Dear Colleagues:
Every month, ASIC will publish an interview with leading experts in the field of EV research, including both members and non-members of ASIC. Below is the first interview with Dr. Fatah Kashanchi conducted by Dr. Leonid Margolis.
Dr. Kashanchi, you are a well-known scientist in the field of Extracellular Vesicles (EVs), and the President of the American Society for Intercellular Communications (ASIC) which focuses mainly on EVs, since they are believed to be important mediators of cell-to-cell communications. Your opinion on different scientific issues will be of interest to the broad circle of our colleagues, especially for young scientists. But first, let me ask you some personal questions regarding your scientific career.
What was your field of research before you started investigating EVs and why did you think at that time that studying EVs is more important or more interesting than what you studied before? Do you have any regrets?
My background is in Microbiology and Immunology. However, the EV field may now be the most important in medicine as it covers all pathogens and non-pathogens. Additionally, many pathogens have signature molecules in EVs, yet there is no replicating pathogen that can actually be found in in vitro assays, animal models, or clinical samples (i.e. the case of HIV where ~97% of obtained samples are not replicating viruses). This was evident early on as seen in the HIV/AIDS field as described in multiple manuscripts, including one from David Ho in 1996 (Science, Vol 271 March -15-1996). The case of HIV-1 is very interesting as the virus exists as RNA, RNA/DNA hybrid, and finally as DNA that is integrated into the genome. This pattern of changes in nucleic acids causes host cells to respond differently, as evident by the activation of innate immune molecules (i.e. IFNs) and subsequent regulation of autophagy (in this case secretory autophagy) and EV release. Therefore, since there are so many unknown principles yet to be discovered in the EV field relative to others (i.e. the field of Microbiology/Immunology), I am very excited and have no regrets about being one of the early contributors to this field.
What do you think are the most important accomplishments of the field over the last years?
There are many noteworthy contributions, but my favorites are the advances in various EV technologies which have allowed for increased purity, sensitivity, and data validations. However, I think we need to develop meaningful technologies that can separate various types of EVs, as well as EVs from viruses and viruses that may be present as cells are perturbed (i.e. drugs of abuse and potential activation of endogenous retroviruses) over time (i.e. kinetics of release). So, newer technologies that can show us real and meaningful events of consequences analyzed by informatics, math modeling, and artificial intelligence (in that order) would be more desirable.
What was for you the most unexpected discovery in the field over the last couple of years?
I am really impressed with the EV biogenesis field highlighted by the Coffey lab (Trends in Cell Biology, 2023) as well as non-EV intercellular communications such as Biomolecular Condensates, RNP complexes, and how they are regulating almost every aspect of cell communication and survival. Similar to the EV field, where it was initially designated as “garbage bags”, these condensates have been considered as RNA artifacts for many years, and they are finally getting proper attention and are in the limelight.
We definitely do not understand essential details regarding how EVs mediate cell-cell communications. What are, in your opinion, three main challenges for this understanding?
- EVs work across multiple different species (i.e. human on mouse, mouse on human, mouse on rat, etc.). Why?
The origins of most EVs are very different, yet there have to be lots of evolutionary similarities and redundancies for them to cross cell types, organs, and species. What are these governing principles and how do we explain the basic function of EVs across species? Also, a big caveat at this point is efficiency of performing function “X” as it crosses evolutionary barriers. - What are the kinetics of EV function in development?
For instance, if one looks at the early stages of development vs. later stages, will we be able to score the significance of “EVs in communication” in early embryogenesis (i.e. alteration in cell cycle) or later stages (i.e. embryo vs. fetal development)? Clearly one would need better knock-down or knock-out reagents and imaging techniques that are reliable in simple animal models and are reproducible in many labs, to answer these questions. - What are the relevant vs. non-relevant cargo in EVs? Or is EV cargo holistic for it to be fully functional?
For instance, when you look at the EV therapeutic arena, one cannot clearly say which of the molecules are critical for repair of a cell, tissue or organ. Although this is an exciting field (i.e. non-cell base repair), it still requires lots of communication between basic scientists, manufacturers, and clinicians before taking the case to the FDA and public for large-scale therapeutics.
- Obviously, the field of EVs has an important implication for translational medicine. How do you envision the field moving in this direction? Will EVs be used in medicine before we understand basic mechanisms of EV functioning, or is this not a prerequisite to use EVs in therapeutics and/or diagnostic?
I think the “low-hanging” fruit at this point is the diagnostic application of EVs. As we saw with the COVID pandemic during 2020-2022, there was a ~30:1 ratio (diagnostic vs. therapeutics) of applications submitted to the FDA. Although that was an emergency situation, companies and most government entities want to see immediate results in their portfolios, which means quick turn around on their investment. However, one place that still pushes for basic sciences and a “cautious” type of science consistently over decades is the NIH in the USA. So, I think with proper funding and review processes, there is a high likelihood of understanding basic mechanisms of EV function over time. This will be a long road, but then again that is why we have scientists in every country who are capable of solving just about any problem thrown at them (i.e. Scientists saving lives during the recent pandemic through both novel diagnostics and vaccine development). - EVs are highly heterogeneous. EVs isolation based on density results in particle populations of different sizes and compositions. Isolation based on size-exclusion chromatography results in populations of different densities and also of different compositions. However, compounds to be approved for therapeutic use need to be pretty homogeneous and well defined. How do you see overcoming this challenge, if it is indeed possible to overcome?
Firstly, I think our colleagues in Europe have spent a considerable amount of time, energy, and funding to standardize the field as exemplified in MISEV 2018 and 2023 Guidelines. This was critical in describing the inherent heterogeneity of EV populations from various sources. However, for the FDA and public to accept EVs as part of a therapeutic regimen, there needs to be a few further steps. For example, including increasing efficacy of EV populations for function, which means one needs to start with lots of material prior to any multi-step purifications, be able to reverse-engineer functional EVs to understand the contribution of each critical component so they can be controlled for amount and efficacy of function as well as for potential toxicity studies, and clear and well defined in vitro and in vivo assays including mono-cultures, co-cultures, 3D cultures and small animal models (i.e. steps needed to move from TRL1 to TRL9) to score for consistent functional readouts. - What do you plan/dream to accomplish in your own experimental work in one or two years ahead?
My goals are to be able to purify highly enriched EVs away from RNA and DNA viruses. This will require lots of biochemical and biophysical assays to clearly score for what is an EV and what is a virus. At this point, I define an EV from virally infected cells as an entity that is not able to replicate in cell culture with normal immune molecules (i.e., IFNs), or cells that do not have normal innate immune molecules or are not able to replicate in animal models (again, normal vs. immune knock out animals). The reverse would be true for a virus, where they would replicate in either normal or knockout innate immune systems. Finally, I am very interested in understanding the dynamics of the EV release from cells in the first 24 hours after infection, provided that a virus would mature and be released at or around 24 hours. The goal here is to figure out what released EVs do to the uninfected neighboring cells, say at 6 hours, prior to a functional virus reaching the same cell in 24 hours. - Finally, a question for you as President of ASIC. There are several national and international Societies focusing on EVs. How is ASIC different from others? What is the main purpose of ASIC?
The type of science being presented at ASIC is great, novel and significant in a user-friendly environment. The society was also charted from the very beginning paying close attention to diversity, equity, and inclusion (DEI) to help meet the needs of scientists from all walks of life in this new field. This has been a critical issue since these scientists are virtually coming from many diverse disciples (i.e., medicine, biochemistry, microbiology, immunology, technology development, regulatory, etc.) with very different standards of thinking and doing science! ASIC provides the time and a friendly platform for exchange of critical information over a short period of time.
- The total price for lodging, meals, and registration is very reasonable (all usually under ~$900.00 for a 2.5-day meeting).
- ASIC meetings are similar to a handful of meetings including Cold Spring Harbor Lab meeting platform with demonstrated intensity and consistency in excellence.
- The meetings are mostly focused on basic sciences of EV and non-EV communications.
- Membership is steadily increasing since 2021 for both junior and senior faculty along with students and postdocs.
- We collectively help our colleagues to collaborate better and to increase the quality of their science and grant submissions (i.e., how to go from 8-10% success rate to 25-30% success rate).
- Advocacy with NIH and other funding agencies to push for having better reviewers and an independent study section for EV and non-EV research at CSR.
- Inclusion of topics related to SBIR/STTR for the technology development and therapeutics to help increase rigor, increase justification for scientific premise and to better utilize the strengths and weaknesses suggested by the review panels.
Thank you for your time.