| Description |
Brain injuries are devastating and complicated due to frequent, permanent side effects and varied symptomatic progressions. While brain injuries are damaging at any stage in life, they have far more tragic consequences in the early, developmental period. Brain injuries early on can result in neurodevelopmental disabilities, or even death. Because of the mechanical nature of brain injuries, damage to the cerebral vasculature is common; this consequence prompts the study of their loading behavior. It is well known that human blood vessels develop throughout life and that development is particularly rapid during infancy. However, the mechanical properties of developing blood vessels remain largely undefined. Characterization of isolated blood vessels may shed great insight into the progression of brain injuries. Two types of vessels were studied to identify age-related changes in mechanical properties: human umbilical artery and ovine middle cerebral artery. In the umbilical artery study, we hypothesized that vessels from a younger gestational age would be less stiff and indicate susceptibility to intraventricular hemorrhage (IVH), a common type of brain injury in preterm infants. Single umbilical arteries were dissected from cord segments collected from births between 24 and 40 weeks. Axial and circumferential strips were taken from artery segments and subjected to uniaxial loading. Umbilical artery properties were not shown to significantly change in either the axial or circumferential directions across the 24-40 week gestation, nor to indicate IVH susceptibility. Traumatic brain injury often results in vascular damage and dysfunction. As a result, these injuries have devastating consequences, especially in the pediatric population. Consequently, it is important to understand the specific loading behavior of young, compared to adult, cerebral vessels. In the ovine cerebral artery study, we hypothesized younger vessels would be less stiff and more distensible compared to older vessels. Whole cerebral arteries were taken from the preterm, or fetal, lambs (~132 days gestation in sheep) up through adult (3€7 years) and subjected to biaxial loading tests. Our findings show significant differences in mechanical properties between younger compared to older ovine cerebral vessels. Differences in mechanical properties between young and older cerebral vessels would likely result in distinct loading behaviors and subsequent levels of damage and dysfunction. As blood vessels develop and grow, their mechanical characteristics can significantly change. Age-related differences in the mechanical properties of vessels should be considered when developing injury or disease models and diagnostic or treatment regimes. |
