Transplantation of GABAergic neurons but not astrocytes induces recovery of sensorimotor function in the traumatically injured brain

Mechanistic and therapeutic relationships of traumatic brain injury and γ-amino-butyric acid (GABA)

Traumatic brain injury (TBI) is a highly prevalent medical condition for which no medications specific for the prophylaxis or treatment of the condition as a whole exist. The spectrum of symptoms includes coma, headache, seizures, cognitive impairment, depression, and anxiety. Although it has been known for years that the inhibitory neurotransmitter γ-amino-butyric acid (GABA) is involved in TBI, no novel therapeutics based upon this mechanism have been introduced into clinical practice. We review the neuroanatomical, neurophysiological, neurochemical, and neuropharmacological relationships of GABA neurotransmission to TBI with a view toward new potential GABA-based medicines. The long-standing idea that excitatory and inhibitory (GABA and others) balances are disrupted by TBI is supported by the experimental data but has failed to invent novel methods of restoring this balance. The slow progress in advancing new treatments is due to the complexity of the disorder that encompasses multiple dynamically interacting biological processes including hemodynamic and metabolic systems, neurodegeneration and neurogenesis, major disruptions in neural networks and axons, frank brain lesions, and a multitude of symptoms that have differential neuronal and neurohormonal regulatory mechanisms. Although the current and ongoing clinical studies include GABAergic drugs, no novel GABA compounds are being explored. It is suggested that filling the gap in understanding the roles played by specific GABAA receptor configurations within specific neuronal circuits could help define new therapeutic approaches. Further research into the temporal and spatial delivery of GABA modulators should also be useful. Along with GABA modulation, research into the sequencing of GABA and non-GABA treatments will be needed.

Therapeutic Application of Stem Cells in the Repair of Traumatic Brain Injury

Traumatic brain injury is the main cause of injury-related deaths and disabilities throughout the world, which is characterized by a disruption of the normal physiology of the brain following trauma. It can potentially cause severe complications such as physical, cognitive, and emotional impairment. In addition to understanding traumatic brain injury pathophysiology, this review explains the therapeutic potential of stem cells following brain injury in two pathways: response of endogenous neurogenic cells and transplantation of exogenous stem cell therapy. After traumatic brain injuries, clinical evidence indicated that endogenous neural progenitor cells might play an important role in regenerative medicine to treat brain injury. This is due to an increased neurogenic regeneration ability of these cells following brain injury. Besides, exogenous stem cell transplantation has also accelerated immature neuronal development and increased endogenous cellular proliferation in the damaged brain region. Therefore, a better understanding of the endogenous neural stem cell’s regenerative ability and the effect of exogenous stem cells on proliferation and differentiation ability may help researchers to understand how to increase functional recovery and tissue repair following injury.

Therapeutic Potential of Astrocyte Transplantation

Cell transplantation is an attractive treatment strategy for a variety of brain disorders, as it promises to replenish lost functions and rejuvenate the brain. In particular, transplantation of astrocytes has come into light recently as a therapy for amyotrophic lateral sclerosis (ALS); moreover, grafting of astrocytes also showed positive results in models of other conditions ranging from neurodegenerative diseases of older age to traumatic injury and stroke. Despite clear differences in etiology, disorders such as ALS, Parkinson's, Alzheimer's, and Huntington's diseases, as well as traumatic injury and stroke, converge on a number of underlying astrocytic abnormalities, which include inflammatory changes, mitochondrial damage, calcium signaling disturbance, hemichannel opening, and loss of glutamate transporters. In this review, we examine these convergent pathways leading to astrocyte dysfunction, and explore the existing evidence for a therapeutic potential of transplantation of healthy astrocytes in various models. Existing literature presents a wide variety of methods to generate astrocytes, or relevant precursor cells, for subsequent transplantation, while described outcomes of this type of treatment also differ between studies. We take technical differences between methodologies into account to understand the variability of therapeutic benefits, or lack thereof, at a deeper level. We conclude by discussing some key requirements of an astrocyte graft that would be most suitable for clinical applications.

The pros and cons of motor, memory, and emotion-related behavioral tests in the mouse traumatic brain injury model

Traumatic brain injury (TBI) is a medical emergency with high morbidity and mortality. Motor, memory, and emotion-related deficits are common symptoms following TBI, yet treatment is very limited. To develop new drugs and find new therapeutic avenues, a wide variety of TBI models have been established to mimic the heterogeneity of TBI. In this regard, along with histologic measures, behavioral functional outcomes provide valuable insight into the underlying neuropathology and guide neurorehabilitation efforts for neuropsychiatric impairment after TBI. Development, characterization, and application of behavioral tests that can assess functional neurologic deficits are essential to the development of translational therapies. This comprehensive review aims to summarize 19 common behavioral tests from three aspects (motor, memory, and emotion-related) that are associated with TBI pathology. Discussion covers the apparatus, the test steps, the evaluation indexes, data collection and analysis, animal performance and applications, advantages and disadvantages as well as precautions to eliminate bias wherever possible. We discussed recent studies on TBI-related preconditioning, biomarkers, and optimized behavioral protocols. The neuropsychologic tests employed in clinics were correlated with those used in mouse TBI models. In summary, this review provides a comprehensive, up-to-date reference for TBI researchers to choose the right neurobehavioral protocol according to the research objectives of their translational investigation.

Transplanted interneurons improve memory precision after traumatic brain injury

Repair of the traumatically injured brain has been envisioned for decades, but regenerating new neurons at the site of brain injury has been challenging. We show GABAergic progenitors, derived from the embryonic medial ganglionic eminence, migrate long distances following transplantation into the hippocampus of adult mice with traumatic brain injury, functionally integrate as mature inhibitory interneurons and restore post-traumatic decreases in synaptic inhibition. Grafted animals had improvements in memory precision that were reversed by chemogenetic silencing of the transplanted neurons and a long-lasting reduction in spontaneous seizures. Our results reveal a striking ability of transplanted interneurons for incorporating into injured brain circuits, and this approach is a powerful therapeutic strategy for correcting post-traumatic memory and seizure disorders.

The Potential of Stem Cells in Treatment of Traumatic Brain Injury

PURPOSE OF REVIEW

Traumatic brain injury (TBI) is a global public health concern, with limited treatment options available. Despite improving survival rate after TBI, treatment is lacking for brain functional recovery and structural repair in clinic. Recent studies have suggested that the mature brain harbors neural stem cells which have regenerative capacity following brain insults. Much progress has been made in preclinical TBI model studies in understanding the behaviors, functions, and regulatory mechanisms of neural stem cells in the injured brain. Different strategies targeting these cell population have been assessed in TBI models. In parallel, cell transplantation strategy using a wide range of stem cells has been explored for TBI treatment in pre-clinical studies and some in clinical trials. This review summarized strategies which have been explored to enhance endogenous neural stem cell-mediated regeneration and recent development in cell transplantation studies for post-TBI brain repair.

RECENT FINDINGS

Thus far, neural regeneration through neural stem cells either by modulating endogenous neural stem cells or by stem cell transplantation has attracted much attention. It is highly speculated that targeting neural stem cells could be a potential strategy to repair and regenerate the injured brain. Neuroprotection and neuroregeneration are major aspects for TBI therapeutic development. With technique advancement, it is hoped that stem cell-based therapy targeting neuroregeneration will be able to translate to clinic in not so far future.

The potential of neural transplantation for brain repair and regeneration following traumatic brain injury

Traumatic brain injury is a major health problem worldwide. Currently, there is no effective treatment to improve neural structural repair and functional recovery of patients in the clinic. Cell transplantation is a potential strategy to repair and regenerate the injured brain. This review article summarized recent development in cell transplantation studies for post-traumatic brain injury brain repair with varying types of cell sources. It also discussed the potential of neural transplantation to repair/promote recovery of the injured brain following traumatic brain injury.

Transplanted Neural Progenitor Cells from Distinct Sources Migrate Differentially in an Organotypic Model of Brain Injury

Brain injury is a major cause of long-term disability. The possibility exists for exogenously derived neural progenitor cells to repair damage resulting from brain injury, although more information is needed to successfully implement this promising therapy. To test the ability of neural progenitor cells (NPCs) obtained from rats to repair damaged neocortex, we transplanted neural progenitor cell suspensions into normal and injured slice cultures of the neocortex acquired from rats on postnatal day 0–3. Donor cells from E16 embryos were obtained from either the neocortex, including the ventricular zone (VZ) for excitatory cells, ganglionic eminence (GE) for inhibitory cells or a mixed population of the two. Cells were injected into the ventricular/subventricular zone (VZ/SVZ) or directly into the wounded region. Transplanted cells migrated throughout the cortical plate with GE and mixed population donor cells predominately targeting the upper cortical layers, while neocortically derived NPCs from the VZ/SVZ migrated less extensively. In the injured neocortex, transplanted cells moved predominantly into the wounded area. NPCs derived from the GE tended to be immunoreactive for GABAergic markers while those derived from the neocortex were more strongly immunoreactive for other neuronal markers such as MAP2, TUJ1, or Milli-Mark. Cells transplanted in vitro acquired the electrophysiological characteristics of neurons, including action potential generation and reception of spontaneous synaptic activity. This suggests that transplanted cells differentiate into neurons capable of functionally integrating with the host tissue. Together, our data suggest that transplantation of neural progenitor cells holds great potential as an emerging therapeutic intervention for restoring function lost to brain damage.

A Combination Therapy of Nicotinamide and Progesterone Improves Functional Recovery following Traumatic Brain Injury

Neuroprotection, recovery of function, and gene expression were evaluated in an animal model of traumatic brain injury (TBI) after a combination treatment of nicotinamide (NAM) and progesterone (Prog). Animals received a cortical contusion injury over the sensorimotor cortex, and were treated with either Vehicle, NAM, Prog, or a NAM/Prog combination for 72 h and compared with a craniotomy only (Sham) group. Animals were assessed in a battery of behavioral, sensory, and both fine and gross motor tasks, and given histological assessments at 24 h post-injury to determine lesion cavity size, degenerating neurons, and reactive astrocytes. Microarray-based transcriptional profiling was used to determine treatment-specific changes on gene expression. Our results confirm the beneficial effects of treatment with either NAM or Prog, demonstrating significant improvements in recovery of function and a reduction in lesion cavitation, degenerating neurons, and reactive astrocytes 24 h post-injury. The combination treatment of NAM and Prog led to a significant improvement in both neuroprotection at 24 h post-injury and recovery of function in sensorimotor related tasks when compared with individual treatments. The NAM/Prog-treated group was the only treatment group to show a significant reduction of cortical loss 24 h post-injury. The combination appears to affect inflammatory and immune processes, reducing expression of a significant number of genes in both pathways. Further preclinical trials using NAM and Prog as a combination treatment should be conducted to identify the window of opportunity, determine the optimal duration of treatment, and evaluate the combination in other pre-clinical models of TBI.

Stem cells in neurology--current perspectives

Central nervous system (CNS) restoration is an important clinical challenge and stem cell transplantation has been considered a promising therapeutic option for many neurological diseases.

OBJECTIVE

The present review aims to briefly describe stem cell biology, as well as to outline the clinical application of stem cells in the treatment of diseases of the CNS.

METHOD

Literature review of animal and human clinical experimental trials, using the following key words: "stem cell", "neurogenesis", "Parkinson", "Huntington", "amyotrophic lateral sclerosis", "traumatic brain injury", "spinal cord injury", "ischemic stroke", and "demyelinating diseases".

CONCLUSION

Major recent advances in stem cell research have brought us several steps closer to their effective clinical application, which aims to develop efficient ways of regenerating the damaged CNS.

Improvement of contusive spinal cord injury in rats by co-transplantation of gamma-aminobutyric acid-ergic cells and bone marrow stromal cells

BACKGROUND AIMS

Cell therapy is considered a promising option for treatment of spinal cord injury (SCI). The purpose of this study is to use combined therapy of bone marrow stromal cells (BMSCs) and BMSC-derived gamma-aminobutyric acid (GABA)ergic inhibitory neurotransmitter cells (BDGCs) for the contusion model of SCI in rats.

METHODS

BDGCs were prepared from BMSCs by pre-inducing them with β-mercaptoethanol followed by retinoic acid and then inducing them by creatine. They were immunostained with BMSC, proneuronal, neural and GABA markers. The BDGCs were intraspinally transplanted into the contused rats, whereas the BMSCs were delivered intravenously. The animals were sacrificed after 12 weeks.

RESULTS

The Basso, Beattie and Bresnahan test showed improvement in the animals with the combined therapy compared with the untreated animals, the animals treated with GABAergic cells only and the animals that received BMSCs. The immunohistochemistry analysis of the tissue sections prepared from the animals receiving the combined therapy showed that the transplanted cells were engrafted and integrated into the injured spinal cord; in addition, a significant reduction was seen in the cavitation.

CONCLUSIONS

The study shows that the combination of GABAergic cells with BMSCs can improve SCI.

Simulated microgravity facilitates cell migration and neuroprotection after bone marrow stromal cell transplantation in spinal cord injury

Introduction

Recently, cell-based therapy has gained significant attention for the treatment of central nervous system diseases. Although bone marrow stromal cells (BMSCs) are considered to have good engraftment potential, challenges due to in vitro culturing, such as a decline in their functional potency, have been reported. Here, we investigated the efficacy of rat BMSCs (rBMSCs) cultured under simulated microgravity conditions, for transplantation into a rat model of spinal cord injury (SCI).

Methods

rBMSCs were cultured under two different conditions: standard gravity (1G) and simulated microgravity attained by using the 3D-clinostat. After 7 days of culture, the rBMSCs were analyzed morphologically, with RT-PCR and immunostaining, and were used for grafting. Adult rats were used for constructing SCI models by using a weight-dropping method and were grouped into three experimental groups for comparison. rBMSCs cultured under 1 g and simulated microgravity were transplanted intravenously immediately after SCI. We evaluated the hindlimb functional improvement for 3 weeks. Tissue repair after SCI was examined by calculating the cavity area ratio and immunohistochemistry.

Results

rBMSCs cultured under simulated microgravity expressed Oct-4 and CXCR4, in contrast to those cultured under 1 g conditions. Therefore, rBMSCs cultured under simulated microgravity were considered to be in an undifferentiated state and thus to possess high migration ability. After transplantation, grafted rBMSCs cultured under microgravity exhibited greater survival at the periphery of the lesion, and the motor functions of the rats that received these grafts improved significantly compared with the rats that received rBMSCs cultured in 1 g. In addition, rBMSCs cultured under microgravity were thought to have greater trophic effects on reestablishment and survival of host spinal neural tissues because cavity formations were reduced, and apoptosis-inhibiting factor expression was high at the periphery of the SCI lesion.

Conclusions

Here we show that transplantation of rBMSCs cultured under simulated microgravity facilitates functional recovery from SCI rather than those cultured under 1 g conditions.

Noninvasive brain stimulation in traumatic brain injury

OBJECTIVE

To review novel techniques of noninvasive brain stimulation (NBS), which may have value in assessment and treatment of traumatic brain injury (TBI).

METHODS

Review of the following techniques: transcranial magnetic stimulation, transcranial direct current stimulation, low-level laser therapy, and transcranial Doppler sonography. Furthermore, we provide a brief overview of TMS studies to date.

MAIN FINDINGS

We describe the rationale for the use of these techniques in TBI, discuss their possible mechanisms of action, and raise a number of considerations relevant to translation of these methods to clinical use. Depending on the stimulation parameters, NBS may enable suppression of the acute glutamatergic hyperexcitability following TBI and/or counter the excessive GABAergic effects in the subacute stage. In the chronic stage, brain stimulation coupled to rehabilitation may enhance behavioral recovery, learning of new skills, and cortical plasticity. Correlative animal models and comprehensive safety trials seem critical to establish the use of these modalities in TBI.

CONCLUSIONS

Different forms of NBS techniques harbor the promise of diagnostic and therapeutic utility, particularly to guide processes of cortical reorganization and enable functional restoration in TBI. Future lines of safety research and well-designed clinical trials in TBI are warranted to determine the capability of NBS to promote recovery and minimize disability.

Isolation of a novel rat neural progenitor clone that expresses Dlx family transcription factors and gives rise to functional GABAergic neurons in culture

Gamma-aminobutyric acid (GABA) ergic interneurons are lost in conditions including epilepsy and central nervous system injury, but there are few culture models available to study their function. Toward the goal of obtaining renewable sources of GABAergic neurons, we used the molecular profile of a functionally incomplete GABAergic precursor clone to screen 17 new clones isolated from GFP(+) rat E14.5 cortex and ganglionic eminence (GE) that were generated by viral introduction of v-myc. The clones grow as neurospheres in medium with FGF2, and after withdrawal of FGF2, they exhibit varying patterns of differentiation. Transcriptional profiling and quantitative reverse transcriptase polymerase chain reaction (RT-PCR) indicated that one clone (GE6) expresses high levels of mRNAs encoding Dlx1, 2, 5, and 6, glutamate decarboxylases, and presynaptic proteins including neuropeptide Y and somatostatin. Protein expression confirmed that GE6 is a progenitor with restricted differentiation giving rise mostly to neurons with GABAergic markers. In cocultures with hippocampal neurons, GE6 neurons became electrically excitable and received both inhibitory and excitatory synapses. After withdrawal of FGF2 in cultures of GE6 alone, neurons matured to express βIII-tubulin, and staining for synaptophysin and vesicular GABA transporter were robust after 1-2 weeks of differentiation. GE6 neurons also became electrically excitable and displayed synaptic activity, but synaptic currents were carried by chloride and were blocked by bicuculline. The results suggest that the GE6 clone, which is ventrally derived from the GE, resembles GABAergic interneuron progenitors that migrate into the developing forebrain. This is the first report of a relatively stable fetal clone that can be differentiated into GABAergic interneurons with functional synapses.

A new method for modulating traumatic brain injury with mechanical tissue resuscitation

BACKGROUND

Traumatic brain injuries remain a treatment enigma with devastating late results. As terminally differentiated tissue, the brain retains little capacity to regenerate, making early attempts to preserve brain cells after brain injury essential.

OBJECTIVE

To resuscitate damaged tissue by modulating edema, soluble cytokines, and metabolic products in the "halo" of damaged tissue around the area of central injury that progressively becomes compromised. By re-equilibrating the zone of injury milieu, it is postulated neurons in this area will survive and function.

METHODS

Mechanical tissue resuscitation used localized, controlled, subatmospheric pressure directly to the area of controlled cortical impact injury and was compared with untreated injured controls and with sham surgery in a rat model. Functional outcome, T2 magnetic resonance imaging hyperintense volume, magnetic resonance imaging spectroscopy metabolite measurement, tissue water content, injury cavity area, and cortical volume were compared.

RESULTS

There were significant differences between mechanical tissue resuscitation treated and untreated groups in levels of myoinositol, N-acetylaspartate, and creatine. Treated animals had significantly less tissue swelling and density than the untreated animals. Nonviable brain tissue areas were smaller in treated animals than in untreated animals. Treated animals performed better than untreated animals in functional tests. Histological analysis showed the remaining viable ipsilateral cerebral area was 58% greater for treated animals than for untreated animals, and the cavity for treated animals was 95% smaller than for untreated animals 1 month after injury.

CONCLUSION

Mechanical tissue resuscitation with controlled subatmospheric pressure can significantly modulate levels of excitatory amino acids and lactate in traumatic brain injury, decrease the water content and volume of injured brain, improve neuronal survival, and speed functional recovery.

Current challenges for the advancement of neural stem cell biology and transplantation research

Transplantation of neural stem cells (NSC) is hoped to become a promising primary or secondary therapy for the treatment of various neurodegenerative disorders of the central nervous system (CNS), as demonstrated by multiple pre-clinical animal studies in which functional recovery has already been demonstrated. However, for NSC therapy to be successful, the first challenge will be to define a transplantable cell population. In the first part of this review, we will briefly discuss the main features of ex vivo culture and characterisation of NSC. Next, NSC grafting itself may not only result in the regeneration of lost tissue, but more importantly has the potential to improve functional outcome through many bystander mechanisms. In the second part of this review, we will briefly discuss several pre-clinical studies that contributed to a better understanding of the therapeutic potential of NSC grafts in vivo. However, while many pre-clinical animal studies mainly report on the clinical benefit of NSC grafting, little is known about the actual in vivo fate of grafted NSC. Therefore, the third part of this review will focus on non-invasive imaging techniques for monitoring cellular grafts in the brain under in vivo conditions. Finally, as NSC transplantation research has evolved during the past decade, it has become clear that the host micro-environment itself, either in healthy or injured condition, is an important player in defining success of NSC grafting. The final part of this review will focus on the host environmental influence on survival, migration and differentiation of grafted NSC.

Use-dependent dendritic regrowth is limited after unilateral controlled cortical impact to the forelimb sensorimotor cortex

Compensatory neural plasticity occurs in both hemispheres following unilateral cortical damage incurred by seizures, stroke, and focal lesions. Plasticity is thought to play a role in recovery of function, and is important for the utility of rehabilitation strategies. Such effects have not been well described in models of traumatic brain injury (TBI). We examined changes in immunoreactivity for neural structural and plasticity-relevant proteins in the area surrounding a controlled cortical impact (CCI) to the forelimb sensorimotor cortex (FL-SMC), and in the contralateral homotopic cortex over time (3-28 days). CCI resulted in considerable motor deficits in the forelimb contralateral to injury, and increased reliance on the ipsilateral forelimb. The density of dendritic processes, visualized with immunostaining for microtubule-associated protein-2 (MAP-2), were bilaterally decreased at all time points. Synaptophysin (SYN) immunoreactivity increased transiently in the injured hemisphere, but this reflected an atypical labeling pattern, and it was unchanged in the contralateral hemisphere compared to uninjured controls. The lack of compensatory neuronal structural plasticity in the contralateral homotopic cortex, despite behavioral asymmetries, is in contrast to previous findings in stroke models. In the cortex surrounding the injury (but not the contralateral cortex), decreases in dendrites were accompanied by neurodegeneration, as indicated by Fluoro-Jade B (FJB) staining, and increased expression of the growth-inhibitory protein Nogo-A. These studies indicate that, following unilateral CCI, the cortex undergoes neuronal structural degradation in both hemispheres out to 28 days post-injury, which may be indicative of compromised compensatory plasticity. This is likely to be an important consideration in designing therapeutic strategies aimed at enhancing plasticity following TBI.

Survival and engraftment of mouse embryonic stem cells in the mammary gland

Embryonic stem (ES) cells have been investigated in many animal models of severe injury and degenerative disease. However, few studies have examined the ability of ES cells to improve functional outcome following mammary gland injury. This study investigates the feasibility of implanting mouse ES cells labeled with enhanced green fluorescence protein in the developing mammary glands in order to acquire lineage-committed cells in mammary (mammary gland epithelial cell or luminal cell). Cells implanted in high numbers (5 × 10(6) cells per mammary gland) survived in the majority of the mice and nearly 38.4% of the surviving cells were CK18(+) at 15th week following the transplantation. Our results may provide a technique instrument on advanced therapy of breast diseases and the mammary regeneration after breast ablated partly.

Role of the NR2A/2B subunits of the N-methyl-D-aspartate receptor in glutamate-induced glutamic acid decarboxylase alteration in cortical GABAergic neurons in vitro

The vulnerability of brain neuronal cell subpopulations to neurologic insults varies greatly. Among cells that survive a pathological insult, for example ischemia or brain trauma, some may undergo morphological and/or biochemical changes that may compromise brain function. The present study is a follow-up of our previous studies that investigated the effect of glutamate-induced excitotoxicity on the GABA synthesizing enzyme glutamic acid decarboxylase (GAD65/67)'s expression in surviving DIV 11 cortical GABAergic neurons in vitro [Monnerie and Le Roux, (2007) Exp Neurol 205:367-382, (2008) Exp Neurol 213:145-153]. An N-methyl-D-aspartate receptor (NMDAR)-mediated decrease in GAD expression was found following glutamate exposure. Here we examined which NMDAR subtype(s) mediated the glutamate-induced change in GAD protein levels. Western blotting techniques on cortical neuron cultures showed that glutamate's effect on GAD proteins was not altered by NR2B-containing diheteromeric (NR1/NR2B) receptor blockade. By contrast, blockade of triheteromeric (NR1/NR2A/NR2B) receptors fully protected against a decrease in GAD protein levels following glutamate exposure. When receptor location on the postsynaptic membrane was examined, extrasynaptic NMDAR stimulation was observed to be sufficient to decrease GAD protein levels similar to that observed after glutamate bath application. Blocking diheteromeric receptors prevented glutamate's effect on GAD proteins after extrasynaptic NMDAR stimulation. Finally, NR2B subunit examination with site-specific antibodies demonstrated a glutamate-induced, calpain-mediated alteration in NR2B expression. These results suggest that glutamate-induced excitotoxic NMDAR stimulation in cultured GABAergic cortical neurons depends upon subunit composition and receptor location (synaptic vs. extrasynaptic) on the neuronal membrane. Biochemical alterations in surviving cortical GABAergic neurons in various disease states may contribute to the altered balance between excitation and inhibition that is often observed after injury.

Pre-differentiated embryonic stem cells promote neuronal regeneration by cross-coupling of BDNF and IL-6 signaling pathways in the host tissue

The mechanism of embryonic stem (ES) cell therapeutic action remains far from being elucidated. Our recent report has shown that transplantation of ES cells, predifferentiated into neuronal progenitors, prevented appearance of chronic pain behaviors in mice after experimentally induced spinal cord injury. In the current study, we tested the hypothesis that this beneficial effect is mediated by antiapoptotic and regenerative signaling pathways activated in the host tissue by transplanted ES cells. Spinal cord injury was induced by unilateral microinjections of quisqualic acid at spinal levels T12-L2. At 1 week after injury, the pre-differentiated towards neuronal phenotype ES cells were transplanted into the site of injury. Here we show that transplantation of pre-differentiated ES cells activate both brain-derived neurotrophic factor (BDNF) and interleukin-6 (IL-6) signaling pathways in the host tissue, leading to activation of cAMP/PKA, phosporylation of cofilin and synapsin I, and promoting regenerative growth and neuronal survival.

Recombinant PBD-1 (porcine beta-defensin 1) expressed in the milk by transplanting transgenic mES-like-derived cells into mouse mammary gland

ES (embryonic stem)-derived cells have been investigated in many animal models of severe injury and degenerative disease. However, few studies have examined the ability of ES-derived cells to improve functional outcome following partially damaged breast and also the modification of mammary tissue to produce costly proteins. This study investigates the feasibility of implanting mES-dK (mouse ES-derived keratinocytes-like) cells stably transfected with a mammary gland special expression vector for the PBD-1 (porcine beta-defensin 1) in developing mammary glands. Our aim was to assess the ability of cell grafting to improve functional outcome following partial damage of the breast, also on the breast modification mammary tissue in mice for the production of PBD-1 protein secreted in the milk. Our results showed that the ratios of the surviving cells labelled with the myoepithelial or luminal cell markers, EMA (epithelial membrane antigen) and CALLA, were 41.7 +/- 15.2% and 28.4 +/- 9.6%, respectively, which revealed that transplanted mES-dK cells survived, integrated in vivo and differentiated into myoepithelial or luminal cells. In addition, Western blot analysis showed that 37.5% (3 out of 8) female transplanted mice had PBD-1 expression in their milk and reached 0.4998, 0.5229 and 0.5195 microg/ml, respectively.

Pyridoxine administration improves behavioral and anatomical outcome after unilateral contusion injury in the rat

The purpose of this project was to evaluate the preclinical efficacy of pyridoxine, or vitamin B(6). Rats received a 3.0 mm unilateral controlled cortical impact (CCI) injury of the sensorimotor cortex or sham surgery. Treatment with vitamin B(6) (600 or 300 mg/kg IP) or vehicle was administered at 30 min and 24 h post-CCI. Somatosensory dysfunction was evaluated with the vibrissae-forelimb placing and bilateral tactile adhesive removal tests. Sensorimotor dysfunction was evaluated with the locomotor placing and the forelimb asymmetry tests. On the forelimb asymmetry test both treatment groups displayed no asymmetry bias on any of the testing days post-CCI and were statistically no different than the shams. Both vitamin B(6) groups displayed a significant improvement in behavioral performance on the locomotor placing test compared to the vehicle-treated group. Administration of 600 mg/kg also significantly reduced tactile adhesive removal latencies on days 2, 4, 6, and 12 post-CCI. Both treatment groups were improved in their rate of recovery post-CCI on the vibrissae-forelimb placing test, but only the recovery seen in the 600-mg/kg group was significantly improved compared to vehicle. Finally, the 600-mg/kg dose resulted in significant cortical sparing compared to the vehicle-treated group. In general, the effects of vitamin B(6) on recovery of function were dose-dependent, with the 600-mg/kg dose consistently showing greater recovery than the 300-mg/kg dose. More experimental analyses are warranted to evaluate the potential preclinical efficacy and mechanistic action of vitamin B(6).

Stem cell biology in traumatic brain injury: effects of injury and strategies for repair

Approximately 350,000 individuals in the US are affected annually by severe and moderate traumatic brain injuries (TBI) that may result in long-term disability. This rate of injury has produced approximately 3.3 million disabled survivors in the US alone. There is currently no specific treatment available for TBI other than supportive care, but aggressive prehospital resuscitation, rapid triage, and intensive care have reduced mortality rates. With the recent demonstration that neurogenesis occurs in all mammals (including man) throughout adult life, albeit at a low rate, the concept of replacing neurons lost after TBI is now becoming a reality. Experimental rodent models have shown that neurogenesis is accelerated after TBI, especially in juveniles. Two approaches have been followed in these rodent models to test possible therapeutic approaches that could enhance neuronal replacement in humans after TBI. The first has been to define and quantify the phenomenon of de novo hippocampal and cortical neurogenesis after TBI and find ways to enhance this (for example by exogenous trophic factor administration). A second approach has been the transplantation of different types of neural progenitor cells after TBI. In this review the authors discuss some of the processes that follow after acute TBI including the changes in the brain microenvironment and the role of trophic factor dynamics with regard to the effects on endogenous neurogenesis and gliagenesis. The authors also discuss strategies to clinically harness the factors influencing these processes and repair strategies using exogenous neural progenitor cell transplantation. Each strategy is discussed with an emphasis on highlighting the progress and limiting factors relevant to the development of clinical trials of cellular replacement therapy for severe TBI in humans.

Cell Therapy From Bench to Bedside Translation in CNS Neurorestoratology Era

Recent advances in cell biology, neural injury and repair, and the progress towards development of neurorestorative interventions are the basis for increased optimism. Based on the complexity of the processes of demyelination and remyelination, degeneration and regeneration, damage and repair, functional loss and recovery, it would be expected that effective therapeutic approaches will require a combination of strategies encompassing neuroplasticity, immunomodulation, neuroprotection, neurorepair, neuroreplacement, and neuromodulation. Cell-based restorative treatment has become a new trend, and increasing data worldwide have strongly proven that it has a pivotal therapeutic value in CNS disease. Moreover, functional neurorestoration has been achieved to a certain extent in the CNS clinically. Up to now, the cells successfully used in preclinical experiments and/or clinical trial/treatment include fetal/embryonic brain and spinal cord tissue, stem cells (embryonic stem cells, neural stem/progenitor cells, hematopoietic stem cells, adipose-derived adult stem/precursor cells, skin-derived precursor, induced pluripotent stem cells), glial cells (Schwann cells, oligodendrocyte, olfactory ensheathing cells, astrocytes, microglia, tanycytes), neuronal cells (various phenotypic neurons and Purkinje cells), mesenchymal stromal cells originating from bone marrow, umbilical cord, and umbilical cord blood, epithelial cells derived from the layer of retina and amnion, menstrual blood-derived stem cells, Sertoli cells, and active macrophages, etc. Proof-of-concept indicates that we have now entered a new era in neurorestoratology.

Functional endothelial progenitor cells derived from adipose tissue show beneficial effect on cell therapy of traumatic brain injury

Endothelial progenitor cells (EPCs) are responsible for postnatal vasculogenesis in physiological and pathological neovascularization. Adipose tissue (AT) is an abundant source of mesenchymal stem cells (MSCs), which have multipotent differentiation ability. We successfully derived EPCs from AT, which maintained a strong proliferative capacity and demonstrated the characteristic endothelial function of uptaking of acetylated low-density lipoprotein. They formed tube-like structures in vitro. Endothelial nitric oxide synthase (eNOS) gene expression in EPCs was similar to that in mature endothelial cells. Transplantation of EPCs derived from AT after the acute phase was applied in rats with traumatic brain injury (TBI). Transplanted EPCs participated in the neovascularization of injured brain. Improving functional recovery, reducement of deficiency volume of brain, host astrogliosis and inflammation were found. These results suggest that adult AT derived stem cells can be induced to functional EPCs and have beneficial effect on cell therapy.

Neurotrophism of bone marrow stromal cells to embryonic stem cells: noncontact induction and transplantation to a mouse ischemic stroke model

Embryonic stem (ES) cell-derived cell products may serve as a source of cells for regenerative medicine. Currently available technologies for the induction of ES cells into neural lineage cells require extended culturing in vitro and complex procedural manipulations, with variable yields of heterogeneous cells, which have hindered the prospective use of cell derivatives for treatment of ischemic stroke. We established a simple and efficient method to derive mouse ES cells into neural lineage cells using an 8-day coculture with the bone marrow stromal cells MS5, followed by a 6-day propagation culture and a 4-day selection culture. The protocol generated a relatively high yield of neural lineage cells without any mesodermal and endodermal lineage commitment. In in vivo study, these derived cells could improve the cognitive function of ischemic stroke mice. Three weeks after transplantation, migration of implanted cells to lesioned areas was noted. It was also evident of a normalization of pyramidal neuron density and morphology in hippocampal CA1 region. One (1/17) episode of teratoma development was noted. Data suggested that MS5 cells may exert a neurotrophic effect to enhance neural differentiation of ES cells and MS5-induced ES cell-derived cells appeared to be applicable to cell therapy for ischemic stroke.

Transplantation of GABA-producing cells for seizure control in models of temporal lobe epilepsy

A high percentage of patients with temporal lobe epilepsy (TLE) are refractory to conventional pharmacotherapy. The progressive neurodegenerative processes associated with a lifetime of uncontrolled seizures mandate the development of alternative approaches to treat this disease. Transplantation of inhibitory cells has been suggested as a potential therapeutic strategy to achieve seizure suppression in humans with intractable TLE. Preclinical investigations over 20 years have demonstrated that multiple cell types from several sources can produce anticonvulsant, and antiepileptogenic, effects in animal models of TLE. Transplanting GABA-producing cells, in particular, has been shown to reduce seizures in several well-established models. This review addresses experimentation using different sources of transplantable GABAergic cells, highlighting progress with fetal tissue, neural cell lines, and stem cells. Regardless of the source of the GABAergic cells used in seizure studies, common challenges have emerged. Several variables influence the anticonvulsant potential of GABA-producing cells. For example, tissue availability, graft survival, immunogenicity, tumorigenicity, and varying levels of cell migration, differentiation, and integration into functional circuits and the microenvironment provided by sclerotic tissue all contribute to the efficacy of transplanted cells. The challenge of understanding how all of these variables work in concert, in a disease process that has no well-established etiology, suggests that there is still much basic research to be done before rational cell-based therapies can be developed for TLE.

The novel apolipoprotein E-based peptide COG1410 improves sensorimotor performance and reduces injury magnitude following cortical contusion injury

It has previously been shown that small peptide molecules derived from the apolipoprotein E (ApoE) receptor binding region are anti-inflammatory in nature and can improve outcome following head injury. The present study evaluated the preclinical efficacy of COG1410, a small molecule ApoE-mimetic peptide (1410 daltons), following cortical contusion injury (CCI). Animals were prepared with a unilateral CCI of the sensorimotor cortex (SMC) or sham procedure. Thirty mins post-CCI the animals received i.v. infusions of 0.8 mg/kg COG1410, 0.4 mg/kg COG1410, or vehicle. Starting on day 2, the animals were tested on a battery of behavioral measures to assess sensorimotor (vibrissae-forelimb placing and forelimb use-asymmetry), and motor (tapered balance beam) performance. Administration of the 0.8 mg/kg dose of COG1410 significantly improved recovery on the vibrissae-forelimb and limb asymmetry tests. However, no facilitation was observed on the tapered beam. The low dose (0.4 mg/kg) of COG1410 did not show any significant differences compared to vehicle. Lesion analysis revealed that the 0.8 mg/kg dose of COG1410 significantly reduced the size of the injury cavity compared to the 0.4 mg/kg dose and vehicle. The 0.8 mg/kg dose also reduced the number of glial fibrillary acid protein (GFAP+) reactive cells in the injured cortex. These results suggest that a single dose of COG1410 facilitates behavioral recovery and provides neuroprotection in a dose and task-dependent manner. Thus, the continued clinical development of ApoE based therapeutics is warranted and could represent a novel strategy for the treatment of traumatic brain injuries.