Cell encapsulation enhances antidepressant effect of the mesenchymal stem cells and counteracts depressive-like behavior of treatment-resistant depressed rats.

Despite the advances in pharmacological therapies, only the half of depressed patients respond to currently available treatment. Thus, the need for further investigation and development of effective therapies, especially those designed for treatment-resistant depression, has been sorely needed. Although antidepressant effects of mesenchymal stem cells (MSCs) have been reported, the potential benefit of this cell therapy on treatment-resistant depression is unknown. Cell encapsulation may enhance the survival rate of grafted cells, but the therapeutic effects and mechanisms mediating encapsulation of MSCs remain unexplored. Here, we showed that encapsulation enhanced the antidepressant effects of MSCs by attenuating depressive-like behavior of Wistar Kyoto (WKY) rats, which are considered as a promising animal model of treatment-resistant depression. The implantation of encapsulated MSCs (eMSCs) into the lateral ventricle counteracted depressive-like behavior and enhanced the endogenous neurogenesis in the subventricular zone (SVZ) and the dentate gyrus (DG) of the hippocampus, whereas the implantation of MSCs without encapsulation or the implantation of eMSCs into the striatum did not show such ameliorative effects. eMSCs displayed robust and stable secretion of vascular endothelial growth factor (VEGF), brain-derived neurotrophic factor, fibroblast growth factor-2, and ciliary neurotrophic factor (CNTF), and the implantation of eMSCs into the lateral ventricle activated relevant pathways associated with these growth factors. Additionally, eMSCs upregulated intrinsic expression of VEGF and CNTF and their receptors. This study suggests that the implantation of eMSCs into the lateral ventricle exerted antidepressant effects likely acting via neurogenic pathways, supporting their utility for depression treatment.

Electrical Stimulation Enhances Migratory Ability of Transplanted Bone Marrow Stromal Cells in a Rodent Ischemic Stroke Model.

BACKGROUND/AIMS: Bone marrow stromal cells (BMSCs) transplantation is an important strategy for the treatment of ischemic stroke. Currently, there are no effective methods to guide BMSCs toward the targeted site. In this study, we investigated the effect of electrical stimulation on BMSCs migration in an ischemic model of rats. METHODS: Adult male Wistar rats weighing 200 to 250 g received right middle cerebral artery occlusion (MCAO) for 90 minutes. BMSCs (2.5×105 cells/ 4 µl PBS) were stereotaxically injected into the left corpus callosum at 1 day after MCAO. After BMSCs injection, a plate electrode with a diameter of 3 mm connected to an implantable electrical stimulator was placed on the right frontal epidural space and a counter electrode was placed in the extra-cranial space. Electrical stimulation at preset current (100 µA) and frequency (100 Hz) was performed for two weeks. Behavioral tests were performed at 1, 4, 8, and 15 days after MCAO using the modified Neurological Severity Score (mNSS) and cylinder test. Rats were euthanized at 15 days after MCAO for evaluation of infarction area and the migration distance and area of BMSCs found in the brain tissue. After evaluating cell migration, we proceeded to explore the mechanisms guiding these observations. MCAO rats without BMSCs transplantation were stimulated with same current and frequency. At 1 and 2 weeks after MCAO, rats were euthanized to evaluate stromal cell-derived factor 1 alpha (SDF-1α) level of brain tissues in the bilateral cortex and striatum. RESULTS: Behavioral tests at 4, 8, and 15 days after MCAO revealed that stimulation group displayed significant amelioration in mNSS and cylinder test compared to control group (p<0.05). Similarly, the infarction areas of stroke rats in stimulation group were significantly decreased compared to control group (p<0.05). Migration distance and area of transplanted BMSCs were significantly longer and wider respectively in stimulation group. An increased concentration gradient of SDF-1α in stimulation group accompanied this enhanced migration of transplanted cells. CONCLUSIONS: These results suggest that electrical stimulation enhances migratory ability of transplanted BMSCs in ischemic stroke model of rats. If we can direct the implanted BMSCs to the site of interest, it may lead to a greater therapeutic effect.

Vagus Nerve Stimulation with Mild Stimulation Intensity Exerts Anti-Inflammatory and Neuroprotective Effects in Parkinson's Disease Model Rats.

BACKGROUND: The major surgical treatment for Parkinson's disease (PD) is deep brain stimulation (DBS), but a less invasive treatment is desired. Vagus nerve stimulation (VNS) is a relatively safe treatment without cerebral invasiveness. In this study, we developed a wireless controllable electrical stimulator to examine the efficacy of VNS on PD model rats. METHODS: Adult female Sprague-Dawley rats underwent placement of a cuff-type electrode and stimulator on the vagus nerve. Following which, 6-hydroxydopamine (6-OHDA) was administered into the left striatum to prepare a PD model. VNS was started immediately after 6-OHDA administration and continued for 14 days. We evaluated the therapeutic effects of VNS with behavioral and immunohistochemical outcome assays under different stimulation intensity (0.1, 0.25, 0.5 and 1 mA). RESULTS: VNS with 0.25-0.5 mA intensity remarkably improved behavioral impairment, preserved dopamine neurons, reduced inflammatory glial cells, and increased noradrenergic neurons. On the other hand, VNS with 0.1 mA and 1 mA intensity did not display significant therapeutic efficacy. CONCLUSIONS: VNS with 0.25-0.5 mA intensity has anti-inflammatory and neuroprotective effects on PD model rats induced by 6-OHDA administration. In addition, we were able to confirm the practicality and effectiveness of the new experimental device.

Long-Term Continuous Cervical Spinal Cord Stimulation Exerts Neuroprotective Effects in Experimental Parkinson's Disease.

BACKGROUND: Spinal cord stimulation (SCS) exerts neuroprotective effects in animal models of Parkinson's disease (PD). Conventional stimulation techniques entail limited stimulation time and restricted movement of animals, warranting the need for optimizing the SCS regimen to address the progressive nature of the disease and to improve its clinical translation to PD patients. OBJECTIVE: Recognizing the limitations of conventional stimulation, we now investigated the effects of continuous SCS in freely moving parkinsonian rats. METHODS: We developed a small device that could deliver continuous SCS. At the start of the experiment, thirty female Sprague-Dawley rats received the dopamine (DA)-depleting neurotoxin, 6-hydroxydopamine, into the right striatum. The SCS device was fixed below the shoulder area of the back of the animal, and a line from this device was passed under the skin to an electrode that was then implanted epidurally over the dorsal column. The rats were divided into three groups: control, 8-h stimulation, and 24-h stimulation, and behaviorally tested then euthanized for immunohistochemical analysis. RESULTS: The 8- and 24-h stimulation groups displayed significant behavioral improvement compared to the control group. Both SCS-stimulated groups exhibited significantly preserved tyrosine hydroxylase (TH)-positive fibers and neurons in the striatum and substantia nigra pars compacta (SNc), respectively, compared to the control group. Notably, the 24-h stimulation group showed significantly pronounced preservation of the striatal TH-positive fibers compared to the 8-h stimulation group. Moreover, the 24-h group demonstrated significantly reduced number of microglia in the striatum and SNc and increased laminin-positive area of the cerebral cortex compared to the control group. CONCLUSIONS: This study demonstrated the behavioral and histological benefits of continuous SCS in a time-dependent manner in freely moving PD animals, possibly mediated by anti-inflammatory and angiogenic mechanisms.

Identification of Somatotopic Organization and Optimal Stimulation Site Within the Subthalamic Nucleus for Parkinson's Disease.

BACKGROUND: Details of the somatotopy within the subthalamic nucleus (STN) are still poorly understood; however, the STN is a common target of deep brain stimulation (DBS) for Parkinson disease. OBJECTIVE: To examine somatotopic organization within the STN and identify optimal stimulation sites from 77 surgical cases with microelectrode recording. METHODS: STN-DBS was performed for 77 patients with Parkinson disease between 2010 and 2014. We performed passive movements of each joint and captured single neuronal activities to identify movement-related cells (MRCs). The sites of MRCs and active contacts were determined by measuring their distances from the first contact of DBS electrode. Their positional correlations were directly and indirectly analyzed. RESULTS: The number of obtained MRCs was 264, of which 151 responded to multiple joints. The average x-, y-, and z-coordinates of the cells of the upper and lower limbs from the midcommisural point were 13.1 ± 1.1 and 12.7 ± 1.2, 0.22 ± 1.3 and -0.45 ± 1.5, and -2.5 ± 1.1 and -3.0 ± 1.4 mm, respectively. Most MRCs were distributed in the upper third of the STN, in its superior, lateral, and posterior regions, along the DBS electrode routes. Active contacts were observed to lie slightly inferior, medial, and posterior to the average MRC position. CONCLUSION: Somatotopic organization of the STN was easier to observe in the present study than in previous studies. Optimal stimulation sites were located inferior, medial, and posterior to the average MRC location. The sites may correspond to associative or motor parts through which fibers from the supplementary motor area pass.

Characteristics and prognostic factors of Parkinson's disease patients with abnormal postures subjected to subthalamic nucleus deep brain stimulation.

OBJECTIVE: In Parkinson's disease (PD), abnormal postures are often accompanied, which interfere with rehabilitation and subsequent functional recovery. This study investigated the relationship between clinical characteristics and improvement in abnormal postures of PD patients who received subthalamic nucleus deep brain stimulation (STN-DBS). METHODS: Seventy-four PD patients were included in this study. Clinical data were analyzed using the patients' functional status at pre- and post-STN-DBS, including anteflexion vs. non-anteflexion, scoliosis vs. non-scoliosis, improved anteflexion vs. non-improved anteflexion, and improved scoliosis vs. non-improved scoliosis. RESULTS: In patients with anteflexion, UPDRS III motor score at off medication was worse than that of patients with non-anteflexion. Patients with scoliosis presented with more comorbid spinal deformity and longer disease duration than those without scoliosis. Cobb angle of patients with asymmetrical psoas major and erector spinal muscles was more than that of patients without the asymmetry. Patients with improved anteflexion after STN-DBS had thicker abdominal oblique muscle and transverse abdominal muscle than those of patients without improved anteflexion. Patients with improved scoliosis were significantly younger at PD onset than those without improvement. CONCLUSIONS: There were only a few prognostic factors recognized in patients with improved postures. The thick abdominal muscle for anteflexion and younger PD onset for scoliosis were significant factors for improvement by STN-DBS. Rehabilitation designed to maintain muscle for correct postures may contribute to the amelioration of abnormal postures by STN-DBS, although multicenter trials are needed.

The Factors Affecting the Difficulty of Percutaneous Cylindrical Electrode Placement for Spinal Cord Stimulation.

OBJECTIVE: Optimal placement of electrodes is important for spinal cord stimulation. Factors affecting the difficulty of percutaneous electrode placement are not well known. In this study, we retrospectively evaluated the factors affecting the difficulty of percutaneous electrode placement. METHODS: We performed a retrospective analysis of 90 consecutive procedures of percutaneous cylindrical electrode implantation at the first author's institution. Age, sex, smoking state, body mass index, the duration of time from the beginning of pain syndrome to operation, diagnosis, the number of previous electrode placements, the previous electrode implantation period, the presence of axial low back pain, the electrode tip level, the pattern of electrode placement, and the reason for reimplantation were selected as factors associated with the success of electrode placement or the operation time of electrode placement. RESULTS: The number of previous electrode placements and the electrode tip level were independently associated with the operation time of electrode placement. According to both univariable and multivariable regression analyses, 1 previous electrode placement lengthened the operation time by approximately 15 minutes. No factors were significantly associated with the success of electrode placement. The more frequently that previous electrode placement was performed, the more difficult electrode placement tended to be. However, electrode reimplantation can be successful given extra time. CONCLUSIONS: This is the first study to evaluate factors affecting the difficulty of percutaneous electrode placement. A history of percutaneous cylindrical electrode placement did not affect the success of current placement, although it lengthened the operation time.

Long-Term Potentiation Enhances Neuronal Differentiation in the Chronic Hypoperfusion Model of Rats.

Several reports have shown that long-term potentiation (LTP) per se effectively enhances neurogenesis in the hippocampus of intact animals. If LTP can enhance neurogenesis in chronic hypoperfusion, this approach could potentially become a new therapeutic strategy for the restoration of cognitive function and for prevention from deterioration of mild cognitive impairment (MCI). Using an in vivo LTP model of rats, we examined whether LTP per se can enhance neurogenesis in hypoperfusion rats that underwent permanent bilateral common carotid artery occlusion (permanent 2-vessel occlusion, P2VO). High frequency stimulation (HFS) in the subacute phase after P2VO enhanced hippocampal cell proliferation and neurogenesis. However, most enhanced cell proliferation and neurogenesis was seen in the hypoperfusion rats that received HFS and for which LTP could finally be induced. In contrast, the same effect was not seen in the LTP induction in the chronic phase. The present findings, which reveal that most enhanced neurogenesis was seen in hypoperfusion rats for which LTP could be finally induced, could explain the ability of LTP-like activities such as learning paradigms and environmental stimuli to increase the rate of neurogenesis in the hippocampus even under hypoperfusion conditions. Moreover, the present findings, which reveal that LTP induction in the chronic phase after P2VO could not effectively enhance neurogenesis in the hypoperfusion rats, could indicate that patients with MCI and even middle-aged healthy control individuals should start LTP-like activities as early as possible and continue with these activities to prevent age-related deterioration of hippocampal function.

Efficacy of Dural Sealant System for Preventing Brain Shift and Improving Accuracy in Deep Brain Stimulation Surgery.

The success of deep brain stimulation (DBS) depends heavily on surgical accuracy, and brain shift is recognized as a significant factor influencing accuracy. We investigated the factors associated with surgical accuracy and showed the effectiveness of a dural sealant system for preventing brain shift in 32 consecutive cases receiving DBS. Thirty-two patients receiving DBS between March 2014 and May 2015 were included in this study. We employed conventional burr hole techniques for the first 18 cases (Group I) and a dural sealant system (DuraSeal) for the subsequent 14 cases (Group II). We measured gaps between the actual positions of electrodes and the predetermined target positions. We then retrospectively evaluated the factors involved in surgical accuracy. The average gap between an electrode's actual and target positions was 1.55 ± 0.83 mm in all cases. Postoperative subdural air volume e, the only factor associated with surgical accuracy (r = 0.536, P < 0.0001), was significantly smaller in Group II (Group I: 43.9 ± 27.7, Group II: 12.1 ± 12.5 ml, P = 0.0006). The average electrode position gap was also significantly smaller in Group II (Group I: 1.77 ± 0.91, Group II: 1.27 ± 0.59 mm, P = 0.035). Use of a dural sealant system could significantly reduce intracranial air volume, which should improve surgical accuracy.

Hippocampal neurogenesis of Wistar Kyoto rats is congenitally impaired and correlated with stress resistance.

The hippocampus is thought to be an important region for depression. However, the relationship between hippocampal neurogenesis and depression is still controversial. Wistar Kyoto (WKY) rats are frequently used as a depression model. WKY rats are known to show physiologically abnormal features, and these features resemble abnormalities seen in depressed patients. However, the neurogenesis of WKY rats is still unknown. In this study, we first evaluated the neurogenesis of WKY rats and compared it to that of Wistar (WIS) rats. No strain effect was observed in the number of cells positive for 5-bromo-2'-deoxyuridine (BrdU) and BrdU/Doublecortin (Dcx) in the subventricular zone (SVZ). However, the number of BrdU- and BrdU/Dcx-positive cells in the dentate gyrus (DG) of the hippocampus was significantly lower in WKY rats than in WIS rats. Next, we evaluated the correlation between neurogenesis and behavior tests. Behavior tests did not affect neurogenesis in either strain. Hippocampal neurogenesis correlated negatively with the results of a forced swim test (FST) on day 2 in each strain. That is, rats with a lower level of native neurogenesis in the DG showed a higher level of learned helplessness induced by the inescapable stress of the FST on day 1. Our findings indicate that hippocampal neurogenesis in WKY rats is congenitally impaired in contrast to that in WIS rats. Native cell proliferation and neurogenesis in the DG are correlated with stress resistance. These findings may be useful for developing new targets for depression treatment.

Efficacy of Fiber Tractography in the Stereotactic Surgery of the Thalamus for Patients with Essential Tremor.

Several targets and targeting methods are utilized in stereotactic surgery to achieve tremor suppression for patients with intractable tremor. Recent developments in magnetic resonance imaging, including diffusion tensor imaging, have enabled the setting of appropriate targets in stereotactic surgery. In this retrospective study, the optimal target to suppress tremors in stereotactic surgery was explored using diffusion tensor image-based fiber tractography. Four tracts were focused on in this study, namely: the cerebello-thalamo-premotor cortical fiber tract, cerebello-thalamo-primary motor cortical fiber tract, spino-thalamo-somatosensory cortical fiber tract, and pyramidal tract. In 10 patients with essential tremor, we evaluated the thalamotomy lesions and active contacts of the lead in thalamic stimulation by diffusion tensor image-based fiber tractography to reveal which part of the cerebral cortex is most affected by stereotactic surgery. Tremor suppression and adverse events were also evaluated in the patients involved in this study. Consequently, the good tremor suppression was achieved in all patients. There had been no permanent adverse events 3 months after surgery. Twelve lesions in thalamotomy patients or active contacts of the lead in thalamic stimulation patients were on the cerebello-thalamo-premotor cortical fiber tract (12/14 lesions or active contacts: 86%). In conclusion, the cerebello-thalamo-premotor cortical fiber tract may be an optimal target for tremor suppression. Diffusion tensor image-based fiber tractography may enable us to both determine the optimal target to achieve strong tremor suppression and to reduce the number of adverse events by keeping lesions or electrodes away from important fiber tracts, such as the pyramidal tract and spinothalamic fibers.

Anti-high mobility group box 1 antibody exerts neuroprotection in a rat model of Parkinson's disease.

The high mobility group box-1 (HMGB1) exists as an architectural nuclear protein in the normal state, but displays an inflammatory cytokine-like activity in the extracellular space under pathological condition. Inflammation in the pathogenesis of Parkinson's disease (PD) has been documented. In this study, we investigated the involvement of HMGB1 in the pathology and the neuroprotective effects of neutralizing anti-HMGB1 monoclonal antibody (mAb) on an animal model of PD. Adult female Sprague-Dawley rats were initially injected with 6-hydroxydopmaine (6-OHDA, 20 µg/4 µl) into the right striatum, then anti-HMGB1 mAb (1 mg/kg), or control mAb was intravenously administered immediately, at 6 and 24 h after 6-OHDA injection. The treatment with anti-HMGB1 mAb significantly preserved dopaminergic neurons in substantia nigra pars compacta and dopaminergic terminals inherent in the striatum, and attenuated PD behavioral symptoms compared to the control mAb-treated group. HMGB1 was retained in the nucleus of neurons and astrocytes by inhibiting the proinflammation-induced oxidative stress in the anti-HMGB1 mAb-treated group, whereas HMGB1 translocation was observed in neurons at 1 day and astrocytes at 7 days after 6-OHDA injection in the control mAb-treated group. Anti-HMGB1 mAb inhibited the activation of microglia, disruption of blood-brain-barrier (BBB), and the expression of inflammation cytokines such as IL-1ß and IL-6. These results suggested that HMGB1 released from neurons and astrocytes was at least partly involved in the mechanism and pathway of degeneration of dopaminergic neurons induced by 6-OHDA exposure. Intravenous administration of anti-HMGB1 mAb stands as a novel therapy for PD possibly acting through the suppression of neuroinflammation and the attenuation of disruption of BBB associated with the disease.

Intra-Arterial Transplantation of Allogeneic Mesenchymal Stem Cells Mounts Neuroprotective Effects in a Transient Ischemic Stroke Model in Rats: Analyses of Therapeutic Time Window and Its Mechanisms.

OBJECTIVE: Intra-arterial stem cell transplantation exerts neuroprotective effects for ischemic stroke. However, the optimal therapeutic time window and mechanisms have not been completely understood. In this study, we investigated the relationship between the timing of intra-arterial transplantation of allogeneic mesenchymal stem cells (MSCs) in ischemic stroke model in rats and its efficacy in acute phase. METHODS: Adult male Wistar rats weighing 200 to 250 g received right middle cerebral artery occlusion (MCAO) for 90 minutes. MSCs (1 × 10(6) cells/ 1 ml PBS) were intra-arterially injected at either 1, 6, 24, or 48 hours (1, 6, 24, 48 h group) after MCAO. PBS (1 ml) was intra-arterially injected to control rats at 1 hour after MCAO. Behavioral test was performed immediately after reperfusion, and at 3, 7 days after MCAO using the Modified Neurological Severity Score (mNSS). Rats were euthanized at 7 days after MCAO for evaluation of infarct volumes and the migration of MSCs. In order to explore potential mechanisms of action, the upregulation of neurotrophic factor and chemotactic cytokine (bFGF, SDF-1α) induced by cell transplantation was examined in another cohort of rats that received intra-arterial transplantation at 24 hours after recanalization then euthanized at 7 days after MCAO for protein assays. RESULTS: Behavioral test at 3 and 7 days after transplantation revealed that stroke rats in 24h group displayed the most robust significant improvements in mNSS compared to stroke rats in all other groups (p's<0.05). Similarly, the infarct volumes of stroke rats in 24h group were much significantly decreased compared to those in all other groups (p's<0.05). These observed behavioral and histological effects were accompanied by MSC survival and migration, with the highest number of integrated MSCs detected in the 24h group. Moreover, bFGF and SDF-1α levels of the infarcted cortex were highly elevated in the 24h group compared to control group (p's<0.05). CONCLUSIONS: These results suggest that intra-arterial allogeneic transplantation of MSCs provides post-stroke functional recovery and reduction of infarct volumes in ischemic stroke model of rats. The upregulation of bFGF and SDF-1α likely played a key mechanistic role in enabling MSC to afford functional effects in stroke. MSC transplantation at 24 hours after recanalization appears to be the optimal timing for ischemic stroke model, which should guide the design of clinical trials of cell transplantation for stroke patients.

Delayed germinal matrix hemorrhage induced by ventriculoperitoneal shunt insertion for congenital hydrocephalus.

Germinal matrix hemorrhages (GMHs) are typically seen in preterm neonates during the first 4 days of life. The authors encountered 2 children with late-onset GMH subsequent to ventriculoperitoneal (VP) shunt insertion for congenital hydrocephalus. Both children were delivered at full term with normal body weight, although they were compromised with the preceding hypoxic events prior to shunt insertion. The first case involved a female infant with severe craniofacial deformities. Because of aspiration pneumonia related to the comorbid upper airway stenosis, endotracheal intubation with intermittent mechanical ventilation was necessary. The associated congenital hydrocephalus was treated with VP shunt insertion when she was 35 days of age, and GMH was confirmed 1 week after shunt placement. During a period of conservative observation, the hemorrhage resolved without any neurological deterioration. The second case involved a male infant with a large intraparenchymal cyst on the left parietal portion. He was intubated for pneumonia at 1 month of age. He had associated congenital hydrocephalus that was progressive, and he was treated with VP shunting at 69 days of age, after his pneumonia had resolved. Postoperative GMH was confirmed, although hydrocephalus was well controlled by VP shunt insertion. Observed conservatively, he fared well and the GMH resolved. These 2 cases had unique features in common; both had congenital anomalies in the CNS and respiratory problems before shunting. The hypoxic insults on the residual germinal matrix layer and sudden decrease in CSF pressure may relate to the occurrence of these late-onset GMHs.