Kenneth Witwer

Dr. Kenneth Witwer

Johns Hopkins University School of Medicine, Baltimore, USA

Research Focus & Metrics

Academic Career Length

18Years (2009-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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23 November 2018 in Journal of Extracellular Vesicles
Verified
Journal Article
Open access
CTClotilde Théry
Clotilde Théry
KWKenneth Witwer
Kenneth Witwer
EAElena Aikawa
Elena Aikawa
MAMaria Jose Alcaraz
Maria Jose Alcaraz
JAJohnathon Anderson
Johnathon Anderson
Ewa Zuba-SurmaEwa Zuba-Surma
Ewa Zuba-Surma
The last decade has seen a sharp increase in the number of scientific publications describing physiological and pathological functions of extracellular vesicles (EVs), a collective term covering various subtypes of cell‐released, membranous structures, called exosomes, microvesicles, microparticles, ectosomes, oncosomes, apoptotic bodies, and many other names. However, specific issues arise when working with these entities, whose size and amount often make them difficult to obtain as relatively pure preparations, and to characterize properly. The International Society for Extracellular Vesicles (ISEV) proposed Minimal Information for Studies of Extracellular Vesicles (“MISEV”) guidelines for the field in 2014. We now update these “MISEV2014” guidelines based on evolution of the collective knowledge in the last four years. An important point to consider is that ascribing a specific function to EVs in general, or to subtypes of EVs, requires reporting of specific information beyond mere description of function in a crude, potentially contaminated, and heterogeneous preparation. For example, claims that exosomes are endowed with exquisite and specific activities remain difficult to support experimentally, given our still limited knowledge of their specific molecular machineries of biogenesis and release, as compared with other biophysically similar EVs. The MISEV2018 guidelines include tables and outlines of suggested protocols and steps to follow to document specific EV‐associated functional activities. Finally, a checklist is provided with summaries of key points.

7 February 2024 in Journal of Extracellular Vesicles
Verified
Journal Article
Open access
Joshua WelshJoshua Welsh
Joshua Welsh
DGDeborah Goberdhan
Deborah Goberdhan
LOLorraine O'Driscoll
Lorraine O'Driscoll
EBEdit Buzas
Edit Buzas
CBCherie Blenkiron
Cherie Blenkiron
KWKenneth Witwer
Kenneth Witwer
Extracellular vesicles (EVs), through their complex cargo, can reflect the state of their cell of origin and change the functions and phenotypes of other cells. These features indicate strong biomarker and therapeutic potential and have generated broad interest, as evidenced by the steady year‐on‐year increase in the numbers of scientific publications about EVs. Important advances have been made in EV metrology and in understanding and applying EV biology. However, hurdles remain to realising the potential of EVs in domains ranging from basic biology to clinical applications due to challenges in EV nomenclature, separation from non‐vesicular extracellular particles, characterisation and functional studies. To address the challenges and opportunities in this rapidly evolving field, the International Society for Extracellular Vesicles (ISEV) updates its ‘Minimal Information for Studies of Extracellular Vesicles’, which was first published in 2014 and then in 2018 as MISEV2014 and MISEV2018, respectively. The goal of the current document, MISEV2023, is to provide researchers with an updated snapshot of available approaches and their advantages and limitations for production, separation and characterisation of EVs from multiple sources, including cell culture, body fluids and solid tissues. In addition to presenting the latest state of the art in basic principles of EV research, this document also covers advanced techniques and approaches that are currently expanding the boundaries of the field. MISEV2023 also includes new sections on EV release and uptake and a brief discussion of in vivo approaches to study EVs. Compiling feedback from ISEV expert task forces and more than 1000 researchers, this document conveys the current state of EV research to facilitate robust scientific discoveries and move the field forward even more rapidly.

1 January 2014 in Journal of Extracellular Vesicles
Verified
Journal Article
Open access
JLJan Olof Lötvall
Jan Olof Lötvall
AHAndrew Hill
Andrew Hill
FHFred Hochberg
Fred Hochberg
EBEdit I. Buzás
Edit I. Buzás
DVDolores Di Vizio
Dolores Di Vizio
CTClotilde Théry
Clotilde Théry
Secreted membrane‐enclosed vesicles, collectively called extracellular vesicles (EVs), which include exosomes, ectosomes, microvesicles, microparticles, apoptotic bodies and other EV subsets, encompass a very rapidly growing scientific field in biology and medicine. Importantly, it is currently technically challenging to obtain a totally pure EV fraction free from non‐vesicular components for functional studies, and therefore there is a need to establish guidelines for analyses of these vesicles and reporting of scientific studies on EV biology. Here, the International Society for Extracellular Vesicles (ISEV) provides researchers with a minimal set of biochemical, biophysical and functional standards that should be used to attribute any specific biological cargo or functions to EVs.

1 January 2013 in Journal of Extracellular Vesicles
Verified
Journal Article
Open access
KWKenneth Witwer
Kenneth Witwer
EBEdit I. Buzás
Edit I. Buzás
LBLynne Bemis
Lynne Bemis
ABAdriana Bora
Adriana Bora
CLCecilia Lässer
Cecilia Lässer
FHFred Hochberg
Fred Hochberg
The emergence of publications on extracellular RNA (exRNA) and extracellular vesicles (EV) has highlighted the potential of these molecules and vehicles as biomarkers of disease and therapeutic targets. These findings have created a paradigm shift, most prominently in the field of oncology, prompting expanded interest in the field and dedication of funds for EV research. At the same time, understanding of EV subtypes, biogenesis, cargo and mechanisms of shuttling remains incomplete. The techniques that can be harnessed to address the many gaps in our current knowledge were the subject of a special workshop of the International Society for Extracellular Vesicles (ISEV) in New York City in October 2012. As part of the “ISEV Research Seminar: Analysis and Function of RNA in Extracellular Vesicles (evRNA)”, 6 round‐table discussions were held to provide an evidence‐based framework for isolation and analysis of EV, purification and analysis of associated RNA molecules, and molecular engineering of EV for therapeutic intervention. This article arises from the discussion of EV isolation and analysis at that meeting. The conclusions of the round table are supplemented with a review of published materials and our experience. Controversies and outstanding questions are identified that may inform future research and funding priorities. While we emphasize the need for standardization of specimen handling, appropriate normative controls, and isolation and analysis techniques to facilitate comparison of results, we also recognize that continual development and evaluation of techniques will be necessary as new knowledge is amassed. On many points, consensus has not yet been achieved and must be built through the reporting of well‐controlled experiments.

28 February 2017 in Nature Methods
Verified
Journal Article
Closed access
ECEV-TRACK Consortium
EV-TRACK Consortium
JDJan Van Deun
Jan Van Deun
PMPieter Mestdagh
Pieter Mestdagh
PAPatrizia Agostinis
Patrizia Agostinis
ÖAÖzden Akay
Özden Akay
AHAn Hendrix
An Hendrix

1 January 2016 in Journal of Extracellular Vesicles
Verified
Journal Article
Open access
PDF file
CGChris Gardiner
Chris Gardiner
DVDolores Di Vizio
Dolores Di Vizio
SSSusmita Sahoo
Susmita Sahoo
CTClotilde Théry
Clotilde Théry
KWKenneth Witwer
Kenneth Witwer
AHAndrew Hill
Andrew Hill
Extracellular vesicles (EVs) represent an important mode of intercellular communication. Research in this field has grown rapidly in the last few years, and there is a plethora of techniques for the isolation and characterization of EVs, many of which are poorly standardized. EVs are heterogeneous in size, origin and molecular constituents, with considerable overlap in size and phenotype between different populations of EVs. Little is known about current practices for the isolation, purification and characterization of EVs. We report here the first large, detailed survey of current worldwide practices for the isolation and characterization of EVs. Conditioned cell culture media was the most widely used material (83%). Ultracentrifugation remains the most commonly used isolation method (81%) with 59% of respondents use a combination of methods. Only 9% of respondents used only 1 characterization method, with others using 2 or more methods. Sample volume, sample type and downstream application all influenced the isolation and characterization techniques employed.