Neuroprotective and neuroregenerative drugs after severe traumatic brain injury : A narrative review from a clinical perspective

Traumatic brain injuries cause enormous individual and socioeconomic burdens. Survivors frequently struggle with motor handicaps as well as impaired cognition and emotion. In addition to the primary mechanical brain damage, complex secondary mechanisms are the main drivers of functional impairment. Many of these pathophysiological mechanisms are now well known: excitotoxic amino acids, breakdown of the blood-brain barrier, neuroinflammation with subsequent damage to cell organelles and membranes, cerebral edema, and apoptotic processes triggering neuronal death; however, paracrine resilience factors may counteract these processes. Specific neuroprotective and neuroregenerative intensive care therapies are few. This review highlights medical approaches aimed at mitigating secondary damage and promoting neurotrophic processes in severe traumatic brain injury. Some pharmacologic attempts that appeared very promising in experimental settings have had disappointing clinical results (progesterone, cyclosporine A, ronopterin, erythropoietin, dexanabinol). Thus, the search for drugs that can effectively limit ongoing posttraumatic neurological damage is ongoing. Some medications appear to be beneficial: N‑methyl-D-aspartate receptor (NMDA) antagonists (esketamine, amantadine, Mg++) reduce excitotoxicity and statins and cerebrolysin are known to counteract neuroinflammation. By supporting the impaired mitochondrial energy supply, oxidative processes are inhibited and neuroregenerative processes, such as neurogenesis, angiogenesis and synaptogenesis are promoted by citicoline and cerebrolysin. First clinical evidence shows an improvement in cognitive and thymopsychic outcomes, underlined by own clinical experience combining different therapeutic approaches. Accordingly, adjuvant treatment with neuroprotective substances appears to be a promising option, although more randomized prospective studies are still needed.

Gut microbiota-brain interaction: An emerging immunotherapy for traumatic brain injury

Individuals suffering from traumatic brain injury (TBI) often experience the activation of the immune system, resulting in declines in cognitive and neurological function after brain injury. Despite decades of efforts, approaches for clinically effective treatment are sparse. Evidence on the association between current therapeutic strategies and clinical outcomes after TBI is limited to poorly understood mechanisms. For decades, an increasing number of studies suggest that the gut-brain axis (GBA), a bidirectional communication system between the central nervous system (CNS) and the gastrointestinal tract, plays a critical role in systemic immune response following neurological diseases. In this review, we detail current knowledge of the immune pathologies of GBA after TBI. These processes may provide a new therapeutic target and rehabilitation strategy developed and used in clinical treatment of TBI patients.

Tailored Reconstituted Lipoprotein for Site-Specific and Mitochondria-Targeted Cyclosporine A Delivery to Treat Traumatic Brain Injury

The secondary damage in traumatic brain injury (TBI) can lead to lifelong disabilities, bringing enormous economic and psychological burden to patients and their families. Mitochondria, as the core mediator of the secondary injury cascade reaction in TBI, is an important target to prevent the spread of cell death and dysfunction. Thus, therapeutics that can accumulate at the damaged sites and subsequently rescue the functions of mitochondria would largely improve the outcome of TBI. Cyclosporine A (CsA), which can maintain the integrity of mitochondrial function, is among the most promising neuroprotective therapeutics for TBI treatment. However, the clinical application of CsA in TBI is largely hindered because of its poor access to the targets. Here, to realize targeted intracellular CsA delivery, we designed a lipoprotein biomimetic nanocarrier by incorporating CsA in the core and decorating a matrix metalloproteinase-9 activatable cell-penetrating peptide onto the surface of the lipoprotein-mimic nanocarrier. This CsA-loaded tailored reconstituted lipoprotein efficiently accumulated at the damaged brain sites, entered the target cells, bound to the membrane of mitochondria, more efficiently reduced neuronal damage, alleviated neuroinflammation, and rescued memory deficits at the dose 1/16 of free CsA in a controlled cortical impact injury mice model. The findings provide strong evidence that the secondary damages in TBI can be well controlled through targeted CsA delivery and highlight the potential of a lipoprotein biomimetic nanocarrier as a flexible nanoplatform for the management of TBI.

The effect of cyclosporin a on ischemia-reperfusion damage in a mouse model of ischemic stroke

OBJECTIVES

We aimed to investigate the protective effects of cyclosporin A (CsA) against ischemia-reperfusion (I/R) damage in a mouse ischemia model and the possible underlying mechanism.

METHODS

Mice were divided equally into five groups: Sham, I/R, Vehicle, I/R plus CsA (10 mg/kg), and I/R plus CsA (20 mg/kg). Nerve function scores, infarct volume, brain water content, and Evans blue (EB) leakage were evaluated, and western blotting was performed to analyze the changes in CypA, p-Akt, NF-κB, MMP-9, and Claudin-5 expression.

RESULTS

CsA can attenuate I/R damage in a mouse ischemic stroke model, as indicated by improved neurological function scores and decreased infarct volume, brain water content, and EB leakage. Additionally, high-dose CsA showed better protective effects than low-dose. The molecular mechanisms underlying the effects of CsA were explored, and it was found that CsA could inhibit the increase in CypA, p-Akt, NF-κB, and MMP-9 protein expression after middle cerebral artery occlusion, while Claudin-5 expression was decreased.

DISCUSSION

CsA showed potential as a neuroprotective drug for the treatment of ischemic stroke patients; besides interfering with the typical NF-κB signaling pathway, the Akt pathway may also be involved in the effects of CsA.

Cyclosporin A ameliorates cerebral oxidative metabolism and infarct size in the endothelin-1 rat model of transient cerebral ischaemia

Cerebral microdialysis can be used to detect mitochondrial dysfunction, a potential target of neuroprotective treatment. Cyclosporin A (CsA) is a mitochondrial stabiliser that in a recent clinical stroke trial showed protective potential in patients with successful recanalisation. To investigate specific metabolic effects of CsA during reperfusion, and hypothesising that microdialysis values can be used as a proxy outcome measure, we assessed the temporal patterns of cerebral energy substrates related to oxidative metabolism in a model of transient focal ischaemia. Transient ischaemia was induced by intracerebral microinjection of endothelin-1 (150 pmol/15 µL) through stereotaxically implanted guide cannulas in awake, freely moving rats. This was immediately followed by an intravenous injection of CsA (NeuroSTAT; 15 mg/kg) or placebo solution during continuous microdialysis monitoring. After reperfusion, the lactate/pyruvate ratio (LPR) was significantly lower in the CsA group vs placebo (n = 17, 60.6 ± 24.3%, p = 0.013). Total and striatal infarct volumes (mm³) were reduced in the treatment group (n = 31, 61.8 ± 6.0 vs 80.6 ± 6.7, p = 0.047 and 29.9 ± 3.5 vs 41.5 ± 3.9, p = 0.033). CsA treatment thus ameliorated cerebral reperfusion metabolism and infarct size. Cerebral microdialysis may be useful in evaluating putative neuroprotectants in ischaemic stroke.

The cysteine-rich whey protein supplement, Immunocal®, preserves brain glutathione and improves cognitive, motor, and histopathological indices of traumatic brain injury in a mouse model of controlled cortical impact

Traumatic brain injury (TBI) is a major public health problem estimated to affect nearly 1.7 million people in the United States annually. Due to the often debilitating effects of TBI, novel preventative agents are highly desirable for at risk populations. Here, we tested a whey protein supplement, Immunocal®, for its potential to enhance resilience to TBI. Immunocal® is a non-denatured whey protein preparation which has been shown to act as a cysteine delivery system to increase levels of the essential antioxidant glutathione (GSH). Twice daily oral supplementation of CD1 mice with Immunocal^® for 28 days prior to receiving a moderate TBI prevented an ~ 25% reduction in brain GSH/GSSG observed in untreated TBI mice. Immunocal® had no significant effect on the primary mechanical injury induced by TBI, as assessed by MRI, changes in Tau phosphorylation, and righting reflex time or apnea. However, pre-injury supplementation with Immunocal® resulted in statistically significant improvements in motor function (beam walk and rotarod) and cognitive function (Barnes maze). We also observed a significant preservation of corpus callosum width (axonal myelination), a significant decrease in degenerating neurons, a reduction in Iba1 (microglial marker), decreased lipid peroxidation, and preservation of brain-derived neurotrophic factor (BDNF) in the brains of Immunocal®-pretreated mice compared to untreated TBI mice. Taken together, these data indicate that pre-injury supplementation with Immunocal® significantly enhances the resilience to TBI induced by a moderate closed head injury in mice. We conclude that Immunocal® may hold significant promise as a preventative agent for TBI, particularly in certain high risk populations such as athletes and military personnel.

Medical Management of the Severe Traumatic Brain Injury Patient

Severe traumatic brain injury (sTBI) is a major contributor to long-term disability and a leading cause of death worldwide. Medical management of the sTBI patient, beginning with prehospital triage, is aimed at preventing secondary brain injury. This review discusses prehospital and emergency department management of sTBI, as well as aspects of TBI management in the intensive care unit where advances have been made in the past decade. Areas of emphasis include intracranial pressure management, neuromonitoring, management of paroxysmal sympathetic hyperactivity, neuroprotective strategies, prognostication, and communication with families about goals of care. Where appropriate, differences between the third and fourth editions of the Brain Trauma Foundation guidelines for the management of severe traumatic brain injury are highlighted.

Stem cell therapy for abrogating stroke-induced neuroinflammation and relevant secondary cell death mechanisms

Ischemic stroke is a leading cause of death worldwide. A key secondary cell death mechanism mediating neurological damage following the initial episode of ischemic stroke is the upregulation of endogenous neuroinflammatory processes to levels that destroy hypoxic tissue local to the area of insult, induce apoptosis, and initiate a feedback loop of inflammatory cascades that can expand the region of damage. Stem cell therapy has emerged as an experimental treatment for stroke, and accumulating evidence supports the therapeutic efficacy of stem cells to abrogate stroke-induced inflammation. In this review, we investigate clinically relevant stem cell types, such as hematopoietic stem cells (HSCs), mesenchymal stem cells (MSCs), endothelial progenitor cells (EPCs), very small embryonic-like stem cells (VSELs), neural stem cells (NSCs), extraembryonic stem cells, adipose tissue-derived stem cells, breast milk-derived stem cells, menstrual blood-derived stem cells, dental tissue-derived stem cells, induced pluripotent stem cells (iPSCs), teratocarcinoma-derived Ntera2/D1 neuron-like cells (NT2N), c-mycER(TAM) modified NSCs (CTX0E03), and notch-transfected mesenchymal stromal cells (SB623), comparing their potential efficacy to sequester stroke-induced neuroinflammation and their feasibility as translational clinical cell sources. To this end, we highlight that MSCs, with a proven track record of safety and efficacy as a transplantable cell for hematologic diseases, stand as an attractive cell type that confers superior anti-inflammatory effects in stroke both in vitro and in vivo. That stem cells can mount a robust anti-inflammatory action against stroke complements the regenerative processes of cell replacement and neurotrophic factor secretion conventionally ascribed to cell-based therapy in neurological disorders.

The use of electronic-neutral penetrating peptides cyclosporin A to deliver pro-apoptotic peptide: A possibly better choice than positively charged TAT

Cell-penetrating peptides (CPPs) are increasingly important in transporting macromolecules across cell membranes, but their use remains confined to narrow clinical applications due to the systemic toxicity induced by their positive charges. Several newly discovered electronic neutral penetrating peptides are not attracting much attention because their penetrating capacity is normally far less powerful than cationic or amphiphilic CPPs. In this study, we found the electronic neutral cyclic peptide cyclosporin A (CsA) exhibited 5.6-fold and 19.1-fold stronger penetrating capacity, respectively, than two reported electronic neutral peptides PFVYLI (PFV) and pentapeptide VPTLQ (VPT) in MCF-7 human breast cancer cells. To systematically evaluate the efficiency and toxicity of CsA, we utilized CsA to deliver a membrane-impenetrable pro-apoptotic peptide (PAD) and compared this to the well-established cationic penetrating peptide TAT (RKKRRQRRR). By conjugating CsA to PAD, the internalization of PAD increased 2.2- to 4.7-fold in four different tumor cell lines, and that of CsA-PAD conjugate was significantly higher than TAT-PAD conjugate in MCF-7 and HeLa human cervical cancer cells. Cytotoxicity studies demonstrated that CsA-PAD exhibited a large increase in cell cytotoxicity compared to PAD in four different tumor cell lines, with the effect being similar or greater than the effect of TAT-PAD, depending upon the cell type. The mechanistic studies demonstrated that modifying CsA or TAT did not change the cytotoxicity mechanism of PAD, which occurred via mitochondrial membrane damage related to apoptosis. In vivo studies showed that CsA-PAD could achieve similar anti-tumor efficacy to TAT-PAD but with much lower systemic toxicity, especially to the heart and liver. In conclusion, our study demonstrates for the first time that the electronic-neutral penetrating peptide CsA can be used as a powerful tool to deliver peptide drugs with similar efficiency and less toxicity than the positively charged TAT peptide.

Translational obstacles with off-label drug use in acute traumatic brain injury

Traumatic brain injury results in significant morbidity and mortality, and there is an urgent need for neuroprotective medications that can prevent the persisting symptoms and disabilities following injury. Several existing pharmacotherapies have been targeted for off-label benefit in traumatic brain injury, as these agents are well characterized and commercially available, easing the process of clinical trial development. Despite promising results in animal models, clinical trials have demonstrated minimal benefit. One possible reason for these failed translations could be that drug selection, characterization and dosing are not routinely established in the appropriate early phase trials before larger scale testing. Examining how recent trials may have bypassed these steps may help future trials to more definitively determine the efficacy of potential therapeutics.

Cyclosporin A protects against Lead neurotoxicity through inhibiting mitochondrial permeability transition pore opening in nerve cells

Mitochondria play a key role in the process of lead (Pb)-induced impairment in nervous system. To further clarify the underlying mechanism of Pb neurotoxicity, this study was designed to investigate the role of mitochondrial permeability transition (MPT) and cyclophilin D (CyPD), a component of MPT pore (MPTP), in Pb-induced mitochondrial apoptosis in nerve cells. In SH-SY5Y and PC12 cells, Cyclosporin A (CSA), a special inhibitor of CyPD, could alleviate cell death, lactate dehydrogenase (LDH) leakage and adenosine 5 triphosphate (ATP) decrease caused by PbAc. In the following experiments, we found PbAc increased the protein level of CyPD and induced MPT pore (MPTP) opening. When cells were pretreated with CSA to inhibit MPTP opening, the Pb-induced impairment of mitochondrial morphology (swelling and rupture) and the loss of mitochondria were attenuated. In addition, CSA obviously ameliorated the Pb-induced damage of mitochondrial function, such as reactive oxygen species (ROS) boost and mitochondrial membrane potential (MMP) collapse, as well as the release of cytochrome C (Cyto C) and apoptosis-inducing factor (AIF) from mitochondria. These beneficial effects could finally result in cell survival under Pb-exposure conditions. Furthermore, scavenging ROS also significantly abrogated MPTP opening and attenuated Pb neurotoxicity. Therefore, we found that MPT played an important role in Pb-induced mitochondrial damage and, ultimately, cell death. Our results provided a potential strategy for inhibiting PbAc neurotoxicity. However, due to the high Pb concentrations used in this study further investigations at Pb concentrations closer to human exposure are needed to verify the results.

The Controlled Cortical Impact Model: Applications, Considerations for Researchers, and Future Directions

Controlled cortical impact (CCI) is a mechanical model of traumatic brain injury (TBI) that was developed nearly 30 years ago with the goal of creating a testing platform to determine the biomechanical properties of brain tissue exposed to direct mechanical deformation. Initially used to model TBIs produced by automotive crashes, the CCI model rapidly transformed into a standardized technique to study TBI mechanisms and evaluate therapies. CCI is most commonly produced using a device that rapidly accelerates a rod to impact the surgically exposed cortical dural surface. The tip of the rod can be varied in size and geometry to accommodate scalability to difference species. Typically, the rod is actuated by a pneumatic piston or electromagnetic actuator. With some limits, CCI devices can control the velocity, depth, duration, and site of impact. The CCI model produces morphologic and cerebrovascular injury responses that resemble certain aspects of human TBI. Commonly observed are graded histologic and axonal derangements, disruption of the blood-brain barrier, subdural and intra-parenchymal hematoma, edema, inflammation, and alterations in cerebral blood flow. The CCI model also produces neurobehavioral and cognitive impairments similar to those observed clinically. In contrast to other TBI models, the CCI device induces a significantly pronounced cortical contusion, but is limited in the extent to which it models the diffuse effects of TBI; a related limitation is that not all clinical TBI cases are characterized by a contusion. Another perceived limitation is that a non-clinically relevant craniotomy is performed. Biomechanically, this is irrelevant at the tissue level. However, craniotomies are not atraumatic and the effects of surgery should be controlled by including surgical sham control groups. CCI devices have also been successfully used to impact closed skulls to study mild and repetitive TBI. Future directions for CCI research surround continued refinements to the model through technical improvements in the devices (e.g., minimizing mechanical sources of variation). Like all TBI models, publications should report key injury parameters as outlined in the NIH common data elements (CDEs) for pre-clinical TBI.

Cyclosporine A Treatment Abrogates Ischemia-Induced Neuronal Cell Death by Preserving Mitochondrial Integrity through Upregulation of the Parkinson's Disease-Associated Protein DJ-1

Aims

Hypoxic‐ischemia alters mitochondrial membrane potential (Δψm), respiratory‐related enzymes, and mitochondrial DNA (mtDNA). Drugs acting on mitochondria, such as cyclosporine A (CsA), may reveal novel mitochondria‐based cell death signaling targets for stroke. Our previous studies showed that Parkinson's disease‐associated protein DJ‐1 participates in the acute endogenous neuroprotection after stroke via mitochondrial pathway. DJ‐1 was detected immediately after stroke and efficiently translocated into the mitochondria offering a new venue for developing treatment strategies against stroke. Here, we examined a molecular interaction between CsA and mitochondrial integrity in the in vitro acute stroke model of oxygen glucose deprivation/reperfusion (OGD/R) injury with emphasis on DJ‐1.

Methods

Primary rat neuronal cells (PRNCs) were exposed to OGD/R injury and processed for immunocytochemistry, ELISA, and mitochondria‐based molecular assays to reveal the role of DJ‐1 in CsA modulation of mitochondrial integrity.

Results

Administration of CsA before stroke onset (24 h pre‐OGD/R) afforded significantly much more robust neuroprotective effects than when CsA was initiated after stroke (2 h post‐OGD/R), revealing that CsA exerted neuroprotection in the early phase of ischemic stroke. CsA prevented the mitochondria‐dependent cell death signaling pathway involved in cytochrome c (Cyt c)‐induced intrinsic apoptotic process. CsA preserved cellular ATP content, but not hexokinase activity under hypoxic conditions. CsA prevented both mtDNA decrement and Δψm degradation after reperfusion, and enhanced secretion of DJ‐1 in the mitochondria, coupled with reduced oxidative stress.

Conclusion

These observations provided evidence that CsA maintained mitochondrial integrity likely via DJ‐1 upregulation, supporting the concept that mitochondria‐based treatments targeting the early phase of disease progression may prove beneficial in stroke.

Reformulating cyclosporine A (CsA): More than just a life cycle management strategy

Cyclosporine A (CsA) is a well-known immunosuppressive agent that gained considerable importance in transplant medicine in the late 1970s due to its selective and reversible inhibition of T-lymphocytes. While CsA has been widely used to prevent graft rejection in patients undergoing organ transplant it was also used to treat several systemic and local autoimmune disorders. Currently, the neuro- and cardio-protective effects of CsA (CiCloMulsion®; NeuroSTAT®) are being tested in phase II and III trials respectively and NeuroSTAT® received orphan drug status from US FDA and Europe in 2010. The reformulation strategies focused on developing Cremophor® EL free formulations and address variable bioavailability and toxicity issues of CsA. This review is an attempt to highlight the progress made so far and the room available for further improvements to realize the maximum benefits of CsA.

Brain Region-Specific Histopathological Effects of Varying Trajectories of Controlled Cortical Impact Injury Model of Traumatic Brain Injury

AIMS

Traumatic brain injury (TBI) occurs when the head is impacted by an external force causing either a closed or penetrating head injury through a direct or accelerating impact. In laboratory research, most of the TBI animal models focus on a specific region to cause brain injury, but traumatic injuries in patients do not always impact the same brain regions. The aim of this study was to examine the histopathological effects of different angles of mechanical injury by manipulating the trajectory of the controlled cortical impact injury (CCI) model in adult Sprague-Dawley rats.

METHODS

The CCI model was manipulated as follows: conventional targeting of the frontal cortex, farthest right angle targeting the frontal cortex, closest right angle targeting the frontal cortex, olfactory bulb injury, and cerebellar injury. Three days after TBI, brains were harvested to analyze cortical and hippocampal cell loss, neuroinflammatory response, and neurogenesis via immunohistochemistry.

RESULTS

Results revealed cell death in the M1 region of the cortex across all groups, and in the CA3 area from olfactory bulb injury group. This observed cell death involved upregulation of inflammation as evidenced by rampant MHCII overexpression in cortex, but largely spared Ki-67/nestin neurogenesis in the hippocampus during this acute phase of TBI.

CONCLUSION

These results indicate a trajectory-dependent injury characterized by exacerbation of inflammation and different levels of impaired cell proliferation and neurogenesis. Such multiple brain areas showing varying levels of cell death after region-specific CCI model may closely mimic the clinical manifestations of TBI.

Involvement of Immune Responses in the Efficacy of Cord Blood Cell Therapy for Cerebral Palsy

This study evaluated the efficacy of umbilical cord blood (UCB) cell for patients with cerebral palsy (CP) in a randomized, placebo-controlled, double-blind trial and also assessed factors and mechanisms related to the efficacy. Thirty-six children (ages 6 months to 20 years old) with CP were enrolled and treated with UCB or a placebo. Muscle strength and gross motor function were evaluated at baseline and 1, 3, and 6 months after treatment. Along with function measurements, each subject underwent (18)F-fluorodeoxyglucose positron emission tomography at baseline and 2 weeks after treatment. Cytokine and receptor levels were quantitated in serial blood samples. The UCB group showed greater improvements in muscle strength than the controls at 1 (0.94 vs. -0.35, respectively) and 3 months (2.71 vs. 0.65) after treatment (Ps<0.05). The UCB group also showed greater improvements in gross motor performance than the control group at 6 months (8.54 vs. 2.60) after treatment (P<0.01). Additionally, positron emission tomography scans revealed decreased periventricular inflammation in patients administered UCB, compared with those treated with a placebo. Correlating with enhanced gross motor function, elevations in plasma pentraxin 3 and interleukin-8 levels were observed for up to 12 days after treatment in the UCB group. Meanwhile, increases in blood cells expressing Toll-like receptor 4 were noted at 1 day after treatment in the UCB group, and they were correlated with increased muscle strength at 3 months post-treatment. In this trial, treatment with UCB alone improved motor outcomes and induced systemic immune reactions and anti-inflammatory changes in the brain. Generally, motor outcomes were positively correlated with the number of UCB cells administered: a higher number of cells resulted in better outcomes. Nevertheless, future trials are needed to confirm the long-term efficacy of UCB therapy, as the follow-up duration of the present trial was short.

Immunosuppression does not affect human bone marrow mesenchymal stromal cell efficacy after transplantation in traumatized mice brain

The need for immunosuppression after allo/xenogenic mesenchymal stromal cell (MSC) transplantation is debated. This study compared the long-term effects of human (h) bone marrow MSC transplant in immunocompetent or immunosuppressed traumatic brain injured (TBI) mice. C57Bl/6 male mice were subjected to TBI or sham surgery followed 24 h later by an intracerebroventricular infusion of phosphate buffer saline (PBS, control) or hMSC (150,000/5 μl). Immunocompetent and cyclosporin A immunosuppressed (CsA) mice were analyzed for gene expression at 72 h, functional deficits and histological analysis at five weeks. Gene expression analysis showed the effectiveness of immunosuppression (INFγ reduction in CsA treated groups), with no evidence of early rejection (no changes of MHCII and CD86 in all TBI groups) and selective induction of T-reg (increase of Foxp3) only in the TBI hMSC group. Five weeks after TBI, hMSC had comparable efficacy, with functional recovery (on both sensorimotor and cognitive deficits) and structural protection (contusion volume, vessel rescue effect, gliotic scar reduction, induction of neurogenesis) in immunosuppressed and immunocompetent mice. Therefore, long-term hMSC efficacy in TBI is not dependent on immunosuppressive treatment. These findings could have important clinical implication since immunosuppression in acute TBI patients may increase their risk of infection and not be tolerated.

Mitochondrial polymorphisms impact outcomes after severe traumatic brain injury

Patient outcomes are variable following severe traumatic brain injury (TBI); however, the biological underpinnings explaining this variability are unclear. Mitochondrial dysfunction after TBI is well documented, particularly in animal studies. The aim of this study was to investigate the role of mitochondrial polymorphisms on mitochondrial function and patient outcomes out to 1 year after a severe TBI in a human adult population. The Human MitoChip V2.0 was used to evaluate mitochondrial variants in an initial set of n=136 subjects. SNPs found to be significantly associated with patient outcomes [Glasgow Outcome Scale (GOS), Neurobehavioral Rating Scale (NRS), Disability Rating Scale (DRS), in-hospital mortality, and hospital length of stay] or neurochemical level (lactate:pyruvate ratio from cerebrospinal fluid) were further evaluated in an expanded sample of n=336 subjects. A10398G was associated with DRS at 6 and 12 months (p=0.02) and a significant time by SNP interaction for DRS was found (p=0.0013). The A10398 allele was associated with greater disability over time. There was a T195C by sex interaction for GOS (p=0.03) with the T195 allele associated with poorer outcomes in females. This is consistent with our findings that the T195 allele was associated with mitochondrial dysfunction (p=0.01), but only in females. This is the first study associating mitochondrial DNA variation with both mitochondrial function and neurobehavioral outcomes after TBI in humans. Our findings indicate that mitochondrial DNA variation may impact patient outcomes after a TBI potentially by influencing mitochondrial function, and that sex of the patient may be important in evaluating these associations in future studies.

A hydrogel composite system for sustained epi-cortical delivery of Cyclosporin A to the brain for treatment of stroke

Stimulation of endogenous neural stem/progenitor cells (NSPCs) with therapeutic factors holds potential for the treatment of stroke. Cyclosporin A (CsA) is a particularly promising candidate molecule because it has been shown to act as a survival factor for these cells over a period of weeks both in vitro and in vivo; however, systemically-delivered CsA compromises the entire immune system, necessitating sustained localized delivery. Herein we describe a local delivery strategy for CsA using an epi-cortical hydrogel of hyaluronan-methylcellulose (HAMC) as the drug reservoir. Three methods of incorporating the drug into the hydrogel (solubilized, particulate, and poly(lactic-co-glycolic) acid (PLGA) microsphere-encapsulated) resulted in tunable release, spanning a period of hours to weeks. Importantly, PLGA-encapsulated CsA released from the hydrogel had equivalent bioactivity to fresh drug as measured by the neurosphere assay. Moreover, when CsA was released from the PLGA/HAMC composite that was injected on the cortex of adult mice, CsA was detected in the NSPC niche at a constant concentration for at least 24days post-implant. Thus this hydrogel composite system may be promising for the treatment of stroke.

Transcranial low-level laser therapy improves neurological performance in traumatic brain injury in mice: effect of treatment repetition regimen

Low-level laser (light) therapy (LLLT) has been clinically applied around the world for a spectrum of disorders requiring healing, regeneration and prevention of tissue death. One area that is attracting growing interest in this scope is the use of transcranial LLLT to treat stroke and traumatic brain injury (TBI). We developed a mouse model of severe TBI induced by controlled cortical impact and explored the effect of different treatment schedules. Adult male BALB/c mice were divided into 3 broad groups (a) sham-TBI sham-treatment, (b) real-TBI sham-treatment, and (c) real-TBI active-treatment. Mice received active-treatment (transcranial LLLT by continuous wave 810 nm laser, 25 mW/cm², 18 J/cm², spot diameter 1 cm) while sham-treatment was immobilization only, delivered either as a single treatment at 4 hours post TBI, as 3 daily treatments commencing at 4 hours post TBI or as 14 daily treatments. Mice were sacrificed at 0, 4, 7, 14 and 28 days post-TBI for histology or histomorphometry, and injected with bromodeoxyuridine (BrdU) at days 21–27 to allow identification of proliferating cells. Mice with severe TBI treated with 1-laser Tx (and to a greater extent 3-laser Tx) had significant improvements in neurological severity score (NSS), and wire-grip and motion test (WGMT). However 14-laser Tx provided no benefit over TBI-sham control. Mice receiving 1- and 3-laser Tx had smaller lesion size at 28-days (although the size increased over 4 weeks in all TBI-groups) and less Fluoro-Jade staining for degenerating neurons (at 14 days) than in TBI control and 14-laser Tx groups. There were more BrdU-positive cells in the lesion in 1- and 3-laser groups suggesting LLLT may increase neurogenesis. Transcranial NIR laser may provide benefit in cases of acute TBI provided the optimum treatment regimen is employed.

Cyclophilin-D inhibition in neuroprotection: dawn of a new era of mitochondrial medicine

Traumatic brain injury and ischemia can result in marked neuronal degeneration and residual impairment of cerebral function. However, no effective pharmacological treatment directed at tissues of the central nervous system (CNS) for acute intervention has been developed. The detailed pathophysiological cascade leading to -neurodegeneration in these conditions has not been elucidated, but cellular calcium overload and mitochondrial dysfunction have been implicated in a wide range of animal models involving degeneration of the CNS. In particular, activation of the calcium-induced mitochondrial permeability transition (mPT) is considered to be a major cause of cell death inferred by the broad and potent neuroprotective effects of -pharmacological inhibitors of mPT, especially modulators of cyclophilin activity and, more specifically, genetic inactivation of the mitochondrial cyclophilin, cyclophilin D. Reviewed are evidence and challenges that could bring on the dawning of mitochondrial medicine aimed at safeguarding energy supply following acute injury to the CNS.

Neuropsychological assessment in a case of adult-onset hemophagocytic lymphohistiocytosis (HLH)

We present a case of an individual diagnosed with hemophagocytic lymphohistiocytosis (HLH), an extremely rare and commonly fatal disorder characterized by rapid dysregulation of immune system processes. Typical age of onset is in childhood, with adult-onset occurring less frequently. The pathophysiology of this condition is characterized by a hyperinflammatory response with infiltration of visceral organs, lymph nodes, bone marrow, and the central nervous system. The clinical presentation has been documented in the extant medical literature. However, there appear to be no published reports of neuropsychological functioning in HLH patients. The patient we present here is a 28-year-old woman with 16 years of education who developed HLH subsequent to systemic lupus erythematosus flare-up. She was initially comatose for 3 weeks. Acute MRI reported multiple subcortical abnormalities, including the brainstem. The patient underwent chemotherapy, immunosuppresant, and steroid treatments. She underwent a neuropsychological evaluation at 2.5 and 7 months post initial presentation. Preliminary neuropsychological evaluation found impairments in motor abilities and aspects of executive functions. Subsequent evaluation showed improved executive function and relative sparing of higher-order cognitive abilities, but continued impairment on motor tests. To our knowledge this is the first study to report neuropsychological data for an adult diagnosed with HLH.

Neuroprotective effect of Cyclosporin A on the development of early brain injury in a subarachnoid hemorrhage model: a pilot study

Cyclosporin A (CsA) has been demonstrated to be neuroprotective in ischemic and traumatic brain injuries by inhibiting mitochondrial permeability transition pore (mPTP) opening, thereby maintaining mitochondrial homeostasis and inhibiting pro-apoptotic protein release. The effects of CsA on early brain injury (EBI) after subarachnoid hemorrhage (SAH), however, have not been investigated. This study was designed to explore the effects of CsA on apoptotic signaling pathways and EBI after experimental SAH using four equal groups (n=36) of adult male SD rats, including the sham group, SAH+vehicle group, SAH+CsA2 group, and SAH+CsA10 group. The rat SAH model was induced by injection of 0.3ml non-heparinized arterial blood into the prechiasmatic cistern. In the SAH+CsA2 and SAH+CsA10 groups, a dose of 2mg/kg and 10mg/kg CsA was directly administered by intercarotid injection at 15min and again 24h after SAH induction. Cerebral tissue samples were extracted 48h after SAH. Increased expressions of Cytochrome C, apoptosis-inducing factor (AIF), and cleaved caspase-3 were observed in the cerebral cortex after SAH. Treatment with high dose (10mg/kg) CsA markedly decreased expressions of Cytochrome C, AIF, and cleaved caspase-3, and inhibited apoptosis pathways. Administration of CsA following SAH significantly ameliorated EBI, including cortical apoptosis, brain edema, blood-brain barrier (BBB) impairment, and neurobehavioral deficits. These findings suggest that early administration of CsA may ameliorate EBI and provide neuroprotection in the SAH model through potential mechanisms that include blockage of mPTP opening and inhibition of apoptotic cell death pathways.

Concussions: What a neurosurgeon should know about current scientific evidence and management strategies

BACKGROUND

There has been a tremendous amount of interest focused on the topic of concussions over the past few decades. Neurosurgeons are frequently consulted to manage patients with mild traumatic brain injuries (mTBI) that have radiographic evidence of cerebral injury. These injuries share significant overlap with concussions, injuries that typically do not reveal radiographic evidence of structural injury, in the realms of epidemiology, pathophysiology, outcomes, and management. Further, neurosurgeons often manage patients with extracranial injuries that have concomitant concussions. In these cases, neurosurgeons are often the only "concussion experts" that patients encounter.

RESULTS

The literature has been reviewed and data have been synthesized on the topic including sections on historical background, epidemiology, pathophysiology, diagnostic advances, clinical sequelae, and treatment suggestions, with neurosurgeons as the intended target audience.

CONCLUSIONS

Neurosurgeons should have a fundamental knowledge of the scientific evidence that has developed regarding concussions and be prepared to guide patients with treatment plans.