Human neural stem cell transplant location-dependent neuroprotection and motor deficit amelioration in rats with penetrating traumatic brain injury.

BACKGROUND: Penetrating traumatic brain injury induces chronic inflammation that drives persistent tissue loss long after injury. Absence of endogenous reparative neurogenesis and effective neuroprotective therapies render injury-induced disability an unmet need. Cell replacement via neural stem cell transplantation could potentially rebuild the tissue and alleviate penetrating traumatic brain injury disability. The optimal transplant location remains to be determined. METHODS: To test if subacute human neural stem cell (hNSC) transplant location influences engraftment, lesion expansion, and motor deficits, rats (n = 10/group) were randomized to the following four groups (uninjured and three injured): group 1 (Gr1), uninjured with cell transplants (sham+hNSCs), 1-week postunilateral penetrating traumatic brain injury, after establishing motor deficit; group 2 (Gr2), treated with vehicle (media, no cells); group 3 (Gr3), hNSCs transplanted into lesion core (intra); and group 4 (Gr4), hNSCs transplanted into tissue surrounding the lesion (peri). All animals were immunosuppressed for 12 weeks and euthanized following motor assessment. RESULTS: In Gr2, penetrating traumatic brain injury effect manifests as porencephalic cyst, 22.53 ± 2.87 (% of intact hemisphere), with p value of <0.0001 compared with uninjured Gr1. Group 3 lesion volume at 17.44 ± 2.11 did not differ significantly from Gr2 (p = 0.36), while Gr4 value, 9.17 ± 1.53, differed significantly (p = 0.0001). Engraftment and neuronal differentiation were significantly lower in the uninjured Gr1 (p < 0.05), compared with injured groups. However, there were no differences between Gr3 and Gr4. Significant increase in cortical tissue sparing (p = 0.03), including motor cortex (p = 0.005) was observed in Gr4 but not Gr3. Presence of transplant within lesion or in penumbra attenuated motor deficit development (p < 0.05) compared with Gr2. CONCLUSION: In aggregate, injury milieu supports transplanted cell proliferation and differentiation independent of location. Unexpectedly, cortical sparing is transplant location dependent. Thus, apart from cell replacement and transplant mediated deficit amelioration, transplant location-dependent neuroprotection may be key to delaying onset or preventing development of injury-induced disability. LEVEL OF EVIDENCE: Preclinical study evaluation of therapeutic intervention, level VI.

Subdural hematoma decompression model: A model of traumatic brain injury with ischemic-reperfusional pathophysiology: A review of the literature.

The prognosis for patients with traumatic brain injury (TBI) with subdural hematoma (SDH) remains poor. In accordance with an increasing elderly population, the incidence of geriatric TBI with SDH is rising. An important contributor to the neurological injury associated with SDH is the ischemic damage which is caused by raised intracranial pressure (ICP) producing impaired cerebral perfusion. To control intracranial hypertension, the current management consists of hematoma evacuation with or without decompressive craniotomy. This removal of the SDH results in the immediate reversal of global ischemia accompanied by an abrupt reduction of mass lesion and an ensuing reperfusion injury. Experimental models can play a critical role in improving our understanding of the underlying pathophysiology and in exploring potential treatments for patients with SDH. In this review, we describe the epidemiology, pathophysiology and clinical background of SDH.

Enduring Neuroprotective Effect of Subacute Neural Stem Cell Transplantation After Penetrating TBI.

Traumatic brain injury (TBI) is the largest cause of death and disability of persons under 45 years old, worldwide. Independent of the distribution, outcomes such as disability are associated with huge societal costs. The heterogeneity of TBI and its complicated biological response have helped clarify the limitations of current pharmacological approaches to TBI management. Five decades of effort have made some strides in reducing TBI mortality but little progress has been made to mitigate TBI-induced disability. Lessons learned from the failure of numerous randomized clinical trials and the inability to scale up results from single center clinical trials with neuroprotective agents led to the formation of organizations such as the Neurological Emergencies Treatment Trials (NETT) Network, and international collaborative comparative effectiveness research (CER) to re-orient TBI clinical research. With initiatives such as TRACK-TBI, generating rich and comprehensive human datasets with demographic, clinical, genomic, proteomic, imaging, and detailed outcome data across multiple time points has become the focus of the field in the United States (US). In addition, government institutions such as the US Department of Defense are investing in groups such as Operation Brain Trauma Therapy (OBTT), a multicenter, pre-clinical drug-screening consortium to address the barriers in translation. The consensus from such efforts including "The Lancet Neurology Commission" and current literature is that unmitigated cell death processes, incomplete debris clearance, aberrant neurotoxic immune, and glia cell response induce progressive tissue loss and spatiotemporal magnification of primary TBI. Our analysis suggests that the focus of neuroprotection research needs to shift from protecting dying and injured neurons at acute time points to modulating the aberrant glial response in sub-acute and chronic time points. One unexpected agent with neuroprotective properties that shows promise is transplantation of neural stem cells. In this review we present (i) a short survey of TBI epidemiology and summary of current care, (ii) findings of past neuroprotective clinical trials and possible reasons for failure based upon insights from human and preclinical TBI pathophysiology studies, including our group's inflammation-centered approach, (iii) the unmet need of TBI and unproven treatments and lastly, (iv) present evidence to support the rationale for sub-acute neural stem cell therapy to mediate enduring neuroprotection.

Amelioration of Penetrating Ballistic-Like Brain Injury Induced Cognitive Deficits after Neuronal Differentiation of Transplanted Human Neural Stem Cells.

Penetrating traumatic brain injury (PTBI) is one of the major cause of death and disability worldwide. Previous studies with penetrating ballistic-like brain injury (PBBI), a PTBI rat model revealed widespread perilesional neurodegeneration, similar to that seen in humans following gunshot wound to the head, which is unmitigated by any available therapies to date. Therefore, we evaluated human neural stem cell (hNSC) engraftment to putatively exploit the potential of cell therapy that has been seen in other central nervous system injury models. Toward this objective, green fluorescent protein (GFP) labeled hNSC (400,000 per animal) were transplanted in immunosuppressed Sprague-Dawley (SD), Fisher, and athymic (ATN) PBBI rats 1 week after injury. Tacrolimus (3 mg/kg 2 days prior to transplantation, then 1 mg/kg/day), methylprednisolone (10 mg/kg on the day of transplant, 1 mg/kg/week thereafter), and mycophenolate mofetil (30 mg/kg/day) for 7 days following transplantation were used to confer immunosuppression. Engraftment in SD and ATN was comparable at 8 weeks post-transplantation. Evaluation of hNSC differentiation and distribution revealed increased neuronal differentiation of transplanted cells with time. At 16 weeks post-transplantation, neither cell proliferation nor glial lineage markers were detected. Transplanted cell morphology was similar to that of neighboring host neurons, and there was relatively little migration of cells from the peritransplant site. By 16 weeks, GFP-positive processes extended both rostrocaudally and bilaterally into parenchyma, spreading along host white matter tracts, traversing the internal capsule, and extending ∼13 mm caudally from transplantation site reaching into the brainstem. In a Morris water maze test at 8 weeks post-transplantation, animals with transplants had shorter latency to platform than vehicle-treated animals. However, weak injury-induced cognitive deficits in the control group at the delayed time point confounded benefits of durable engraftment and neuronal differentiation. Therefore, these results justify further studies to progress towards clinical translation of hNSC therapy for PTBI.

Microdialysis as Clinical Evaluation of Therapeutic Hypothermia in Rat Subdural Hematoma Model.

Cerebral microdialysis (MD) is a fine laboratory technique which has been established for studying physiological, pharmacological, and pathological changes in the experimental studies of traumatic brain injury (TBI). This technique has also been well translated and widely applied to clinical bedside monitoring to provide pathophysiological analysis in severe TBI patients. The MD technique is thus well suited for straightforward translation from basic science to clinical application.In this chapter, we describe our evaluation of MD method in acute subdural hematoma (ASDH) rat model. With 100 kDa cut-off microdialysis membrane, we could measure several biomarkers such as ubiquitin carboxy hydrolase L1 (UCH-L1), a neuronal marker and glial fibrillary acidic protein (GFAP), and a glial marker in extracellular fluid. In this experiment, we could detect that the peak of extracellular UCH-L1 in the early hypothermia group was significantly lower than in the normothermia group. Also, in the late phase of reperfusion (>2.5 h after decompression), extracellular GFAP in the early hypothermia group was lower than in the normothermia. These data thus suggested that early, preoperatively induced hypothermia could mediate the reduction of neuronal and glial damage in the reperfusion phase of ischemia/reperfusion brain injury.Microdialysis allows for the direct measurement of extracellular molecules in an attempt to characterize metabolic derangements before they become clinically relevant. Advancements in technology have allowed for the bedside assay of multiple markers of ischemia and metabolic dysfunction, and the applications for traumatic brain injury have been well established. As clinicians become more comfortable with these tools their widespread use and potential for clinical impact with continue to rise.

Evidence to support mitochondrial neuroprotection, in severe traumatic brain injury.

Traumatic brain injury (TBI) is still the leading cause of disability in young adults worldwide. The major mechanisms - diffuse axonal injury, cerebral contusion, ischemic neurological damage, and intracranial hematomas have all been shown to be associated with mitochondrial dysfunction in some form. Mitochondrial dysfunction in TBI patients is an active area of research, and attempts to manipulate neuronal/astrocytic metabolism to improve outcomes have been met with limited translational success. Previously, several preclinical and clinical studies on TBI induced mitochondrial dysfunction have focused on opening of the mitochondrial permeability transition pore (PTP), consequent neurodegeneration and attempts to mitigate this degeneration with cyclosporine A (CsA) or analogous drugs, and have been unsuccessful. Recent insights into normal mitochondrial dynamics and into diseases such as inherited mitochondrial neuropathies, sepsis and organ failure could provide novel opportunities to develop mitochondria-based neuroprotective treatments that could improve severe TBI outcomes. This review summarizes those aspects of mitochondrial dysfunction underlying TBI pathology with special attention to models of penetrating traumatic brain injury, an epidemic in modern American society.

Pupillary reactivity as an early indicator of increased intracranial pressure: The introduction of the Neurological Pupil index.

BACKGROUND: This paper introduces the 7/5/2011al Pupil index (NPi), a sensitive measure of pupil reactivity and an early indicator of increasing intracranial pressure (ICP). This may occur in patients with severe traumatic brain injury (TBI), aneurysmal subarachnoid hemorrhage, or intracerebral hemorrhage (ICH). METHODS: 134 patients (mean age 46 years, range 18-87 years, 54 women and 80 men) in the intensive care units at eight different clinical sites were enrolled in the study. Pupillary examination was performed using a portable hand-held pupillometer. RESULTS: Patients with abnormal pupillary light reactivity had an average peak ICP of 30.5 mmHg versus 19.6 mmHg for the normal pupil reactivity population (P = 0.0014). Patients with "nonreactive pupils" had the highest peaks of ICP (mean = 33.8 mmHg, P = 0.0046). In the group of patients with abnormal pupillary reactivity, we found that the first evidence of pupil abnormality occurred, on average, 15.9 hours prior to the time of the peak of ICP. CONCLUSIONS: Automated pupillary assessment was used in patients with possible increased ICP. Using NPi, we were able to identify a trend of inverse relationship between decreasing pupil reactivity and increasing ICP. Quantitative measurement and classification of pupillary reactivity using NPi may be a useful tool in the early management of patients with causes of increased ICP.

Assessment of mitochondrial impairment in traumatic brain injury using high-resolution proton magnetic resonance spectroscopy.

OBJECTIVES: The goal of this study was to demonstrate the posttraumatic neurochemical damage in normal-appearing brain and to assess mitochondrial dysfunction by measuring N-acetylaspartate (NAA) levels in patients with severe head injuries, using proton (1H) magnetic resonance (MR) spectroscopy. METHODS: Semiquantitative analysis of NAA relative to creatine-containing compounds (Cr) and choline (Cho) was carried out from proton spectra obtained by means of chemical shift (CS) imaging and single-voxel (SV) methods in 25 patients with severe traumatic brain injuries (TBIs) (Glasgow Coma Scale scores < or = 8) using a 1.5-tesla MR unit. Proton MR spectroscopy was also performed in 5 healthy volunteers (controls). RESULTS: The SV studies in patients with diffuse TBI showed partial reduction of NAA/Cho and NAA/Cr ratios within the first 10 days after injury (means +/- standard deviations 1.59 +/- 0.46 and 1.44 +/- 0.21, respectively, in the patients compared with 2.08 +/- 0.26 and 2.04 +/- 0.31, respectively, in the controls; nonsignificant difference). The ratios gradually declined in all patients as time from injury increased (mean minimum values NAA/Cho 1.05 +/- 0.44 and NAA/Cr 1.05 +/- 0.30, p < 0.03 and p < 0.02, respectively). This reduction was greater in patients with less favorable outcomes. In patients with focal injuries, the periphery of the lesions revealed identical trends of NAA/Cho and NAA/Cr decrease. These reductions correlated with outcome at 6 months (p < 0.01). Assessment with multivoxel methods (CS imaging) demonstrated that, in diffuse injury, NAA levels declined uniformly throughout the brain. At 40 days postinjury, initially low NAA/Cho levels had recovered to near baseline in patients who had good outcomes, whereas no recovery was evident in patients with poor outcomes (p < 0.01). CONCLUSIONS: Using (1)H-MR spectroscopy, it is possible to detect the posttraumatic neurochemical damage of the injured brain when conventional neuroimaging techniques reveal no abnormality. Reduction of NAA levels is a dynamic process, evolving over time, decreasing and remaining low throughout the involved tissue in patients with poor outcomes. Recovery of NAA levels in patients with favorable outcomes suggests marginal mitochondrial impairment and possible resynthesis from vital neurons.

Assessment of mitochondrial impairment and cerebral blood flow in severe brain injured patients.

BACKGROUND: We believe that in traumatic brain injury (TBI), the reduction of N-acetyl aspartate (NAA) occurs in the presence of adequate cerebral blood flow (CBF) which would lend support to the concept of mitochondrial impairment. The objective of this study was to test this hypothesis in severely injured patients (GCS 8 or less) by obtaining simultaneous measures of CBF and NAA. METHODS: Fourteen patients were studied of which six patients presented as diffuse injury at admission CT, while focal lesions were present in eight patients. CBF using stable xenon method was measured at the same time that NAA was measured by magnetic resonance proton spectroscopy (1HMRS) in the MR suite. Additionally, diffusion weighted imaging (DWI) and maps of the apparent diffusion coefficient (ADC) were assessed. FINDINGS: In diffuse injury, NAA/Cr reduction occurred uniformly throughout the brain where the values of CBF in all patients were well above ischemic threshold. In focal injury, we observed ischemic CBF values in the core of the lesions. However, in areas other than the core, CBF was above ischemic levels and NAA/Cr levels were decreased. CONCLUSIONS: Considering the direct link between energy metabolism and NAA synthesis in the mitochondria, this study showed that in the absence of an ischemic insult, reductions in NAA concentration reflects mitochondrial dysfunction.

Quantitation of ischemic events after severe traumatic brain injury in humans: a simple scoring system.

BACKGROUND: Cerebral ischemia is recognized as one of the most important mechanisms responsible for secondary brain damage following severe traumatic brain injury (TBI), contributing to an increased mortality and a worse neurologic outcome. METHOD: A simple 5-item scoring system, taking into account the occurrence of specific potentially brain-damaging events (hypoxemia, hypotension, low cerebral blood flow, herniation, and low cerebral perfusion pressure) has been tested in a large population of severe TBI patients. Aims of this retrospective study were to validate the ability of the proposed ischemic score to predict neurologic outcome and to correlate the ischemic score with the results of microdialysis-based neurochemical monitoring and brain tissue oxygen monitoring. FINDINGS: In a population of 172 severe TBI patients, a significant correlation was found between ischemic score and neurologic outcome, both at 3 months (r = -0.32; P < 0.01) and at 6 months (r = -0.31; P < 0.01). Significant correlations were also found with the most important neurochemical analytes. CONCLUSIONS: The ischemic score proposed here, may be determined during the acute intensive care unit period, and correlates closely with outcome, which can only be determined 3 to 6 months, after injury. It also shows a correlation with neurochemical analytes.