Penn Bioengineering is proud to congratulate Sunghee Estelle Park, Ph.D. on her appointment as Assistant Professor in the Weldon School of Biomedical Engineering at Purdue University. Park earned her Ph.D. at Penn Bioengineering, graduating in July 2023. She conducted doctoral research in the BIOLines Lab of Dan Huh, Associate Professor in Bioengineering. Her appointment at Purdue will begin January 2024.
During her Ph.D. research, Park forged a unique path that combined principles in developmental biology, stem cell biology, organoids, and organ-on-a-chip technology to develop innovative in vitro models that can faithfully replicate the pathophysiology of various human diseases. Using a microengineered model of the human retina, she discovered previously unknown roles of the MAPK, IL-17, PI3K-AKT, and TGF-β signaling pathways in the pathogenesis of age-related macular degeneration (AMD), presenting novel therapeutic targets that could be further investigated for the development of AMD treatments. More recently, she tackled a significant challenge in the organoid field, the limited tissue growth and maturity in conventional organoid cultures, by designing microengineered systems that enabled organoids to grow with unprecedented levels of maturity and human-relevance. By integrating these platforms with bioinformatics and computational analyses, she identified novel disease-specific biomarkers of inflammatory bowel disease (IBD) and intestinal fibrosis, including previously unknown link between the presence of lncRNA and the development of IBD.
“The unique interdisciplinary expertise I gained from these projects has shaped me into a scholar with a strong collaborative ethos, a quality I hold in high esteem as we work towards advancing our knowledge and management of health and disease,” says Park.
Her vision as an independent researcher is to become a leading faculty who makes impactful contributions to our fundamental understanding of the factors influencing the structural and functional changes of human organs in health and disease. To achieve this, she plans to lead a stem cell bioengineering laboratory with a primary focus on tissue engineering and regenerative medicine. This will involve developing human organoids-on-a-chip systems and establishing next-generation biomedical devices and therapies tailored for regenerative and personalized medicine.
“I am grateful to all my Ph.D. mentors and lab mates at the BIOLines lab and especially my advisor Dr. Dan Huh, for his exceptional guidance, unwavering support, and invaluable mentorship throughout my Ph.D. journey,” says Park. “Dan’s expertise, dedication, and commitment to excellence have been instrumental in shaping both my research and professional development, while also training me to become an independent scientist and mentor.”
Congratulations to Dr. Park from everyone at Penn Bioengineering!
The Solomon R. Pollack Award for Excellence in Graduate Bioengineering Research is given annually to the most deserving Bioengineering graduate students who have successfully completed research that is original and recognized as being at the forefront of their field. This year, the Department of Bioengineering at the University of Pennsylvania recognizes the stellar work of four graduate students in Bioengineering.
Dissertation: “Ionizable Lipid Nanoparticles for mRNA CAR T Cell Engineering”
Margaret earned a bachelor’s degree in Biomedical Engineering from the University of Delaware where she conducted research in the Day Lab on the use of antibody-coated gold nanoparticles for the detection of circulating tumor cells. She conducted doctoral research in the lab of Michael J. Mitchell, J. and Peter Skirkanich Assistant Professor in Bioengineering. After defending her thesis at Penn in 2022, Margaret began postdoctoral training at the Massachusetts Institute of Technology (MIT) in the Hammond Lab where she is investigating the design and application of polymeric nanoparticles for combination therapies in ovarian cancer. She plans to use these experiences to continue a research career focused on drug delivery systems.
“Maggie was an absolutely prolific Ph.D. student in my lab, who pioneered the development of new mRNA lipid nanoparticle technology to engineer the immune system to target and kill tumor cells,” says Mitchell. “Maggie is incredibly well deserving of this honor, and I am so excited to see what she accomplishes next as a Postdoctoral Fellow at MIT and ultimately as a professor running her own independent laboratory at a top academic institution.”
Dissertation: “Designing Hyaluronic Acid Granular Hydrogels for Biomaterials Applications”
Victoria is currently a Princeton University Presidential Postdoctoral Research Fellow in the lab of Sujit S. Datta, where she studies microbial community behavior in 3D environments. She obtained her Ph.D. in 2022 as an NSF Graduate Research Fellow at Penn Bioengineering under the advisement of Jason A. Burdick, Adjunct Professor in Bioengineering at Penn and Bowman Endowed Professor in Chemical and Biological Engineering at the University of Colorado, Boulder. She received a B.ChE. in Chemical Engineering from the University of Delaware in 2018 as a Eugene DuPont Scholar. Outside of research, Victoria is highly active in volunteer and leadership roles within the American Institute of Chemical Engineers (AIChE), currently serving as Past Chair of the Young Professionals Community and a member of the Career and Education Operating Council (CEOC). Victoria’s career aspiration is to become a professor of chemical engineering and to lead a research program at the interaction of biomaterials, soft matter, and microbiology.
“Victoria was a fantastic Ph.D. student,” says Burdick. “She worked on important projects related to granular materials from the fundamentals to applications in tissue repair. She was also a leader in outreach activities, a great mentor to numerous undergraduates, and is already interviewing towards an independent academic position.”
Dissertation: “Characterizing Medial Temporal Lobe Neurodegeneration Due to Tau Pathology in Alzheimer’s Disease Using Postmortem Imaging”
Sadhana completed her B.S. in Electrical Engineering at the University of Cape Town, South Africa in 2014 and her M.S. in Biomedical Engineering from Carnegie Mellon University in 2017. Outside of the lab, she enjoys spending time in nature and exploring restaurants in Philadelphia with friends. She focused her doctoral work on the development of computational image analysis techniques applied to ex vivo human brain imaging data in the Penn Image Computing and Science Laboratory of Paul Yushkevich, Professor of Radiology at the Perelman School of Medicine and member of the Penn Bioengineering Graduate Group. She hopes to continue working at the intersection of machine learning and biomedical imaging to advance personalized healthcare and drug development.
“Dr. Sadhana Ravikumar’s Ph.D. work is a tour de force that combines novel methodological contributions crafted to address the challenge of anatomical variability in ultra-high resolution ex vivo human brain MRI with new clinical knowledge on the contributions of molecular pathology to neurodegeneration in Alzheimer’s disease,” says Yushkevich. “I am thrilled that this excellent contribution, as well as Sadhana’s professionalism and commitment to mentorship, have been recognized through the Sol Pollack award.”
Dissertation: “Remote Force Guided Assembly of Complex Orthopaedic Tissues”
Hannah was a Ph.D. candidate in the lab of Robert Mauck, Mary Black Ralston Professor in Orthopaedic Surgery and in Bioengineering. She successfully defended her thesis and graduated in August 2022. During her Ph.D., Hannah advanced the state-of-the-art in articular cartilage repair by harnessing remote fields, such as magnetism and gravity. Using these non-invasive forces, she was able to control cell positioning within engineered tissues, similar to the cell patterns within native cartilage, and enhance the integration between cartilage and bone. Her work could be used in many tissue engineering applications to recreate complex tissues and tissue interfaces. Hannah earned a B.S. in Biological Engineering from the Massachusetts Institute of Technology (MIT) in 2017 during which time she was also a member of the women’s varsity soccer team. At Penn, Hannah was also involved in the Graduate Association of Bioengineers (GABE) intramurals & leadership, and helped jumpstart the McKay DEI committee. Since completing her Ph.D., Hannah has begun her postdoctoral research as a Schmidt Science Fellow in Jason Burdick’s lab at the University of Colorado Boulder where she looks to improve in vitro disease models for osteoarthritis.
“Hannah was an outstanding graduate student, embodying all that is amazing about Penn BE – smart, driven, inventive and outstanding in every way,” says Mauck. “ I can’t wait to see where she goes and what she accomplishes!”
Congratulations to our four amazing 2023 Sol Pollack Award winners!
People who spend eight or more hours a day staring at a computer screen may notice their eyes becoming tired or dry, and, if those conditions are severe enough, they may eventually develop dry eye disease (DED). DED is a common disease with shockingly few FDA-approved drug options, partially because of the difficulties of modeling the complex pathophysiology in human eyes. Enter the blinking eye-on-a-chip: an artificial human eye replica constructed in the laboratory of Penn Engineering researchers.
This eye-on-a-chip, complete with a blinking eyelid, is helping scientists and drug developers to improve their understanding and treatment of DED, among other potential uses. The research, published in Nature Medicine, outlines the accuracy of the eye-on-a-chip as an organ stand-in and demonstrates its utility as a drug testing platform.
They collaborated with Vivian Lee, Vatinee Bunya and Mina Massaro-Giordano from the Department of Ophthalmology in Penn’s Perelman School of Medicine, as well as with Vivek Shenoy, Eduardo D. Glandt President’s Distinguished Professor in Penn Engineering’s Department of Materials Science and Engineering. Other collaborators included Woo Byun, Andrei Georgescu and Yoon-suk Yi, members of Huh’s lab, and Farid Alisafaei, a member of Shenoy’s lab.
Huh’s lab specializes in creating organs-on-a-chip that provide microengineered in vitro platforms to mimic their in vivo counterparts, including lung and bone marrow proxies launched into space this May to study astronaut illness. The lab has spent years fine-tuning its eye-on-a-chip, which earned them the 2018 Lush Prize for its promise in animal-free testing of drugs, chemicals, and cosmetics.
In this study, Huh and Seo focused on engineering an eye model that could imitate a healthy eye and an eye with DED, allowing them to test an experimental drug without risk of human harm.
To construct their eye-on-a-chip, Huh’s team starts with a porous scaffold engineered with 3D printing, about the size of a dime and the shape of a contact lens, on which they grow human eye cells. The cells of the cornea grow on the inner circle of scaffolding, dyed yellow, and the cells of the conjunctiva, the specialized tissue covering the white part of human eyes, grow on the surrounding red circle. A slab of gelatin acts as the eyelid, mechanically sliding over the eye at the same rate as human blinking. Fed by a tear duct, dyed blue, the eyelid spreads artificial tear secretions over the eye to form what is called a tear film.
“From an engineering standpoint, we found it interesting to think about the possibility of mimicking the dynamic environment of a blinking human eye. Blinking serves to spread tears and generate a thin film that keeps the ocular surface hydrated. It also helps form a smooth refractive surface for light transmission. This was a key feature of the ocular surface that we wanted to recapitulate in our device,” says Huh.
For people with DED, that tear film evaporates faster than it’s replenished, resulting in inflammation and irritation. A common cause of DED is the reduced blinking that occurs during excessive computer usage, but people can develop the disease for other reasons as well. DED affects about 14 percent of the world’s population but has been notably difficult to develop new treatments for, with 200 failed clinical drug trials since 2010 and only two currently available FDA-approved drugs for treatment.
Huh’s lab has been considering the drug-testing potential of organs-on-a-chip since their initial conceptualization, and, because of its surface-level area of impact, DED seemed the perfect place to start putting their eye model to the test. But before they started a drug trial, the team had to ensure their model could really imitate the conditions of DED.
“Initially, we thought modeling DED would be as simple as just keeping the culture environment dry. But as it turns out, it’s an incredibly complex multifactorial disease with a variety of sub-types,” Huh says. “Regardless of type, however, there are two core mechanisms that underlie the development and progression of DED. First, as water evaporates from the tear film, salt concentration increases dramatically, resulting in hyperosmolarity of tears. And second, with increased tear evaporation, the tear film becomes thinner more rapidly and often ruptures prematurely, which is referred to as tear film instability. The question was: Is our model capable of modeling these core mechanisms of dry eye?”
The answer, after much experimentation, was yes. The team evoked DED conditions in their eye-on-a-chip by cutting their device’s artificial blinking in half and carefully creating an enclosed environment that simulated the humidity of real-life conditions. When put to the test against real human eyes, both healthy and with DED, the corresponding eye-on-a-chip models proved their similarity to the actual organ on multiple clinical measures. The eyes-on-a-chip mimicked actual eyes’ performance in a Schirmer strip, which tests liquid production; in an osmolarity test, which looks at tear film salt content; and in a keratography test, which evaluates the time it takes for a tear film to break up.
Having confirmed their eye-on-a-chip’s ability to mirror the performance of a human eye in normal and DED-inducing settings, Huh’s team turned to the pharmaceutical industry to find a promising DED drug candidate to test-drive their model. They landed on an upcoming drug based on lubricin, a protein primarily found in the lubricating fluid that protects joints.
“When people think of DED, they normally treat it as a chronic disease driven by inflammation,” says Huh, “but there’s now increasing evidence suggesting that mechanical forces are important for understanding the pathophysiology of DED. As the tear film becomes thinner and more unstable, friction between the eyelids and the ocular surface increases, and this can damage the epithelial surface and also trigger adverse biological responses such as inflammation. Based on these observations, there is emerging interest in developing ophthalmic lubricants as a topical treatment for dry eye. In our study, we used an lubricin-based drug that is currently undergoing clinical trials. When we tested this drug in our device, we were able to demonstrate its friction-lowering effects, but, more importantly, using this model we discovered its previously unknown capacity to suppress inflammation of the ocular surface.”
By comparing the testing results of their models of a healthy eye, an eye with DED, and an eye with DED plus lubricin, Huh and Seo were able to further scientists’ understanding of how lubricin works and show the drug’s promise as a DED treatment.
Similarly, the process of building a blinking eye-on-a-chip pushed forward scientists’ understanding of the eye itself, providing insights into the role of mechanics in biology. Collaborating with Shenoy, director of the Center for Engineering MechanoBiology, the team’s attention was drawn to how the physical blinking action was affecting the cells they cultivated to engineer an artificial eye on top of their scaffolding.
“Initially, the corneal cells start off as a single layer, but they become stratified and form multiple layers as a result of differentiation, which happens when these cells are cultured at the air-liquid interface. They also form tight cell-cell junctions and express a set of markers during differentiation,” Huh says. “Interestingly, we found out that mechanical forces due to blinking actually help the cells differentiate more rapidly and more efficiently. When the corneal cells were cultured under air in the presence of blinking, the rate and extent of differentiation increased significantly in comparison to static models without blinking. Based on this result, we speculate that blink-induced physiological forces may contribute to differentiation and maintenance of the cornea.”
In other words, human cornea cells growing on the scientists’ scaffold more quickly became specialized and efficient at their particular jobs when the artificial eyelid was blinking on top of them, suggesting that mechanical forces like blinking contribute significantly to how cells function. These types of conceptual advances, coupled with drug discovery applications, highlight the multifaceted value that engineered organs-on-a-chip can contribute to science.
Huh and Seo’s eye-on-a-chip is still just dipping its toes into the field of drug testing, but this first step is a victory that represents years of work refining their artificial eye to reach this level of accuracy and utility.
“Although we have just demonstrated proof-of-concept,” says Seo, “I hope our eye-on-a-chip platform is further advanced and used for a variety of applications besides drug screening, such as testing of contact lenses and eye surgeries in the future.”
“We are particularly proud of the fact that our work offers a great and rare example of interdisciplinary efforts encompassing a broad spectrum of research activities from design and fabrication of novel bioengineering systems to in vitro modeling of complex human disease to drug testing,” says Huh. “I think this is what makes our study unique and representative of innovation that can be brought about by organ-on-a-chip technology.”
This work was supported by the National Institutes of Health through grants 1DP2HL127720–0, R01EY026972 and K08EY025742–01, the National Science Foundation through grants CMMI:15–48571, and Research to Prevent Blindness.