Arthur H M Burghes

The Ohio State University, Columbus, Ohio, United States

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Publications (88)666.46 Total impact

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    ABSTRACT: Objectives: Spinal muscular atrophy (SMA) is caused by reduced levels of SMN which results in motoneuron loss. Therapeutic strategies to increase SMN levels including drug compounds, antisense oligonucleotides or scAAV9 gene therapy have proved effective in mice. We wished to determine whether reduction of SMN in postnatal motoneurons resulted in SMA in a large animal model, whether SMA could be corrected after development of muscle weakness and the response of clinically relevant biomarkers.Methods: Using intrathecal delivery of scAAV9 expressing a shRNA targeting pig SMN1, SMN was knocked down in motoneurons postnatally to SMA levels. This resulted in an SMA phenotype representing the first large animal model of SMA. Restoration of SMN was performed at different time points with scAAV9 expressing human SMN (scAAV9-SMN) and electrophysiology measures and pathology were performed.Results: Knockdown of SMN in postnatal motoneurons results in overt proximal weakness, fibrillations on electromyography (EMG) indicating active denervation, and reduced compound muscle action potential (CMAP) and motor unit number estimates (MUNE), like human SMA. Neuropathology showed loss of motoneurons and motor axons. Pre-symptomatic delivery of scAAV9-SMN prevented SMA symptoms indicating all changes are SMN dependent. Delivery of scAAV9-SMN after symptom onset had a marked impact on phenotype, electrophysiological measures and pathology.Interpretation: High SMN levels are critical in postnatal motoneurons and reduction of SMN results in a SMA phenotype which is SMN dependent. Importantly, clinically relevant biomarkers including CMAP and MUNE are responsive to SMN restoration and abrogation of phenotype can be achieved even after symptom onset. This article is protected by copyright. All rights reserved.
    Annals of Neurology 12/2014; DOI:10.1002/ana.24332 · 11.91 Impact Factor
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    ABSTRACT: Spinal Muscular Atrophy (SMA) is the most frequent lethal genetic neurodegenerative disorder in infants. The disease is caused by low abundance of the survival of motor neuron (SMN) protein leading to motor neuron degeneration and progressive paralysis. We previously demonstrated that a single intravenous injection (IV) of self-complementary adeno-associated virus 9 carrying the human SMN cDNA (scAAV9-SMN) resulted in widespread transgene expression in spinal cord motor neurons in SMA mice as well as nonhuman primates and complete rescue of the disease phenotype in mice. Here, we evaluated the dosing and efficacy of scAAV9-SMN delivered directly to the cerebral spinal fluid (CSF) via single injection. We found widespread transgene expression throughout the spinal cord in mice and nonhuman primates when using a ten times lower dose compared to the IV application. Interestingly, in nonhuman primates, lower doses than in mice can be used for similar motor neuron targeting efficiency. Moreover, the transduction efficacy is further improved when subjects are kept in the Trendelenburg position to facilitate spreading of the vector. We present a detailed analysis of transduction levels throughout the brain, brainstem and spinal cord of nonhuman primates, providing new guidance for translation towards therapy for a wide range of neurodegenerative disorders.Molecular Therapy (2014); doi:10.1038/mt.2014.210.
    Molecular Therapy 10/2014; DOI:10.1038/mt.2014.210 · 6.43 Impact Factor
  • Muscle & Nerve 09/2014; 50(3). DOI:10.1002/mus.24318 · 2.31 Impact Factor
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    ABSTRACT: Spinal Muscular Atrophy (SMA) is an autosomal recessive disease causing degeneration of lower motor neurons and muscle atrophy. One therapeutic avenue for SMA is targeting signaling pathways in muscle to ameliorate atrophy. Muscle Atrophy F-box, MAFbx, and Muscle RING Finger 1, MuRF1, are muscle-specific ubiquitin ligases upregulated in skeletal and cardiac muscle during atrophy. Homozygous knock-out of MAFbx or MuRF1 causes muscle sparing in adult mice subjected to atrophy by denervation. We wished to determine whether blockage of the major muscle atrophy pathways by deletion of MAFbx or MuRF1 in a mouse model of SMA would improve the phenotype. Deletion of MAFbx in the Δ7 SMA mouse model had no effect on the weight and the survival of the mice while deletion of MuRF1 was deleterious. MAFbx-/-–SMA mice showed a significant alteration in fiber size distribution tending towards larger fibers. In skeletal and cardiac tissue MAFbx and MuRF1 transcripts were upregulated whereas MuRF2 and MuRF3 levels were unchanged in Δ7 SMA mice. We conclude that deletion of the muscle ubiquitin ligases does not improve the phenotype of a Δ7 SMA mouse. Furthermore, it seems unlikely that the beneficial effect of HDAC inhibitors is mediated through inhibition of MAFbx and MuRF1.
    Neuromuscular Disorders 05/2014; DOI:10.1016/j.nmd.2014.02.007 · 3.13 Impact Factor
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    ABSTRACT: Spinal muscular atrophy (SMA) is an early-onset motor neuron disease characterized by loss of spinal motor neurons which leads to skeletal muscle atrophy. Proximal SMA results from the loss or mutation of the survival motor neuron (SMN) gene. In humans, the SMN gene is duplicated to produce two nearly identical genes, SMN1 and SMN2. SMN1 is lost in SMA but SMN2 is retained; in fact, the number of SMN2 copies correlates with disease severity. The SMN2 inducer D156844 increases the survival and improves phenotype of SMNΔ7 SMA mice. Maternal diet also modifies the survival and phenotype of these mice. In this study, we show the effect of maternal diet on the protective effects of D156844 in SMNΔ7 SMA mice. SMA mice maintained on the PicoLab20 Mouse diet survived longer when treated with D156844; the effect of diet was additive to the effect of D156844 on these mice. Brain levels of D156844 were higher in neonatal mice maintained on the PicoLab20 diet than those on the Harlan-Teklad 22/5 diet. SMN protein levels in the spinal cord were modestly elevated in D156844-treated, PicoLab20-maintained SMA mice. These data show that maternal diet does influence the responsiveness of D156844 in neonatal SMNΔ7 SMA mice.
    Experimental Neurology 03/2014; DOI:10.1016/j.expneurol.2014.03.005 · 4.62 Impact Factor
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    Neuromuscular Disorders 03/2014; 24:S3. DOI:10.1016/S0960-8966(14)70011-2 · 3.13 Impact Factor
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    ABSTRACT: Preclinical therapies that restore survival motor neuron (SMN) protein levels can dramatically extend survival in spinal muscular atrophy (SMA) mouse models. Biomarkers are needed to effectively translate these promising therapies to clinical trials. Our objective was to investigate electrophysiological biomarkers of compound muscle action potential (CMAP), motor unit number estimation (MUNE) and electromyography (EMG) using an SMA mouse model. Sciatic CMAP, MUNE, and EMG were obtained in SMNΔ7 mice at ages 3-13 days and at 21 days in mice with SMN selectively reduced in motor neurons (ChAT(Cre) ). To investigate these measures as biomarkers of treatment response, measurements were obtained in SMNΔ7 mice treated with antisense oligonucleotide (ASO) or gene therapy. CMAP was significantly reduced in SMNΔ7 mice at days 6-13 (p<0.01), and MUNE was reduced at days 7-13 (p<0.01). Fibrillations were present on EMG in SMNΔ7 mice but not controls (p=0.02). Similar findings were seen at 21 days in ChAT(Cre) mice. MUNE in ASO-treated SMNΔ7 mice were similar to controls at day 12 and 30. CMAP reduction persisted in ASO-treated SMNΔ7 mice at day 12 but was corrected at day 30. Similarly, CMAP and MUNE responses were corrected with gene therapy to restore SMN. These studies confirm features of preserved neuromuscular function in the early postnatal period and subsequent motor unit loss in SMNΔ7 mice. SMN restoring therapies result in preserved MUNE and gradual repair of CMAP responses. This provides preclinical evidence for the utilization of CMAP and MUNE as biomarkers in future SMA clinical trials.
    01/2014; 1(1):34-44. DOI:10.1002/acn3.23
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    ABSTRACT: Amyotrophic lateral sclerosis (ALS) causes motor neuron degeneration, paralysis, and death. Accurate disease modeling, identifying disease mechanisms, and developing therapeutics is urgently needed. We previously reported motor neuron toxicity through postmortem ALS spinal cord-derived astrocytes. However, these cells can only be harvested after death, and their expansion is limited. We now report a rapid, highly reproducible method to convert adult human fibroblasts from living ALS patients to induced neuronal progenitor cells and subsequent differentiation into astrocytes (i-astrocytes). Non-cell autonomous toxicity to motor neurons is found following coculture of i-astrocytes from familial ALS patients with mutation in superoxide dismutase or hexanucleotide expansion in C9orf72 (ORF 72 on chromosome 9) the two most frequent causes of ALS. Remarkably, i-astrocytes from sporadic ALS patients are as toxic as those with causative mutations, suggesting a common mechanism. Easy production and expansion of i-astrocytes now enables rapid disease modeling and high-throughput drug screening to alleviate astrocyte-derived toxicity.
    Proceedings of the National Academy of Sciences 12/2013; 111(2). DOI:10.1073/pnas.1314085111 · 9.81 Impact Factor
  • Neuromuscular Disorders 10/2013; 23(9-10):797. DOI:10.1016/j.nmd.2013.06.558 · 3.13 Impact Factor
  • Neuromuscular Disorders 10/2013; 23(9-10):771. DOI:10.1016/j.nmd.2013.06.476 · 3.13 Impact Factor
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    W David Arnold, Arthur H M Burghes
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    ABSTRACT: In neurodegenerative disorders effective treatments are urgently needed, along with methods to detect that the treatment worked. In this review we discuss the rapid progress in the understanding of recessive proximal spinal muscular atrophy and how this is leading to exciting potential treatments of the disease. Spinal muscular atrophy is a caused by loss of the Survival Motor Neuron 1 (SMN1) gene and reduced levels of SMN protein. The critical downstream targets of SMN deficiency that result in motor neuron loss are not known. However, increasing SMN levels has a marked impact in mouse models, and these therapeutics are rapidly moving towards clinical trials. Promising preclinical therapies, the varying degree of impact on the mouse models, and potential measures of treatment effect are reviewed. One key issue discussed is the variable outcome of increasing SMN at different stages of disease progression. ANN NEUROL 2013. © 2013 American Neurological Association.
    Annals of Neurology 08/2013; 74(3). DOI:10.1002/ana.23995 · 11.91 Impact Factor
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    ABSTRACT: Spinal muscular atrophy (SMA) is caused by loss of the Survival Motor Neuron 1 (SMN1) gene, resulting in reduced SMN protein. Humans possess the additional SMN2 gene (or genes) that does produce low level of full length SMN, but cannot adequately compensate for loss of SMN1 due to aberrant splicing. The majority of SMN2 gene transcripts lack exon 7 and the resultant SMNΔ7 mRNA is translated into an unstable and non-functional protein. Splice intervention therapies to promote exon 7 retention and increase amounts of full-length SMN2 transcript offer great potential as a treatment for SMA patients. Several splice silencing motifs in SMN2 have been identified as potential targets for antisense oligonucleotide mediated splice modification. A strong splice silencer is located downstream of exon 7 in SMN2 intron 7. Antisense oligonucleotides targeting this motif promoted SMN2 exon 7 retention in the mature SMN2 transcripts, with increased SMN expression detected in SMA fibroblasts. We report here systematic optimisation of phosphorodiamidate morpholino oligonucleotides (PMO) that promote exon 7 retention to levels that rescued the phenotype in a severe mouse model of SMA after intracerebroventricular delivery. Furthermore, the PMO gives the longest survival reported to date after a single dosing by ICV.
    PLoS ONE 04/2013; 8(4):e62114. DOI:10.1371/journal.pone.0062114 · 3.53 Impact Factor
  • Paul N. Porensky, Arthur H.M. Burghes
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    ABSTRACT: Spinal Muscular Atrophy (SMA) is an autosomal recessive disease effecting ~1 in 10,000 live births. The most striking component is the loss of alpha motor neurons in the ventral horn of the spinal cord, resulting in progressive paralysis and eventually premature death. There is no current treatment paradigm other than supportive care, though the past 15 years has seen a striking advancement in understanding of both SMA genetics and molecular mechanisms. A variety of disease modifying interventions are rapidly bridging the translational gap from the laboratory to clinical trials, including the application of antisense oligomer (ASO) therapy for the correction of aberrant RNA splicing characteristic of SMA. Survival motor neuron (SMN) is a ubiquitously expressed 38-KD protein. Humans have two genes that produce SMN, SMN1 and SMN2, the former of which is deleted or non-functional in the majority of patients with SMA. These two genes are nearly identical, with one exception a C to T transition (C6T) within exon 7 of SMN2. C6T disrupts a modulator of splicing, leading to the exclusion of exon 7 from ~90% of mRNA transcript. The resultant truncated Δ7SMN protein does not oligomerize efficiently and is rapidly degraded. SMA can therefore be considered a disease of too little SMN protein. A number of cis-acting splice modifiers have been identified in the region of exon 7, the steric block of which enhances the retention of the exon and a resultant full length mRNA sequence. ASOs targeted to these splice-motifs have shown impressive phenotype rescue in multiple SMA mouse models.
    Human gene therapy 04/2013; DOI:10.1089/hum.2012.225 · 4.20 Impact Factor
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    ABSTRACT: SMN is expressed in all tissues but its deficiency in SMA selectively affects neurons. Using mice that model severe SMA we have tested whether SMN needs to be replaced in all tissues. Furthermore we have used antisense morpholinos (ASO) directed against ISS-N1 delivered to the nervous system to correct SMA mice. Using mice lines that can either remove mouse SMN expression or restore mouse SMN expression when Cre is expressed we have determined the spatial requirement for SMN in SMA. Removal of SMN from neurons to create SMA neurons in the background of all other cells with normal SMN results in mice with a severe phenotype likewise restoration of SMN to neurons with all other tissues remaining at low levels results in correction. While the Cre drivers clearly indicate that motor neurons are one of the critical neural types for SMN restoration it is not the only neuronal type that requires high SMN levels. Furthermore we have knockdown SMN in pig motor neurons and other neuronal populations in the pig using intrathecal delivery of AAV9-shRNA this resulted in a clear SMA like phenotype. Furthermore with efficient transduction of motor neurons the cell bodies of the motor neuron where retained but ventral root axons showed a marked loss indicating that reduction in SMN results in motor axonal problems prior to the cell body. In mice the intracerebralventricular delivery of ASO has a marked impact on SMA mice we are now investigating the distribution of ASO after intrathecal or ICV delivery initial results indicate it is possible to obtain wide distribution in the nervous system of both adult and neonatal animals.
    Neuromuscular Disorders 10/2012; 22(9-10):907-908. DOI:10.1016/j.nmd.2012.06.342 · 3.13 Impact Factor
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    ABSTRACT: Spinal muscular atrophy (SMA) is caused by mutation of the Survival Motor Neurons 1 (SMN1) gene and is characterized by degeneration of spinal motor neurons. The severity of SMA is primarily influenced by the copy number of the SMN2 gene. Additional modifier genes that lie outside the SMA locus exist and one gene that could modify SMA is the Zinc Finger Protein (ZPR1) gene. To test the significance of ZPR1 downregulation in SMA, we examined the effect of reduced ZPR1 expression in mice with mild and severe SMA. We report that the reduced ZPR1 expression causes increase in the loss of motor neurons, hypermyelination in phrenic nerves, increase in respiratory distress and disease severity and reduces the lifespan of SMA mice. The deficiency of SMN-containing sub-nuclear bodies correlates with the severity of SMA. ZPR1 is required for the accumulation of SMN in sub-nuclear bodies. Further, we report that ZPR1 overexpression increases levels of SMN and promotes accumulation of SMN in sub-nuclear bodies in SMA patient fibroblasts. ZPR1 stimulates neurite growth and rescues axonal growth defects in SMN-deficient spinal cord neurons from SMA mice. These data suggest that the severity of disease correlates negatively with ZPR1 levels and ZPR1 may be a protective modifier of SMA.
    Human Molecular Genetics 03/2012; 21(12):2745-58. DOI:10.1093/hmg/dds102 · 6.68 Impact Factor
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    ABSTRACT: Spinal muscular atrophy (SMA) is an inherited motor neuron disease caused by homozygous loss of the Survival Motor Neuron 1 (SMN1) gene. In the absence of SMN1, inefficient inclusion of exon 7 in transcripts from the nearly identical SMN2 gene results in ubiquitous SMN decrease but selective motor neuron degeneration. Here we investigated whether cell type-specific differences in the efficiency of exon 7 splicing contribute to the vulnerability of SMA motor neurons. We show that normal motor neurons express markedly lower levels of full-length SMN mRNA from SMN2 than do other cells in the spinal cord. This is due to inefficient exon 7 splicing that is intrinsic to motor neurons under normal conditions. We also find that SMN depletion in mammalian cells decreases exon 7 inclusion through a negative feedback loop affecting the splicing of its own mRNA. This mechanism is active in vivo and further decreases the efficiency of exon 7 inclusion specifically in motor neurons of severe-SMA mice. Consistent with expression of lower levels of full-length SMN, we find that SMN-dependent downstream molecular defects are exacerbated in SMA motor neurons. These findings suggest a mechanism to explain the selective vulnerability of motor neurons to loss of SMN1.
    Molecular and Cellular Biology 01/2012; 32(1):126-38. DOI:10.1128/MCB.06077-11 · 5.04 Impact Factor
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    ABSTRACT: Spinal muscular atrophy (SMA) is an autosomal-recessive disorder characterized by α-motor neuron loss in the spinal cord anterior horn. SMA results from deletion or mutation of the Survival Motor Neuron 1 gene (SMN1) and retention of SMN2. A single nucleotide difference between SMN1 and SMN2 results in exclusion of exon 7 from the majority of SMN2 transcripts, leading to decreased SMN protein levels and development of SMA. A series of splice enhancers and silencers regulate incorporation of SMN2 exon 7; these splice motifs can be blocked with antisense oligomers (ASOs) to alter SMN2 transcript splicing. We have evaluated a morpholino (MO) oligomer against ISS-N1 [HSMN2Ex7D(-10,-29)], and delivered this MO to postnatal day 0 (P0) SMA pups (Smn-/-, SMN2+/+, SMNΔ7+/+) by intracerebroventricular (ICV) injection. Survival was increased markedly from 15 days to >100 days. Delayed CNS MO injection has moderate efficacy, and delayed peripheral injection has mild survival advantage, suggesting that early CNS ASO administration is essential for SMA therapy consideration. ICV treatment increased full-length SMN2 transcript as well as SMN protein in neural tissue, but only minimally in peripheral tissue. Interval analysis shows a decrease in alternative splice modification over time. We suggest that CNS increases of SMN will have a major impact on SMA, and an early increase of the SMN level results in correction of motor phenotypes. Finally, the early introduction by intrathecal delivery of MO oligomers is a potential treatment for SMA patients.
    Human Molecular Genetics 12/2011; 21(7):1625-38. DOI:10.1093/hmg/ddr600 · 6.68 Impact Factor
  • Neuromuscular Disorders 10/2011; 21(9):685-685. DOI:10.1016/j.nmd.2011.06.905 · 3.13 Impact Factor
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    ABSTRACT: Amyotrophic lateral sclerosis (ALS) is a fatal motor neuron disease, with astrocytes implicated as contributing substantially to motor neuron death in familial (F)ALS. However, the proposed role of astrocytes in the pathology of ALS derives in part from rodent models of FALS based upon dominant mutations within the superoxide dismutase 1 (SOD1) gene, which account for <2% of all ALS cases. Their role in sporadic (S)ALS, which affects >90% of ALS patients, remains to be established. Using astrocytes generated from postmortem tissue from both FALS and SALS patients, we show that astrocytes derived from both patient groups are similarly toxic to motor neurons. We also demonstrate that SOD1 is a viable target for SALS, as its knockdown significantly attenuates astrocyte-mediated toxicity toward motor neurons. Our data highlight astrocytes as a non-cell autonomous component in SALS and provide an in vitro model system to investigate common disease mechanisms and evaluate potential therapies for SALS and FALS.
    Nature Biotechnology 08/2011; 29(9):824-8. DOI:10.1038/nbt.1957 · 39.08 Impact Factor
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    ABSTRACT: Adeno-associated virus type 9 (AAV9) is a powerful tool for delivering genes throughout the central nervous system (CNS) following intravenous injection. Preclinical results in pediatric models of spinal muscular atrophy (SMA) and lysosomal storage disorders provide a compelling case for advancing AAV9 to the clinic. An important translational step is to demonstrate efficient CNS targeting in large animals at various ages. In the present study, we tested systemically injected AAV9 in cynomolgus macaques, administered at birth through 3 years of age for targeting CNS and peripheral tissues. We show that AAV9 was efficient at crossing the blood-brain barrier (BBB) at all time points investigated. Transgene expression was detected primarily in glial cells throughout the brain, dorsal root ganglia neurons and motor neurons within the spinal cord, providing confidence for translation to SMA patients. Systemic injection also efficiently targeted skeletal muscle and peripheral organs. To specifically target the CNS, we explored AAV9 delivery to cerebrospinal fluid (CSF). CSF injection efficiently targeted motor neurons, and restricted gene expression to the CNS, providing an alternate delivery route and potentially lower manufacturing requirements for older, larger patients. Our findings support the use of AAV9 for gene transfer to the CNS for disorders in pediatric populations.
    Molecular Therapy 08/2011; 19(11):1971-80. DOI:10.1038/mt.2011.157 · 6.43 Impact Factor

Publication Stats

5k Citations
666.46 Total Impact Points


  • 1992–2014
    • The Ohio State University
      • • Department of Neurology
      • • Department of Neurological Surgery
      • • Department of Molecular Genetics
      • • Department of Molecular and Cellular Biochemistry
      • • Pathology
      Columbus, Ohio, United States
  • 2013
    • Mahidol University
      Krung Thep, Bangkok, Thailand
  • 2012
    • Columbia University
      • Department of Neurology
      New York City, New York, United States
  • 2010–2011
    • Nationwide Children's Hospital
      • Center for Gene Therapy
      Columbus, OH, United States
  • 2003
    • Molecular and Cellular Biology Program
      Seattle, Washington, United States
  • 1994
    • University of Groningen
      • Department of Medical Genetics
      Groningen, Groningen, Netherlands