessel density continues to increase until day 14.
- VEGF enhances DNA synthesis in capillary endothelial cells, highlighting its role in stimulating angiogenesis.
Abstract:
The density and distribution of whole mount BrdU-anti-BrdU labeled endothelial cells (days 6-15) in the chick chorioallantoic membrane (CAM) was analyzed with computer-assisted microscopy. A significant loss of proliferative activity was noted after day 10: the density of labeled nuclei (in 10(-2) mm-2) decreased from a median 7.78 (days 6, 8, 10) to 2.42 (days 12, 14, 15). CAMs initially showed random patterns of labeled endothelial cells, but changed to clearly focal patterns after day 12. A regular arrangement of labeled nuclei was never seen. After application of vascular endothelial growth factor (VEGF) to the day 13 CAM, a significant increase in proliferative activity (11.50) and a random distribution of labeled endothelial cells was observed on day 15. Development of CAM precapillary vessels was assessed in terms of length density (in mm-1, mean +/- standard deviation), which was augmented three-fold from day 6 (1.22 +/- 0.05) to day 14 (3.54 +/- 0.23) and then remained nearly constant. VEGF application from day 13 to 15 raised arterial length per unit area to 4.53 +/- 0.77. It is concluded that normally a local regulation of endothelial proliferation and differentiation develops in the CAM, which doubles capillary endothelial cell density but simultaneously adapts to the decreasing need for endothelial cells, and thus maintains the quasi two-dimensional vessel pattern. However, proliferative foci persist in the capillary layer after day 10, and precapillary vessel density continues to increase until day 14. VEGF enhances DNA synthesis in all capillary endothelial cells.(ABSTRACT TRUNCATED AT 250 WORDS)