Novel therapies in development for the treatment of traumatic brain injury

The association between self-reported traumatic brain injury, neuropsychological function, and compliance among people serving community sentences

BACKGROUND

Traumatic brain injury is overrepresented in incarcerated samples and has been linked to a number of poor correctional outcomes. Despite this, no research has explored the impact of a recent TBI on compliance outcomes for individuals serving community-based.

METHOD

We screened for a history of TBI in 106 adults on community sentences and collected compliance (arrests, sentence violations) and related variables (e.g., risk scores, substance use) over 6 months. Sixty-four participants also completed the Repeatable Battery for the Assessment of Neuropsychological Status (RBANS), the Comprehensive Trail Making Test and Color-Word Inference Test.

RESULTS

A TBI in the last year predicted a significantly higher likelihood of arrest, even when controlling for risk of reconviction and current substance use, but was not associated with non-compliance with sentence conditions nor with performance on the neuropsychological tests. In addition, no significant associations were found between performance on neuropsychological tests and measures of non-compliance.

CONCLUSIONS

TBI in the last year was an independent predictor of arrest. This result suggests that those with a recent TBI on a community sentence may need additional monitoring or support to reduce the risk of reoffending.

Efficacy of stem cell secretome in the treatment of traumatic brain injury: A systematic review and meta-analysis of preclinical studies

Traumatic brain injury (TBI) remains a public health challenge and represents one of the major contributors to disability and mortality worldwide among all trauma-related injuries. This study aimed to determine a precise effect size of secretome intervention in TBI. We performed a systematic literature search through Cochrane, MEDLINE Complete, PubMed and Scopus databases for articles published until June 2021. The search terms used include cells OR stem cells OR mesenchymal stem cells AND secretome OR conditioned medium OR extracellular vesicles OR exosomes OR microvesicles AND traumatic brain injury OR head injury. Neurological deficits and neuroinflammation were the outcome measures assessed after the intervention. Thirty-one (31) studies involving mouse, rat and swine were enrolled for the meta-analysis. Secretome significantly improved structural and functional recovery when compared with control. The mean effect sizes were as follows: modified neurological severity score (mNSS) (-2.65, 95% CI: -3.42, -1.87, p < 0.00001), impact size (-3.02 mm³, 95% CI: -4.97, -1.08, p = 0.002) and latency to platform (-17.20 s, 95% CI: -23.91, -10.50, p < 0.00001). Similarly, intervention with secretome reduced neuroinflammation after TBI. The results of meta-regression showed that the source of secretome, TBI models and duration of follow-up did not influence the mNSS. Furthermore, the methodological quality of the studies was moderate as shown by the risk of bias assessment. Publication bias was observed for the mNSS. This meta-analysis provides preclinical evidence of secretome intervention in TBI, suggesting that it can be explored as a therapeutic agent for TBI and other neurological disorders in humans.

Down-Regulated Expression of Magnesium Transporter Genes Following a High Magnesium Diet Attenuates Sciatic Nerve Crush Injury

BACKGROUND

Magnesium supplementation has potential for use in nerve regeneration. The expression of some magnesium transporter genes is reflective of the intracellular magnesium levels.

OBJECTIVE

To assess the expression of various magnesium transporter genes as they relate to neurological alterations in a sciatic nerve injury model.

METHODS

Sciatic nerve injury was induced in rats, which were then fed either basal or high magnesium diets. Magnesium concentrations and 5 magnesium transporter genes (SLC41A1, MAGT1, CNNM2, TRPM6, and TRPM7) were measured in the tissue samples.

RESULTS

The high magnesium diet attenuated cytoskeletal loss in a dose-dependent manner in isolated nerve explants. The high magnesium diet augmented nerve regeneration and led to the restoration of nerve structure, increased S-100, and neurofilaments. This increased regeneration was consistent with the improvement of neurobehavioral and electrophysiological assessment. The denervated muscle morphology was restored with the high magnesium diet, and that was also highly correlated with the increased expression of desmin and acetylcholine receptors in denervated muscle. The plasma magnesium levels were significantly elevated after the animals consumed a high magnesium diet and were reciprocally related to the down-regulation of CNNM2, MagT1, and SCL41A1 in the blood monocytes, nerves, and muscle tissues of the nerve crush injury model.

CONCLUSION

The increased plasma magnesium levels after consuming a high magnesium diet were highly correlated with the down-regulation of magnesium transporter genes in monocytes, nerves, and muscle tissues after sciatic nerve crush injury. The study findings suggest that there are beneficial effects of administering magnesium after a nerve injury.

The amyloid precursor protein derivative, APP96-110, is efficacious following intravenous administration after traumatic brain injury

Following traumatic brain injury (TBI) neurological damage is ongoing through a complex cascade of primary and secondary injury events in the ensuing minutes, days and weeks. The delayed nature of secondary injury provides a valuable window of opportunity to limit the consequences with a timely treatment. Recently, the amyloid precursor protein (APP) and its derivative APP96-110 have shown encouraging neuroprotective activity following TBI following an intracerebroventricular administration. Nevertheless, its broader clinical utility would be enhanced by an intravenous (IV) administration. This study assessed the efficacy of IV APP96-110, where a dose-response for a single dose of 0.005mg/kg– 0.5mg/kg APP96-110 at either 30 minutes or 5 hours following moderate-severe diffuse impact-acceleration injury was performed. Male Sprague-Dawley rats were assessed daily for 3 or 7 days on the rotarod to examine motor outcome, with a separate cohort of animals utilised for immunohistochemistry analysis 3 days post-TBI to assess axonal injury and neuroinflammation. Animals treated with 0.05mg/kg or 0.5mg/kg APP96-110 after 30 minutes demonstrated significant improvements in motor outcome. This was accompanied by a reduction in axonal injury and neuroinflammation in the corpus callosum at 3 days post-TBI, whereas 0.005mg/kg had no effect. In contrast, treatment with 0.005m/kg or 0.5mg/kg APP96-110 at 5 hours post-TBI demonstrated significant improvements in motor outcome over 3 days, which was accompanied by a reduction in axonal injury in the corpus callosum. This demonstrates that APP96-110 remains efficacious for up to 5 hours post-TBI when administered IV, and supports its development as a novel therapeutic compound following TBI.

Neurotrauma: The Crosstalk between Neurotrophins and Inflammation in the Acutely Injured Brain

Traumatic brain injury (TBI) is a major cause of morbidity and mortality among young individuals worldwide. Understanding the pathophysiology of neurotrauma is crucial for the development of more effective therapeutic strategies. After the trauma occurs, immediate neurologic damage is produced by the traumatic forces; this primary injury triggers a secondary wave of biochemical cascades together with metabolic and cellular changes, called secondary neural injury. In the scenario of the acutely injured brain, the ongoing secondary injury results in ischemia and edema culminating in an uncontrollable increase in intracranial pressure. These areas of secondary injury progression, or areas of “traumatic penumbra”, represent crucial targets for therapeutic interventions. Neurotrophins are a class of signaling molecules that promote survival and/or maintenance of neurons. They also stimulate axonal growth, synaptic plasticity, and neurotransmitter synthesis and release. Therefore, this review focuses on the role of neurotrophins in the acute post-injury response. Here, we discuss possible endogenous neuroprotective mechanisms of neurotrophins in the prevailing environment surrounding the injured areas, and highlight the crosstalk between neurotrophins and inflammation with focus on neurovascular unit cells, particularly pericytes. The perspective is that neurotrophins may represent promising targets for research on neuroprotective and neurorestorative processes in the short-term following TBI.

Combined Magnesium/Polyethylene Glycol Facilitates the Neuroprotective Effects of Magnesium in Traumatic Brain Injury at a Reduced Magnesium Dose

AIMS

While a number of studies have shown that free magnesium (Mg) decline is a feature of traumatic brain injury (TBI), poor central penetration of Mg has potentially limited clinical translation. This study examines whether polyethylene glycol (PEG) facilitates central penetration of Mg after TBI, increasing neuroprotection while simultaneously reducing the dose requirements for Mg.

METHODS

Rats were exposed to diffuse TBI and administered intravenous MgCl2 either alone (254 μmol/kg or 25.4 μmol/kg) or in combination with PEG (1 g/kg PEG) at 30-min postinjury. Vehicle-treated (saline or PEG) and sham animals served as controls. All animals were subsequently assessed for blood-brain barrier permeability and edema at 5 h, and functional outcome for 1 week postinjury.

RESULTS

Optimal dose (254 μmol/kg) MgCl2 or Mg PEG significantly improved all outcome parameters compared to vehicle or PEG controls. Intravenous administration of 10% MgCl2 alone (25.4 μmol/kg) had no beneficial effect on any of the outcome parameters, whereas 10% Mg in PEG had the same beneficial effects as optimal dose Mg administration.

CONCLUSION

Polyethylene glycol facilitates central penetration of Mg following TBI, reducing the concentration of Mg required to confer neuroprotection while simultaneously reducing the risks associated with high peripheral Mg concentration.

The Neuroprotective Properties of the Amyloid Precursor Protein Following Traumatic Brain Injury

Despite the significant health and economic burden that traumatic brain injury (TBI) places on society, the development of successful therapeutic agents have to date not translated into efficacious therapies in human clinical trials. Injury to the brain is ongoing after TBI, through a complex cascade of primary and secondary injury events, providing a valuable window of opportunity to help limit and prevent some of the severe consequences with a timely treatment. Of note, it has been suggested that novel treatments for TBI should be multifactorial in nature, mimicking the body's own endogenous repair response. Whilst research has historically focused on the role of the amyloid precursor protein (APP) in the pathogenesis of Alzheimer's disease, recent advances in trauma research have demonstrated that APP offers considerable neuroprotective properties following TBI, suggesting that APP is an ideal therapeutic candidate. Its acute upregulation following TBI has been shown to serve a beneficial role following trauma and has lead to significant advances in understanding the neuroprotective and neurotrophic functions of APP and its metabolites. Research has focused predominantly on the APP derivative sAPPα, which has consistently demonstrated neuroprotective and neurotrophic functions both in vitro and in vivo following various traumatic insults. Its neuroprotective activity has been narrowed down to a 15 amino acid sequence, and this region is linked to both heparan binding and growth-factor-like properties. It has been proposed that APP binds to heparan sulfate proteoglycans to exert its neuroprotective action. APP presents us with a novel therapeutic compound that could overcome many of the challenges that have stalled development of efficacious TBI treatments previously.

Improved fracture healing in patients with concomitant traumatic brain injury: proven or not?

Over the last 3 decades, scientific evidence advocates an association between traumatic brain injury (TBI) and accelerated fracture healing. Multiple clinical and preclinical studies have shown an enhanced callus formation and an increased callus volume in patients, respectively, rats with concomitant TBI. Over time, different substances (cytokines, hormones, etc.) were in focus to elucidate the relationship between TBI and fracture healing. Until now, the mechanism behind this relationship is not fully clarified and a consensus on which substance plays the key role could not be attained in the literature. In this review, we will give an overview of current concepts and opinions on this topic published in the last decade and both clinical and pathophysiological theories will be discussed.

The up-regulation of voltage-gated sodium channel Nav1.6 expression following fluid percussion traumatic brain injury in rats

BACKGROUND

The influx of Na and the depolarization mediated by voltage-gated sodium channels (VGSCs) is an early event in traumatic brain injury (TBI) induced cellular abnormalities and is therefore well positioned as an upstream target for pharmacologic modulation of the pathological responses to TBI. Alteration in the expression of the VGSC alpha-subunit has occurred in a variety of neuropathological states including focal cerebral ischemia, spinal injury, and epilepsy.

OBJECTIVE

In this study, changes in Nav1.6 mRNA and protein expression were investigated in rat hippocampus after TBI.

METHODS

Forty-eight adult male Sprague Dawley rats were randomly assigned to control or TBI groups. TBI was induced with a lateral fluid percussion device. Expression of mRNA and protein for Nav1.6 in the bilateral hippocampus was examined at 2, 12, 24, and 72 hours after injury by real-time quantitative polymerase chain reaction and Western blot. Immunofluorescence was performed to localize the expression of Nav1.6 protein in the hippocampus.

RESULTS

Expression of >Nav1.6 mRNA was significantly up-regulated in the bilateral hippocampus at 2 and 12 hours post-TBI. Significant up-regulation of Nav1.6 protein was identified in the ipsilateral hippocampus from 2 to 72 hours post-TBI and in the contralateral hippocampus from 2 to 24 hours post-TBI. Expression of Nav1.6 occurred predominantly in neurons in the hippocampus.

CONCLUSION

Results of the study showed significant up-regulation of mRNA and protein for Nav1.6 in rat hippocampal neurons after TBI.

Multifunctional drugs for head injury

Traumatic brain injury (TBI) remains one of the leading causes of mortality and morbidity worldwide in individuals under the age of 45 years, and, despite extensive efforts to develop neuroprotective therapies, there has been no successful outcome in any trial of neuroprotection to date. In addition to recognizing that many TBI clinical trials have not been optimally designed to detect potential efficacy, the failures can be attributed largely to the fact that most of the therapies investigated have been targeted toward an individual injury factor. The contemporary view of TBI is that of a very heterogenous type of injury, one that varies widely in etiology, clinical presentation, severity, and pathophysiology. The mechanisms involved in neuronal cell death after TBI involve an interaction of acute and delayed anatomic, molecular, biochemical, and physiological events that are both complex and multifaceted. Accordingly, neuropharmacotherapies need to be targeted at the multiple injury factors that contribute to the secondary injury cascade, and, in so doing, maximize the likelihood of a successful outcome. This review focuses on a number of such multifunctional compounds that have shown considerable success in experimental studies and that show maximum promise for success in clinical trials.

Animal models of post-traumatic epilepsy

Epilepsy is a major unfavorable long-term consequence of traumatic brain injury (TBI). Moreover, TBI is one of the most important predisposing factors for the development of epilepsy, particularly in young adults. Understanding the molecular and cellular cascades that lead to the development of post-traumatic epilepsy (PTE) is key for preventing its development or modifying the disease process in such a way that epilepsy, if it develops, is milder and easier-to-treat. Tissue from TBI patients undergoing epileptogenesis is not available for such studies, which underscores the importance of developing clinically relevant animal models of PTE. The goal of this review is to (1) provide a description of PTE in humans, which is critical for the development of clinically relevant models of PTE, (2) review the characteristics of currently available PTE models, and (3) provide suggestions for the development of future models of PTE based on our current understanding of the mechanisms of TBI and epilepsy. The development of clinically relevant models of PTE is critical to advance our understanding of the mechanisms of post-traumatic epileptogenesis and epilepsy, as well as for producing breakthroughs in the development and testing of novel antiepileptogenic treatments.

Differential regulation of the CXCR2 chemokine network in rat brain trauma: Implications for neuroimmune interactions and neuronal survival

Chemokine receptors represent promising targets to attenuate inflammatory responses and subsequent secondary damage after brain injury. We studied the response of the chemokines CXCL1/CINC-1 and CXCL2/MIP-2 and their receptors CXCR1 and CXCR2 after controlled cortical impact injury in adult rats. Rapid upregulation of CXCL1/CINC-1 and CXCL2/MIP-2, followed by CXCR2 (but not CXCR1), was observed after injury. Constitutive neuronal CXCR2 immunoreactivity was detected in several brain areas, which rapidly but transiently downregulated upon trauma. A second CXCR2-positive compartment, mainly colocalized with the activated microglia/macrophage marker ED1, was detected rapidly after injury in the ipsilateral cortex, progressively emerging into deeper areas of the brain later in time. It is proposed that CXCR2 has a dual role after brain injury: (i) homologous neuronal CXCR2 downregulation would render neurons more vulnerable to injury, whereas (ii) chemotaxis and subsequent differentiation of blood-borne cells into a microglial-like phenotype would be promoted by the same receptor.

Pre-Injury Magnesium Treatment Prevents Traumatic Brain Injury–Induced Hippocampal ERK Activation, Neuronal Loss, and Cognitive Dysfunction in the Radial-Arm Maze Test

We studied the effect of pre-injury magnesium (Mg(2+)) treatment on hippocampal extracellular signal- regulated kinase (ERK) activation induced by lateral fluid-percussion (FP) brain injury, and on working and reference memory in the radial-arm maze test in rats subjected to such traumatic brain injury (TBI) (n = 56) or to sham injury (n = 12). In the ipsilateral hippocampus, an increase in the phospho-ERK level was detected at 10 min after injury in rats subjected to FP brain injury of moderate severity (1.9-2.0 atm) as compared to sham-injured controls (p < 0.01), and was maintained for at least 120 min after injury (p < 0.05). In the contralateral hippocampus, the phospho-ERK level was transiently increased at 10 min after injury but fell to nearly its basal level by 30 min. When MgCl(2) solution (150 micromol) was infused intravenously from 20 min to 5 min before injury (n = 4-5), brain injury-induced ERK activation was significantly inhibited in the ipsilateral hippocampus at 60 min but not at 10 min after injury. Mg(2+) treatment also significantly prevented injury- induced neuronal loss in the ipsilateral hippocampus (p < 0.05 vs. vehicle-treated, brain-injured controls). At 2 weeks after injury, Mg2+ treatment was found to have significantly prevented injury-induced impairments in working (p < 0.0001 vs. vehicle-treated, brain-injured controls) and reference memory (p < 0.05) in the radial-arm maze test. The present study demonstrates that pretreatment with Mg(2+) prevents post-traumatic hippocampal ERK activation and neuronal loss, and cognitive dysfunction in the radial-arm maze test.

Animal models of head trauma

Animal models of traumatic brain injury (TBI) are used to elucidate primary and secondary sequelae underlying human head injury in an effort to identify potential neuroprotective therapies for developing and adult brains. The choice of experimental model depends upon both the research goal and underlying objectives. The intrinsic ability to study injury-induced changes in behavior, physiology, metabolism, the blood/tissue interface, the blood brain barrier, and/or inflammatory- and immune-mediated responses, makes in vivo TBI models essential for neurotrauma research. Whereas human TBI is a highly complex multifactorial disorder, animal trauma models tend to replicate only single factors involved in the pathobiology of head injury using genetically well-defined inbred animals of a single sex. Although such an experimental approach is helpful to delineate key injury mechanisms, the simplicity and hence inability of animal models to reflect the complexity of clinical head injury may underlie the discrepancy between preclinical and clinical trials of neuroprotective therapeutics. Thus, a search continues for new animal models, which would more closely mimic the highly heterogeneous nature of human TBI, and address key factors in treatment optimization.

Recent advances in the development of multifactorial therapies for the treatment of traumatic brain injury

Traumatic brain injury (TBI) is one of the leading causes of death and disability in the industrialised world and remains a major health problem with serious socioeconomic consequences. So far, despite encouraging preclinical results, almost all neuroprotection trials have failed to show any significant efficacy in the treatment of clinical TBI. This may be due, in part, to the fact that most of the therapies investigated have targeted an individual injury factor. It is now recognised that TBI is a very heterogeneous type of injury that varies widely in its aetiology, clinical presentation, severity and pathophysiology. The pathophysiological sequelae of TBI are mediated by an interaction of acute and delayed molecular, biochemical and physiological events that are both complex and multifaceted. Accordingly, a successful TBI treatment may have to simultaneously attenuate many injury factors. Recent efforts in experimental TBI have, therefore, focused on the development of neuropharmacotherapies that target multiple injury factors and thus improve the likelihood of a successful outcome. This review will focus on three such novel compounds that are currently being assessed in clinical trials; progesterone, dexanabinol and dexamethasone, and provide an update on the progress of both magnesium and cyclosporin A.

The effects of magnesium sulfate on blood-brain barrier disruption caused by intracarotid injection of hyperosmolar mannitol in rats

The study was performed to evaluate whether magnesium sulfate could alter the degree of disruption of the blood-brain barrier (BBB) caused by hyperosmotic mannitol. Wistar adult female rats were infused with 25% mannitol into the left internal carotid artery. Each animal received intraperitoneally a 300 mg/kg loading dose of magnesium sulfate, dissolved in 0.9% saline, followed by a further 100 mg/kg dose. In the other group, intracarotid infusion of magnesium sulfate was performed at a dose of 150 mg/kg 10 min before mannitol administration. Evans blue (EB) dye was used as a marker of BBB disruption. The measured serum glucose and magnesium levels increased after mannitol and/or magnesium administration when compared with their initial values before treatment (P < 0.01). Water content of the left hemisphere was significantly increased by hyperosmotic mannitol (P < 0.01). The increased water content in the mannitol-perfused hemisphere was significantly decreased by magnesium treatment (P < 0.05). The content of EB dye in the mannitol-perfused hemisphere markedly increased when compared with the right hemisphere of the same brain (P < 0.01). The EB dye content in the mannitol-perfused hemisphere following both intraperitoneal and intraarterial administration of magnesium decreased when compared with mannitol alone (P < 0.01). We conclude that although magnesium sulfate administration by both intracarotid arterial and intraperitoneal routes attenuates BBB disruption caused by hyperosmolar mannitol, particularly intraperitoneal route of magnesium sulfate administration may provide a useful strategy to limit the transient osmotic opening of the BBB.

The pathobiology of moderate diffuse traumatic brain injury as identified using a new experimental model of injury in rats

Experimental models of traumatic brain injury have been developed to replicate selected aspects of human head injury, such as contusion, concussion, and/or diffuse axonal injury. Although diffuse axonal injury is a major feature of clinical head injury, relatively few experimental models of diffuse traumatic brain injury (TBI) have been developed, particularly in smaller animals such as rodents. Here, we describe the pathophysiological consequences of moderate diffuse TBI in rats generated by a newly developed, highly controlled, and reproducible model. This model of TBI caused brain edema beginning 20 min after injury and peaking at 24 h post-trauma, as shown by wet weight/dry weight ratios and diffusion-weighted magnetic resonance imaging. Increased permeability of the blood-brain barrier was present up to 4 h post-injury as evaluated using Evans blue dye. Phosphorus magnetic resonance spectroscopy showed significant declines in brain-free magnesium concentration and reduced cytosolic phosphorylation potential at 4 h post-injury. Diffuse axonal damage was demonstrated using manganese-enhanced magnetic resonance imaging, and intracerebral injection of a fluorescent vital dye (Fluoro-Ruby) at 24-h and 7-day post-injury. Morphological evidence of apoptosis and caspase-3 activation were also found in the cerebral hemisphere and brainstem at 24 h after trauma. These results show that this model is capable of reproducing major biochemical and neurological changes of diffuse clinical TBI.

Tumor necrosis factor alpha expression and protein levels after fluid percussion injury in rats: the effect of injury severity and brain temperature

OBJECTIVE

Tumor necrosis factor alpha (TNFalpha) is elevated in some models of traumatic brain injury (TBI). However, it is unclear how TNFalpha messenger ribonucleic acid (mRNA) expression and protein levels are affected by injury severity and posttraumatic temperature modification. This study determined the regional and temporal profile of TNFalpha levels after moderate and severe TBI and assessed the effects of posttraumatic hypothermia or hyperthermia on this proinflammatory cytokine.

METHODS

Adult male Sprague-Dawley rats were subjected to sham procedures (no injury), moderate fluid-percussion TBI (1.8-2.2 atm), or severe fluid-percussion TBI (2.4-2.6 atm). After 1 to 72 hours of survival, animals were killed, and brain samples, cerebrospinal fluid, and serum were harvested for enzyme-linked immunosorbent assay quantification of TNFalpha levels. In a subsequent study, a 3-hour period of posttraumatic hypothermia (33 degrees C) or hyperthermia (39.5 degrees C) was applied, followed by immediate killing and cytokine assay. Another group was subjected to moderate TBI (1.8-2.2 atm), followed by killing at 15 minutes or at 1, 3, or 24 hours for TNFalpha reverse transcriptase-polymerase chain reaction analysis.

RESULTS

A significant increase in TNFalpha mRNA and protein levels in cellular lysates of injured cortex and ipsilateral hippocampus was noted by 1 hour after TBI; it was sustained to 3 hours, followed by a rapid decline. Increased injury severity was associated with increased protein levels at remote injury sites and in the injured cerebral cortex at 72 hours. Posttraumatic hypothermia significantly reduced TNFalpha mRNA expression in the hippocampus compared with that in normothermic rats. In contrast, no temperature effects on TNFalpha protein levels were documented.

CONCLUSION

Rapid and marked increase in TNFalpha mRNA expression and protein levels follows moderate and severe TBI. Injury severity and posttraumatic temperature play a modest but significant role on TNFalpha expression and protein levels. These findings suggest that the effects of posttraumatic temperature on histopathological and behavioral outcome primarily may involve secondary mediators that do not operate directly through their effect on TNFalpha.

Pathophysiology of cerebral ischemia and brain trauma: similarities and differences

Current knowledge regarding the pathophysiology of cerebral ischemia and brain trauma indicates that similar mechanisms contribute to loss of cellular integrity and tissue destruction. Mechanisms of cell damage include excitotoxicity, oxidative stress, free radical production, apoptosis and inflammation. Genetic and gender factors have also been shown to be important mediators of pathomechanisms present in both injury settings. However, the fact that these injuries arise from different types of primary insults leads to diverse cellular vulnerability patterns as well as a spectrum of injury processes. Blunt head trauma produces shear forces that result in primary membrane damage to neuronal cell bodies, white matter structures and vascular beds as well as secondary injury mechanisms. Severe cerebral ischemic insults lead to metabolic stress, ionic perturbations, and a complex cascade of biochemical and molecular events ultimately causing neuronal death. Similarities in the pathogenesis of these cerebral injuries may indicate that therapeutic strategies protective following ischemia may also be beneficial after trauma. This review summarizes and contrasts injury mechanisms after ischemia and trauma and discusses neuroprotective strategies that target both types of injuries.