Intravascular flow fields shape intussusceptive pillars in the chick chorioallantoic membrane

Abstract

Intussusceptive (nonsprouting) angiogenesis is an essential process in the development of the chick chorioallantoic membrane (CAM). The influence of intravascular flow fields on intussusceptive pillar formation in the CAM, however, remains largely unknown. Using fluorescent vascular tracers and digital time‐series video reconstructions, intussusceptive pillars and the surrounding flow fields were identified during the development days 12–16. The mechanical forces within the CAM vessels, including wall shear stress, velocity, and blood pressure, were mapped using 3D finite element models and computational flow simulations. The pillars demonstrated a quasi‐circular circumference (shape factor 0.41+0.13) and comprised 1.7+1.2% of the bifurcation cross‐sectional area within 2nd and 3rd order vessels. The presence of pillars was independent of vessel diameter (R=0.32) or bifurcation angle (R=0.48) (p>0.4), but blood flow surrounding the pillars demonstrated a narrow range of velocities. More importantly, the location and geometry of the pillar correlated closely with the streamlines of the dominant vessel flow (p=0.02). We conclude that these spatial dynamics reflect a responsiveness of blood vessels to intravascular flow fields and indicate the importance of mechanical forces in shaping both intussusceptive angiogenesis and vessel structure in the microcirculation.Grant Funding Source: NIH Grant HL47078, HL75426 and HL94567