Genetic variation in retinal vascular patterning predicts variation in pial collateral extent and stroke severity.

The presence of a native collateral circulation in tissues lessens injury in occlusive vascular diseases. However, differences in genetic background cause wide variation in collateral number and diameter in mice, resulting in large variation in protection. Indirect estimates of collateral perfusion suggest that wide variation also exists in humans.

Aging causes collateral rarefaction and increased severity of ischemic injury in multiple tissues.

Objective: Aging is a major risk factor for increased ischemic tissue injury. Whether collateral rarefaction and impaired remodeling contribute to this is unknown. We quantified the number and diameter of native collaterals and their remodeling in 3-, 16-, 24-, and 31-month-old mice.

Wide genetic variation in the native pial collateral circulation is a major determinant of variation in severity of stroke.

Severity of stroke varies widely among individuals. Whether differences in the extent of the native (preexisting) pial collateral circulation exist and contribute to this variability is unknown. We addressed these questions and probed for potential genetic contributions using morphometric analysis of the collateral circulation in 15 inbred mouse strains recently shown to exhibit wide differences in infarct volume.