Neuroprotective effect of the surfactant poloxamer 188 in a model of intracranial hemorrhage in rats

Long-acting dolutegravir formulations prevent neurodevelopmental impairments in a mouse model

The World Health Organization has recommended dolutegravir (DTG) as a preferred first-line treatment for treatment naive and experienced people living with human immunodeficiency virus type one (PLWHIV). Based on these recommendations 15 million PLWHIV worldwide are expected to be treated with DTG regimens on or before 2025. This includes pregnant women. Current widespread use of DTG is linked to the drug's high potency, barrier to resistance, and cost-effectiveness. Despite such benefits, potential risks of DTG-linked fetal neurodevelopmental toxicity remain a concern. To this end, novel formulation strategies are urgently needed in order to maximize DTG's therapeutic potentials while limiting adverse events. In regard to potential maternal fetal toxicities, we hypothesized that injectable long-acting nanoformulated DTG (NDTG) could provide improved safety by reducing drug fetal exposures compared to orally administered native drug. To test this notion, we treated pregnant C3H/HeJ mice with daily oral native DTG at a human equivalent dosage (5 mg/kg; n = 6) or vehicle (control; n = 8). These were compared against pregnant mice injected with intramuscular (IM) NDTG formulations given at 45 (n = 3) or 25 (n = 4) mg/kg at one or two doses, respectively. Treatment began at gestation day (GD) 0.5. Magnetic resonance imaging scanning of live dams at GD 17.5 was performed to obtain T1 maps of the embryo brain to assess T1 relaxation times of drug-induced oxidative stress. Significantly lower T1 values were noted in daily oral native DTG-treated mice, whereas comparative T1 values were noted between control and NDTG-treated mice. This data reflected prevention of DTG-induced oxidative stress when delivered as NDTG. Proteomic profiling of embryo brain tissues harvested at GD 17.5 demonstrated reductions in oxidative stress, mitochondrial impairments, and amelioration of impaired neurogenesis and synaptogenesis in NDTG-treated mice. Pharmacokinetic (PK) tests determined that both daily oral native DTG and parenteral NDTG achieved clinically equivalent therapeutic plasma DTG levels in dams (4,000-6,500 ng/mL). Importantly, NDTG led to five-fold lower DTG concentrations in embryo brain tissues compared to daily oral administration. Altogether, our preliminary work suggests that long-acting drug delivery can limit DTG-linked neurodevelopmental deficits.

P188 Therapy in In Vitro Models of Traumatic Brain Injury

Traumatic brain injury (TBI) is a significant cause of morbidity and mortality worldwide. Varied mechanisms of injury contribute to the heterogeneity of this patient population as demonstrated by the multiple published grading scales and diverse required criteria leading to diagnoses from mild to severe. TBI pathophysiology is classically separated into a primary injury that is characterized by local tissue destruction as a result of the initial blow, followed by a secondary phase of injury constituted by a score of incompletely understood cellular processes including reperfusion injury, disruption to the blood-brain barrier, excitotoxicity, and metabolic dysregulation. There are currently no effective pharmacological treatments in the wide-spread use for TBI, in large part due to challenges associated with the development of clinically representative in vitro and in vivo models. Poloxamer 188 (P188), a Food and Drug Administration-approved amphiphilic triblock copolymer embeds itself into the plasma membrane of damaged cells. P188 has been shown to have neuroprotective properties on various cell types. The objective of this review is to provide a summary of the current literature on in vitro models of TBI treated with P188.

Case Report: Radioactive Holmium-166 Microspheres for the Intratumoral Treatment of a Canine Pituitary Tumor

Introduction: In this case study, a client-owned dog with a large pituitary tumor was experimentally treated by intratumoral injection of radioactive holmium-166 microspheres (166HoMS), named 166Ho microbrachytherapy. To our knowledge, this is the first intracranial intratumoral treatment through needle injection of radioactive microspheres. Materials and Methods: A 10-year-old Jack Russell Terrier was referred to the Clinic for Companion Animal Health (Faculty of Veterinary Medicine, Utrecht University, The Netherlands) with behavioral changes, restlessness, stiff gait, and compulsive circling. MRI and CT showed a pituitary tumor with basisphenoid bone invasion and marked mass effect. The tumor measured 8.8 cm3 with a pituitary height-to-brain area (P/B) ratio of 1.86 cm-1 [pituitary height (cm) ×10/brain area (cm2)]. To reduce tumor volume and neurological signs, 166HoMS were administered in the tumor center by transsphenoidal CT-guided needle injections. Results: Two manual CT-guided injections were performed containing 0.6 ml of 166HoMS suspension in total. A total of 1097 MBq was delivered, resulting in a calculated average tumor dose of 1866 Gy. At 138 days after treatment, the tumor volume measured 5.3 cm3 with a P/B ratio of 1.41 cm-1, revealing a total tumor volume reduction of 40%. Debulking surgery was performed five months after 166HoMS treatment due to recurrent neurological signs. The patient was euthanized two weeks later at request of the owners. Histopathological analysis indicated a pituitary adenoma at time of treatment, with more malignant characteristics during debulking surgery. Conclusion: The 40% tumor volume reduction without evident severe periprocedural side effects demonstrated the feasibility of intracranial intratumoral 166HoMS treatment in this single dog.

Poloxamer 188 Exerts Direct Protective Effects on Mouse Brain Microvascular Endothelial Cells in an In Vitro Traumatic Brain Injury Model

Traumatic Brain Injury (TBI), the main contributor to morbidity and mortality worldwide, can disrupt the cell membrane integrity of the vascular endothelial system, endangering blood-brain barrier function and threatening cellular subsistence. Protection of the vascular endothelial system might enhance clinical outcomes after TBI. Poloxamer 188 (P188) has been shown to improve neuronal function after ischemia/reperfusion (I/R) injury as well as after TBI. We aimed to establish an in vitro compression-type TBI model, comparing mild-to-moderate and severe injury, to observe the direct effects of P188 on Mouse Brain Microvascular Endothelial Cells (MBEC). Confluent MBEC were exposed to normoxic or hypoxic conditions for either 5 or 15 h (hours). 1 h compression was added, and P188 was administered during 2 h reoxygenation. A direct effect of P188 on MBEC was tested by assessing cell number/viability, cytotoxicity/membrane damage, metabolic activity, and total nitric oxide production (tNOp). While P188 enhanced cell number/viability, metabolic activity, and tNOp, an increase in cytotoxicity/membrane damage after mild-to-moderate injury was prevented. In severely injured MBEC, P188 improved metabolic activity only. P188, present during reoxygenation, influenced MBEC function directly in simulated I/R and compression-type TBI.

Evaluation of In Vitro Neuronal Protection by Postconditioning with Poloxamer 188 Following Simulated Traumatic Brain Injury

Traumatic brain injury (TBI) leads to morbidity and mortality worldwide. Reperfusion after ischemia adds detrimental injury to cells. Ischemia/reperfusion (I/R) injures cells in a variety of ways including cell membrane disruption. Hence, methods to improve endogenous membrane resealing capacity are crucial. Poloxamer (P) 188, an amphiphilic triblock copolymer, was found to be effective against I/R and mechanical injury in various experimental settings. The aim of this study was to establish an in vitro mouse neuronal TBI model and, further, to investigate if postconditioning with P188 directly interacts with neurons after compression and simulated I/R injury, when administered at the start of reoxygenation. Cellular function was assessed by cell number/viability, mitochondrial viability, membrane damage by lactated dehydrogenase (LDH) release and FM1-43 incorporation as well as apoptosis-activation by Caspase 3. Five hours hypoxia ± compression with 2 h reoxygenation proved to be a suitable model for TBI. Compared to normoxic cells not exposed to compression, cell number and mitochondrial viability decreased, whereas membrane injury by LDH release/FM1-43 dye incorporation and Caspase 3 activity increased in cells exposed to hypoxic conditions with compression followed by reoxygenation. P188 did not protect neurons from simulated I/R and/or compression injury. Future research is indicated.

Muscle membrane integrity in Duchenne muscular dystrophy: recent advances in copolymer-based muscle membrane stabilizers

The scientific premise, design, and structure-function analysis of chemical-based muscle membrane stabilizing block copolymers are reviewed here for applications in striated muscle membrane injury. Synthetic block copolymers have a rich history and wide array of applications from industry to biology. Potential for discovery is enabled by a large chemical space for block copolymers, including modifications in block copolymer mass, composition, and molecular architecture. Collectively, this presents an impressive chemical landscape to leverage distinct structure-function outcomes. Of particular relevance to biology and medicine, stabilization of damaged phospholipid membranes using amphiphilic block copolymers, classified as poloxamers or pluronics, has been the subject of increasing scientific inquiry. This review focuses on implementing block copolymers to protect fragile muscle membranes against mechanical stress. The review highlights interventions in Duchenne muscular dystrophy, a fatal disease of progressive muscle deterioration owing to marked instability of the striated muscle membrane. Biophysical and chemical engineering advances are presented that delineate and expand upon current understanding of copolymer-lipid membrane interactions and the mechanism of stabilization. The studies presented here serve to underscore the utility of copolymer discovery leading toward the therapeutic application of block copolymers in Duchenne muscular dystrophy and potentially other biomedical applications in which membrane integrity is compromised.

Interaction Forces between Supported Lipid Bilayers in the Presence of PEGylated Polymers

Using the surface forces apparatus (SFA), interaction forces between supported lipid bilayers were measured in the presence of polyethylene glycol and two other commercially available pegylated triblock polymers, Pluronic F68 and F127. Pluronic F68 has a smaller central hydrophobic block compared to F127 and therefore is more hydrophilic. The study aimed to unravel the effects of polymer architecture and composition on the interactions between the bilayers. Our keys findings show that below the critical aggregation concentration (CAC) of the polymers, a soft, weakly anchored, polymer layer is formed on the surface of the bilayers. The anchoring strength of this physisorbed layer was found to increase significantly with the size of the hydrophobic block of the polymer, and was strongest for the more hydrophobic polymer, F127. Above the CAC, a dense polymer layer, exhibiting gel-like properties, was found to rapidly grow on the bilayers even after mechanical disruption. The cohesive interaction maintaining the gel layer structure was found to be stronger for F127, and was also found to promote the formation of highly structured aggregates on the bilayers.

Poloxamer 188 Attenuates Cerebral Hypoxia/Ischemia Injury in Parallel with Preventing Mitochondrial Membrane Permeabilization and Autophagic Activation

While the previous studies have shown poloxamer 188 (P188)'s neuroprotection in cultured HT22 cells under oxygen-glucose deprivation (OGD) insults, we investigated whether P188 is a potential neuroprotective agent in primary cortical neurons (PCNs) and in cerebral ischemia in vivo and whether the possible underlying mechanisms correlate with regulating mitochondrial membrane permeability (MMP) and autophagy. The protective effects of P188 were tested in PCNs in vitro exposed to OGD, as well as in cerebral ischemia in vivo. Cell death and viability were detected with LDH and MTT assay, and mitochondrial membrane potential was assessed using fluorescence microscopy. The apoptosis and autophagy of PCNs were investigated by expressions of cyt-c, caspase-3, light chain 3 (LC3), and Beclin-1. In addition, a mouse middle cerebral artery occlusion (MCAO) model was used to produce focal ischemia, and mice were treated with P188 and rapamycin after MCAO 10 min. The infarct volume, neurological scores, and phosphorylation of mammalian target of rapamycin (mTOR) were evaluated. The in vitro results showed that P188 prevented OGD-induced primary cerebrocortical neuron death and inhibited loss of mitochondrial membrane potential, the release of mitochondrial apoptogenic factor cytochrome c from mitochondria to the cytoplasm, and activation of caspase-3. P188 suppressed the activation of autophagy by decreasing LC3-II and Beclin-1 levels under OGD accordingly. Moreover, the in vivo results showed that P188 and rapamycin remarkably reduced the infarct volume and neurological deficits in the MCAO mouse model of cerebral ischemia, respectively. Both P188 and rapamycin induced phosphorylation of mTOR and reversed the decreased level upon MCAO. These data indicate that P188 prevents neuronal cell death resulting from ischemic brain injury and that its neuroprotective effects are mediated by preventing mitochondrial membrane integrity damage and autophagic activation. Given that it has low toxicity, P188 might become a potential novel therapy for ischemic injury.

The pharmacokinetics and pharmacodynamics of Kollidon VA64 dissociate its protective effects from membrane resealing after controlled cortical impact in mice

Membrane-resealing agents such as poloxamer P188 improve the outcome in experimental brain injury paradigms; however, whether membrane resealing is a key mechanism for protection has not been shown in vivo. We previously reported that Kollidon VA64, a polymeric membrane-resealing agent, reduces cell membrane permeability and improves brain edema, brain tissue damage, and functional outcome after controlled cortical impact in mice, without rescuing resealed cells from death. To reconcile these disparate findings, we used a dual-pulse labeling protocol to determine membrane-resealing kinetics by VA64/P188 in vivo. Membrane resealing after controlled cortical impact in mice by intravenous or intracerebroventricular VA64 and poloxamer P188 was transient, with most cells becoming repermeabilized within 2 hours, even with multiple-dose paradigms that maintained high VA64 blood levels. Moreover, VA64 reduced cytotoxic brain edema in a water intoxication model devoid of plasmalemma permeability (P<0.05 versus P188, VA30, mannitol, and vehicle). We conclude that VA64 reduces cytotoxic and traumatic brain edema independent of membrane resealing. The results suggest that classic membrane-resealing agents such as poloxamer P188, and the newly discovered VA64, exert protective effects in central nervous system injury paradigms by mechanisms other than or in addition to maintaining permeable cell membranes sealed.

Poloxamer-188 can attenuate blood-brain barrier damage to exert neuroprotective effect in mice intracerebral hemorrhage model

Blood-brain barrier (BBB) disruption and brain edema formation play important roles in the secondary neuronal death and neurological dysfunction induced by intracerebral hemorrhage (ICH). Poloxamer 188 (P188), a multiblock copolymer surfactant, has been shown to be capable of sealing damaged cell membranes and decrease neuronal cell death. In this study, we explored whether P188 had a protective effect against ICH and its underlying mechanisms. Male ICR mice were subjected to infusion of type IV collagenase (to induce ICH) of saline (for shams) into the left striatum. The results showed that P188-12 mg post-treatment by tail intravenous injection significantly ameliorated the neurological symptoms and brain edema, attenuated BBB permeability, and decreased cell insults and injury volume at 24 and 72 h after ICH. Furthermore, P188 maintained the protein levels of tight junction (TJ) proteins including claudin-5, occludin, and zonula occludens-1, and reversed the increases of nuclear factor-kappaB (NF-κB), matrix metalloproteinase (MMP)-2, and MMP-9 protein expression at 72 h post ICH. Immunofluorescence showed P188 treatment rearranged the structure of TJ proteins in a continuous and linear pattern. Therefore, the present study concludes that P188 can protect against ICH, and the protective effect was associated with preventing BBB disruption through NF-κB-MMPs-mediated TJ proteins degradation.

Poloxamer 188 protects neurons against ischemia/reperfusion injury through preserving integrity of cell membranes and blood brain barrier

Poloxamer 188 (P188), a multiblock copolymer surfactant, has been shown to protect against ischemic tissue injury of cardiac muscle, testes and skeletal muscle, but the mechanisms have not been fully understood. In this study, we explored whether P188 had a protective effect against cerebral ischemia/reperfusion injury and its underlying mechanisms. The in vivo results showed that P188 significantly reduced the infarct volume, ameliorated the brain edema and neurological symptoms 24 h after ischemia/reperfusion. In the long-term outcome study, P188 markedly alleviated brain atrophy and motor impairments and increased survival rate in 3 weeks of post stroke period. Additionally, P188 protected cultured hippucampal HT22 cells against oxygen-glucose deprivation and reoxygenation (OGD/R) injury. The ability in membrane sealing was assessed with two fluorescent membrane-impermeant dyes. The results showed that P188 treatment significantly reduced the PI-positive cells following ischemia/reperfusion injury and repaired the HT22 cell membrane rupture induced by Triton X-100. In addition, P188 inhibited ischemia/reperfusion-induced activation of matrix metalloproteinase (MMP)-9 and leakage of Evans blue. Therefore, the present study concludes that P188 can protect against cerebral ischemia/reperfusion injury, and the protection involves multi-mechanisms in addition to the membrane resealing.

Affinity for, and localization of, PEG-functionalized silica nanoparticles to sites of damage in an ex vivo spinal cord injury model

Background

Traumatic spinal cord injury (SCI) leads to serious neurological and functional deficits through a chain of pathophysiological events. At the molecular level, progressive damage is initially revealed by collapse of plasma membrane organization and integrity produced by breaches. Consequently, the loss of its role as a semi-permeable barrier that generally mediates the regulation and transport of ions and molecules eventually results in cell death. In previous studies, we have demonstrated the functional recovery of compromised plasma membranes can be induced by the application of the hydrophilic polymer polyethylene glycol (PEG) after both spinal and brain trauma in adult rats and guinea pigs. Additionally, efforts have been directed towards a nanoparticle-based PEG application.

The in vivo and ex vivo applications of PEG-decorated silica nanoparticles following CNS injury were able to effectively and efficiently enhance resealing of damaged cell membranes.

Results

The possibility for selectivity of tetramethyl rhodamine-dextran (TMR) dye-doped, PEG-functionalized silica nanoparticles (TMR-PSiNPs) to damaged spinal cord was evaluated using an ex vivo model of guinea pig SCI. Crushed and nearby undamaged spinal cord tissues exhibited an obvious difference in both the imbibement and accumulation of the TMR-PSiNPs, revealing selective labeling of compression-injured tissues.

Conclusions

These data show that appropriately functionalized nanoparticles can be an efficient means to both 1.) carry drugs, and 2.) apply membrane repair agents where they are needed in focally damaged nervous tissue.

Kollidon VA64, a membrane-resealing agent, reduces histopathology and improves functional outcome after controlled cortical impact in mice

Loss of plasma membrane integrity is a feature of acute cellular injury/death in vitro and in vivo. Plasmalemma-resealing agents are protective in acute central nervous system injury models, but their ability to reseal cell membranes in vivo has not been reported. Using a mouse controlled cortical impact (CCI) model, we found that propidium iodide-positive (PI+) cells pulse labeled at 6, 24, or 48 hours maintained a degenerative phenotype and disappeared from the injured brain by 7 days, suggesting that plasmalemma permeability is a biomarker of fatal cellular injury after CCI. Intravenous or intracerebroventricular administration of Kollidon VA64, poloxamer P188, or polyethylene glycol 8000 resealed injured cell membranes in vivo (P<0.05 versus vehicle or poloxamer P407). Kollidon VA64 (1 mmol/L, 500 μL) administered intravenously to mice 1  hour after CCI significantly reduced acute cellular degeneration, chronic brain tissue damage, brain edema, blood-brain barrier damage, and postinjury motor deficits (all P<0.05 versus vehicle). However, VA64 did not rescue pulse-labeled PI+ cells from eventual demise. We conclude that PI permeability within 48 hours of CCI is a biomarker of eventual cell death/loss. Kollidon VA64 reduces secondary damage after CCI by mechanisms other than or in addition to resealing permeable cells.

Plasmalemma permeability and necrotic cell death phenotypes after intracerebral hemorrhage in mice

BACKGROUND AND PURPOSE

Traumatic and ischemic brain injury induce plasmalemma permeability and necrosis; however, no studies have examined these aspects of cellular injury in intracerebral hemorrhage models.

METHODS

In vivo propidium iodide (PI) and YOYO-1 were used to assess plasmalemma damage after collagenase-induced intracerebral hemorrhage in mice. Ex vivo aspartylglutamylvalylaspartic acid, terminal deoxynucleotidyltransferase-mediated dUTP nick end labeling, and electron microscopy were used to assess the relationship between plasmalemma permeability and mode of cell death. Cell types vulnerable to plasmalemma damage were determined by immunohistochemistry.

RESULTS

Plasmalemma permeability was first detected in the lesion at 1 to 3 hours and peaked at 48 to 72 hours. Neurons and IBA-1-positive cells with morphological features of monocytes were sensitive, whereas resident microglia and astrocytes were resistant to plasmalemma permeability. PI+ cells colocalized with fluorescent-labeled caspase substrates and terminal deoxynucleotidyltransferase-mediated dUTP nick end labeling beginning at 3 to 6 hours. At 48 hours, greater than half of injured cells were PI+/aspartylglutamylvalylaspartic acid- or PI+/terminal deoxynucleotidyltransferase-mediated dUTP nick end labeling- suggesting necrosis, and <5% were PI-/terminal deoxynucleotidyltransferase-mediated dUTP nick end labeling+ or PI-/aspartylglutamylvalylaspartic acid+. Electron microscopy confirmed ultrastructural features of necrosis at 24 hours after intracerebral hemorrhage, high mobility group box protein-1 was released from permeable cells, and mice deficient in receptor interacting protein kinase (RIPK) 3, a known necrosis trigger, had 50% less PI+ cells at 24 hours. Permeable cells remained in the brain for at least 24 hours with <10% spontaneous resealing.

CONCLUSIONS

Necrosis contributes to cell demise after intracerebral hemorrhage. Programmed necrosis and plasmalemma damage may represent novel therapeutic targets to prevent cell death or rescue injured cells after intracerebral hemorrhage.

Advances in neuroprotective strategies: potential therapies for intracerebral hemorrhage

Intracerebral hemorrhage (ICH) is associated with higher mortality and morbidity than any other form of stroke. However, there currently are no treatments proven to improve outcomes after ICH, and therefore, new effective therapies are urgently needed. Growing insight into ICH pathophysiology has led to the development of neuroprotective strategies that aim to improve the outcome through reduction of secondary pathologic processes. Many neuroprotectants target molecules or pathways involved in hematoma degradation, inflammation or apoptosis, and have demonstrated potential clinical benefits in experimental settings. We extensively reviewed the current understanding of ICH pathophysiology as well as promising experimental neuroprotective agents with particular focus on their mechanisms of action. Continued advances in ICH knowledge, increased understanding of neuroprotective mechanisms, and improvement in the ability to modulate molecular and pathologic events with multitargeting agents will lead to successful clinical trials and bench-to-bedside translation of neuroprotective strategies.

Chitosan nanoparticle-based neuronal membrane sealing and neuroprotection following acrolein-induced cell injury

Background

The highly reactive aldehyde acrolein is a very potent endogenous toxin with a long half-life. Acrolein is produced within cells after insult, and is a central player in slow and progressive "secondary injury" cascades. Indeed, acrolein-biomolecule complexes formed by cross-linking with proteins and DNA are associated with a number of pathologies, especially central nervous system (CNS) trauma and neurodegenerative diseases. Hydralazine is capable of inhibiting or reducing acrolein-induced damage. However, since hydralazine's principle activity is to reduce blood pressure as a common anti-hypertension drug, the possible problems encountered when applied to hypotensive trauma victims have led us to explore alternative approaches. This study aims to evaluate such an alternative - a chitosan nanoparticle-based therapeutic system.

Results

Hydralazine-loaded chitosan nanoparticles were prepared using different types of polyanions and characterized for particle size, morphology, zeta potential value, and the efficiency of hydralazine entrapment and release. Hydralazine-loaded chitosan nanoparticles ranged in size from 300 nm to 350 nm in diameter, and with a tunable, or adjustable, surface charge.

Conclusions

We evaluated the utility of chitosan nanoparticles with an in-vitro model of acrolein-mediated cell injury using PC -12 cells. The particles effectively, and statistically, reduced damage to membrane integrity, secondary oxidative stress, and lipid peroxidation. This study suggests that a chitosan nanoparticle-based therapy to interfere with "secondary" injury may be possible.

Mechanical membrane injury induces axonal beading through localized activation of calpain

Diffuse axonal injury (DAI), a major component of traumatic brain injury, is characterized by a sequence of neurochemical reactions initiated at the time of trauma and resulting in axonal degeneration and cell death. Calcium influx through mechanically induced axolemmal pores and subsequent activation of calpains are thought to be responsible for the cytoskeletal damage leading to impaired axonal transport. Focal disruption of cytoskeleton accompanied by the accumulation of transported membranous cargo leads to axonal beading which is the characteristic morphology of DAI. By applying fluid shear stress injury on cultured primary neurons, acute calcium (Ca(2+)) and calpain responses of axons to mechanical trauma were investigated. Intracellular Ca(2+) concentration ([Ca(2+)](i)) shows a steady increase following injury that can be blocked by sealing membrane pores with Poloxamer 188 and by chelating intra- or extracellular Ca(2+). Calpain activity increases in response to mechanical injury and this increase depends on Ca(2+) availability and on axolemmal permeability. Both the [Ca(2+)](i) increase and calpain activity exhibit focal peaks along the axons which co-localize with mitochondria and predict future axonal bead locations. These findings suggest that mechanoporation may be the initiating mechanism resulting in ensuing calcium fluxes and subsequent calpain activity and that post-injury membrane repair may be a valid therapeutic approach for acute intervention in DAI.