mouse neurons

Breakefield Laboratory - Xandra O. Breakefield

The Breakefield laboratory uses molecular genetic techniques to elucidate the etiology of inherited neurological diseases and to develop vectors which can deliver genes to the nervous system for therapeutic purposes.

Lab Phone: 617-726-5728


The Breakefield laboratory has expertise in molecular genetics and neuroscience focusing on understanding and treating diseases of the nervous system. Their recent work includes characterization of the nucleic acid content of exosomes (microvesicles) released by tumor cells, including their use as biomarkers in the serum of cancer patients for genetic evaluation of tumors, their ability to carry out horizontal gene transfer to other cells to promote tumor growth; and their potential for tumor therapy. In addition, since identifying the gene for early onset torsion dystonia in 1997, they have worked on understanding the function of the defective protein, torsinA. They have found that torsinA, an AAA+ ATPase in the lumen of the nuclear envelope and endoplasmic reticulum, is involved in positioning of the nucleus during cell migration and in chaperoning proteins in the secretory pathway. They are also actively involved in use of viral vectors, including lentivirus and AAV and for gene therapy in the nervous system.

Group Members

The research team at the Breakefield Lab

beakefield group pic

Xandra O. Breakefield, PhD

Principal Investigator

Xandra O. Breakefield, PhD

  • Professor of Neurology,
    Harvard Medical School
  • Geneticist, Neurology and Radiology
    Massachusetts General Hospital



Research Scientists

Leonora Balaj


Shilpa Prabhakar

Leonora Balaj, Post Doctorate Fellow

Shilpa Prabhakar, MSc, Lab Manager

Research Interests

My research focuses on the utilization and development of adeno-associated virus (AAV) vectors for efficient gene transfer to target organs of the body, in particular the central nervous system (CNS).  AAV is currently the lead candidate for gene therapy to the brain, as it efficiently delivers transgenes to neurons after direct injection.  Some AAV vectors can also deliver genes to the brain after vascular injection. This is a preferred route of injection as it is non-invasive and has the potential to provide widespread access of virus vector to the brain. Some limitations which may hamper the general use of AAV for human gene therapy via the vascular route are neutralizing antibodies to the virus itself, uptake by non-target organs such as the liver and low efficiency of crossing the blood-brain barrier.  Our goal is to overcome these barriers using different strategies including: (1) our recent discovery that AAV vectors can associate with endogenous lipid structures called microvesicles and (2) genetic engineering of the virus.

Current Lab Members

  • Naoto Ito, PhD – Instructor, PhD in Biochemistry from University of Tokyo, Tokyo, Japan
  • Charles Lai, PhD – Instructor, PhD in Cell and Developmental Biology from University of British Columbia, Vancouver, Canada
  • Noriko Wakabayashi-Ito, PhD – Research Scientist, PhD from University of Tokyo, Tokyo, Japan
  • Bence Gyorgy, MD/PhD – Postdoctoral fellow, M.D., PhD in Immunology/Genetics from Semmelweis University, Budapest, Hungary
  • Mikolaj Zaborowski, MD – Postdoctoral fellow, M.D. from Poznań University of Medical Sciences, Poland
  • Leonora Balaj, PhD – Postdoctoral fellow, PhD in Medicine in VU University, Amsterdam, the Netherlands
  • Shilpa Prabhakar, MS – Laboratory Manager, Master in Genetics in Bangalore University, Bangalore, India
  • Xuan Zhang, MD/MS – Research Technologist, M.D., Master in Pharmacology from Suchow University, Suchow, China
  • Jyostna Dhakal – Research Technician, Wilson College, Chambersburg, USA
  • Erik Abels, MS – PhD graduate student, VU University, Amsterdam, the Netherlands
  • Martin Ingelsson, PhD - Visiting Associate Professor from Uppsala University, Sweden
  • Niek Maas, MS - PhD graduate student, University Medical Center, Utrecht, the Netherlands
  • Andrea Maas - MS graduate student, VU University, Amsterdam, the Netherlands
  • David Yellen – undergraduate student
  • Robin Sobolewski-Lamberti – Senior Grants Manager
  • Suzanne McDavitt – Editorial Associate


  • Jeffrey Hewet, BS,  Bridgewater State College
  • Brian Niland, BS, University of Maine
  • Lisa Pike, BS, Brandeis University
  • Christian Badr, MS, University of Henri, Poincare in France
  • Okay Saydam, PhD, University of Zurich, Switzerland
  • Thomas Wurdinger, PhD, Free University, Amsterdam, The Netherlands
  • Maria Luisa Cortes, PhD, Autonomous University of Madrid, Spain
  • Bakhos Tannous, PhD, University of Windsor, Canada  
  • Casey McGuire, Assistant Professor at MGH Neurology


Updated 3/25/2015 

Research Projects

Research summary

Our research has centered on understanding and treating diseases of the nervous system. My particular expertise is in molecular genetics, including human genetics, gene therapy and biomarker development with a focus on movement disorders and brain tumors. Since identifying the gene for early onset torsion dystonia in 1997, we have worked on understanding the function of the defective protein, torsinA. We have shown that torsinA, an AAA+ ATPase in the lumen of the nuclear envelope and endoplasmic reticulum of all cells is involved in positioning of the nucleus during cell migration and in chaperoning proteins in the secretory pathway. We are currently focusing on identifying the gene responsible for X-linked dystonia-parkinsonism and its relationship to other forms of dystonia. We have also used viral vectors, including retrovirus, HSV and AAV, as well as migratory neuroprecursor cells, for delivery of genes encoding therapeutic proteins and pro-drug activating enzymes for experimental tumors of the nervous system. In addition, we are characterizing the nucleic acid content of extracellular vesicles released by tumor cells, including their use as biomarkers in the serum, their ability to carry out horizontal cell communication; and their potential for therapy of neurologic diseases.

HSV Amplicon Vector Designs

DNA replication

nuclear fate


HSV Amplicon Vector Designs

A major focus of the Breakefield laboratory is on design and development of HSV amplicon vectors for stable, non-toxic delivery of genes in vivo. These vectors have a transgene capacity of 150 kb allowing them to carry entire genes, including regulatory elements and splice junctions. They express no viral genes and elicit only a mild immune response. They have proven to be highly effective in gene delivery in the nervous system in models of lysosomal storage diseases, ataxia telangiectasia, neurofibromatosis and brain tumors.

Vectors for gene delivery are derived from herpes simplex virus type 1 (the common cold sore virus).  These virions provide an efficient means to shuttle genes to the cell nucleus. The virions bind to and enter most cells through fusion of the virion envelope with the plasma membrane. Viron capsids and associated tegument proteins are then taken to the cell nucleus via microtubule mediated transport. At the nucleopores the capsid opens and viral DNA is threaded into the nucleus.

The virion has four compartments, all of which can be used as delivery vehicles. The envelope can be modified so that it targets infection to specific cell types (Grandi et al., 2004). Proteins in the tegument, such as VP16, can be fused with  reporter proteins, such as GFP (Bearer et al., 2000) or functional proteins to temporarily alter the physiology of infected cells. Capsid proteins can also be modified as fusion proteins and up to 150 kb of foreign DNA can be incorporated in the capsids for delivery.

In infected cells the viral DNA is replicated from origins of replication, ori, as a rolling circle with 150 kb lengths being placed in the capsids in a capsid-full state with cleavage at pac signals. Plasmid DNA bearing ori and pac signals are packaged as concatenates in virions in the presence of viral functions and can be prepared as helper virus free stocks (Saeki et al., 2003).

Several modifications have been incorporated into amplicon plasmids to control the fate of the DNA when it enters the cell nucleus. These include incorporation of the latent origin of DNA replication and EBNA1 sequences from Epstein Barr virus that allow replication of amplicon DNA as an extrachromosomal element (Sena-Esteves et al., 2002; Hampl et al., 2003). Further, elements of retrovirus and AAV have been incorporated into amplicon vectors such that infected cells are able to generate retrovirus vectors and integrate genes into the host cell genome at specific sites (Oehmig et al., 2004).



Other Research Projects

  • Gene Therapy for Brain Tumors
  • Torsion Dystonia and TorsinA
  • Gene Therapy for Neurofibromatosis Type 2
  • Gene Therapy for Ataxia Telangiectasia

Research Positions

Read about and apply for residency, fellowship and observership programs at

Apply for temporary positions (summer interns) through the Bulfinch Temporary Service Web site at Search for all opportunities using ID# 2200484.

All applicants should register with the Mass General Careers Web site at Request a list of current open positions at


NCBI PubMed Publications

  1. Nery, F.C.*, Armata, I.A.*, Farley, J.E., Cho, J.A. , Yaqub, U., Chen, P., da Hora, C.C., Wang, Q., Tagaya, M., Klein, C., Tannous, B., Caldwell, K.A., Caldwell, G.A., Lencer, W.I., Ye, Y., Breakefield, X.O.: TorsinA participates in endoplasmic reticulum-associated degradation. Nature Communications 2:393, 2011. PMCID: PMC3529909
  2. Wakabayashi-Ito, N., Doherty, O.M., Moriyama, H., Breakefield, X.O., Gusella, J.F., O’Donnell, J.M., Ito, N.: dtorsin, the Drosophila ortholog of the early-onset dystonia TOR1A (DYT1), plays a novel role in dopamine metabolism. PLoS One 6:e26183, 2011. PMCID: PMC3192163
  3. Atai, N.A., Ryan, S.D., Kothary, R., Breakefield, X.O., Nery, F.C.: Untethering the nuclear envelope and cytoskeleton: biologically distinct dystonias arising from a common cellular dysfunction. Int’l J. Cell Biology 2012:634214, 2012. PMCID: PMC3352338
  4. Prabhakar, S., Taherian, M., Gianni, D., Conlon, T.J., Fulci, G., Brockmann, J., Stemmer-Rachamimov, A.O., Sena-Esteves, M., Breakefield, X.O., Brenner, G.J.: Regression of schwannomas induced by AAV-mediated delivery of caspase-1. Human Gene Therapy 24:152-162, 2013. PMCID: PMC3581065
  5. Chen, W.W.*, Balaj, L.*, Liau, L.M., Samuels, M.L., Kotsopoulos, S.K., Maguire, C.A., LoGuidice, L., Soto, H., Garrett, M., Zhu, L.D., Sivaraman, S., Chen, C., Wong, E.T., Carter, B.S., Hochberg, F.H., Breakefield, X.O., Skog, J.: BEAMing and droplet digital PCR analysis of mutant IDH1 mRNA in glioma patient serum and cerebrospinal fluid extracellular vesicles. Molecular Therapy – Nucleic Acids 2:e109, 2013. doi:10.1038/mtna.2013.28 (published online July 23) *These authors contributed equally to this work. PMCID: PMC373287
  6. Prabhakar, S., Goto, J., Zuang, X., Sena-Esteves, M., Bronson, R., Brockmann, J., Gianni, D., Wojtkiewicz, G.R., Chen, J.W., Stemmer-Rachamimov, A., Kwiatkowski, D.J., Breakefield, X.O.: Stochastic model of Tsc1 lesions in mouse brain. PLoS One 8:e64224, 2013. PMCID: PMC3655945
  7. Lai, C.P., Mardini, O., Ericsson, M., Prabhakar, S., Maguire, C., Chen, J.W., Tannous, B.A., Breakefield, X.O.: Dynamic biodistribution of extracellular vesicles in vivo using a multimodal imaging reporter. ACS Nano 8:483-494, 2014. PMCID: PMC3934350
  8. György, B.*, Hung, M.E.*, Breakefield, X.O.**, Leonard, J.N.**: Therapeutic applications of extracellular vesicles – clinical promise and open questions. Annual Review Pharmacology and Toxicology Oct 3 [Epub ahead of print] 2014. *Co-first authors, **Co-last authors
  9. Maguire, C.A., Ramirez, S.H., Merkel, S.F., Sena-Esteves, M., Breakefield, X.O.: Gene therapy for the nervous system: challenges and new strategies. Neurotherapeutics (Special Issue) 11:817-839, 2014
  10. Rajendran, L., Bali, J., Barr, M.M., Court, F.A., Krämer-Albers, E-M., Picou, F., Raposo, G., van der Vos, K.E., van Niel, G., Wang, J., Breakefield, X.O.: Emerging roles of extracellular vesicles in the nervous system. J Neuroscience 34:15482-15489, 2014.
  11. Chen, P. Burdette, A.J., Porter, J.C., Ricketts, J.C., Fox, S.A., Nery, F.C., Hewett, J.W., Berkowitz, L.A., Breakefield, X.O., Caldwell, K.A., Caldwell, G.A.: The early-onset torsion dystonia associated protein, torsinA, is a homeostatic regulatory of endoplasmic reticulum. Human Molecular Genetics, 19>3502-3515, 2010.
  12. Saydam, O., Shen, Y., Würdinger, T., Senol, O., Boke, E., James, M.F., Tannous, B.A., Stemmer-Rachamimov, A.O., Yi, M. Stephens, R.M., Fraefel, C., Gusella, J.F., Krichevsky, A.M., Breakefield, X.O.: Downregulated microRNA-200a in meningiomas promotes tumor growth by reducing E-cadherin and activating the Wnt/{beta}-catenin signaling pathway. Molecular and Cellular Biology, 29:5923-5940, 2009
  13. Tannous, B.A., Christensen, A.P., Pike, L., Wurdinger, T., Perry, K.F., Saydam, O., Jacobs, A.H., Garcia-Anoveras, J., Weissleder, R., Sena-Esteves, M., Corey, D.P., Breakefield, X.O.: Mutant sodium channel for tumor therapy. Molecular Therapy, 17:810-819, 2009
  14. Würdinger, T., Tannous, B., Saydam, O., Skog, J., Grau, S., Soutschek, J., Weissleder, R., Breakefield, X.O., Krichevsky, A.M.: miR-296 regulates growth factor receptor overexpression in angiogenic endothelial cells. Cancer Cell, 14:382-393, 2008.
  15. Skog, J., Würdinger, T., van Rijn, S., Meijer, D., Gainche, L., Curry, W.T.Jr., Carter, B.S., Krichevsky, A.M., Breakefield, X.O.: Glioblastoma microvesicles transport RNA and protein that promote tumor growth and provide diagnostic biomarkers. Nature Cell Biology, 10:1470-1476,>

Lab Phone: 617-726-5728

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