Drag-Reducing Polymer Enhances Microvascular Perfusion in the Traumatized Brain with Intracranial Hypertension

Abstract

SUMMARY Current treatments for traumatic brain injury (TBI) have not focused on improving microvascular perfusion. Drag-reducing polymers (DRP), linear, long-chain, blood soluble non-toxic macromolecules, may offer a new approach to improving cerebral perfusion by primary alteration of the fluid dynamic properties of blood. Nanomolar concentrations of DRP have been shown to improve hemodynamics in animal models of ischemic myocardium and limb, but have not yet been studied in the brain. Recently, we demonstrated that that DRP improved microvascular perfusion and tissue oxygenation in a normal rat brain. We hypothesized that DRP could restore microvascular perfusion in hypertensive brain after TBI. Using the in-vivo 2-photon laser scanning microscopy we examined the effect of DRP on microvascular blood flow and tissue oxygenation in hypertensive rat brains with and without TBI. DRP enhanced and restored capillary flow, decreased microvascular shunt flow and, as a result, reduced tissue hypoxia in both un-traumatized and traumatized rat brains at high ICP. Our study suggests that DRP could be an effective treatment for improving microvascular flow in brain ischemia caused by high ICP after TBI.

Rheological effects of drag-reducing polymers improve cerebral blood flow and oxygenation after traumatic brain injury in rats

“…26,27 To induce moderate extradural FPI, rats were subjected to a fluid pressure pulse of 1.5 atmospheres at 50 ms duration, sham animals were subjected to craniotomy only. 23 …”

“…Blood glucose levels were similarly elevated in all rats likely due to the stress of surgery and anesthesia as in our previous reports. [23][24][25] TBI FPI resulted in a transient fall ($70 ms) in mean arterial pressure to $80% of baseline (73.4 AE 8.4 mmHg), followed by a slow recovery to 100% within 11 AE 3.6 min (94.2 AE 9.6 mmHg). ICP was unchanged and remained at 10.1 AE 4.8 mmHg throughout the study.…”

Drag reducing polymers decrease hepatic injury and metastases after liver ischemia-reperfusion

“…Although the in vivo effects of DRPs are incompletely understood, they act primarily in the microvasculature to reduce microturbulence at bifurcations and significantly increase near-wall blood flow velocity [ 33 ]. As a consequence, DRPs significantly increase blood flow, increase the number of functioning capillaries and increase microvascular flow volume [ 34 – 36 ].…”

Induced Dynamic Intracranial Pressure and Cerebrovascular Reactivity Assessment of Cerebrovascular Autoregulation After Traumatic Brain Injury with High Intracranial Pressure in Rats

“…The animal protocol was approved by the Institutional Animal Care and Use Committee of the University of New Mexico Health Sciences Center and carried out in accordance with the National Institutes of Health Guide for the Care and Use of Laboratory Animals. The procedures used in this study have been described in our previous publications [6-9].…”

“…This transition was correlated with loss of CBF autoregulation undetected by static autoregulatory curves but identified by induced dynamic ICP (iPRx) and cerebrovascular (iCVRx) reactivity [8]. More recently we proved existence of MVS flow in cerebral microcirculation after traumatic brain injury (TBI) with high ICP [9]. …”