CIRM Scholar Jessica Gluck on using stem cells to make biological pacemakers for the heart

As part of our CIRM scholar series, we feature the research accomplishments of students and postdocs that have received CIRM funding.

Jessica Gluck, CIRM Scholar

Jessica Gluck, CIRM Scholar

I’d like to introduce you to one of our CIRM Scholars, Jessica Gluck. She’s currently a Postdoctoral Fellow at UC Davis working on human stem cell models of heart development. Jessica began her education in textiles and materials science at North Carolina State University, but that developed into a passion for biomedical engineering and stem cell research, which she pursued during her PhD at UC Los Angeles. During her graduate research, Jessica developed 3D bio-scaffolds that help human stem cells differentiate into functioning heart cells.

We asked Jessica to discuss her latest foray in the fields of stem cells and heart development.

Q: What are you currently working on in the lab?

JG: I work as a postdoc at UC Davis in the lab of Deborah Lieu. She’s working on developing pacemaking cardiomyocytes (heart cells) from human induced pluripotent stem cells (iPS cells). Pacemaking cells are the cells of the heart that are in charge of rhythm and synchronicity. Currently, we’re able to take iPS cells and get them to a cardiomyocyte state, but we want to further develop them into a pacemaking cell.

So ultimately, we’re trying to make a biological pacemaker. We can figure out how we can make a cell become the cell that tells your heart to beat, and there’s two things we can get out of that. First, if we understand how we get these beating cells, the ones that are telling the other heart cells to beat, we might be able to understand how different heart diseases progress, and we might be able to come up with a new way to prevent or treat that disease. Second, if we understand how we’re getting these pacemaking cells, we could hopefully bioengineer a biological pacemaker so you wouldn’t necessarily need an electronic pacemaker. With a biological one, a patient wouldn’t have to go back to the doctor to have their battery replaced. And they wouldn’t have to have multiple follow up surgeries throughout their life.

Q: What models are you using to study these pacemaking cells?

JG: I’m looking at my project from two different directions. On one side, we’re using a pig model, and we’re isolating cells from the sinoatrial (SA) node, which is where the pacemaking cells actually reside in your heart. And there’s really not that many of these cells. You probably have about a billion cells in your heart, but there’s maybe 100,000 of these pacemaking cells that are actually controlling the uniform beating of the heart. So we’re looking at the native SA node in the pig heart to see if it’s structurally any different than ventrical or atrial heart tissue.

Diagram of the heart depicting the Sinoatrial Node. (Image from Texas Heart Institute.

Diagram of the heart depicting the Sinoatrial Node. (Image from Texas Heart Institute)

We’ve found that the SA node is definitely different. So we’re de-cellularizing that tissue (removing the cells but not the matrix, or support structure, that keeps them in place) thinking that we could use the native matrix as a scaffold to help guide these heart cells to become the pacemaking phenotype. On the other side, we’re taking dishes with a known elasticity and we’re coating them with different proteins to see if we can tease out if there’s something that an individual protein does or a certain stiffness that actually is part of the driving force of making a pacemaking cell. We’ve gotten some pretty good preliminary results. So hopefully the next phase will be seeing how functional the cells are after they’ve been on these de-cellularized matrices.

Q: Why does your lab work with pig models?

JG: Pig hearts are pretty close to the human heart – their anatomy is pretty similar. To give you context, a pig heart is slightly larger than the size of your two hands clasped together. But the SA node, when you isolate it out, is only a couple of millimeters squared. It’s a lot smaller than we originally thought, and if we had gone with a smaller animal model, we wouldn’t be able to tangibly study or manipulate the SA node area. Because we are at UC Davis, we have a Meat Lab on campus, and we are able to get the pig hearts from them.

Q: Have you run into any road blocks with your research?

JG: For anybody that’s working with cardiomyocytes, the biggest problem is getting stem cells to become mature cardiomyocytes. Some labs have shown that you can get cells to a more mature cardiomyocyte after it’s been in culture for almost 100 days, but that’s not exactly feasible or that helpful.

We’ve been able to isolate out a small population of cells that we’re pretty sure are pacemaking cells. Over the last year, we’ve realized that a lot of the information that we thought we knew about pacemaking cells isn’t necessarily specific to pacemaking cells. Many of the biological markers that people have published in the literature are present in pacemaking cells, but we realized that they are also present in other heart cells like atrial cells, just in a lower amount. So we haven’t really been able to pick one specific biomarker that we’ve been able to say, yes this is actually a pacemaking cell. Instead, we have a small percentage of cells that we’re able to study. But we’re trying to figure out if there’s a way that we could increase our yield, or if there’s something fundamentally different about the environment that would also increase the yield of these pacemaking cells. So we’ve had a lot of trouble shooting along the way.

Q: What was your experience like as a CIRM scholar?

JG: I became a CIRM scholar in the spring of 2014. It was through the UC Davis Stem Cell Training Program. The opportunity was very helpful for me because it was in my first year as a postdoc at Davis. I earned my PhD at UCLA, so I was dealing with being on a new campus, trying to figure out whose lab I could go to to borrow random things and where to find equipment that I needed to use. So it was helpful to be around a group of other people that were also doing stem cell projects. Even though a lot of us were focused on different areas, it was still helpful to talk to other people, especially if you get somebody’s perspective that isn’t necessarily in your field. They might come up with a random idea that you haven’t thought of before.

Over the course of the year, we had a journal club, which was always interesting to see what’s going on in the field. I also went to the annual International Society for Stem Cell Research meeting in Vancouver using CIRM funding. And as part of the program, we also worked with the CIRM Bridges program between UC Davis and Cal State Sacramento. There were Bridges master’s students that were there with us. It was interesting to hear their take on everything, and they were very enthusiastic. We have had two master’s students work in our lab. I think it was very beneficial to them because they got a lot of hands on training and both have gone on to jobs in the regenerative medicine field.

Q: What is the future of stem cell research?

JG: If you’re looking at heart disease and stem cell treatments, there’s been some interesting clinical trials that have come out that have some promising results. I think that for a couple of those studies, people might have jumped the gun a little getting the treatments into the clinic. There’s still a lot that people should study in the lab before we move on to clinical trials. But I do think that we will see something in the next 20 years where stem cell research is going to have a huge therapeutic benefit. The field is just moving so quickly, and I think it will be really interesting to see what advances are made.

For our research, I’ve always been fairly realistic, and unfortunately, I don’t think we will see this biological pacemaker any time soon. But I think that the research that we produce along the way will be very beneficial to the field and our work will hopefully improve the foundation of what is known about pacemaking cells. What I think is really interesting about our lab’s work, is that we are moving into a 3D culture environment. Cells behave very differently in the body as opposed to on a plastic petri dish. So I think it’s very encouraging that we are seeing a lot more labs moving towards a more physiologically relevant model.

Q: What are your future goals?

I’ve been lucky that I’ve been able to work with very well established professors and also brand new faculty. But I’ve seen how difficult the funding climate is – it’s very daunting. So I’m really not sure what will happen next, and I’m keeping my options open.

I’ve really enjoyed working with our undergraduate and graduate students. I’ve gotten involved with outreach programs in Sacramento that promote science to young kids. It’s something that I’ve really enjoyed, and it’s very interesting telling people that I work in stem cells. Middle school kids seem to think that stem cells are magic. It’s fun to explain the very basics of stem cells and to see the light bulb moment where they understand it. I’m hoping to end up in a career that is still within the stem cell field but more towards teaching or outreach programs.

Q: What is your favorite thing about being a scientist?

JG: The thing I really like is having a puzzle that you’re trying to figure out the answer to. It’s great because every time you answer one question, that answer is going to lead you to at least three or four more new questions. I think that that’s really interesting especially trying to figure out how all the puzzle pieces fit together, and I’ve really enjoyed getting to work with people in very different fields. My parents think its funny because they said even as a little kid, I hated not knowing the answers to questions – and still do! They were completely understanding as to why I stayed in school as long as I did.

You can learn more about Jessica’s research by following her on Twitter: @JessicaGluckPhD


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