Kenneth Whitaker Witwer, Ph.D.

Headshot of Kenneth Whitaker Witwer
  • Associate Professor of Molecular and Comparative Pathobiology

Research Interests

microRNA; RNA interference; extracellular vesicles; exosomes; retrovirology; genome editing; HIV/AIDS; immunology; Alzheimer's more


Dr. Kenneth W. Witwer is an associate professor of molecular and comparative pathobiology and neurology at the Johns Hopkins University School of Medicine. His research focuses on extracellular vesicles, RNA-mediated regulation, biomarker discovery, and therapeutic modulation of innate and intrinsic defenses. His group is particularly interested in neurodegenerative diseases including the HIV-associated neurocognitive disorders, Alzheimer's, and Parkinson's.

Witwer has served as Secretary General and Executive Chair of Science and Meetings for the International Society for Extracellular Vesicles (ISEV), the leading scientific organization in his field. He has been a scientific advisor to the US National Institutes of Health (Extracellular RNA Communication Consortium, Stage 1) and the US Environmental Protection Agency (FIFRA SAP). He is an associate editor of the Journal of Extracellular Vesicles. more


  • Associate Professor of Molecular and Comparative Pathobiology
  • Associate Professor of Neurology

Departments / Divisions

  • Molecular and Comparative Pathobiology
  • Neurology

Centers & Institutes



  • Ph.D.; Johns Hopkins University School of Medicine (Maryland) (2010)
  • B.A.; Pennsylvania State University (Pennsylvania) (1999)

Additional Training

  • Johns Hopkins University School of Medicine, Baltimore, MD, 2011, Molecular and Comparative Pathobiology

Research & Publications

Research Summary

Dr. Witwer investigates extracellular vesicles (EVs) and ribonucleic acids (RNAs) in human disease, including HIV, neurodegenerative diseases, and substance use. RNA molecules are found not only inside, but also outside of human cells in biological fluids such as blood plasma, urine, and cerebrospinal fluid. Although quite labile, these molecules are protected from degradation by molecular shuttles such as EVs. Rapidly expanding research programs over the last several years indicate that EVs and their nucleic acid cargo may provide early warning of disease, contribute to the defense against disease, and serve as models for effective therapies. 


Major funded projects

  • Next-generation extracellular vesicle biologics to target central nervous system and peripheral reservoirs of HIV (NIAID)
  • Extracellular Vesicle and Extracellular RNA Biomarkers of HIV-1 Central Nervous System Pathogenesis and Cigarette Use (NIDA)
  • Extracellular Vesicle-Mediated Immunomodulation in HIV Infection and Nicotine Abuse (NIDA)
  • Novel Separation Methods for exRNA Carriers: Extracellular Vesicles, Lipoprotein Particles, and Protein Aggregates (Common Fund/NCI)
  • Microglial exosomes/extracellular vesicles as novel markers of neuroinflammation in Parkinson’s disease (Michael J. Fox Foundation)
  • Novel Approaches to Capture, Sorting, and Characterization of CNS-Origin Extracellular Vesicles  (NIMH)

Research Opportunities

Motivated prospective postdoctoral, graduate, and undergraduate researchers are encouraged to contact Dr. Witwer directly about available opportunities. Rotation projects are open to Cellular and Molecular Medicine students.

Lab Website: Ken Witwer Laboratory

Technology Expertise Keywords

miRNA, genome editing, ultracentrifugation, microarray, RNA-seq, in situ hybridization, molecular biology, immunofluorescence, immunohistochemistry; single particle tracking

Selected Publications

View all on PubMed

Liao Z, Martin Jaular L, Soueidi E, Jouve M, Muth DC, Schøyen TH, Seale T, Haughey NJ, Ostrowski M, Théry C*, Witwer KW*. Acetylcholinesterase is not a generic marker of extracellular vesicles. Journal of Extracellular Vesicles 2019.

Théry C* and Witwer KW,* et al (corresponding of 382 authors). Minimal Information for Studies of Extracellular Vesicles 2018 (MISEV2018): a position statement of the International Society for Extracellular Vesicles and update of the MISEV2014 guidelines. Journal of Extracellular Vesicles 2018.

EV-TRACK Consortium, Van Deun J, Mestdagh P, et al. EV-TRACK: transparent reporting and centralizing knowledge in extracellular vesicle research. Nature Methods 2017.

Kim V, Mears B, Powell BH, Witwer KW. Mutant Cas9-transcriptional activator activates HIV-1 in the presence and absence of LTR-specific guide RNAs. Science Matters 2017.

Eitan E, Hutchison ER, Marosi K, Comotto J, Mustapic M, Nigam S, Suire C, Maharana C, Machairaki V, Witwer KW, Kapogiannis D, Koliatsos VE, Mattson MP. Extracellular Vesicle-Associated Aβ Mediates Trans-Neuronal Bioenergetic and Ca2+-Handling Deficits in Alzheimer's Disease Models. Nature Partner Journal Aging and Mechanisms of Disease 2016.

Contact for Research Inquiries

Edward D. Miller Research Building
733 N. Broadway
Room 829
Baltimore, MD 21205 map
Phone: 410-955-9770
Fax: 410-955-9823

Email me

Academic Affiliations & Courses

Graduate Program Affiliation

Dr. Witwer is a faculty member of the Cellular and Molecular Medicine graduate program ( 

Courses and Syllabi

  • Rigor and Reproducibility in Research
    Cellular and Molecular Medicine and now hosted on Docebo:

Activities & Honors


  • Catalyst Award, Johns Hopkins University, 2017
  • Center for AIDS Research Scholar Award, Johns Hopkins University , 2014
  • Richard T. Johnson Young Investigator Award, International Society for NeuroVirology, 2009
  • Graduate Research Fellowship, National Science Foundation , 2003 - 2006
  • Turock Young Scientist Award, Turock Family Foundation, 2002
  • Young Investigator Award, 18th Conference on Retroviruses and Opportunistic Infections, 2011
  • Travel Grant, International Society for NeuroVirology, 2009
  • Keystone Symposia Scholarship, Keystone Symposia, 2011
  • Scholl Scholarship, Penn State University, 2001 - 2002


  • International Society for Extracellular Vesicles, 2012
  • International Society for NeuroVirology, 2009
  • American Association for the Advancement of Science, 2002

Professional Activities

  • Executive Chair of Science and Meetings, International Society for Extracellular Vesicles
  • Secretary General, International Society for Extracellular Vesicles
  • Associate Editor, Journal of Extracellular Vesicles
  • Editorial Board Member, Clinical Chemistry (American Association for Clinical Chemistry)
  • Co-Chair, 2020 Gordon Research Conference on Extracellular Vesicles
  • Vice-Chair, 2018 Gordon Research Conference on Extracellular Vesicles
  • Chair, Local Organizing Committee, ISEV2015, International Society for Extracellular Vesicles
  • Panelist, Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA) Scientific Advisory Panel (SAP) on Human Health and Ecological Risk Assessments for SmartStax PRO, US Environmental Protection Agency
  • Panelist, Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA) Scientific Advisory Panel (SAP) on RNAi technology as a pesticide, US Environmental Protection Agency
  • Executive Committee Member-at-Large, International Society for Extracellular Vesicles
  • Ad-hoc reviewer, More than 110 scientific journals

Videos & Media

Recent News Articles and Media Coverage

Johns Hopkins, NanoView Biosciences Using EVs to ID HIV-Related Neurological Disorder Biomarkers. John Gilmore, GenomeWeb. 2019

NIH Awards $940K to Johns Hopkins-Led Team for Extracellular Vesicle Research. GenomeWeb. 2019

Stem Cells Make More ‘Cargo’ Packets to Carry Cellular Aging Therapies. Science Daily. 2019

Swarming Behavior Discovered in Fish-Dwelling Parasite. Rachel Butch, Hopkins Medicine Newsroom. 2018

Fact or Artifact? Jef Akst, The Scientist. 2014

HIV Denial: Alive and Well in 2014. Tara Smith, Aetiology. 2014

So Science...May have Gotten it Wrong. Now What? Virginia Hughes, National Geographic Phenomena. 2013

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