Dongsheng Fan

Triple Transduction with Adeno-Associated Virus Vectors Expressing Tyrosine Hydroxylase, Aromatic-L-Amino-Acid Decarboxylase, and GTP Cyclohydrolase I for Gene Therapy of Parkinson's Disease

Parkinsons disease (PD), a neurological disease suited to gene therapy, is biochemically characterized by a severe decrease in the dopamine content of the striatum. One current strategy for gene therapy of PD involves local production of dopamine in the striatum achieved by inducing the expression of enzymes involved in the biosynthetic pathway for dopamine. We previously showed that the coexpression of tyrosine hydroxylase (TH) and aromatic-L-amino-acid decarboxylase (AADC), using two separate adeno-associated virus (AAV) vectors, resulted in more effective dopamine production and more remarkable behavioral recovery in 6-hydroxydopamine-lesioned parkinsonian rats, compared with the expression of TH alone. Not only levels of TH and AADC but also levels of tetrahydrobiopterin (BH4), a cofactor of TH, and GTP cyclohydrolase I (GCH), a rate-limiting enzymes for BH4 biosynthesis, are reduced in parkinsonian striatum. In the present study, we investigated whether transduction with separate AAV vectors expressing TH, AADC, and GCH was effective for gene therapy of PD. In vitro experiments showed that triple transduction with AAV-TH, AAV-AADC, and AAV-GCH resulted in greater dopamine production than double transduction with AAV-TH and AAV-AADC in 293 cells. Furthermore, triple transduction enhanced BH4 and dopamine production in denervated striatum of parkinsonian rats and improved the rotational behavior of the rats more efficiently than did double transduction. Behavioral recovery persisted for at least 12 months after stereotaxic intrastriatal injection. These results suggest that GCH, in addition to TH and AADC, is important for effective gene therapy of PD.

Protective effects of resveratrol through the up-regulation of SIRT1 expression in the mutant hSOD1-G93A-bearing motor neuron-like cell culture model of amyotrophic lateral sclerosis

Resveratrol has recently been widely reported to be an age-delaying and neuroprotective compound, and it appears to produce these benefits by activating silent mating type information regulation 2 homolog 1 (SIRT1). However, the role that SIRT1 activation plays in the pathogenesis of amyotrophic lateral sclerosis (ALS) remains unclear. In the present study, SIRT1 expression was found to be much lower in the mutant hSOD1G93A-bearing VSC4.1 cells compared to hSOD1wt cells when both were cultured in low-serum medium, indicating the involvement of SIRT1 activation defects in the pathogenesis of ALS under energetic stress. Further investigation revealed that a 24-h treatment with 0.5-20μM resveratrol had a dose-dependent protective effect on this ALS cell model, and the effects of resveratrol on increasing cell viability, preventing cell apoptosis and elevating cellular ATP levels through promoting mitochondria biogenesis were blocked by SIRT1 inhibition. This further demonstrated a role for SIRT1 activation in the protection of neuronal cells from degeneration. These findings suggest that resveratrol can protect the ALS cell model from mutant SOD1-mediated toxicity through up-regulating the expression of SIRT1, which represents a potential therapeutic target for preventing the motor neuron degeneration in ALS patients.

Preliminary investigation of effect of granulocyte colony stimulating factor on amyotrophic lateral sclerosis

We investigated the safety and efficacy of the granulocyte colony stimulating factor (G-CSF) in 13 patients with amyotrophic lateral sclerosis (ALS). Five-day administration of 2 µg/kg once a day was followed by a six-month observation period. The primary and secondary endpoints were the changes of ALS functional rating scale (ALSFRS) and the compound muscle action potential (CMAP) amplitude, respectively. We found that the declines of ALSFRS and CMAP amplitude after G-CSF administration were significantly less than those measured prior to the treatment. The results suggest G-CSF is safe in ALS patients, and may affect the rate of motor decline.

Inhibition of Sirt1 promotes neural progenitors toward motoneuron differentiation from human embryonic stem cells.

Several protocols direct human embryonic stem cells (hESCs) toward differentiation into functional motoneurons, but the efficiency of motoneuron generation varies based on the human ESC line used. We aimed to develop a novel protocol to increase the formation of motoneurons from human ESCs. In this study, we tested a nuclear histone deacetylase protein, Sirt1, to promote neural precursor cell (NPC) development during differentiation of human ESCs into motoneurons. A specific inhibitor of Sirt1, nicotinamide, dramatically increased motoneuron formation. We found that about 60% of the cells from the total NPCs expressed HB9 and βIII-tubulin, commonly used motoneuronal markers found in neurons derived from ESCs following nicotinamide treatment. Motoneurons derived from ESC expressed choline acetyltransferase (ChAT), a positive marker of mature motoneuron. Moreover, we also examined the transcript levels of Mash1, Ngn2, and HB9 mRNA in the differentiated NPCs treated with the Sirt1 activator resveratrol (50 μM) or inhibitor nicotinamide (100 μM). The levels of Mash1, Ngn2, and HB9 mRNA were significantly increased after nicotinamide treatment compared with control groups, which used the traditional protocol. These results suggested that increasing Mash1 and Ngn2 levels by inhibiting Sirt1 could elevate HB9 expression, which promotes motoneuron differentiation. This study provides an alternative method for the production of transplantable motoneurons, a key requirement in the development of hESC-based cell therapy in motoneuron disease.

Clinical features of Hirayama disease in mainland China

The aim of this study was to investigate patients with Hirayama disease in mainland China. A total of 192 patients (167 males, 25 females) collected from mainland China were included. Their clinical features, electrophysiology, imaging, muscle biopsy and laboratory tests, treatments, and prognosis were analysed. We compared the results with data from other countries or regions. The mean age at onset was 16.8 years. Onset was insidious, with symptoms of muscle weakness and atrophy in the distal muscles of the upper limb. Tremor on finger extension was noted in 77.6% of patients and cold paresis in 81.3%. The clinical course plateaued within five years in 89.1% of patients. Time from disease onset to definitive diagnosis of our series is longer than that from other countries or regions. There is no geographically based difference in the clinical presentation of Hirayama disease. Thus, our study supports the notion that Hirayama disease is a benign self-limited disorder with juvenile preponderance and asymmetric muscular atrophy of the distal portion of the upper limb. Hirayama disease is under-recognized in mainland China.

Prevention of dopaminergic neuron death by adeno-associated virus vector-mediated GDNF gene transfer in rat mesencephalic cells in vitro.

Glial cell line-derived neurotrophic factor (GDNF) is known as a potent neurotrophic factor for dopaminergic neurons. Since adeno-associated virus (AAV) vector is a suitable vehicle for gene transfer into neurons, rat E14 mesencephalic cells were transduced with an AAV vector expressing GDNF. When compared with mock transduction, a larger number of dopaminergic neurons survived in AAV-GDNF-transduced cultures (234% and 325% of controls at 1 and 2 weeks, respectively; P < 0.01). Furthermore, the dopaminergic neurons in the latter cultures grew more prominent neurites than those in the former. These findings suggest that AAV vector-mediated GDNF gene transfer may prevent dopaminergic neuron death, and is therefore a logical approach for the treatment of Parkinsons disease.

ATXN2 CAG repeat expansions increase the risk for Chinese patients with amyotrophic lateral sclerosis

Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disorder with unclear etiology. Recently, intermediate CAG repeat expansions in ATXN2, the gene responsible for spinocerebellar ataxia type 2 (SCA2), have been identified as a possible genetic risk factor for ALS. In this study, we analyzed the ATXN2 CAG repeat length in Chinese patients with ALS to evaluate the relationship between the genotype and phenotype. We studied 1,067 patients with ALS and 506 controls from mainland China (excluding Tibet). We collected clinical data and analyzed fluorescent PCR products to assess ATXN2 CAG repeat length in all of the samples. We observed that intermediate CAG repeat expansions in ATXN2 (CAG repeat length >30) were associated with ALS (p = 0.004). There was no significant difference in clinical characteristics between the groups with and without intermediate CAG repeat expansions in ATXN2. Our data indicate that, for ALS patients from mainland China, intermediate CAG repeat expansions in ATXN2 increase the risk of ALS but have no effect on disease phenotype.

Magnesium Modulates Amyloid-β Protein Precursor Trafficking and Processing

Alzheimers disease (AD), the most common form of dementia, is characterized by the presence of excessive deposits of aggregated amyloid-beta (Abeta), which is derived from the amyloid-beta protein precursor (AbetaPP) following processing by beta- and gamma-secretase. Metal elements are implicated in the pathophysiology of AD. Magnesium affects many biochemical mechanisms vital for neuronal properties and synaptic plasticity, and magnesium levels were reported to be decreased in various tissues including brain of AD patients. However, the exact role of magnesium in the neurodegenerative process of AD remains elusive. In this study, we investigated the effects of physiological (0.8 mM, as normal control), low (0-0.4 mM), and high (1.2-4.0 mM) concentrations of extracellular magnesium ([Mg2+]o) on AbetaPP processing and Abeta secretion. Here we show the effects of varying [Mg2+]o on AbetaPP processing is time- and dose-dependent. After 24 h treatment, high [Mg2+]o increased C-terminal fragment-alpha (CTFalpha) levels and soluble alpha-secretase cleaved AbetaPP (sAbetaPPalpha) release via enhancing retention of AbetaPP on plasma membrane. In contrast, low [Mg2+]o enhanced CTFbeta accumulation and Abeta secretion, and reduced cell surface AbetaPP level. Varying [Mg2+]o did not alter protein contents of full length AbetaPP. However, decreased total intracellular magnesium level by magnesium deprivation over 24 hr impaired cell viability. Normal AbetaPP processing could be restored when magnesium was adjusted back to physiological concentration. These data demonstrate that AbetaPP processing can be modulated by magnesium and at high [Mg2+]o, AbetaPP processing favors the alpha-secretase cleavage pathway. Our findings suggest that supplementation of magnesium has a therapeutic potential for preventing AD.

Natural history and clinical features of sporadic amyotrophic lateral sclerosis in China

Objectives To describe the natural history and clinical features of sporadic amyotrophic lateral sclerosis (ALS) in Chinese patients, and to report data on the prognostic factors for survival. Methods All patients referred to our ALS centre between 2003 and 2012 were followed up every 3 months. Survival and tracheotomy were predefined as primary outcome measures. Group differences were analysed using parametric and non-parametric tests as appropriate. Survival was analysed using the Kaplan-Meier method and Cox regression analysis. Results Of the 1624 patients with ALS, 75.1% had limb-onset, 14.0% had bulbar-onset, 7.8% had flail-arm syndrome (FAS), 2.6% had progressive muscular atrophy and 0.5% had primary lateral sclerosis. The male:female ratio was 1.7:1, and the mean age at onset was 49.8 years. The median diagnostic delay was 14 months, and the median survival time after symptom onset was 71 months. Male gender, older age at symptom onset, lower body mass index, shorter diagnostic delay, bulbar-onset ALS phenotype, higher Airlie House category at presentation, rural place of residence, use of traditional Chinese medicine and a history of contact with pesticides were associated with poorer survival, whereas female gender or an FAS phenotype may have a better prognosis. Conclusions The clinical characteristics and outcomes of Chinese patients with sporadic ALS were different compared with patients from other countries. Compared with other studies, the age at onset of Chinese patients was earlier, the percentage of bulbar-onset ALS was lower and the prognosis was better. This study substantially advances the understanding of the clinical features and epidemiology of this rare disease.

Replication analysis of SNPs on 9p21.2 and 19p13.3 with amyotrophic lateral sclerosis in East Asians

We performed a replication study of the 2 genetic variants, rs2814707 on 9p21.2 and rs12608932 on 19p13.3 that are recently reported to be most significantly associated with sporadic amyotrophic lateral sclerosis (ALS) in Caucasians. Both rs12608932 and rs2814707 showed no evidence of association in Japanese and Chinese (rs12608932, combined p = 0.58, odds ratio [OR] = 1.03, 95% confidence interval [CI] 0.93-1.13; rs2814707, combined p = 0.88, OR = 1.10, 95% CI 0.93-1.30). The association of these loci with susceptibility to sporadic ALS is considered negative in East Asians.