Micromechanical forces regulate vascular patterning in the chick chorioallantoic membrane (15.3)

Abstract

Mechanical forces have been implicated in blood vessel growth associated with diverse activities such as organ development and wound healing; however, the link between mechanical forces and network structure remains elusive. To test the hypothesis of a direct effect of mechanical force on axial blood vessel growth, we studied ex ovo chick embryo chorioallanotic membranes (CAMs) between embryonic development days 10 to 13. Uniaxial stretch was applied to CAMs for 72 hours using computer‐controlled servomotors to provide a reproducible stretch field. Sholl analysis of fluorescent micrographs of CAM vasculature and scanning electron microscopy (SEM) of vascular corrosion casts were used to characterize vascular structure. Distinct vessel branching was observed across the stretch field and among stretch and control CAMs. Vessel bifurcation angles were significantly lower in stretched CAMs (30.8°; 69.2°, p< 0.01). Mean interbranch length was longer in stretched compared to control CAMs (2.63 mm ± 0.58; 0.93 mm ± 0.33, p< 0.01). Corrosion casting and SEM demonstrated marked sprouting and intussusceptive angiogenesis in the capillary plexus in stretched areas of CAM. Mechanical stretch in the CAM may stimulate axial growth of conducting vessels and both sprouting and intussusceptive angiogenesis in gas exchange capillaries. These results indicate that mechanical force may have vessel‐specific influences on vascular patterning.Grant Funding Source: Supported by NIH 5T32‐CA009535