Author Archives: Neica Joseph

Using Microporous Annealed Particle (MAP) hydrogels to remedy damaged stroke tissue

Neica Joseph

Mentors: Katrina Wilson, Tatiana Segura, Ph.D.

Department of Biomedical Engineering, Duke University

Ischemic strokes account for 87% of strokes worldwide and occur when a blood clot obstructs blood flow to the brain, causing subsequent death of tissue and resulting in long-term disability. Current treatments must be quickly administered after the stroke onset to be effective, resulting in only 5% of patients finding treatments helpful. Therefore, alternative treatments and therapies are highly sought after/would be helpful. One alternative is the use of hydrogels for cellular regrowth. Microporous Annealed Particles (MAP) gels—porous hydrogels that are injected into the stroke infarct—can be used long after the stroke onset to reduce brain inflammation and promote angiogenesis and neurogenesis. In this study, photothrombotic strokes were administered to mice, and MAP hydrogels were injected in the stroke infarct to test the impact of the hydrogels to repair damaged brain tissue. Brain samples were acquired and analyzed, and previous results suggest reduced brain inflammation, a thinner glial scar separating the stroke tissue from healthy tissue, and the recruitment of neural progenitor cells. Further research would involve testing different hydrogel compositions, such as the addition of growth factors, variations in nanoparticle concentrations, and gel porosity.

Strong Muscles + GRFT

At the Bursac lab, Anuj is working on engineering muscle cells by differentiating human iPSCs (as well as primary cells) into cardiac and skeletal tissue. These cells generate forces that model actual human tissue, which is pretty cool! In one of our core BME classes, we did a lot of work with muscle cells, action potentials, various muscle models (i.e Hill’s model), and a myriad of other things related to the work of Bursac lab. What gets me the most, though, is that this is Tissue Engineering. Can you imagine scientists growing an arm for you (well, not really, but really)? Vasculature, muscle, skin grafts, and even organs can be replicated! You name it (cue Thanksgiving grandma song)!

Anuj will also look into co-culturing endothelial cells & skeletal tissue together to better model human tissue. Another side project will study the use of Apelin 13, a peptide expressed largely in the heart, liver, and kidneys, and may have an angiogenic effect on vasculature. The lab is studying Apelin 13’s impact on endothelial and muscle cells, as well as its role on the cardiovascular system. Of course, the Engineer says that they liked an Engineer’s presentation the most! I mean, he speaks my language…To take second place, James Zheng’s research on the antiviral lectin GriffiThsin’s role in recognizing the spike proteins on the COVID-19 virus takes the cake for me. He’s also an Engineer. Maybe I listen harder to those who endure the struggles of P-reqs? Nonetheless, it was a great joy to listen to everyone’s chalk talk and find out more about their research. I’ll look forward to the poster presentations!

Day in the life in the Segura lab…

I never thought I’d be handling rodents so closely, but lately, my life seems to revolve around them. As mentioned in my previous blog posts, my mentor and I are studying the impact of particular hydrogels on damaged stroke tissue in the brain. This requires administering stroke, hydrogel delivery, putting the mice down, and brain analysis. For the first step, you pick up the mouse by its tail and rest it on your palm to deliver it to a chamber that delivers anesthetics. Once the little one is under, you open up the head, administer the stroke, and drill a hole in the skull where you’ll put the hydrogel. A few days later, you inject the hydrogel, and then you can harvest brains at predetermined time points.

Being at the Segura lab, I’ve observed and performed procedures with both my mentor and other graduate students in the lab. I’ve committed to doing animal studies in the Segura lab, so if there’s nothing to do at the bench, I’ll go shadow someone in the surgery room. Friday, however, was the day the mice were sacrificed, and I watched my mentor perform the “brain harvesting” procedure and even attempted to help—but I’d need a lot more practice with handling surgical tools and trying not to snip organs that we need (which would suck). I’ve also done the brain sectioning at -20 °C and I swear I almost got frostbite (but I didn’t!). I can’t imagine doing surgeries on people, but I guess that’s why we have doctors for that.

I really enjoy working at the Segura lab. I love collaborating with undergrads and learning from graduating students, doing benchwork, and participating in mice surgeries! I can see myself doing this for the next 8 years, so maybe a Ph.D. is somewhere down the line? I guess we’ll see!

My first brain sections: very subpar, but we all start somewhere!


A Beacon of Light: Tatiana Segura

Dr Tatiana Segura was raised in Colombia and came to the United States to finish high school and obtain her college education. She always liked science, reading and analyzing text, and wanted to do lab work. It was interesting to me that she reads a lot from text but “always imagines the experiment.” Whenever I read a paper, I just want to know the facts and results, but it’s almost as if Dr. Segura is there with the research team performing with them. Since America is the land of opportunities, Dr. Segura was able to do her undergrad at UC Berkeley in Bioengineering and went to Northwestern for grad school in Chemical Engineering so that she could do experiments of her own.

When I asked Dr Segura how she knew what research to dive into, she responded “some research comes out of luck and curiosity,” claiming that once you know the nuances of a problem, you get excited by it, and if she ended up in another lab at the start of her career, she would’ve found something she loved. I think this applies to BSURF or any REU student matched to a lab (or people in a lab in general). Though many of us make it by chance, or by someone else recognizing us, we fall in love with our research question, bench mentors, other undergraduates as we get rooted into the lab. If you don’t love your work, why do it?

Dr Segura loves teaching students, both in lab and in class. Her students can utilize what is taught right away, and she can help them in a meaningful way. Besides teaching, she loves learning about research and getting excited by new concepts/approaches to problems that her colleagues take on. Her advice to brewing scientists? Get involved! If you don’t have time to do research, read, listen, ask questions and talk to people. Build your network and get connected. However, nothing falls in line without the will to learn things. I hope we all form new wrinkles in our brains by the end of BSURF, even if that’s a myth!


Lab Rats…

Every 40 seconds, someone has had a stroke in the United States [1]. This occurs when an obstruction in the blood vessels prevents the brain from getting ample oxygen and nutrients, causing a cavity of dead tissue in the brain. This brain tissue has a limited capacity to regrow, and the resulting cavity is lacking in blood vessels and neuronal connections.

The Segura lab is leading in this work, as they’ve come up with various hydrogel networks that carry growth factors (amongst other things) to promote the regrowth of this dead brain tissue. We use mice–model organisms–to study the impact of these gels, meaning I give a bunch of mice some strokes for the greater progress of science. I’ve been part of over 60 mice surgeries since I’ve been in the lab, and the general process includes anesthetizing the mice, injecting a substance to induce the formation of free radicals that can cause blood clots, projecting a laser onto specific portions of the open skull to induce stroke, and injecting the hydrogel into the stroke cavity a few days later. The mice are only partially impaired, and seem active immediately after inducing strokes, unlike human patients who need countless rehabilitation and medical attention. The mice will be sacrificed at predetermined time points and brain slices will be studied to determine the impact of the gels on the regeneration of blood vessels and neuronal growth.

I’m excited to be a part of this lab and collaborate with other researchers to study strokes. Blacks are twice as likely to have strokes than whites and have the highest death rate afterward [2]. I know of at least four people in my family who’ve had strokes, so this research hits close to home. I also hope to shadow some behavioral studies at the lab with the aims of studying the impact of strokes in general, as well as the use of hydrogel on the behavior of the mice. I’m just really happy to be a part of the Segura lab!

Let’s Hit The Ground Running!

I just finished my first week at the Segura Lab, a Biomedical Engineering Lab interested in the impact of hydrogels on diseased sites of the body. My project focuses on the stroke response to hydrogels, and on Friday, I did my first animal test where I administered strokes to a couple of mice. I didn’t imagined to be so involved in the first “surgery” I watched, and it was definetely a surreal experience for me! My bench mentor said that we’d hit the ground running with these surgeries, and she wasn’t joking at all XD. Afterwards, we plan to analyze the impact of the hydrogels (a medium for drug delivery) on stroke sites and look for tissue and neuronal growth.

I’m really looking forward to contributing to the lab, be that making hydrogels, handling animals, studying tissue samples, building community with fellow undergrads, and becoming more like a scientist. I’m also looking to get my feet wet and observing behavioral studies in mice with strokes and the impact of hydrogels on the animals in rehabilitation and neuronal growth.

Furthermore, I hear that the Segura lab is also known to be very social, where students meet in their free time to play board games, go on runs together, and GET BOBA! You can tell that I’m really excited about the later. I’m excited to be here, and can’t wait to see what the summer has in store for me!