Abnormalities in spinal cord ultrastructure in a rat model of post-traumatic syringomyelia

Berliner, Joel; Hemley, Sarah J.; Najafi, Elmira; Bilston, Lynne E.; Stoodley, Marcus A.; Lam, Magdalena

doi:10.1186/s12987-020-0171-4

“…This anomaly can be explained by the fact that the fluid–structure interaction model neglects the elastic forces in the connective tissue (extracellular matrix) in the PVS. The PVS contains collagen fibers and fibroblasts, that are continuous with the extracellular space of the surrounding tissue [ 102 , 103 ]. Collagen networks can have a highly non-linear elastic response when the loading is changed from compression to tension, and exhibit hysteresis during large, cyclic deformations [ 104 , 105 ].…”

Section: Resultsmentioning

confidence: 99%

Functional hyperemia drives fluid exchange in the paravascular space

Kedarasetti

¹

,

Turner

²

,

Echagarruga

³

et al. 2020

Fluids Barriers CNS

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The brain lacks a conventional lymphatic system to remove metabolic waste. It has been proposed that directional fluid movement through the arteriolar paravascular space (PVS) promotes metabolite clearance. We performed simulations to examine if arteriolar pulsations and dilations can drive directional CSF flow in the PVS and found that arteriolar wall movements do not drive directional CSF flow. We propose an alternative method of metabolite clearance from the PVS, namely fluid exchange between the PVS and the subarachnoid space (SAS). In simulations with compliant brain tissue, arteriolar pulsations did not drive appreciable fluid exchange between the PVS and the SAS. However, when the arteriole dilated, as seen during functional hyperemia, there was a marked exchange of fluid. Simulations suggest that functional hyperemia may serve to increase metabolite clearance from the PVS. We measured blood vessels and brain tissue displacement simultaneously in awake, head-fixed mice using two-photon microscopy. These measurements showed that brain deforms in response to pressure changes in PVS, consistent with our simulations. Our results show that the deformability of the brain tissue needs to be accounted for when studying fluid flow and metabolite transport.

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“…This anomaly can be explained by the fact that the uid-structure interaction model neglects the elastic forces in the connective tissue (extracellular matrix) in the PVS. The PVS contains collagen bers and broblasts, that are continuous with the extracellular space of the surrounding tissue 105,106 . Collagen networks can have a highly non-linear elastic response when the loading is changed from compression to tension, and exhibit hysteresis during large, cyclic deformations 107,108 .…”

Section: Arteriolar Dilations During Functional Hyperemia Can Drive Umentioning

confidence: 99%

Functional hyperemia drives fluid exchange in the paravascular space

Kedarasetti

¹

,

Turner

²

,

Echagarruga

³

et al. 2020

Preprint

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The brain lacks a conventional lymphatic system to remove metabolic waste. It has been proposed that fluid movement through the arteriolar paravascular space (PVS) promotes metabolite clearance. We performed simulations to understand how arteriolar pulsations and dilations, and brain deformability affect PVS fluid flow. In simulations with compliant brain tissue, arteriolar pulsations did not drive appreciable flows in the PVS. However, when the arteriole dilated as in functional hyperemia, there was a marked movement of fluid. Simulations suggest that functional hyperemia may also serve to increase fluid exchange between the PVS and the subarachnoid space. We measured blood vessels and brain tissue displacement simultaneously in awake, head-fixed mice using two-photon microscopy. These measurements showed that brain deforms in response to pressure changes in PVS, as predicted by simulations. Our results show that the deformability of the brain tissue needs to be accounted for when studying fluid flow and metabolite transport.Acknowledgements: This work was supported by NSF Grant CBET 1705854.

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“…The PVS contains collagen bers and broblasts, that are continuous with the extracellular space of the surrounding tissue 108,109 . Collagen networks can have a highly non-linear elastic response when the loading is changed from compression to tension, and exhibit hysteresis during large, cyclic deformations 110,111 .…”

Section: Part 3 -Measurement Of Brain Tissue Deformation In-vivomentioning

confidence: 99%

Functional hyperemia drives fluid exchange in the paravascular space

Kedarasetti

¹

,

Turner

²

,

Echagarruga

³

et al. 2020

Preprint

0

View full text Add to dashboard Cite

The brain lacks a conventional lymphatic system to remove metabolic waste. It has been proposed that directional fluid movement through the arteriolar paravascular space (PVS) promotes metabolite clearance. We performed simulations to examine if arteriolar pulsations and dilations can drive directional CSF flow in the PVS and found that arteriolar wall movements do not drive directional CSF flow. We propose an alternative method of metabolite clearance from the PVS, namely fluid exchange between the PVS and the subarachnoid space (SAS). In simulations with compliant brain tissue, arteriolar pulsations did not drive appreciable fluid exchange between the PVS and the SAS. However, when the arteriole dilated, as seen during functional hyperemia, there was a marked exchange of fluid. Simulations suggest that functional hyperemia may serve to increase metabolite clearance from the PVS. We measured blood vessels and brain tissue displacement simultaneously in awake, head-fixed mice using two-photon microscopy. These measurements showed that brain deforms in response to pressure changes in PVS, consistent with our simulations. Our results show that the deformability of the brain tissue needs to be accounted for when studying fluid flow and metabolite transport.Acknowledgements: This work was supported by NSF Grant CBET 1705854.

show abstract

Abnormalities in spinal cord ultrastructure in a rat model of post-traumatic syringomyelia

Cited by 22 publications

References 55 publications

Functional hyperemia drives fluid exchange in the paravascular space

Functional hyperemia drives fluid exchange in the paravascular space

Functional hyperemia drives fluid exchange in the paravascular space

Functional hyperemia drives fluid exchange in the paravascular space

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