Response of cerebral microvasculature to brain injury

Abstract

There is increasing evidence that there is a direct response of the cerebral microvasculature to head injury. We have investigated using SEM and TEM the response of microvessels within the white matter of the baboon brain to lateral head acceleration. There is rapid endothelial disruption and swelling of perivascular astrocytes near the sites of petechial haemorrhage. The formation of microvilli in all vessels reaches a peak at 6 h and extends at least 5 mm from the site of haemorrhage. The astrocyte response suggests a partial recovery by 6 h. The endothelial response is most marked in arterioles and venules and is maintained for 6 days after injury. We suggest there is a biphasic cerebrovascular response to brain injury. First there is rapid astrocytic swelling possibly correlated with transient disruption of the blood-brain barrier. This is followed by morphological changes in the endothelium of all vessels which are most marked in arterioles and venules and extend considerable distances throughout the neuropile. This response is discussed in the light of disruption of the blood-brain barrier.

Ultrastructural study of brain microvessels in patients with traumatic cerebral contusions

“…The predominant and constant incidence of structural changes on microvessel endothelial cells led us to think that fluid passage through these perturbed cells may be an important factor in traumatic brain oedema. This is in accord with some experimental models showing passage of tracers directly through endothelial cells [20,25] as well as with the suggestion that in human traumatic brain injury intracellular oedema plays a major role in the swelling process [4,9]. So the constant finding of oedema inside endothelial cells with closed tight-junctions led us to think about the possibility of primary ionic permeability alterations related to stretch-activated receptors [8,10,22,24]: The dynamic loading of the brain caused either by impulsive (acceleration-deceleration) forces or by direct impact is transformed, at least in part, in deformation force.…”

Blood-Brain Barrier Disruption Is an Early Event That May Persist for Many Years After Traumatic Brain Injury in Humans

“…As regards possible structural correlates of this acute BBB disruption, ultrastructural studies in animal models of TBI have identified a variety of alterations in vascular endothelia in the Page 14 of 22 acute phase following injury, including the formation of vacuoles, craters and microvilli (47,(57)(58)(59) some of which were later identified in human TBI (60,61). These very rapid changes in vascular structure and function have been attributed to a range of mechanisms such as direct perturbation of the vessels by mechanical forces, including the immediate disruption of vascular endothelial cells.…”

“…Additional, secondary insults following injury might also be detrimental to normal endothelial integrity and function, including acute rises in arterial pressure or intravascular thrombus formation (45,56,57). Finally, active physiological changes have also been described in both animals and humans following TBI, including increased transendothelial vesicular transport with otherwise intact tight junctions (47,59,61,62) as well as alterations to other components of the BBB, such as early astrocyte disruption and swelling (45,58).…”

A transmission and scanning electron microscopic study of tumoral and peritumoral microblood vessels in human gliomas

“…For SEM, the tissues were fixed in the Karnovosky's fixative for at least 7 days at 4 ~ C. Thereafter they were processed like routine formalin fixed specimens and embedded in paraffin [21]. From the paraffin block, 5u sections were cut and stained with H & E stain, and examined under light microscope to confirm the presence of MBVs.…”