Vanessa Niu, Class of 2026

I reached out to Professor Bitan to learn more about his laboratory, how his career progressed to where it is today, his research in amyloidoses and their relation to neurodegenerative diseases. Dr. Bitan was kind enough to meet with me and explained his fascinating research, including development of biomarkers for diagnosis of neurodegenerative diseases and “molecular tweezers” as a potential future treatment for patients. Furthermore, Dr. Bitan detailed his ongoing findings regarding exophers, a novel cell compartment involved in a non-cell-autonomous waste clearance mechanism. 

Vanessa Niu (VN): What experiences led you to pursue your current research in neurodegenerative diseases and developing diagnostics and therapy?

Professor Bitan: 
​I have always thought that the brain was an interesting topic to research, but my original training was in organic chemistry. I did work a little bit during my graduate-school time on a neuropeptide called Substance P, but I was mainly doing chemistry: organic synthesis, special amino acids, combining them into peptides. I was not involved in the biology.

I wanted to get more involved in biology and in my postdoctoral studies, I joined a group that was more involved in both chemistry and biology. I expressed my wish to work more on the biological side, and they said that I could gravitate towards this direction gradually: if I made the substances I needed to study, I could then also study their biological features. So that is how I started learning how to do basic cell culture experiments and other biochemical experiments.

But that was still not in a biological field that really grabbed my interest. My first postdoc was in bone biology. Later, when I moved to a second postdoctoral training opportunity, that is when I got the opportunity to start working on a protein called amyloid-beta (Aβ), which is involved in Alzheimer's, and that was my introduction to the field.

I started from the point of view of biochemistry and biophysics and tried to understand how and what controls the way Aβ molecules stick to each other and form oligomers and aggregates. This research allowed me to start learning a lot more about Alzheimer's disease and then more about other related diseases. Until this day, my main focus is diseases where this phenomenon of protein self-assembly into oligomers and aggregates that should not have been there, that are not part of our normal physiology. But we have moved past these initial studies of how this process happens and into studies of what we can do to stop this process, how we can remove those offending proteins from brain cells, and also how to detect them and how to diagnose these diseases.

VN: What is the main focus of your ongoing research or past studies?

Professor Bitan: 
We have a number of projects running in the lab, all focused on these neurodegenerative diseases that involve the abnormal self-assembly of proteins into toxic species.

One of them is a project that has been running now for over 15 years, in which we have been developing small molecules called ‘molecular tweezers’ that act as broad-spectrum inhibitors of protein aggregation. More recently, we found that they have a tendency, when we use them with cells or with animals, to concentrate inside the cells in acidic compartments: the lower the pH, the more they go into those compartments. The molecular tweezers start by entering the cells through endocytosis, and then they go into the early endosomes, more into the late endosomes as the pH decreases, and eventually, they like to concentrate in the lysosomes where the pH is really low (about 4.5). That is a really important feature of these compounds because it allows them to concentrate and act exactly where they are most needed. Cells direct the aggregated proteins into these compartments to degrade them. But when the cells get overwhelmed with too much of these aggregated proteins, the degradation and clearance processes gradually shut down. When we add the molecular tweezers and they go exactly to those compartments, they allow the clearance mechanisms to resume their function because they negate the tendency of the proteins to aggregate. They separate the molecules and then the lysosomes can resume degrading them.

Another major project in my lab is a biomarker project. The main difficulty when we want to get biomarkers for brain diseases is we can't get into the brain; we can't just take a biopsy and see what is going on there. The two classical methods have been brain imaging and analysis of the cerebrospinal fluid (CSF). Neither one is ideal. Brain imaging does not necessarily provide the resolution that we want to get and doesn't give us a molecular-level vision of what is going on in the brain; it's also expensive and requires using radio-chemicals that are not particularly good for the brain. CSF analysis obviously requires a lumbar puncture which is invasive and is refused by many patients. It's particularly challenging if we want to use that to monitor a clinical trial and we need to get samples at multiple time points. 
The field has been trying very hard to shift to less invasive methods, such as blood tests, urine tests, or saliva tests. The challenge there is the blood-brain barrier may prevent the important biochemical changes in the brain from manifesting in the peripheral fluids. So the way we and many other groups have been tackling this challenge is to use extracellular vesicles that are secreted by our cells into the intercellular space. They are secreted by basically every cell in the body, and some of them that are secreted inside the brain can cross the blood-brain barrier and end up in the blood. We have methods to isolate those from the blood so we don't need a lumbar puncture, we don't need to get into the brain… we just need a blood sample. Then, we can isolate the extracellular vesicles that came out of brain cells and measure specific proteins in them. That gives us an idea of the biochemical changes that occur inside the brain. We have used that, for example, to distinguish between closely related neurodegenerative diseases to help with diagnosis, and we are doing something similar to that right now to monitor the effect of a particular treatment in a clinical trial.

Lastly, there is a relatively new project in my lab where we serendipitously discovered a new compartment in cells that previously had only been reported in C. elegans worms. They have been found first in neurons and later in muscle cells. They are thought of as a way of the cells to get rid of cellular waste. What happens is, from the plasma membrane, there is an evagination of a big blob that moves away but doesn't completely disconnect. It remains connected and can sit there for hours while it's still connected, receiving more material from the originating cells until eventually, it will disconnect. At that point, cells of the immune system will come and phagocytose it and degrade the contents. This is a really new mechanism. We have always been thinking about the degradation and clearance of cellular waste as a cell-autonomous process. This is a discovery that was made only a few years ago in the C. elegans worms of a non-cell-autonomous mechanism, by which cells basically take out a big garbage bag, remove it, and someone else comes to clean it up.
Around the same time that the original paper was published in Nature in 2017, we were working on a mouse experiment. These were mice that expressed a form of the protein tau that is related to a disease called frontotemporal dementia. We treated those mice with our molecular tweezers and  their brains. The postdoc working on this project observed something that looked exactly like those compartments that were reported in the worms. They are called exophers. It comes from “exo”... out, and “pher” is the Latin root for carry. So, “carry out”. I believe we are the only group so far that has seen exophers in mammalian cells. We have not yet published this discovery yet, but we deposited the initial findings in bioRxiv (bio-archive). We have been studying this phenomenon in the last few years; we observed these structures in many different cell culture systems, in mice, and in human brains. We actually see that there is an elevation of these structures in the brains of people who died of diseases like Alzheimer's disease.

VN: How have you applied your research to develop novel treatments for patients and physicians in your field?

Professor Bitan: 
In our drug development efforts, we have not yet gotten to the point that we can treat patients. We have done a number of animal experiments to demonstrate that the compounds are efficacious and safe. We now need to do some of what the FDA requires to get what is called an IND status; IND stands for investigational new drug. Without that status, we cannot do a clinical trial. And to get to that point, the FDA has a list of requirements including experiments that are really expensive. We are trying to get the money to get to that point.

In the biomarker work, we are working primarily with patient samples that are collected here at UCLA and at other universities and research institutions. We isolate from these samples the extracellular vesicles and then measure the biomarkers of interest.

VN: What is the process like in your lab for publishing your current, ongoing research? How have you navigated hardships in your lab?

Professor Bitan: 
The process is the usual process. We do our research, we document all our findings, and when we believe we have a complete-enough story to tell, we publish it. Before that, if we think we have exciting findings to share with the community, we may present them at conferences before the final publication. That's the usual process, I believe, in every research lab. Everyone who has worked on the project will get to be a co-author. The main person leading the project is typically the first author.
In terms of hardships, the main hardship is always getting enough funding to do our research. Research is expensive. We have to pay everyone who is involved if it's not an undergrad volunteer, we have to buy the equipment, we have to buy all the supplies, and that can be expensive. We are constantly trying to get the funding needed to do our research. Sometimes we are more successful than other times.

VN: How do you see your research contributing to neurological advancements and patient treatment?

Professor Bitan: 
Well, if I can break it down to these three projects, I think that the most immediate one is the biomarkers project. We have already been participating in clinical trials, and we are also using the biomarkers to measure the effectiveness of treatments in animal models. So that can support the development of new treatments. There is always a challenge to measure how effective the treatment has been. It's an even bigger challenge in people. But the challenge does exist also in animal models, such as mice because, not at the same level of complexity, but every mouse is an individual. They have their personality, they have their mood on that particular day, they may not be feeling that great, they may have eaten a little too much the night before. All kinds of things happen that alter their behavior on any given day, and when we try to compare them, for example, mice that receive treatment to mice that receive placebo, there's always, of course, a distribution of values. They don't all behave the same way. So we're looking for differences that are statistically meaningful. If we only rely on behavior, that can be quite variable. With mice, we also, at the end of the experiment, analyze their brain. So we have a better assessment of how effective the drug was, but that is not translatable to patients. So in order to have a measurement that is translatable, we collect blood, we isolate the extracellular vesicles, and we measure our biomarkers in them. This is a strategy we can immediately translate into human clinical trials. 

The second one, I believe, is the drug development project. I hope we can get the funding that will allow us to go through the FDA requirements and get the compounds into clinical trials. The exopher project–I don't know at this point. We think that it could be a very relevant mechanism to what happens in neurodegenerative diseases. And we actually think… it is such a new project, it's such a new discovery that we do not know yet what to expect. We think that these exophers can be a double-edged sword. On one hand, they help take out the trash, including aggregated proteins. On the other hand, they may help spread those aggregated proteins to other cells, and we know that this is a process that happens in the brain of people with Alzheimer's, Parkinson's, many of these neurodegenerative diseases. So, the jury's out yet, whether they are good, bad, or both. 

VN: What is your favorite part of research and teaching as a professor?

Professor Bitan: 
I really enjoy the contact with the people I work with. I enjoy brainstorming with people, talking about our research, talking about new questions, where we can take the research, how to solve problems–all of this scientific discussion is very stimulating. And I also really enjoy teaching. I like the interaction with the students. I always feel that I learn from the students, and if they also have learned from me and they tell me about it, I feel appreciated. I feel that I have contributed to the scientific development of the next generation.

VN: What is your philosophy for running a good lab?
​
Professor Bitan: 
My philosophy is to try to treat people so that they feel appreciated–that they're not just workers who come to do experiments, but they are individuals. I see myself not just as their supervisor, but as their mentor. I try to teach them from my experience how to become a scientist, how to work ethically, and how to think about scientific problems and scientific questions. I try to foster camaraderie in the lab. I try to weed out anyone in the interview process that I think might be problematic. I like to work with people who are friendly and respectful. From time to time, I try to initiate lab activities outside of work.

One thing I learned from someone who was my first graduate student back in 2007, when she left the lab and went to work for a company, she told me about what they do in their weekly meetings that I since then adopted, which is just to check in with everyone, not just about the science but also “how have you been doing”, “what's new this week”, “what have you been up to”. I found that people are really responsive to that and appreciate that. I appreciate knowing what's going on with people.
​
VN: What advice do you wish someone told you when you were an undergraduate? Do you have any advice for aspiring scientists?
​
Professor Bitan: 
There are a couple of things that I have shared with people over the years, which I learned the hard way. One was that the people you work with are more important than the scientific question. If you're working in a good environment, you're likely to be successful. More likely than if you chose to work on a particular question, but the people around you are not cooperative or friendly. That was a lesson I needed to learn.

The second, is that the goal does not necessarily justify the means. I had an experience early in my career in which I was not in the best environment. I tried to cram two years into one year in order to get my master's degree. In the beginning, I talked with my advisor and he said it was possible so I did it. But at the end of that year, I was so jaded and exhausted and not in a good mood that I would not advise anyone to try to do that. Take your time, enjoy the ride. It's much more important than achieving the goal of a degree, a paper, or something like that at the end. The important thing is that we enjoy our work, enjoy our scientific growth, and be led by our curiosity.​