A novel 3-D model of chick chorioallantoic membrane for ameliorated studies in angiogenesis

Decisive indulgence of angiogenesis requires a more holistic assessment and several in vivo assays have been developed that permit a more realistic appraisal of the angiogenic response. One of the most popular assays to study angiogenic activity is the chick chorioallantoic membrane (CAM). Although CAM assay is a vital technique used to study normal and putative angiogenesis, a serious drawback in its utilization is the lack of quantitative assessment of vascularization. In this study, we proposed a new 3-D model of the developing CAM for precise quantification of normal vasculature of CAM from Day 4 to Day 13 of incubation. Image probing technique was used to quantify different 3-D parameters of vascular microarchitecture. A significant increase (P < 0.05) in surface roughness (Sa) was observed at Day 5 of incubation, while highly significant increase (P < 0.01) in Sa values was observed at Day 6 of incubation. Maximum increase (P < 0.001) in Sa values was observed from Day 7 to Day 9 of incubation and slight decrease in Sa values was observed in successive days. Similar results were observed for root mean square values (Sq), absolute heights of the surface (Sz), and amount of lowest valleys (Sy) on CAM. A significant increase (P < 0.05) in developed surface area (Sdr) from Day 5 of incubation, reaching to its maximum (P < 0.01) at Day 9 also was noted. Similarly, significant increase (P < 0.05) in fluid core retention (Sci) illustrates presence of copious fluid in blood vessels. Image probing technique offers a useful modality for visualizing 3-D microvascular architecture of CAM to exaggerate the fine details and reveal the hidden information that can be helpful for precise quantification of angiogenesis. This approach can be used to evaluate the angiogenic and antiangiogenic potential of different biological substances and also can be a valuable independent prognostic indicator in a wide variety of human cancers.