Stem cell-based gut-on-a-chip: a new path to personalized medicine

“Personalized medicine” is a trendy phrase these days, frequently used in TV ads for hospitals, newspaper articles about medicine’s future and even here in the Stem Cellar. The basic gist is that by analyzing a patient’s unique biology, a physician can use disease treatments that are most likely to work in that individual.


Emulate’s Organ-on-a-Chip device.
Image: Emulate, Inc.

This concept is pretty straight-forward but it’s not always clear to me how it would play out as a routine clinical service for patients. A recent publication in Cellular and Molecular Gastroenterology and Hepatology by scientists at Cedars-Sinai and Emulate, Inc. paints a clearer picture. The report describes a device, Emulate’s Intestine-Chip, that aims to personalize drug treatments for people suffering from gastrointestinal diseases like inflammatory bowel disease and Chrohn’s disease.

Intestine-Chip combines the cutting-edge technologies of induced pluripotent stem cells (iPSCs) and microfluidic engineering. For the iPSC part of the equation, skin or blood samples are collected from a patient and reprogrammed into stem cells that can mature into almost any cell type in the body. Grown under the right conditions in a lab dish, the iPSCs self-organize into 3D intestinal organoids, structures made up of a few thousand cells with many of the hallmarks of a bona fide intestine.


Miniature versions of a human intestinal lining, known as organoids, derived from induced pluripotent stem cells (iPSCs).
Image: Cedars-Sinai Board of Governors Regenerative Medicine Institute

These iPSC-derived organoids have been described in previous studies and represent a breakthrough for studying human intestinal diseases. Yet, they vary a lot in shape and size, making it difficult to capture consistent results. And because the intestinal organoids form into hollow tubes, it’s a challenge to get drugs inside the organoid, a necessary step to systematically test the effects of various drugs on the intestine.

The Intestine-Chip remedies these drawbacks. About the size of a double A battery, the Chip is made up of specialized plastic engineered with tiny tunnels, or micro-channels. The research team placed the iPSC-derived intestinal organoid cells into the micro-channels and showed that passing fluids with a defined set of ingredients through the device can prod the cells to mimic the human intestine.

RMI IntestinalChip

Cells of a human intestinal lining, after being placed in an Intestine-Chip, form intestinal folds as they do in the human body. Image: Cedars-Sinai Board of Governors Regenerative Medicine Institute

The Intestine-Chip not only looks like a human intestine but acts like one too. A protein known to be at high levels in inflammatory bowel disease was passed through the microchannel and the impact on the intestinal cells matched what is seen in patients. Clive Svendsen, Ph.D., a co-author on the study and director of the Cedars-Sinai Board of Governors Regenerative Medicine Institute, explained the exciting applications that the Intestine-Chip opens up for patients:


Clive Svendsen

“This pairing of biology and engineering allows us to re-create an intestinal lining that matches that of a patient with a specific intestinal disease—without performing invasive surgery to obtain a tissue sample,” he said in a press release. “We can produce an unlimited number of copies of this tissue and use them to evaluate potential therapies. This is an important advance in personalized medicine.”

Emulate’s sights are not just set on the human intestine but for the many other organs affected by disease. And because disease rarely impacts only one organ, a series of Organs-on-Chips for a particular patient could be examined together. Geraldine A. Hamilton, Ph.D., president and chief scientific officer of Emulate, Inc. summed up this point in a companion press release:


Geraldine Hamilton

“By creating a personalized Patient-on-a-Chip, we can really begin to understand how diseases, medicines, chemicals and foods affect an individual’s health.”



In a stem cell first, functioning human kidney structures grown in living animals

One of the ultimate quests in the stem cell field – growing organs to repair diseased or damaged ones – took a significant step forward this week. In a first, researchers at the University of Manchester, in the U.K., showed that human embryonic stem cell-derived kidney tissue forms into functional kidney structures, capable of filtering blood and producing urine, when implanted under the skin of mice.


Cross-section of human stem cell-derived kidney tissue grown in mouse. When injected in blood, dextran (green) was taken up by the kidney structure, proving it’s functional. (Credit University of Manchester/ Stem Cell Reports)

When a person has end-stage kidney disease, their body can no longer filter out waste products and extra fluid from the blood which leads to serious health complications, even death. Blood filtration therapy, called dialysis, can substitute for a kidney but the average life expectancy is only about 10 years for patients receiving dialysis. Kidney transplants are another answer for treating kidney disease, but organ availability is in limited supply. About 2.2 million people die worldwide from a lack of access to these treatment options. So other therapeutic approaches to help end-stage kidney disease sufferers are sorely needed.

The current study, published in Stem Cell Reports, used human embryonic stem cells to grow kidney tissue in the lab. While the lab-grown tissues showed hallmarks of kidney structures, they were unable to fully develop into mature kidney structures in a culture dish. So the scientists tried implanting the human kidney tissue under the skin of mice and left it there for 12 weeks. The team showed that kidney structures, called glomeruli, which play a key role in filtering the blood, formed over that time and had become vascularized, or connected with the animal’s blood supply. The team further showed those structures were functional by injecting a fluorescently tagged substance called dextran. Tracing the fate of the dextran in the blood showed that it had been filtered and taken up by tubular structures in the kidney tissue which indicates urine production had begun.

Professor Sue Kimber, one of the leaders of the study, summed up the significance and current limitations of these results in a press release:


Sue Kimber

“We have proved beyond any doubt these structures function as kidney cells by filtering blood and producing urine – though we can’t yet say what percentage of function exists. What is particularly exciting is that the structures are made of human cells which developed an excellent capillary blood supply, becoming linked to the vasculature of the mouse.

Though this structure was formed from several hundred glomeruli, and humans have about a million in their kidneys – this is clearly a major advance. It constitutes a proof of principle- but much work is yet to be done.”

To be sure, curing a person suffering from end-stage kidney disease with a stem cell-grown kidney is some ways off. But, on the nearer horizon, this advance will provide a means to study the human kidney in a living animal, a powerful tool for uncovering insights into kidney disease and new therapeutic approaches.

Harnessing DNA as a programmable instruction kit for stem cell function

DNA is the fundamental molecule to all living things. The genetic sequences embedded in its double-helical structure contain the instructions for producing proteins, the building blocks of our cells. When our cells divide, DNA readily unzips into two strands and makes a copy of itself for each new daughter cell. In a Nature Communications report this week, researchers at Northwestern University describe how they have harnessed DNA’s elegant design, which evolved over a billion years ago, to engineer a programmable set of on/off instructions to mimic the dynamic interactions that cells encounter in the body. This nano-sized toolkit could provide a means to better understand stem cell behavior and to develop regenerative therapies to treat a wide range of disorders.


Instructing cells with programmable DNA-protein hybrids: switching bioactivity on and off Image: Stupp lab/Northwestern U.

While cells are what make up the tissues and organs of our bodies, it’s a bit more complicated than that. Cells also secrete proteins and molecules that form a scaffold between cells called the extracellular matrix. Though it was once thought to be merely structural, it’s clear that the matrix also plays a key role in regulating cell function. It provides a means to position multiple cell signaling molecules in just the right spot at the right time to stimulate a particular cell behavior as well as interactions between cells. This physical connection between the matrix, molecules and cells called a “niche” plays an important role for stem cell function.

Since studying cells in the laboratory involves growing them on plastic petri dishes, researchers have devised many methods for mimicking the niche to get a more accurate picture of how cells response to signals in the body. The tricky part has been to capture three main characteristics of the extracellular matrix all in one experiment; that is, the ability to add and then reverse a signal, to precisely position cell signals and to combine signals to manipulate cell function. That’s where the Northwestern team and its DNA toolkit come into the picture.

They first immobilized a single strand of DNA onto the surface of a material where cells are grown. Then they added a hybrid molecule – they call it “P-DNA” – made up of a particular signaling protein attached to a single strand of DNA that pairs with the immobilized DNA. Once those DNA strands zip together, that tethers the signaling protein to the material where the cells encounter it, effectively “switching on” that protein signal. Adding an excess of single-stranded DNA that doesn’t contain the attached protein, pushes out the P-DNA which can be washed away thereby switching off the protein signal. Then the P-DNA can be added back to restart the signal once again.

Because the DNA sequences can be easily synthesized in the lab, it allows the researchers to program many different instructions to the cells. For instance, combinations of different protein signals can be turned on simultaneously and the length of the DNA strands can precisely control the positioning of cell-protein interactions. The researchers used this system to show that spinal cord neural stem cells, which naturally clump together in neurospheres when grown in a dish, can be instructed to spread out on the dish’s surface and begin specializing into mature brain cells. But when that signal is turned off, the cells ball up together again into the neurospheres.

Team lead Samuel Stupp looks to this reversible, on-demand control of cell activity as means to develop patient specific therapies in the future:


Samuel Stupp

“People would love to have cell therapies that utilize stem cells derived from their own bodies to regenerate tissue. In principle, this will eventually be possible, but one needs procedures that are effective at expanding and differentiating cells in order to do so. Our technology does that,” he said in a university press release.



Stem cell stories that caught our eye: spinal cord injury trial update, blood stem cells in lungs, and using parsley for stem cell therapies

More good news on a CIRM-funded trial for spinal cord injury. The results are now in for Asterias Biotherapeutics’ Phase 1/2a clinical trial testing a stem cell-based therapy for patients with spinal cord injury. They reported earlier this week that six out of six patients treated with 10 million AST-OPC1 cells, which are a type of brain cell called oligodendrocyte progenitor cells, showed improvements in their motor function. Previously, they had announced that five of the six patients had shown improvement with the jury still out on the sixth because that patient was treated later in the trial.

 In a news release, Dr. Edward Wirth, the Chief Medical officer at Asterias, highlighted these new and exciting results:

 “We are excited to see the sixth and final patient in the AIS-A 10 million cell cohort show upper extremity motor function improvement at 3 months and further improvement at 6 months, especially because this particular patient’s hand and arm function had actually been deteriorating prior to receiving treatment with AST-OPC1. We are very encouraged by the meaningful improvements in the use of arms and hands seen in the SciStar study to date since such gains can increase a patient’s ability to function independently following complete cervical spinal cord injuries.”

Overall, the trial suggests that AST-OPC1 treatment has the potential to improve motor function in patients with severe spinal cord injury. So far, the therapy has proven to be safe and likely effective in improving some motor function in patients although control studies will be needed to confirm that the cells are responsible for this improvement. Asterias plans to test a higher dose of 20 million cells in AIS-A patients later this year and test the 10 million cell dose in AIS-B patients that a less severe form of spinal cord injury.

 Steve Cartt, CEO of Asterias commented on their future plans:

 “These results are quite encouraging, and suggest that there are meaningful improvements in the recovery of functional ability in patients treated with the 10 million cell dose of AST-OPC1 versus spontaneous recovery rates observed in a closely matched untreated patient population. We look forward to reporting additional efficacy and safety data for this cohort, as well as for the currently-enrolling AIS-A 20 million cell and AIS-B 10 million cell cohorts, later this year.”

Lungs aren’t just for respiration. Biology textbooks may be in need of some serious rewrites based on a UCSF study published this week in Nature. The research suggests that the lungs are a major source of blood stem cells and platelet production. The long prevailing view has been that the bone marrow was primarily responsible for those functions.

The new discovery was made possible by using special microscopy that allowed the scientists to view the activity of individual cells within the blood vessels of a living mouse lung (watch the fascinating UCSF video below). The mice used in the experiments were genetically engineered so that their platelet-producing cells glowed green under the microscope. Platelets – cell fragments that clump up and stop bleeding – were known to be produced to some extent by the lungs but the UCSF team was shocked by their observations: the lungs accounted for half of all platelet production in these mice.

Follow up experiments examined the movement of blood cells between the lung and bone marrow. In one experiment, the researchers transplanted healthy lungs from the green-glowing mice into a mouse strain that lacked adequate blood stem cell production in the bone marrow. After the transplant, microscopy showed that the green fluorescent cells from the donor lung traveled to the host’s bone marrow and gave rise to platelets and several other cells of the immune system. Senior author Mark Looney talked about the novelty of these results in a university press release:

Mark Looney, MD

“To our knowledge this is the first description of blood progenitors resident in the lung, and it raises a lot of questions with clinical relevance for the millions of people who suffer from thrombocytopenia [low platelet count].”

If this newfound role of the lung is shown to exist in humans, it may provide new therapeutic approaches to restoring platelet and blood stem cell production seen in various diseases. And it will give lung transplants surgeons pause to consider what effects immune cells inside the donor lung might have on organ rejection.

Add a little vanilla to this stem cell therapy. Typically, the only connection between plants and stem cell clinical trials are the flowers that are given to the patient by friends and family. But research published this week in the Advanced Healthcare Materials journal aims to use plant husks as part of the cell therapy itself.

Though we tend to focus on the poking and prodding of stem cells when discussing the development of new therapies, an equally important consideration is the use of three-dimensional scaffolds. Stem cells tend to grow better and stay healthier when grown on these structures compared to the flat two-dimensional surface of a petri dish. Various methods of building scaffolds are under development such as 3D printing and designing molds using materials that aren’t harmful to human tissue.

Human fibroblast cells growing on decellularized parsley.
Image: Gianluca Fontana/UW-Madison

But in the current study, scientists at the University of Wisconsin-Madison took a creative approach to building scaffolds: they used the husks of parsley, vanilla and orchid plants. The researchers figured that millions of years of evolution almost always leads to form and function that is much more stable and efficient than anything humans can create. Lead author Gianluca Fontana explained in a university press release how the characteristics of plants lend themselves well to this type of bioengineering:

Gianluca Fontana, PhD

“Nature provides us with a tremendous reservoir of structures in plants. You can pick the structure you want.”

The technique relies on removing all the cells of the plant, leaving behind its outer layer which is mostly made of cellulose, long chains of sugars that make up plant cell walls. The resulting hollow, tubular husks have similar shapes to those found in human intestines, lungs and the bladder.

The researchers showed that human stem cells not only attach and grow onto the plant scaffolds but also organize themselves in alignment with the structures’ patterns. The function of human tissues rely on an organized arrangement of cells so it’s possible these plant scaffolds could be part of a tissue replacement cell product. Senior author William Murphy also points out that the scaffolds are easily altered:

William Murphy, PhD

“They are quite pliable. They can be easily cut, fashioned, rolled or stacked to form a range of different sizes and shapes.”

And the fact these scaffolds are natural products that are cheap to manufacture makes this a project well worth watching.

Taking Steps Toward Personalized Heart Transplants

Over five million Americans have heart failure (HF), a condition in which the heart muscles become too weak to pump an adequate amount of blood, oxygen and nutrients to the body’s other organs. People with heart failure suffer from shortness of breath, chronic weakness and a fifty percent chance of dying within the first five years of diagnosis.


Heart failure weakens the heart’s ability to pump blood to the body.
Image credit: Fran Milner,

Heart transplants: swapping one disease for another
The only true cure for heart failure is an organ transplant but donor organs are in limited supply. And those lucky enough to receive a transplant need to take life long immunosuppressive drugs to fight off organ rejection, which often leads to other serious health problems like risk of infection, high blood pressure, diabetes and kidney failure.

It’s not a pretty picture for patients and with a cost to the nation of $32 billion annually, heart failure affects us all.

In a recent Circulation Research journal article, a team at the Massachusetts General Hospital (MGH) Center for Regenerative Medicine (CRM) reported on an incremental yet important step toward an alternative approach to heart transplants: growing bioengineered hearts with a patient’s own stem cells.

Bioengineered hearts: been there, done that
Bioengineered hearts may sound far fetched but eight years have already passed since researchers showed it’s possible with animal models. In that 2008 study, scientists at the University of Minnesota soaked rat hearts in detergents that cleaned away all of the heart cells, leaving behind a scaffold of connective tissue that is secreted by the cells. They then “re-seeded” the scaffold with rat progenitor heart muscle cells. Incredibly, after 4 days in a bioreactor, the tissue began contracting. After 8 days, using electrical stimulation, the hearts could pump with measurable strength.


Custom built bioreactor with a partially recellularized human whole-heart cardiac scaffold. Image credit: Bernhard Jank, MD, Ott Lab, CRM MGH

Harald Ott, the first author of that proof of concept study, now leads the MGH team in the current study. With an eye toward bringing this method to the clinic, Ott aimed to reproduce the rat studies using human cells and hearts. Specific consent was obtained to recover seventy-three human hearts donated after brain death or cardiac death and were determined to be unusable for clinical transplant.

Just as in the previous study, heart scaffolds were created by clearing away the cells from these organs. Half a billion human heart muscle cells, or cardiomyocytes, that had been grown from human induced pluripotent stem cells (iPS) were then injected into the scaffolds. At this early stage of research, the team did not attempt to reseed the entire heart but specifically focused on areas around the left ventricle – the heart chamber responsible for pumping oxygenated blood out to the rest of the body.

In order to recellularize the scaffold under conditions that resemble the contractions that actually occur in a human heart inside the body, pressure was rhythmically applied using a balloon inside the ventricle – watch it in action by downloading this video.

Screen Shot 2016-03-15 at 9.22.17 AM

Decellularized heart scaffold is injected with iPS heart muscle cells and incubated in a bioreactor to grow new heart muscle (Circ Res. 2016;118:56-72).

After incubating the heart for 14 days in a bioreactor, the team confirmed the cardiomyocytes had formed into functioning heart muscle, or myocardial, tissue that contracted upon electrical stimulation (watch the beating heart by downloading this video).

Looking ahead to a “grow yourself a new heart” future
These results set a course for a future in which scientists could grow a new, personalized heart for people with heart failure. Since the bioengineered heart would be built using iPS cells derived from the patient’s own skin or blood sample, this technique would likely get around the problems of organ rejection and the need for immunosuppressive drugs. Additional analysis in the current study also confirmed that the donor heart scaffold itself, which is void of cells, probably will not pose tissue rejection problems either.

The other key problem, a limited supply of donor hearts, was also addressed. Heart scaffolds donated after cardiac death performed just as well as those donated after brain death which would make this technique available to more patients waiting anxiously for a transplant.

The MGH team would be the first to tell you this “grow yourself a new heart” scenario is still off on the horizon. But as first author, Jacques Guyette, stated in a news release, there are milestones to reach along the way:

“Regenerating a whole heart is most certainly a long-term goal that is several years away, so we are currently working on engineering a functional myocardial [heart muscle tissue] patch that could replace cardiac tissue damaged due a heart attack or heart failure.”

Related Links:

Growing Stem Cell Research in California (Video)

How a Gladstone scientist is using bioengineering to push the pace of stem cell research

At CIRM, we strive to fund the most promising stem cell research and speed the advancement of stem cell treatments to patients who need them. Because we are a state agency, we generally focus on funding scientists, universities, and companies located in California. But we recognize that high quality stem cell research is ongoing throughout the country. That’s why CIRM has programs that fund research originating outside California and that recruit talented stem cell scientists to join our state’s vibrant stem cell community.

Today we want to share a video we produced titled, “Growing Stem Cell Research in California” that provides an example of how CIRM has catalyzed the growth of stem cell research by helping recruit Dr. Todd McDevitt, a leading biomedical engineer in stem cell research, to the Gladstone Institutes in San Francisco.

Todd started his lab at the Georgia Institute of Technology in Atlanta and moved to the Gladstone a year ago to conduct research using human pluripotent stem cells to engineer 3D micro-tissues for use in drug development and disease modeling. His move was made possible by a CIRM Research Leadership Award, which allowed the Gladstone to recruit Todd and is now his lab’s major source of funding.

Todd McDevitt, Gladstone Institutes

Todd McDevitt, Gladstone Institutes

With an expertise in tissue engineering, Todd and his team are collaborating with other researchers at the Gladstone on projects that use human stem cells to create organ-like tissues to advance research and therapeutic development for a wide range of areas including brain disease, heart disease and spinal cord injury.

Todd is a young and talented scientist who is using his expertise in bioengineering to push the pace of stem cell research ultimately, we hope, to improve human health. You can read more about Todd’s first year anniversary at the Gladstone in their latest news release.

Scientists use cotton candy to make artificial blood vessels

Cotton candy gets a bad rap. The irresistible, brightly colored cloud of sugar is notorious for sending kids into hyperactive overdrive and wreaking havoc on teeth. While it’s most typically found at a state fair or at a sports stadium, cotton candy is now popping up at the lab bench and is re-branding itself into a useful tool that will help scientists develop artificial blood vessels for lab-grown organs.Pink_and_blue_cotton_candy

How is this sticky, sweet substance transitioning from stomachs to the lab? The answer comes from a Professor at Vanderbilt University, Dr. Leon Bellan. He develops 3D microfluidic materials for biomedical applications. Recently he and his students have tackled an obstacle that has plagued the fields of tissue engineering and 3D organ modeling – making enough blood vessels to keep engineered organs alive. The story was covered by the blog Inhabitat.

Scientists are using 3D organoids or “mini-organs” derived from stem cells to model organ development and human disease in a dish. While methods to make organoids have advanced to the point where various cell types of an organ are generated, these organoids do not develop a proper capillary system – a distribution of blood vessels that allows blood to bring water, oxygen and nutrients to tissue cells. Inevitably, cells located in the center of organoids die because they don’t have access to life-saving nutrients that the cells at the surface do.

Spinning cotton candy in the lab.

Bellan lab member spins cotton candy in the lab.

Bellan came up with a sweet solution to this problem. His team discovered that you can use cotton candy to make an artificial capillary system. Conveniently, the strands of cotton candy are similar in size to human blood vessels. Bellan and his team “spin” cotton candy fibers to generate a network of sugar strands that are held in place with a special polymer. Then, they pour a gelatinous mold over the strands, let that harden, and dissolve the sugar with an enzyme solution. What’s left is an intricate network of channels that are similar to the human capillary system.

Free of cotton candy, these artificial channels are now ready to be turned into functioning human capillaries. Bellan and his team were able to grow human endothelial cells (the cells that line your blood vessels) in these channels. The cells in these artificial blood vessels are able to survive for over a week.


Gelatin mold with cotton candy made channels.

Their work is still preliminary but Bellan is excited about their technology’s potential for tissue engineering applications. In a video interview, he explained:

Leon Bellan. Photo by Joe Howell

Leon Bellan.
(Photo by Joe Howell)

“We’re really try to attack a fundamental hurdle for the entire field. The sci-fi version would be that you would like to be able to build an organ from scratch.”


Hopefully, Bellan and his group will be able to turn their sweet dream into a reality and help scientists develop properly functioning artificial organs that can be transplanted into humans.

To learn more about this fascinating technique, check out this video:

Related links:

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