Bicontinuous materials, like this representation of a cube of gelatin and hyaluronic acid, have greater internal surface area, allowing cells to travel faster between two points. (Credit: Karen Xu)
One of the most important but least understood aspects of healing is cell migration, or the process of cells moving from one part of the body to another. “If you are an ambulance out in the woods,” says Karen Xu, an M.D/Ph.D. student in Medicine and Bioengineering, “and there are no paths for you to move forward, it will be a lot harder for you to get to a site that needs you.”
Earlier this year, Xu co-authored a paper in Nature Communications describing a new cue to help cells get to where they need to go: a material made chiefly of hyaluronic acid and gelatin, two gooey substances commonly found outside cells in joints and connective tissue.
“Hundreds of thousands of people tear their meniscus every year,” says Robert Mauck, Mary Black Ralston Professor in Orthopaedic Surgery in Penn Medicine and Professor in Bioengineering at Penn Engineering and one of Xu’s advisors, as well as a senior author on the paper. “This material could potentially speed up their recovery.”
What makes the material — known as a hydrogel due to its blend of gelatinous matter and water — unique is that the combination of hyaluronic acid and gelatin forms a complex network of paths, providing cells many different ways to travel between two points.
This property is known as bicontinuity, and is exemplified by two discrete continuous phases that are each connected throughout the entire volume of the material (for example with a sponge, with phases of cellulose and air; in the hydrogel, this is comprised of gelatin and hyaluronic acid) resulting in a dizzying array of patterns that dramatically increase the surface area inside the material.
To test the hydrogel’s efficacy, Xu and her collaborators — including co-advisor Jason Burdick, formerly the Robert D. Bent Professor in Bioengineering at Penn Engineering and now the Bowman Endowed Professor at the University of Colorado Boulder, and the paper’s other senior author — first created several different versions of the hydrogel to find the sweet spot at which the constituents formed the bicontinuous structure and had the highest internal surface area. “We found that a precise combination of the various hydrogel components and control over their mixing was needed to form the bicontinuous structure,” says Burdick.
Karen Xu, a 2024 doctoral graduate in Bioengineering at the University of Pennsylvania, is one of 100 doctoral students in the U. S. and Canada selected to receive a $25,000 Scholar Award from the P.E.O. Sisterhood.
The P.E.O. Scholar Awards were established in 1991 to provide substantial merit-based awards for women of the United States and Canada who are pursuing a doctoral-level degree at an accredited college or university. Scholar Awards recipients are a select group of women chosen for their high level of academic achievement and their potential for having a positive impact on society.
The P.E.O., founded January 21, 1869, at Iowa Wesleyan College, Mount Pleasant, Iowa, is a philanthropic educational organization dedicated to supporting higher education for women. There are approximately 6,000 local chapters in the United States and Canada with nearly a quarter of a million active members.
Xu graduated summa cum laude with a B.S.E. in Biomedical Engineering from Duke University in 2018, after which she joined the M.D.-Ph.D. program at the University of Pennsylvania. She completed her Ph.D. in Bioengineering in spring 2024, funded by an NIH NRSA F30 fellowship, and is set to earn her M.D. in 2026. Under the mentorship of Jason Burdick, Bowman Endowed Professor in Chemical and Biological Engineering at the University of Colorado Boulder and Adjunct Professor in Bioengineering in Penn Engineering, and Robert Mauck, Mary Black Ralston Professor in Orthopaedic Surgery in the Perelman School of Medicine and in Bioengineering in Penn Engineering, her doctoral research has focused on engineering disease models to facilitate therapeutic discoveries. Her doctoral thesis involved the fabrication of hydrogels as tissue mimics to investigate how extracellular environments affect cell behaviors, thereby informing repair of dense connective tissues.
Beyond her research, Xu has taught with the Educational Pipeline Program at the Netter Center and the Perelman School of Medicine, where she hopes to inspire and support the next generation of healthcare workers and scientists.
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.
Margaret Billingsley
Dissertation: “Ionizable Lipid Nanoparticles for mRNA CAR T Cell Engineering”
Maggie Billingsley
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.”
Victoria Muir
Dissertation: “Designing Hyaluronic Acid Granular Hydrogels for Biomaterials Applications”
Victoria Muir
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.”
Sadhana Ravikumar
Dissertation: “Characterizing Medial Temporal Lobe Neurodegeneration Due to Tau Pathology in Alzheimer’s Disease Using Postmortem Imaging”
Sadhana Ravikumar
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.”
Hannah Zlotnick
Dissertation: “Remote Force Guided Assembly of Complex Orthopaedic Tissues”
Hannah Zlotnick
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!
Qazi obtained his Ph.D. at the Technical University of Berlin and the Charité Hospital in Berlin, Germany working on translational approaches for musculoskeletal tissue repair using biomaterials and stem cells under the co-advisement of Georg Duda, Director of the Berlin Institute of Health and David Mooney, Mercator Fellow at Charité – Universitätsmedizin Berlin. After arriving at Penn in 2019, Qazi performed research on microscale granular hydrogels in the Polymeric Biomaterials Laboratory of Jason Burdick, Adjunct Professor in Bioengineering at Penn and Bowman Endowed Professor in Chemical and Biological Engineering at the University of Colorado, Boulder. While conducting postdoctoral research, Qazi also collaborated with the groups of David Issadore, Associate Professor in Bioengineering and in Electrical and Systems Engineering, and Daeyeon Lee, Professor and Evan C. Thompson Term Chair for Excellence in Teaching in Chemical and Biomolecular Engineering and member of the Penn Bioengineering Graduate Group. Qazi’s postdoctoral research was supported through a fellowship from the German Research Foundation, and resulted in several publications in high-profile journals, including Advanced Materials, Cell Stem Cell, Small, and ACS Biomaterials Science and Engineering.
“Taimoor has done really fantastic research as a postdoctoral fellow in the group,” says Burdick. “Purdue has a long history of excellence in biomaterials research and will be a great place for him to build a strong research program.”
Qazi’s future research program will engineer biomaterials to make fundamental and translational advances in musculoskeletal tissue engineering, including the study of how rare tissue-resident cells respond to spatiotemporal signals and participate in tissue repair, and developing modular hydrogels that permit minimally invasive delivery for tissue regeneration. The ultimate goal is to create scalable, translational, and biologically inspired healthcare solutions that benefit a patient population that is expected to grow manifold in the coming years.
Qazi is looking to build a strong and inclusive team of scientists and engineers with diverse backgrounds interested in tackling problems at the interface of translational medicine, materials science, bioengineering, and cell biology, and will be recruiting graduate students immediately. Interested students can contact him directly at thqazi@seas.upenn.edu.
“I am excited to launch my independent research career at a prestigious institution like Purdue,” says Qazi. “Being at Penn and particularly in the Department of Bioengineering greatly helped me prepare for the journey ahead. I am grateful for Jason’s mentorship over the years and the access to resources provided by Jason, Dave Issadore, Ravi, Dave Meany and other faculty which support the training and professional development of postdoctoral fellows in Penn Bioengineering.”
Congratulations to Dr. Qazi from everyone at Penn Bioengineering!
Dani S. Bassett, J. Peter Skirkanich Professor in Bioengineering and in Electrical and Systems Engineering
Bassett runs the Complex Systems lab which tackles problems at the intersection of science, engineering, and medicine using systems-level approaches, exploring fields such as curiosity, dynamic networks in neuroscience, and psychiatric disease. They are a pioneer in the emerging field of network science which combines mathematics, physics, biology and systems engineering to better understand how the overall shape of connections between individual neurons influences cognitive traits.
Jason Burdick, Ph.D.
Jason A. Burdick, Robert D. Bent Professor in Bioengineering
Burdick runs the Polymeric Biomaterials Laboratory which develops polymer networks for fundamental and applied studies with biomedical applications with a specific emphasis on tissue regeneration and drug delivery. The specific targets of his research include: scaffolding for cartilage regeneration, controlling stem cell differentiation through material signals, electrospinning and 3D printing for scaffold fabrication, and injectable hydrogels for therapies after a heart attack.
César de la Fuente, Ph.D.
César de la Fuente, Presidential Assistant Professor in Bioengineering and Chemical & Biomedical Engineering in Penn Engineering and in Microbiology and Psychiatry in the Perelman School of Medicine
De la Fuente runs the Machine Biology Group which combines the power of machines and biology to prevent, detect, and treat infectious diseases. He pioneered the development of the first antibiotic designed by a computer with efficacy in animals, designed algorithms for antibiotic discovery, and invented rapid low-cost diagnostics for COVID-19 and other infections.
Carl June, M.D.
Carl H. June, Richard W. Vague Professor in Immunotherapy in the Perelman School of Medicine and member of the Bioengineering Graduate Group
June is the Director for the Center for Cellular Immunotherapies and the Parker Institute for Cancer Therapy and runs the June Lab which develops new forms of T cell based therapies. June’s pioneering research in gene therapy led to the FDA approval for CAR T therapy for treating acute lymphoblastic leukemia (ALL), one of the most common childhood cancers.
Vivek Shenoy, Ph.D.
Vivek Shenoy, Eduardo D. Glandt President’s Distinguished Professor in Bioengineering, Mechanical Engineering and Applied Mechanics (MEAM), and in Materials Science and Engineering (MSE)
Shenoy runs the Theoretical Mechanobiology and Materials Lab which develops theoretical concepts and numerical principles for understanding engineering and biological systems. His analytical methods and multiscale modeling techniques gain insight into a myriad of problems in materials science and biomechanics.
The highly anticipated annual list identifies researchers who demonstrated significant influence in their chosen field or fields through the publication of multiple highly cited papers during the last decade. Their names are drawn from the publications that rank in the top 1% by citations for field and publication year in the Web of Science™ citation index.
Bassett and Burdick were both on the Highly Cited Researchers list in 2019 and 2020.
The methodology that determines the “who’s who” of influential researchers draws on the data and analysis performed by bibliometric experts and data scientists at the Institute for Scientific Information™ at Clarivate. It also uses the tallies to identify the countries and research institutions where these scientific elite are based.
David Pendlebury, Senior Citation Analyst at the Institute for Scientific Information at Clarivate, said: “In the race for knowledge, it is human capital that is fundamental and this list identifies and celebrates exceptional individual researchers who are having a great impact on the research community as measured by the rate at which their work is being cited by others.”
The full 2021 Highly Cited Researchers list and executive summary can be found online here.
The Department of Bioengineering is proud to congratulate Claudia Loebel, M.D., Ph.D. on her appointment as Assistant Professor in the Department of Materials Science and Engineering at the University of Michigan. Loebel is part of the University of Michigan’s Biological Sciences Scholar program, which recruits junior instructional faculty in major areas of biomedical investigation. Loebel’s appointment will begin in Fall 2021.
Loebel got her M.D. in 2011 from Martin-Luther University in Halle-Wittenberg, Germany and her Ph.D. in Health Sciences and Technology from ETH Zurich, Switzerland in 2016. There she worked under her advisors Professors Marcy Zenobi-Wong from ETH Zurich and David Eglin from AO Research Institute Davos. At Penn, she conducted postdoctoral research in the Polymeric Biomaterials Laboratory of Jason Burdick, Robert D. Bent Professor in Bioengineering, and as a Visiting Research Scholar in the Mauck Laboratory of the McKay Orthopaedic Research Laboratory in the Perelman School of Medicine.
Loebel was awarded a K99/R00 Pathway to Independence Award through the National Institutes of Health (NIH), which supports her remaining time as a postdoc as well as her time as an independent investigator at the University of Michigan. Loebel is excited about training the next generation of scientists and engineers and being part of their journey in becoming independent and diverse thinkers.
Loebel’s research area is inspired by the interface between material science and regenerative engineering and how it can address specific problems related to tissue development, repair, and regeneration. By developing mechanically and strucatally dynamic biomaterials, microfabrication, and matrix manipulation techniques her works aim to recreate complex cell-matrix interactions and model tissue morphogenesis and disease. The ultimate goal of her research is to use these engineered systems to develop and translate more effective therapeutic treatments for diseases such as fibrotic, inflammatory, and congenital disorders. Her lab’s work will initially focus on developing engineering lung alveolar organoids, aiming to build models of acute and chronic pulmonary diseases and for personalized medicine.
Loebel says, “I am grateful to all my Ph.D. and postdoc mentors for their continuous support and especially Jason who, over the last few years, has trained me in becoming an independent scientist and mentor. This transition would not have been possible without such a great mentor team behind me.”
Congratulations Dr. Loebel from everyone at Penn Bioengineering!
Christopher B. Rodell completed his Ph.D. in Penn Bioengineering in 2016 and has since gone on to complete a postdoc at the Center for Systems Biology at Massachusetts General Hospital and Harvard Medical School. He is now an Assistant Professor in the School of Biomedical Engineering, Science and Health Systems at Drexel University. Chris caught up with the BE Blog to talk about his love of Philly and the Penn Bioengineering community:
Chris Rodell, Ph.D.
“Yes, Penn is a great place to study – it’s full of brilliant instructors and classmates. No big surprises there. But Penn Bioengineering is so much more than that! It’s a community with passion, grit, and great times that reflect the city as a whole.
I grew up in the South, so I didn’t really know much about the school or Philly in general when I first visited. But what stood out to me was the people. From the professors to the grad students and even the other visiting students, nearly everyone I met was genuinely excited to talk about their work and just wanted to have a good time doing it. Looking back, I realize that’s exactly what I needed to thrive in a research-based education. Whether studying for a class or pulling long hours at lab, it takes some grit to make it through an engineering degree. But being passionate and having others to share your excitement with make it fun. Penn Bioengineering is a really unique place where I always felt welcome to talk with anyone – the sense of community and openness is probably one of the biggest reasons for their great success in education, research, and productive collaboration.
Through my time at Penn, I was fortunate enough to work with Jason Burdick who is, as everyone told me, ‘one of smartest and nicest people you’ll ever meet.’ I also had the opportunity to build a network of lifelong friends and mentors that span the school of engineering, the medical school, and the broader academic community of Philadelphia. These connections have continued to provide me a sense of community as I embark on an independent research career at Drexel, and I’m excited to be back in Philly!”
This post is part of BE’s Alumni Spotlight series. Read more testimonies from BE Alumni on the BE website.
New research from Robert Mauck, Mary Black Ralston Professor in Orthopaedic Surgery and Bioengineering and Director of Penn Medicine’s McKay Orthopaedic Research Laboratory, announces a “new biosealant therapy may help to stabilize injuries that cause cartilage to break down, paving the way for a future fix or – even better – begin working right away with new cells to enhance healing.” Their research was published in Advanced Healthcare Materials. The study’s lead author was Jay Patel, a former postdoctoral fellow in the McKay Lab and now Assistant Professor at Emory University and was contributed to by Claudia Loebel, a postdoctoral research in the Burdick lab and who will begin an appointment as Assistant Professor at the University of Michigan in Fall 2021. In addition, the technology detailed in this publication is at the heart of a new company (Forsagen LLC) spun out of Penn with support from the Penn Center for Innovation (PCI) Ventures Program, which will attempt to spearhead the system’s entry into the clinic. It is co-founded by both Mauck and Patel, along with study co-author Jason Burdick, Professor in Bioengineering, and Ana Peredo, a PhD student in Bioengineering.
Jason Burdick, Andrew C. Daly and Matthew Davidson
Bioprinting is currently used to generate model tissues for research and has potential applications in regenerative medicine. Existing bioprinting techniques rely on printing cells embedded in hydrogels, which results in low-cell-density constructs that are well below what is required to grow functional tissues. Maneuvering different kinds of cells into position to replicate the complex makeup of an organ, particularly at organlike cell densities, is still beyond their capabilities.
Now, researchers at the School of Engineering and Applied Science have demonstrated a new bioprinting technique that enables the bioprinting of spatially complex, high-cell-density tissues.
Using a self-healing hydrogel that allows dense clusters of cells to be picked and placed in a three-dimensional suspension, the researchers constructed a model of heart tissue that featured a mix of cells that mimic the results of a heart attack.
The study was led by Jason Burdick, Robert D. Bent Professor in the Department of Bioengineering, and Andrew C. Daly, a postdoctoral researcher in his lab. Fellow Burdick lab postdoc Matthew Davidson also contributed to the study, which has been published in the journal Nature Communications.
Even without a bioprinter, groups of cells can be made to clump into larger aggregates, known as spheroids. For Burdick and colleagues, these spheroids represented a potential building block for a better approach to bioprinting.
“Spheroids are often useful for studying biological questions that rely on the cells’ 3D microenvironments or in the construction of new tissues,” says Burdick. “However, we’d like to produce even higher levels of organization by ‘printing’ different kinds of spheroids in specific arrangements and have them fuse together into structurally complex microtissues.”
The nature of scientific progress is often summarized by the Isaac Newton quotation, “If I have seen further it is by standing on the shoulders of giants.” Each new study draws on dozens of earlier ones, forming a chain of knowledge stretching back to Newton and the scientific giants his work referenced.
Scientific publishing and referencing has become more formal since Newton’s time, with databases of citations allowing for sophisticated quantitative analyses of that flow of information between researchers.
The Institute for Scientific Information and the Web of Science Group provide a yearly snapshot of this flow, publishing a list of the researchers who are in the top 1 percent of their respective fields when it comes to the number of times their work has been cited.
Danielle Bassett, J. Peter Skirkanich Professor in the departments of Bioengineering and Electrical and Systems Engineering, and Jason Burdick, Robert D. Bent Professor in the department of Bioengineering, are among the 6,389 researchers named to the 2020 list.
Bassett is a pioneer in the field of network neuroscience, which incorporates elements of mathematics, physics, biology and systems engineering to better understand how the overall shape of connections between individual neurons influences cognitive traits. Burdick is an expert in tissue engineering and the design of biomaterials for regenerative medicine; by precisely tailoring the microenvironment within these materials, they can influence stem cell differentiation or trigger the release of therapeutics.
New research from 
