Li-Kai Tsai

Valproic Acid Attenuates Blood–Brain Barrier Disruption in a Rat Model of Transient Focal Cerebral Ischemia: The Roles of HDAC and MMP-9 Inhibition

Valproic acid (VPA), a histone deacetylase (HDAC) inhibitor, is known to protect against cerebral ischemia. The effects of VPA on blood–brain barrier (BBB) disruption were investigated in rats subjected to transient middle cerebral artery occlusion (MCAO). Postischemic VPA treatment remarkably attenuated MCAO-induced BBB disruption and brain edema. Meanwhile, VPA significantly reduced MCAO-induced elevation of matrix metalloproteinase-9 (MMP-9), degradation of tight junction proteins, and nuclear translocation of nuclear factor-κB (NF-κB). Sodium butyrate, another HDAC inhibitor, mimicked these effects of VPA. Our findings suggest that BBB protection by VPA involves HDAC inhibition-mediated suppression of NF-κB activation, MMP-9 induction, and tight junction degradation.

Intracranial dural arteriovenous fistulas with or without cerebral sinus thrombosis: analysis of 69 patients

Objectives: To compare the characteristics of dural arteriovenous fistulas (AVFs) with or without cerebral sinus thrombosis (CST), and to analyse the determinants of aggressive manifestations in patients with dural AVF. Methods: We investigated 69 patients aged 51.4 (SD 15) years who were diagnosed as having dural AVF. According to the location of the lesion and venous drainage pattern, dural AVF was classified into three sites (cavernous sinus, large sinus, and other) and five types (by Cognard’s method). Aggressive manifestations of dural AVF were defined as intracranial haemorrhage, venous infarction, seizure, altered mental status, and intracranial hypertension. The diagnosis of CST was based on cerebral angiography. Logistic regression methods were used to analyse the determinants of aggressive manifestation in patients with dural AVF. Results: CST was found in 39% of the patients with dural AVF. It was located at almost either the sinus around the dural AVF or the downstream venous flow pathways of the dural AVF. There was no significant difference with regard to sex, location, or type of dural AVF between patients with dural AVF with and without CST. The location “other sinuses” and the type of dural AVF “IIb/IIa+b/III/IV/V” were significantly related to aggressive manifestations of dural AVF (odds ratio 19 (p = 0.001) and 5.63 (p = 0.033), respectively). Presence of CST in patients with dural AVF had an odds ratio of 4.25 (p = 0.12) for development of aggressive manifestations. Conclusions: CST affects two fifths of patients with dural AVF. The location and type of dural AVF are major determinants of aggressive manifestations in patients with dural AVF.

Mesenchymal Stem Cells Primed With Valproate and Lithium Robustly Migrate to Infarcted Regions and Facilitate Recovery in a Stroke Model

Background and Purpose— The migratory efficiency of mesenchymal stem cells (MSC) toward cerebral infarct after transplantation is limited. Valproate (VPA) and lithium enhance in vitro migration of MSC by upregulating CXC chemokine receptor 4 and matrix metalloproteinase-9, respectively. Ability of VPA and lithium to promote MSC homing and to improve functional recovery was assessed in a rat model of cerebral ischemia. Methods— MSC primed with VPA (2.5 mmol/L, 3 hours) and/or lithium chloride (2.5 mmol/L, 24 hours) were transplanted into rats 24 hours after transient middle cerebral artery occlusion (MCAO). Neurological function was assessed via rotarod test, Neurological Severity Score, and body asymmetry test for 2 weeks. Infarct volume was analyzed by MRI. The number of homing MSC and microvessel density in the infarcted regions were measured 15 days after MCAO using immunohistochemistry. Results— Priming with VPA or lithium increased the number of MSC homing to the cerebral infarcted regions, and copriming with VPA and lithium further enhanced this effect. MCAO rats receiving VPA-primed and/or lithium-primed MSC showed improved functional recovery, reduced infarct volume, and enhanced angiogenesis in the infarcted penumbra regions. These beneficial effects of VPA or lithium priming were reversed by AMD3100, a CXC chemokine receptor 4 antagonist, and GM6001, a matrix metalloproteinase inhibitor, respectively. Conclusions— Priming with VPA and/or lithium promoted the homing and migration ability of MSC, improved functional recovery, reduced brain infarct volume, and enhanced angiogenesis in a rat MCAO model. These effects were likely mediated by VPA-induced CXC chemokine receptor 4 overexpression and lithium-induced matrix metalloproteinase-9 upregulation.

Chronic Valproate Treatment Enhances Postischemic Angiogenesis and Promotes Functional Recovery in a Rat Model of Ischemic Stroke

Background and Purpose— Enhanced angiogenesis facilitates neurovascular remodeling processes and promotes brain functional recovery after stroke. Previous studies from our laboratory demonstrated that valproate (VPA), a histone deacetylase inhibitor, protects against experimental brain ischemia. The present study investigated whether VPA could enhance angiogenesis and promote long-term functional recovery after ischemic stroke. Methods— Male rats underwent middle cerebral artery occlusion for 60 minutes followed by reperfusion for up to 14 days. Assessed parameters were: locomotor function through the Rotarod test; infarct volume through T2-weighted MRI; microvessel density through immunohistochemistry; relative cerebral blood flow through perfusion-weighted imaging; protein levels of proangiogenic factors through Western blotting; and matrix metalloproteinase-2/9 activities through gelatin zymography. Results— Postischemic VPA treatment robustly improved the Rotarod performance of middle cerebral artery occlusion rats on Days 7 and 14 after ischemia and significantly reduced brain infarction on Day 14. Concurrently, VPA markedly enhanced microvessel density, facilitated endothelial cell proliferation, and increased relative cerebral blood flow in the ipsilateral cortex. The transcription factor hypoxia-inducible factor-1&agr; and its downstream proangiogenic factors, vascular endothelial growth factor and matrix metalloproteinase-2/9, were upregulated after middle cerebral artery occlusion and significantly potentiated by VPA in the ipsilateral cortex. Acetylation of histone-H3 and H4 was robustly increased by chronic VPA treatment. The beneficial effects of VPA on Rotarod performance and microvessel density were abolished by hypoxia-inducible factor-1&agr; inhibition. Conclusions— Chronic VPA treatment enhances angiogenesis and promotes functional recovery after brain ischemia. These effects may involve histone deacetylase inhibition and upregulation of hypoxia-inducible factor-1&agr; and its downstream proangiogenic factors vascular endothelial growth factor and matrix metalloproteinase-2/9.

The mood stabilizers valproic acid and lithium enhance mesenchymal stem cell migration via distinct mechanisms.

Mesenchymal stem cells (MSCs) show high potential for the therapy of several human diseases; however, the effectiveness of MSC transplantation has been hampered by the relatively poor migratory capacity of these cells toward disease target sites. This study investigated whether treatment of MSCs with two mood stabilizers—valproic acid (VPA) and lithium—would enhance cell migration and, if so, to explore the mechanisms underlying their effects. Short-term (3 h) exposure of MSCs to a relatively high concentration (2.5 mM) of VPA markedly increased the transcript and protein levels of CXC chemokine receptor 4 (CXCR4). VPA-induced CXCR4 expression required inhibition of histone deacetylases (HDACs), including the HDAC1 isoform, and involved histone hyperacetylation at the promoter region of the CXCR4 gene. Notably, VPA treatment enhanced stromal cell-derived factor-1α (SDF-1α)-mediated MSC migration, which was completely blocked by AMD3100, a CXCR4 antagonist. Treatment of MSCs with lithium (2.5 mM for 1 day) selectively elevated the transcript and protein levels of matrix metalloproteinase-9 (MMP-9) and its enzymatic activity; these effects were mimicked by inhibition or gene silencing of glycogen synthase kinase-3β (GSK-3β). Lithium treatment also potentiated SDF-1α-dependent MSC migration across the extracellular matrix, which was suppressed by two MMP-9 inhibitors, doxycycline and GM6001. Combining VPA and lithium treatment further increased MSC migration. Overall, VPA and lithium stimulated MSC migration through distinct targets and mediators: HDAC-CXCR4 and GSK-3β-MMP-9, respectively.

Establishing a standardized therapeutic testing protocol for spinal muscular atrophy

Several mice models have been created for spinal muscular atrophy (SMA); however, there is still no standard preclinical testing system for the disease. We previously generated type III-specific SMA model mice, which might be suitable for use as a preclinical therapeutic testing system for SMA. To establish such a system and test its applicability, we first created a testing protocol and then applied it as a means to investigate the use of valproic acid (VPA) as a possible treatment for SMA. These SMA mice revealed tail/ear/foot deformity, muscle atrophy, poorer motor performances, smaller compound muscle action potential and lower spinal motoneuron density at the age of 9 to 12 months in comparison with age-matched wild-type littermate mice. In addition, VPA attenuates motoneuron death, increases spinal SMN protein level and partially normalizes motor function in SMA mice. These results suggest that the testing protocol developed here is well suited for use as a standardized preclinical therapeutic testing system for SMA.

Valproic acid treatment in six patients with spinal muscular atrophy

Sir, Currently, no curative treatment is available for spinal muscular atrophy (SMA). Valproic acid (VPA) increased spinal motor neuron (SMN) protein levels in cells derived from SMA patients [1,2]. SMA mice also showed less degeneration of spinal motor neurons with preservation of motor function after VPA treatment [3]. Until now, little information is available regarding the therapeutic effects of VPA in SMA patients. We reviewed the clinical course of six SMA patients (Table 1) treated with VPA. They all had homozygous deletion of SMN1 gene. Muscle power in four limbs was assessed by Medical Research Council (MRC) score (0–5). Patient’s global muscle power is represented as a sum (0–100) of individual MRC score assessed from 20 muscles, including bilateral shoulder abductors, elbow/wrist/knee flexor/ extensors, finger/hip flexors and ankle extensors.

Restoring BCl-XL levels benefits a mouse model of spinal muscular atrophy

Currently, no curative treatment is available for spinal muscular atrophy (SMA). Since the degeneration of spinal motor neurons in SMA is mediated by apoptosis, over-expression of an anti-apoptotic factor, Bcl-x(L), may benefit SMA. Here, we crossed a mouse model of SMA with Bcl-x(L) transgenic mice to create SMA/Bcl-x(L) mice. The Bcl-x(L) expression in the spinal neurons of SMA/Bcl-x(L) mice was nearly double that in SMA mice. SMA/Bcl-x(L) mice showed preserved motor function, normalized electrophysiological tests, diminished muscle atrophy, and less motor neuron degeneration. In addition, the life span of SMA/Bcl-x(L) mice was 1.5 times longer than that of SMA mice. Therefore, over-expression of Bcl-x(L) has a potential for amelioration of SMA, and Bcl-x(L) may be another attractive therapeutic target other than survival motor neuron (SMN) protein for use in future drug screening for SMA.

Dysphagia screening decreases pneumonia in acute stroke patients admitted to the stroke intensive care unit

Dysphagia increases the risk of pneumonia in stroke patients. This study aimed to evaluate bedside swallowing screening for prevention of stroke-associated pneumonia (SAP) in acute stroke patients admitted to the intensive care unit (ICU). Consecutive acute stroke patients admitted to the stroke ICU from May 2006 to March 2007 were included. Patients were excluded if they were intubated on the first day of admission or had a transient ischemic attack. A 3-Step Swallowing Screen was introduced since October 2006 and therefore patients were divided into pre-screen and post-screen groups. A binary logistic regression model was used to determine independent risk factors for SAP and in-hospital death. There were 74 and 102 patients included in the pre- and post-screen groups, respectively. Pneumonia was associated with higher National Institutes of Health Stroke Scale (NIHSS) score, older age, nasogastric and endotracheal tube placement. After adjusting for age, gender, NIHSS score and nasogastric and endotracheal tube insertion, dysphagia screening was associated with a borderline decrease in SAP in all stroke patients (odds ratio, 0.42; 95% CI, 0.18-1.00; p=0.05). However, dysphagia screening was not associated with reduction of in-hospital deaths. Systematic bedside swallowing screening is helpful for prevention of SAP in acute stroke patients admitted to the ICU.

IGF-1 delivery to CNS attenuates motor neuron cell death but does not improve motor function in type III SMA mice☆

The efficacy of administering a recombinant adeno-associated virus (AAV) vector encoding human IGF-1 (AAV2/1-hIGF-1) into the deep cerebellar nucleus (DCN) of a type III SMA mouse model was evaluated. High levels of IGF-1 transcripts and protein were detected in the spinal cord at 2 months post-injection demonstrating that axonal connections between the cerebellum and spinal cord were able to act as conduits for the viral vector and protein to the spinal cord. Mice treated with AAV2/1-hIGF-1 and analyzed 8 months later showed changes in endogenous Bax and Bcl-xl levels in spinal cord motor neurons that were consistent with IGF-1-mediated anti-apoptotic effects on motor neurons. However, although AAV2/1-hIGF-1 treatment reduced the extent of motor neuron cell death, the majority of rescued motor neurons were non-functional, as they lacked axons that innervated the muscles. Furthermore, treated SMA mice exhibited abnormal muscle fibers, aberrant neuromuscular junction structure, and impaired performance on motor function tests. These data indicate that although CNS-directed expression of IGF-1 could reduce motor neuron cell death, this did not translate to improvements in motor function in an adult mouse model of type III SMA.