Recovery Of Behavioral Function Research Articles

Constructing Linear-Oriented Pre-Vascularized Human Spinal Cord Tissues for Spinal Cord Injury Repair.

Repairing spinal cord injury (SCI) is a global medical challenge lacking effective clinical treatment. Developing human-engineered spinal cord tissues that can replenish lost cells and restore a regenerative microenvironment offers promising potential for SCI therapy. However, creating vascularized human spinal cord-like tissues (VSCT) that mimic the diverse cell types and longitudinal parallel structural features of spinal cord tissues remains a significant hurdle. In the present study, VSCTs are engineered using embryonic human spinal cord-derived neural and endothelial cells on linear-ordered collagen scaffolds (LOCS). Studies have shown that astrocytes and endothelial cells align along the scaffolds in VSCT, supporting axon extension from various human neurons myelinated by oligodendrocytes. After transplantation into SCI rats, VSCT survives at the injury sites and promotes endogenous neural regeneration and vascularization, ultimately reducing scarring and enhancing behavioral functional recovery. It suggests that pre-vascularization of engineered spinal cord tissues is beneficial for SCI treatment and highlights the important role of exogenous endothelial cells in tissue engineering.

EBP50 is a key molecule for the Schwann cell-axon interaction in peripheral nerves

Peripheral nerve injury disrupts the Schwann cell-axon interaction and the cellular communication between them. The peripheral nervous system has immense potential for regeneration extensively due to the innate plastic potential of Schwann cells (SCs) that allows SCs to interact with the injured axons and exert specific repair functions essential for peripheral nerve regeneration. In this study, we show that EBP50 is essential for the repair function of SCs and regeneration following nerve injury. The increased expression of EBP50 in the injured sciatic nerve of control mice suggested a significant role in regeneration. The ablation of EBP50 in mice resulted in delayed nerve repair, recovery of behavioral function, and remyelination following nerve injury. EBP50 deficiency led to deficits in SC functions, including proliferation, migration, cytoskeleton dynamics, and axon interactions. The adeno-associated virus (AAV)-mediated local expression of EBP50 improved SCs migration, functional recovery, and remyelination. ErbB2-related proteins were not differentially expressed in EBP50-deficient sciatic nerves following injury. EBP50 binds and stabilizes ErbB2 and activates the repair functions to promote regeneration. Thus, we identified EBP50 as a potent SC protein that can enhance the regeneration and functional recovery driven by NRG1-ErbB2 signaling, as well as a novel regeneration modulator capable of potential therapeutic effects.

Preparation of Upconversion Nanoparticles (UCNPs)-Polyethylene Glycol (PEG)/Merocyanine540 (M540) Photosensitizer by Core–Shell Structure and Its Application in the Treatment of Spinal Cord Injury

The objective of this study is to investigate the adjuvant effect of UCNP-PEG-M540 based on a core–shell structure in spinal cord injury (SCI) treatment. 90 female healthy adult SD rats were divided into a control (Ctrl) group, a UCNP, and a UCNP-PEG-M540 group according to different transplantation materials to observe the recovery of behavioral function and axonal regeneration in rats to evaluate the application effect. The diameter of the UCNP was approximately 24 nm, and the distribution was uniform, which conformed to nanoscale particles. The diffraction pattern of UCNP based on the core–shell structure was basically the same as that of the UCNP naked core. At 4–12 weeks of treatment, the BBB score of the UCNP-PEG-M540 group was higher based on that of the Ctrl and UCNP groups; the IOD value of NF200-positive staining in the UCNP-PEG-M540 group was much higher to that in the Ctrl group and UCNP group; the IOD value of GFAP-positive staining and the gray value of CFAP were lower to those of the Ctrl group and UCNP group. UCNP-PEG-M540 based on a core–shell structure can further promote the absorption of 980 nm near-infrared light in injured tissues of SCI rats and inhibit glial cell aggregation, thereby reducing the formation of glial cells and promoting the repair of SCI and the recovery of behavioral function.

Neuroprotective Effects of Vinpocetine Against Ischemia-Reperfusion Injury Via Inhibiting NLRP3 Inflammasome Signaling Pathway

Ischemic stroke is one of the main causes of serious disability and death worldwide. NLRP3 inflammasome is an intracellular pattern recognition receptor composed of polyprotein complex, which participates in mediating a series of inflammatory responses and is considered as a potential target for the treatment of ischemic stroke. Vinpocetine, a derivative of vincamine, has been widely used in the prevention and treatment of ischemic stroke. However, the therapeutic mechanism of vinpocetine is not clear, and its effect on NLRP3 inflammasome remains to be determined. In this study, we used the mouse model of transient middle cerebral artery occlusion (tMCAO) to simulate the occurrence of ischemic stroke. Different doses of vinpocetine (5, 10, 15 mg/kg/d) were injected intraperitoneally for 3 days after ischemia–reperfusion in mice. The effects of different doses of vinpocetine on the degree of ischemia–reperfusion injury in mice were observed by TTC staining and modified neurological severity score scale, and the optimal dose was determined. Then, based on this optimal dose, we observed the effects of vinpocetine on apoptosis, microglial proliferation and NLRP3 inflammasome. In addition, we compared the effects of vinpocetine and MCC950 (a specific inhibitor of NLRP3 inflammasome) on NLRP3 inflammasome. Our results show that vinpocetine can effectively reduce the infarct volume and promote the recovery of behavioral function in stroke mice, and the maximal beneficial effects were observed at the dose of 10 mg/kg/d. Vinpocetine can effectively inhibit the apoptosis of peri-infarct neurons, promote the expression of Bcl-2, inhibit the expression of Bax and Cleaved Caspase-3, and reduce the proliferation of peri-infarct microglia. In addition, vinpocetine, like MCC950, can reduce the expression of NLRP3 inflammasome. Therefore, vinpocetine can effectively alleviate the ischemia–reperfusion injury in mice, and the inhibition of NLRP3 inflammasome may be an important therapeutic mechanism of vinpocetine.

Rat Bone Mesenchymal Stem Cell-Derived Exosomes Loaded with miR-494 Promoting Neurofilament Regeneration and Behavioral Function Recovery after Spinal Cord Injury.

Exosomes (Exo) exhibit numerous advantages (e.g., good encapsulation, high targeting efficiency, and easy to penetrate the blood-brain barrier to the central nervous system). Exosomes are recognized as prominent carriers of mRNAs, siRNAs, miRNAs, proteins, and other bioactive molecules. As confirmed by existing studies, miR-494 is important to regulate the occurrence, progression, and repair of spinal cord injury (SCI). We constructed miR-494-modified exosomes (Exo-miR-494). As indicated from related research in vitro and vivo, Exo-miR-494 is capable of effectively inhibiting the inflammatory response and neuronal apoptosis in the injured area, as well as upregulating various anti-inflammatory factors and miR-494 to protect neurons. Moreover, it can promote the regeneration of the neurofilament and improve the recovery of behavioral function of SCI rats.

Agrin Involvement in Synaptogenesis Induced by Exercise in a Rat Model of Experimental Stroke

Background Agrin is a proteoglycan that aggregates nicotinic acetylcholine receptors (AChRs) on neuromuscular junctions and takes part in synaptogenesis in the development of the central nervous system. However, its effects on neural repair and synaptogenesis after stroke are still unclear. Objective This study aimed to investigate the effects of agrin on neural repair and synaptogenesis after stroke and the effects of exercise on this process in vivo and in vitro. Methods Exercise with gradually increased intensity was initiated at 1 day after middle cerebral artery occlusion (MCAO) for a maximum of 14 days. Neurological deficit scores and foot fault tests were used to assess the behavioral recovery. Western blotting, immunofluorescence, and electron microscopic images were used to detect the expression of agrin, synaptogenesis-related proteins, and synaptic density in vivo. In vitro, the ischemic neuron model was established via oxygen-glucose deprivation (OGD). The lentivirus overexpressed agrin and CREB inhibitor were used to investigate the mechanism by which agrin promoted synaptogenesis. Results Exercise promoted behavioral recovery and this beneficial role was linked to the upregulated expression of agrin and increased synaptic density. Overexpressed agrin promoted synaptogenesis in OGD neuron, CREB inhibitor downregulated the expression of agrin and hampered synaptogenesis in cultured neurons. Conclusions These results indicated that exercise poststroke improved the recovery of behavioral function after stroke. Synaptogenesis was an important and beneficial factor, and agrin played a critical role in this process and could be a potential therapeutic target for the treatment of stroke and other nervous system diseases.

A Window of Vascular Plasticity Coupled to Behavioral Recovery after Stroke.

Stroke causes remodeling of vasculature surrounding the infarct, but whether and how vascular remodeling contributes to recovery are unclear. We established an approach to monitor and compare changes in vascular structure and blood flow with high spatiotemporal precision after photothrombotic infarcts in motor cortex using longitudinal 2-photon and multiexposure speckle imaging in mice of both sexes. A spatially graded pattern of vascular structural remodeling in peri-infarct cortex unfolded over the first 2 weeks after stroke, characterized by vessel loss and formation, and selective stabilization of a subset of new vessels. This vascular structural plasticity was coincident with transient activation of transcriptional programs relevant for vascular remodeling, reestablishment of peri-infarct blood flow, and large improvements in motor performance. Local vascular plasticity was strongly predictive of restoration of blood flow, which was in turn predictive of behavioral recovery. These findings reveal the spatiotemporal evolution of vascular remodeling after stroke and demonstrate that a window of heightened vascular plasticity is coupled to the reestablishment of blood flow and behavioral recovery. Our findings support that neovascularization contributes to behavioral recovery after stroke by restoring blood flow to peri-infarct regions. These findings may inform strategies for enhancing recovery from stroke and other types of brain injury.SIGNIFICANCE STATEMENT An improved understanding of neural repair could inform strategies for enhancing recovery from stroke and other types of brain injury. Stroke causes remodeling of vasculature surrounding the lesion, but whether and how the process of vascular remodeling contributes to recovery of behavioral function have been unclear. Here we used longitudinal in vivo imaging to track vascular structure and blood flow in residual peri-infarct cortex after ischemic stroke in mice. We found that stroke created a restricted period of heightened vascular plasticity that was associated with restoration of blood flow, which was in turn predictive of recovery of motor function. Therefore, our findings support that vascular remodeling facilitates behavioral recovery after stroke by restoring blood flow to peri-infarct cortex.

Abstract WP149: Post-stroke Vascular Remodeling and the Role of Neural Precursor Cells

The time course, mode, regulation, and relevance to functional recovery of post-stroke vascular remodeling are poorly defined. We tracked peri-infarct vascular remodeling in mice with repeated in vivo two-photon imaging of vascular structure (labeled with transgenic expression of green fluorescent protein) and multi-exposure speckle imaging of cortical blood flow over months after photothrombotic cortical lesions. Vascular structure in the intact brain is remarkably stable. In contrast, we found that peri-infarct vasculature (micro- and macrovessels) underwent long-term structural changes, including formation and elimination of vessel segments, beginning within days of infarction. Remodeling continued after peri-infarct blood flow was restored and was most pronounced in superficial vessels. Histological methods indicated that vascular density was rapidly (within days of ischemia) and persistently (at least one month) increased surrounding the infarct. Past findings suggest that neural precursor cells (NPCs) originating in the subventricular zone associate closely with remodeling blood vessels in peri-infarct cortex. To evaluate the role of NPCs in vascular remodeling, we used a pharmacogenetic method to ablate NPCs. NPC ablation prior to infarct altered the pattern of vascular remodeling: the neovascularization response was exaggerated and the orientation of peri-infarct vessels was disordered compared to the normal pattern of vessels oriented towards the lesion. As well, NPC ablation worsened recovery of behavioral function after ischemia. Collectively, these results suggest that vascular remodeling is a chronic process instigated by stroke and that proper vascular patterning is directed by NPCs. NPCs likely contribute to behavioral recovery after brain injury at least in part through their influence on neovascularization.

Adaptive neurogenesis in the cerebral cortex and contralateral subventricular zone induced by unilateral cortical devascularization: Possible modulation by dopamine neurotransmission.

Understanding endogenous neurogenesis and neuronal replacement to mature circuits is a topic of discussion as a therapeutic alternative under acute and chronic neurodegenerative disorders. Adaptive neurogenic response may result as a result of ischemia which could support long-term recovery of behavioral functions. Endogenous sources of neural progenitors may be stimulated by changes in blood flow or neuromodulation. Using a mouse model of unilateral cortical devascularization, we have observed reactive neurogenesis in the perilesional cortex and subventricular zone neurogenic niche. C57BL/6L 4weeks old male mice were craneotomized at 1mm caudal from frontal suture and 1mm lateral from midline to generate a window of 3mm side. Brain injury was produced by removal of the meninges and superficial vasculature of dorsal parietal cortex. BrdU agent (50mg/kg, ip) was injected to lesioned and sham animals, during days 0 and 1 after surgery. Sagittal sections were analyzed at 1, 4, 7, and 10days post-injury. A time-dependent increase in BrdU+ cells in the perilesional parietal cortex was accompanied by augmented BrdU+ cells in the sub ventricular and rostral migratory stream of ipsilateral and contralateral hemispheres. Neural progenitors and neuroblasts proliferated in the lesioned and non-lesioned subventricular zone and rostral migratory stream on day 4 after injury. Augmented contralateral neurogenesis was associated with an increase in vesicular monoamine transporter 2 protein in the striosomal sub ventricular neurogenic niche of non-lesioned hemisphere.

Minocycline Promotes BDNF Expression of N2a Cells via Inhibition of miR-155-Mediated Repression After Oxygen-Glucose Deprivation and Reoxygenation.

Minocycline, an anti-infective agent of a tetracycline derivative, is reported to improve behavioral functional recovery after cerebral ischemia via enhancing the levels of brain-derived neurotrophic factor (BDNF). However, the precise mechanisms that minocycline targets to enhance the expression of BDNF are not fully defined. In the present study, we observed the neuroprotective effect and its potential mechanisms of minocycline using oxygen-glucose deprivation/reoxygenation (OGD/R)-treated N2a cells. We found that 50µM minocycline protected against neuronal apoptosis induced by OGD/R injury, with increased expression ratio of Bcl-2/Bax and reduced expression of caspase-3. Interestingly, minocycline resulted in the up-regulation of only BDNF protein, not BDNF mRNA in N2a cells treated with OGD/R. Furthermore, we found that minocycline inhibited OGD/R-induced up-regulation of miR-155 targeted BDNF transcripts. Moreover, miR-155 mimic could partially abolish the neuroprotective effects of minocycline via inhibiting the levels of BDNF protein. These findings suggest that minocycline is neuroprotective against ischemic brain injury through their modulation of miR-155-mediated BDNF repression.

Immature Midbrain Dopaminergic Neurons Derived from Floor-Plate Method Improve Cell Transplantation Therapy Efficacy for Parkinson's Disease.

Recent reports have indicated human embryonic stem cells‐derived midbrain dopamine (mDA) neurons as proper cell resources for use in Parkinson's disease (PD) therapy. Nevertheless, no detailed and systematic study has been conducted to identify which differentiation stages of mDA cells are most suitable for transplantation in PD therapy. Here, we transplanted three types of mDA cells, DA progenitors (differentiated in vitro for 16 days [D16]), immature DA neurons (D25), and DA neurons (D35), into PD mice and found that all three types of cells showed high viability and strong neuronal differentiation in vivo. Both D25 and D35 cells showed neuronal maturation and differentiation toward TH+ cells and, accordingly, satisfactory behavioral functional recovery. However, transplanted D16 cells were less capable of producing functional recovery. These findings provide a valuable guideline for standardizing the differentiation stage of the transplantable cells used in clinical cell therapy for PD. Stem Cells Translational Medicine 2017;6:1803–1814

A Novel Rodent Orthotopic Forelimb Transplantation Model That Allows for Reliable Assessment of Functional Recovery Resulting From Nerve Regeneration.

Improved nerve regeneration and functional outcomes would greatly enhance the utility of vascularized composite allotransplantation (VCA) such as hand and upper extremity transplantation. However, research aimed at achieving this goal has been limited by the lack of a functional VCA animal model. We have developed a novel rat midhumeral forelimb transplant model that allows for the characterization of upper extremity functional recovery following transplantation. At the final end point of 12 weeks, we found that animals with forelimb transplantation including median, ulnar and radial nerve coaptation demonstrated significantly improved grip strength and forelimb function as compared to forelimb transplantation without nerve approximation (grip strength: 1.71N ± 0.57 vs. no appreciable recovery; IBB scale: 2.6 ± 0.7? vs. 0.8 ± 0.40; p = 0.0005), and similar recovery to nerve transection-and-repair only (grip strength: 1.71N ± 0.57 vs. 2.03 ± 0.42.6; IBB scale: 2.6 ± 0.7 vs. 2.8 ± 0.8; p = ns). Moreover, all forelimb transplant animals with nerve coaptation displayed robust axonal regeneration with myelination and reduced flexor muscle atrophy when compared to forelimb transplant animals without nerve coaptation. In conclusion, this is the first VCA small-animal model that allows for reliable and reproducible measurement of behavioral functional recovery in addition to histologic evaluation of nerve regeneration and graft reinnervation.

Nrf2 activator ameliorates hemorrhagic transformation in focal cerebral ischemia under warfarin anticoagulation

Background and purposeOxidative stress has been reported to be a main cause of neuronal cell death in ischemia reperfusion injury (IRI). Nuclear factor-erythroid 2-related factor 2 (Nrf2) is an important factor involved in anti-oxidative responses. We previously reported that bardoxolone methyl (BARD), an Nrf2 activator, prevented damage induced by IRI. In this study, we investigated the effect of BARD on hemorrhagic transformation in the context of blood brain barrier (BBB) protection. MethodsMice received pre-treatment with warfarin (4.0mg/kg, p.o.). IRI was subsequently induced 18h after the warfarin administration by transient middle cerebral artery occlusion (MCAO) for 6h. BARD (0.06, 0.2, 0.6 or 2.0mg/kg) or saline was injected intravenously immediately after reperfusion. The infarct volume, neurological score, intracranial hemorrhage volume, and BBB permeability were evaluated 24h after MCAO. The survival rate and behavioral functional recovery were evaluated for 7days following IRI. Furthermore, the effects of BARD on BBB components were investigated by western blotting and immunostaining analysis. ResultsBARD suppressed warfarin-mediated increases in the intracranial hemorrhage volume without affecting the infarct volume. BBB permeability was also suppressed by administration of BARD. Western blotting showed that BARD increased expression of BBB components such as endothelial cells, pericytes, and tight junction proteins. Furthermore, immunostaining showed that BARD induced localization of Nrf2 to endothelial cells and pericytes. ConclusionsBARD suppressed the exacerbation hemorrhage caused by warfarin pretreatment and ameliorated BBB disruption by protecting endothelial cells, pericytes, and tight junction protein expressions. These results indicate that Nrf2 activators may be an effective therapy against hemorrhagic transformation caused by anticoagulant drugs.

Minocycline upregulates cyclic AMP response element binding protein and brain-derived neurotrophic factor in the hippocampus of cerebral ischemia rats and improves behavioral deficits.

Background and purposeThe cAMP response element binding protein (CREB) plays an important role in the mechanism of cognitive impairment and is also pivotal in the switch from short-term to long-term memory. Brain-derived neurotrophic factor (BDNF) seems a promising avenue in the treatment of cerebral ischemia injury since this neurotrophin could stimulate structural plasticity and repair cognitive impairment. Several findings have displayed that the dysregulation of the CREB–BDNF cascade has been involved in cognitive impairment. The aim of this study was to investigate the effect of cerebral ischemia on learning and memory as well as on the levels of CREB, phosphorylated CREB (pCREB), and BDNF, and to determine the effect of minocycline on CREB, pCREB, BDNF, and behavioral functional recovery after cerebral ischemia.MethodsThe animal model was established by permanent bilateral occlusion of both common carotid arteries. Behavior was evaluated 5 days before decapitation with Morris water maze and open-field task. Four days after permanent bilateral occlusion of both common carotid arteries, minocycline was administered by douche via the stomach for 4 weeks. CREB and pCREB were examined by Western blotting, reverse transcription polymerase chain reaction, and immunohistochemistry. BDNF was measured by immunohistochemistry and Western blotting.ResultsThe model rats after minocycline treatment swam shorter distances than control rats before finding the platform (P=0.0007). The number of times the platform position was crossed for sham-operation rats was more than that of the model groups in the corresponding platform location (P=0.0021). The number of times the platform position was crossed for minocycline treatment animals was significantly increased compared to the model groups in the corresponding platform position (P=0.0016). CREB, pCREB, and BDNF were downregulated after permanent bilateral occlusion of both common carotid arteries in the model group. Minocycline increased the expression of CREB, pCREB, and BDNF, and improved cognitive suffered from impairment of permanent bilateral occlusion of both common carotid arteries.ConclusionMinocycline improved cognitive impairment from cerebral ischemia via enhancing CREB, pCREB, and BDNF activity in the hippocampus.

Relative contributions of CA3 and medial entorhinal cortex to memory in rats.

The hippocampal CA1 field processes spatial information, but the relative importance of intra- vs. extra-hippocampal sources of input into CA1 for spatial behavior is unclear. To characterize the relative roles of these two sources of input, originating in the hippocampal field CA3 and in the medial entorhinal cortex (MEC), we studied effects of discrete neurotoxic lesions of CA3 or MEC on concurrent spatial and nonspatial navigation tasks, and on synaptic transmission in afferents to CA1. Lesions in CA3 or MEC regions that abolished CA3-CA1, or reduced MEC-CA1 synaptic transmission, respectively, impaired spatial navigation and unexpectedly interfered with cue response, suggesting that in certain conditions of training regimen, hippocampal activity may influence behavior otherwise supported by nonhippocampal neural networks. MEC lesions had milder and temporary behavioral effects, but also markedly amplified transmission in the CA3-CA1 pathway. Extensive behavioral training had a similar, but more modest effect on CA3-CA1 transmission. Thus, cortical input to the hippocampus modulates CA1 activity both directly and indirectly, through heterosynaptic interaction, to control information flow in the hippocampal loop. Following damage to hippocampal cortical input, the functional coupling of separate intra- and extra-hippocampal inputs to CA1 involved in normal learning may initiate processes that support recovery of behavioral function. Such a process may explain how CA3 lesions, which do not significantly modify the basic features of CA1 neural activity, nonetheless impair spatial recall, whereas lesions of EC input to CA1, which reduce the spatial selectivity of CA1 firing in foraging rats, have only mild effects on spatial navigation.

Compensatory limb use and behavioral assessment of motor skill learning following sensorimotor cortex injury in a mouse model of ischemic stroke.

Mouse models have become increasingly popular in the field of behavioral neuroscience, and specifically in studies of experimental stroke. As models advance, it is important to develop sensitive behavioral measures specific to the mouse. The present protocol describes a skilled motor task for use in mouse models of stroke. The Pasta Matrix Reaching Task functions as a versatile and sensitive behavioral assay that permits experimenters to collect accurate outcome data and manipulate limb use to mimic human clinical phenomena including compensatory strategies (i.e., learned non-use) and focused rehabilitative training. When combined with neuroanatomical tools, this task also permits researchers to explore the mechanisms that support behavioral recovery of function (or lack thereof) following stroke. The task is both simple and affordable to set up and conduct, offering a variety of training and testing options for numerous research questions concerning functional outcome following injury. Though the task has been applied to mouse models of stroke, it may also be beneficial in studies of functional outcome in other upper extremity injury models.

Membrane resealing as a promising strategy for early treatment of neurotrauma

Membrane resealing as a promising strategy for early treatment of neurotrauma

Injury-induced regulation of steroidogenic gene expression in the cerebellum.

Sex steroids assist adult neural tissue in the protection from and repair of damage resulting from neural injury; some steroids may be synthesized in the brain. Songbirds are especially useful models to explore steroidal neuroprotection and repair. First, the full suite of cholesterol transporters and steroidogenic enzymes are expressed in the zebra finch (ZF) brain. Second, estrogens promote recovery of behavioral function after damage to the adult ZF cerebellum. Third, the estrogen synthetic enzyme aromatase is rapidly upregulated in reactive glia following neural injury, including in the ZF cerebellum. We hypothesized that cerebellar injury would locally upregulate steroidogenic factors upstream of aromatase, providing the requisite substrate for neuroestrogen synthesis. We tested this hypothesis by lesioning the cerebellum of adult songbirds using both males and females that peripherally synthesize steroids in different amounts. We then used quantitative PCR to examine expression of mRNAs for the neurosteroidogenic factors TSPO, StAR, SCC, 3β-HSD, CYP17, and aromatase, at 2 and 8 days post-lesion. Compared to sham lesions, cerebellar lesions significantly upregulated mRNA levels of TSPO and aromatase. Sex differences in response to the lesions were detected for TSPO, StAR, and aromatase. All birds responded to experimental conditions by showing time-dependent changes in the expression of TSPO, SCC, and aromatase, suggesting that acute trauma or stress may impact neurosteroidogensis for many days. These data suggest that the cerebellum is an active site of steroid synthesis in the brain, and each steroidogenic factor likely provides neuroprotection and promotes repair.

Z-Bisdehydrodoisynolic acid (Z-BDDA): An estrogenic seco-steroid that enhances behavioral recovery following moderate fluid percussion brain injury in male rats

Several lines of research suggest that estrogens (and estrogenic compounds) are neuroprotective following experimental traumatic brain injury. However, therapeutic use of estrogens in this and other regards remains controversial. Therefore, analysis of estrogen-like compounds without potential problems similar to estrogens seems warranted. (±) Z-Bisdehydrodoisynolic acid (Z-BDDA) is a seco-steroid that has potent estrogenic as well as antioxidant activities in vitro and in vivo. We evaluated the therapeutic potential of Z-BDDA (300 μg/0.1 cc/100 g body weight, sc) to promote the recovery of behavioral function following lateral fluid percussion injury (FPI) to the brain in male rats. Two hours subsequent to FPI, treatment with Z-BDDA began with a bolus subcutaneous (sc) injection followed by booster treatments given 24 and 48 h later. Behavioral testing was initiated on the second day after FPI and results of Z-BDDA treatments were compared to treatment with vehicle only and to sham FPI surgery. Z-BDDA effectively enhanced recovery of coordinated limb movement assessed by locomotor placing performance across the duration of the study. Z-BDDA treated animals also performed better on a spatial memory task in the Morris water maze, showing improved learning curves across days of testing. Vestibulomotor function, measured by beam walk performance, appeared to improve in Z-BDDA treated animals, however these results did not reach statistical significance ( p > 0.05). Following cessation of the behavioral testing, all animals underwent assessments of gross neuroanatomical pathology. Cortical lesion size and cell death analysis with Fluoro-jade B failed to reveal Z-BDDA enhanced neuroprotection. These findings support our hypothesis that Z-BDDA can facilitate behavioral recovery following FPI in adult male rats although the mechanism(s) of these effects remain to be determined.

Potential Role of Dental Stem Cells in the Cellular Therapy of Cerebral Ischemia

Stem cell based therapies for cerebral ischemia (CI) utilize different cell sources including embryonic stem cells (ESCs), neural stem cells (NSCs), umbilical cord blood cells (UCBCs), mesenchymal stem cells (MSCs), and some immortalized cell lines. To date, experimental studies showed that all of these cell sources have been successful to some extent in attenuating the ischemic damage and improving functional recovery after brain injury. Bone marrow derived MSCs seem to be the most widely used and well characterized cell source, which can be also employed for autologous transplantation. Currently, there are two main theories behind the therapeutic effect of stem cell transplantation for treating CIs. The first concept is cell replacement theory in which transplanted stem cells differentiate into progenitor and specialized somatic cells to supersede dying cells. The other hypothesis is based on immuno-modulatory, neuro-protective and neuro-trophic abilities of stem cells which help reducing stroke size and increasing the recovery of behavioral functions. Recent studies focusing on alternative stem cell sources have revealed that dental stem cells (DSCs), including dental pulp stem cells (DPSCs) and dental follicle cells (DFCs) possess properties of MSCs and NSCs. They differentiate into neural linage cells and some other cell types such as osteocytes, adipocytes, chondrocytes, muscle cells and hepatocytes. This review is intended to examine stem cell therapy approaches for CI and emphasize potential use of DSCs as an alternative cell source for the treatment of brain ischemia.