Virginia Mattis - Academia.edu (original) (raw)

Papers by Virginia Mattis

npj Regenerative Medicine

In pursuit of treating Parkinson’s disease with cell replacement therapy, differentiated induced ... more In pursuit of treating Parkinson’s disease with cell replacement therapy, differentiated induced pluripotent stem cells (iPSC) are an ideal source of midbrain dopaminergic (mDA) cells. We previously established a protocol for differentiating iPSC-derived post-mitotic mDA neurons capable of reversing 6-hydroxydopamine-induced hemiparkinsonism in rats. In the present study, we transitioned the iPSC starting material and defined an adapted differentiation protocol for further translation into a clinical cell transplantation therapy. We examined the effects of cellular maturity on survival and efficacy of the transplants by engrafting mDA progenitors (cryopreserved at 17 days of differentiation, D17), immature neurons (D24), and post-mitotic neurons (D37) into immunocompromised hemiparkinsonian rats. We found that D17 progenitors were markedly superior to immature D24 or mature D37 neurons in terms of survival, fiber outgrowth and effects on motor deficits. Intranigral engraftment to th...

Spinal muscular atrophy (SMA) is the leading genetic cause of infant mortality and is caused by t... more Spinal muscular atrophy (SMA) is the leading genetic cause of infant mortality and is caused by the loss of a functional SMN1 gene. In humans, there exists a nearly-identical copy gene known as SMN2 that encodes an identical protein as SMN1, but differs by a silent C to T transition within exon 7. This single nucleotide difference produces an alternatively spliced isoform, SMND7, which encodes a rapidly degraded protein. The absence of the short peptide encoded by SMN exon 7 is critical in the disease development process; however, heterologous sequences can partially compensate for the SMN exon 7 peptide in several cellular assays. Consistent with this, aminoglycosides, compounds that can suppress efficient recognition of stop codons, resulted in significantly increased levels of SMN protein in SMA patient fibroblasts. We now examine the potential therapeutic capabilities of a novel aminoglycoside, TC007. In an intermediate SMA model (Smn2/2; SMN21/1; SMND7), when delivered directly to the central nervous system (CNS), TC007 induces SMN in both the brain and spinal cord, significantly increases lifespan (30%) and increases ventral horn cell number, consistent with its ability to increase SMN levels in induced pluripotent stem cell-derived human SMA motor neuron cultures. Collectively, these experiments are the first in vivo examination of therapeutics for SMA designed to induce read-through of the SMND7 stop codon to show increased benefit by direct administration to the CNS.

Research article Roles of PI3K and JAK pathways in viability of retinal ganglion cells after acut... more Research article Roles of PI3K and JAK pathways in viability of retinal ganglion cells after acute elevation of intraocular pressure in rats with different autoimmune backgrounds

1 A non-sequence specific requirement for SMN protein activity: the role of aminoglycosides in in... more 1 A non-sequence specific requirement for SMN protein activity: the role of aminoglycosides in inducing elevated

Methods in Molecular Biology, 2018

Huntington's disease (HD) is an autosomal dominant neurodegenerative disorder caused by expan... more Huntington's disease (HD) is an autosomal dominant neurodegenerative disorder caused by expanded polyglutamine (polyQ)-encoding repeats in the Huntingtin (HTT) gene. Traditionally, HD cellular models consisted of either patient cells not affected by disease or rodent neurons expressing expanded polyQ repeats in HTT. As these models can be limited in their disease manifestation or proper genetic context, respectively, human HD pluripotent stem cells (PSCs) are currently under investigation as a way to model disease in patient-derived neurons and other neural cell types. This chapter reviews embryonic stem cell (ESC) and induced pluripotent stem cell (iPSC) models of disease, including published differentiation paradigms for neurons and their associated phenotypes, as well as current challenges to the field such as validation of the PSCs and PSC-derived cells. Highlighted are potential future technical advances to HD PSC modeling, including transdifferentiation, complex in vitro multiorgan/system reconstruction, and personalized medicine. Using a human HD patient model of the central nervous system, hopefully one day researchers can tease out the consequences of mutant HTT (mHTT) expression on specific cell types within the brain in order to identify and test novel therapies for disease.

A: Pathogenic mechanisms, 2021

Background Circular RNAs (circRNAs) are a special group of non-coding RNAs formed by back-splicin... more Background Circular RNAs (circRNAs) are a special group of non-coding RNAs formed by back-splicing. Mostly cytosolic in eukaryotic cells, circRNAs are particularly enriched and conserved in neurons and originate from protein-coding genes to function as global regulators of gene expression. Recent studies showed that circRNAs partake in brain physiology and pathology, contributing to neurological disorders, such as myotonic dystrophy type 1, Parkinson’s and Alzheimer’s Diseases. Here, we identified the first ever known brain enriched RNA circle originating from the Huntington’s Disease gene HTT (CircHTT: 484 nt, Ex 2-6, chr4:3088665-3109150) which is conserved in mouse and minipig. Aims and Methods To functionally characterize circHTT and its implication for HD pathogenesis, we first studied its expression pattern in human and mouse body districts and in iPS-derived neuronal cell lines with different CAG repeats. Then, overexpression and down-regulation of the circle were used to determine the effects on transcription of the HD gene and translation of wild-type and mutant protein. Results CircHTT expression increases significantly with increasing CAG repeats in terminally differentiated cortical neurons. Furthermore, circHtt is significantly more expressed in brain districts of Q111 and zQ175 knock-in mice. These findings indicate that the expression of circHTT/Htt occurs in a CAG repeat dependent manner in neuronal cells, typical hallmark of HD pathology. Strikingly, overexpression of the circular RNA in human HEK293T, PC3, mouse STHdh Q7/7, Q7/111 and Q111/111 cell lines consistently increase wild-type huntingtin, while decreasing mutant huntingtin protein, with no alteration of the HTT/Htt transcript level. Conclusions In conclusion, we identified a brain enriched RNA circle originating from the HD gene locus that is sensitive to the HD mutation and may modulate huntingtin expression. Our observations might pave the way to new trials of therapeutic intervention.

Glia, 2021

Inactivating mutations in the thyroid hormone (TH) transporter monocarboxylate transporter 8 (MCT... more Inactivating mutations in the thyroid hormone (TH) transporter monocarboxylate transporter 8 (MCT8) causes a rare and debilitating form of X‐linked psychomotor disability known as Allan Herndon Dudley syndrome (AHDS). One of the most prominent pathophysiological symptoms of MCT8‐deficiency is hypomyelination. Here, patient‐derived induced pluripotent stem cells (iPSCs) were used to study the role of MCT8 and TH on the maturation of oligodendrocytes. Interestingly, neither MCT8 mutations nor reduced TH affected the in vitro differentiation of control or MCT8‐deficient iPSCs into oligodendrocytes. To assess whether patient‐derived iPSC‐derived oligodendrocyte progenitor cells (iOPCs) could provide myelinating oligodendrocytes in vivo, cells were transplanted into the shiverer mouse corpus callosum where they survived, migrated, and matured into myelinating oligodendrocytes, though the myelination efficiency was reduced compared with control cells. When MCT8‐deficient and healthy control iOPCs were transplanted into a novel hypothyroid immunodeficient triple knockout mouse (tKO, mct8−/−; oatp1c1−/−; rag2−/−), they failed to provide behavioral recovery and did not mature into oligodendrocytes in the hypothyroid corpus callosum, demonstrating the critical role of TH transport across brain barriers in oligodendrocyte maturation. We conclude that MCT8 plays a cell autonomous role in oligodendrocyte maturation and that functional TH transport into the central nervous system will be required for developing an effective treatment for MCT8‐deficient patients.

Pathogenic mechanisms, 2018

Background Huntington’s Disease (HD), is a hereditary, fatal neurodegenerative disorder due to CA... more Background Huntington’s Disease (HD), is a hereditary, fatal neurodegenerative disorder due to CAG trinucleotide expansion in exon 1 of the HD gene (HTT). Recent findings revealed that the process of alternative splicing (AS) might be compromised in HD. AS regulation is crucial not only to the establishment of a repertoire of protein coding isoforms extremely relevant for the proper physiological characteristics of the nervous system, but also to the biogenesis of circular RNAs (circRNAs), unusually stable, highly expressed non-coding RNAs produced by the circularization of exons which, seems to have important roles during neuronal development and functioning. Aims Therefore, the overarching goal of our research was to take advantage of genetically engineered Htt knock-in (KI) mouse cellular and in vivo model systems bearing normal or pathological Htt CAG repeat lengths to discover alterations in linear and back-splicing events that might reflect on the levels of expression as well as the composition of a repertoire of proteins, thus contributing to HD striatal vulnerability and pathogenesis. Methods/techniques To discover alterations in linear splicing, we resourced to a publicly available dataset (Langfelder P. et al., 2016, Nature Neuroscience) analyzing full transcriptomic profiling dataset for striatum, cortex and liver at different developmental time points, identifying and quantifying the total numbers of differential AS events for each genotype/sample type and time point. Results/outcome Our analysis demonstrated that specifically for the striatum – most vulnerable to HD degeneration – the total number of detected, differential AS events increased significantly at 6 and 10 month with increasing CAG expansion. Interestingly, not all the AS events increased with CAG-expansion and age, but only a specific subtype of AS event – EXON SKIPPING – revealed to be strongly and specifically affected. On the other hand, we identified and characterized the first circular RNA originating locally from the HTT locus, expressed in whole body, but predominantly in the brain and spinal cord and presenting augmented expression level with increasing HTT CAG size. Moreover, at genome-wide level, data analysis of circRNA-seq showed a decreased circRNAs production when mutant huntingtin is expressed. Specifically, 12 circRNAs, identified by stringent cut-off criteria, showed continuous decreased expression following CAG expansion in neuronal progenitor cells. Since, most of the CAG-sensitive circRNAs have annotated human orthologues, their expression can be further characterized and functionally studied in human cell lines. Conclusions In conclusion, our results support the idea that AS machinery is responding to HD mutational process altering both linear and back-splicing events locally at the HTT locus, but also at genome-wide level. This knowledge will pave the way to new trials of therapeutic intervention aimed to possibly target spliceosomal-circRNAs alterations through specific drugs or genetic manipulation.

Journal of Huntington's Disease, 2019

Background: Huntington's disease (HD) is an inherited neurodegenerative disease and is characteri... more Background: Huntington's disease (HD) is an inherited neurodegenerative disease and is characterized by atrophy of certain regions of the brain in a progressive manner. HD patients experience behavioral changes and uncontrolled movements which can be primarily attributed to the atrophy of striatal neurons. Previous publications describe the models of the HD striatum using induced pluripotent stem cells (iPSCs) derived from HD patients with a juvenile onset (JHD). In this model, the JHD iPSC-derived striatal cultures had altered neurodevelopment and contained a high number of nestin expressing progenitor cells at 42 days of differentiation. Objective: To further characterize the altered neurodevelopmental phenotype and evaluate potential phenotypic reversal. Methods: Differentiation of human iPSCs towards striatal fate and characterization by means of immunocytochemistry and stereological quantification. Results: Here this study demonstrates a distinct delay in the differentiation of the JHD neural progenitor population. However, reduction of the JHD aberrant progenitor populations can be accomplished either by targeting the canonical Notch signaling pathway or by treatment with HTT antisense oligonucleotides (ASOs). Conclusions: In summary, this data is postulated to reflect a potential overall developmental delay in JHD.

Frontiers in Neuroscience, 2019

In Huntington's disease (HD), while the ubiquitously expressed mutant Huntingtin (mtHTT) protein ... more In Huntington's disease (HD), while the ubiquitously expressed mutant Huntingtin (mtHTT) protein primarily compromises striatal and cortical neurons, glia also undergo disease-contributing alterations. Existing HD models using human induced pluripotent stem cells (iPSCs) have not extensively characterized the role of mtHTT in patientderived astrocytes. Here physiologically mature astrocytes are generated from HD patient iPSCs. These human astrocytes exhibit hallmark HD phenotypes that occur in mouse models, including impaired inward rectifying K + currents, lengthened spontaneous Ca 2+ waves and reduced cell membrane capacitance. HD astrocytes in co-culture provided reduced support for the maturation of iPSC-derived neurons. In addition, neurons exposed to chronic glutamate stimulation are not protected by HD astrocytes. This iPSC-based HD model demonstrates the critical effects of mtHTT on human astrocytes, which not only broadens the understanding of disease susceptibility beyond cortical and striatal neurons but also increases potential drug targets.

Molecular Biology of the Cell, 2018

The huntingtin protein participates in several cellular processes that are disrupted when the pol... more The huntingtin protein participates in several cellular processes that are disrupted when the polyglutamine tract is expanded beyond a threshold of 37 CAG DNA repeats in Huntington’s disease (HD). Cellular biology approaches to understand these functional disruptions in HD have primarily focused on cell lines with synthetically long CAG length alleles that clinically represent outliers in this disease and a more severe form of HD that lacks age onset. Patient-derived fibroblasts are limited to a finite number of passages before succumbing to cellular senescence. We used human telomerase reverse transcriptase (hTERT) to immortalize fibroblasts taken from individuals of varying age, sex, disease onset, and CAG repeat length, which we have termed TruHD cells. TruHD cells display classic HD phenotypes of altered morphology, size and growth rate, increased sensitivity to oxidative stress, aberrant adenosine diphosphate/adenosine triphosphate (ADP/ATP) ratios, and hypophosphorylated hunti...

Cell reports, Jan 23, 2018

Huntington's disease (HD) is a neurodegenerative disease caused by an expanded CAG repeat in ... more Huntington's disease (HD) is a neurodegenerative disease caused by an expanded CAG repeat in the Huntingtin (HTT) gene. Induced pluripotent stem cell (iPSC) models of HD provide an opportunity to study the mechanisms underlying disease pathology in disease-relevant patient tissues. Murine studies have demonstrated that HTT is intricately involved in corticogenesis. However, the effect of mutant Hungtintin (mtHTT) in human corticogenesis has not yet been thoroughly explored. This examination is critical, due to inherent differences in cortical development and timing between humans and mice. We therefore differentiated HD and non-diseased iPSCs into functional cortical neurons. While HD patient iPSCs can successfully differentiate toward a cortical fate in culture, the resulting neurons display altered transcriptomics, morphological and functional phenotypes indicative of altered corticogenesis in HD.

Nature Neuroscience, 2018

Huntington modeling improves with age Direct conversion of adult Huntington's disease patient fib... more Huntington modeling improves with age Direct conversion of adult Huntington's disease patient fibroblasts into medium spiny neurons recapitulates hallmark phenotypes such as cell death, in contrast to models that lack epigenetic markers of aging. This successful 'disease-in-a-dish' highlights the benefits of capturing age in an adult-onset disorder model.

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Frontiers in neuroscience, 2017

Huntington's disease (HD) is a devastating neurodegenerative disorder caused by a polyglutami... more Huntington's disease (HD) is a devastating neurodegenerative disorder caused by a polyglutamine (polyQ) expansion in exon 1 of the () gene. We have previously demonstrated that spliceosome-mediated -splicing is a viable molecular strategy to specifically reduce and repair mutant HTT (mtHTT). Here, the targeted tethering efficacy of the pre-mRNA -splicing modules (PTM) in HTT was optimized. Various PTMs that targeted the 3' end of HTT intron 1 or the intron 1 branch point were shown -splice into an HTT mini-gene, as well as the endogenous HTT pre-mRNA. PTMs that specifically target the endogenous intron 1 branch point increased the -splicing efficacy from 1-5 to 10-15%. Furthermore, lentiviral expression of PTMs in a human HD patient iPSC-derived neural culture significantly reversed two previously established polyQ-length dependent phenotypes. These results suggest that pre-mRNA repair of mtHTT could hold therapeutic benefit and it demonstrates an alternative platform to cor...

Stem cell reports, Jan 23, 2018

Trophic factor delivery to the brain using stem cell-derived neural progenitors is a powerful way... more Trophic factor delivery to the brain using stem cell-derived neural progenitors is a powerful way to bypass the blood-brain barrier. Protection of diseased neurons using this technology is a promising therapy for neurodegenerative diseases. Glial cell line-derived neurotrophic factor (GDNF) has provided benefits to Parkinsonian patients and is being used in a clinical trial for amyotrophic lateral sclerosis. However, chronic trophic factor delivery prohibits dose adjustment or cessation if side effects develop. To address this, we engineered a doxycycline-regulated vector, allowing inducible and reversible expression of a therapeutic molecule. Human induced pluripotent stem cell (iPSC)-derived neural progenitors were stably transfected with the vector and transplanted into the adult mouse brain. Doxycycline can penetrate the graft, with addition and withdrawal providing inducible and reversible GDNF expression in vivo, over multiple cycles. Our findings provide proof of concept for ...

Nature Neuroscience, 2017

Brain Research, 2017

Huntington׳s Disease (HD) is a fatal neurodegenerative disorder caused by expanded polyglutamine ... more Huntington׳s Disease (HD) is a fatal neurodegenerative disorder caused by expanded polyglutamine repeats in the Huntingtin (HTT) gene. While the gene was identified over two decades ago, it remains poorly understood why mutant HTT (mtHTT) is initially toxic to striatal medium spiny neurons (MSNs). Models of HD using non-neuronal human patient cells and rodents exhibit some characteristic HD phenotypes. While these current models have contributed to the field, they are limited in disease manifestation and may vary in their response to treatments. As such, human HD patient MSNs for disease modeling could greatly expand the current understanding of HD and facilitate the search for a successful treatment. It is now possible to use pluripotent stem cells, which can generate any tissue type in the body, to study and potentially treat HD. This review covers disease modeling in vitro and, via chimeric animal generation, in vivo using human HD patient MSNs differentiated from embryonic stem cells or induced pluripotent stem cells. This includes an overview of the differentiation of pluripotent cells into MSNs, the established phenotypes found in cell-based models and transplantation studies using these cells. This review not only outlines the advancements in the rapidly progressing field of HD modeling using neurons derived from human pluripotent cells, but also it highlights several remaining controversial issues such as the &amp;amp;amp;amp;amp;amp;amp;#39;ideal&amp;amp;amp;amp;amp;amp;amp;#39; series of pluripotent lines, the optimal cell types to use and the study of a primarily adult-onset disease in a developmental model. This article is part of a Special Issue entitled SI: Exploiting human neurons.