A National Institute of Allergy and Infectious Diseases lab freezer used for COVID-19 vaccine research. Both of the current mRNA-based COVID vaccines require ultra-cold freezers to prevent their mRNA from degrading, spurring research into other ways to stabilize the molecule.
As the technology behind two of the COVID-19 vaccines, Messenger RNA (mRNA) is having a moment. A single-stranded counterpart to DNA, mRNA translates its genetic code into proteins; by injecting mRNA engineered to produce proteins found on the exterior of the virus, the vaccine can train a person’s immune system to recognize the real thing without making them sick.
However, because mRNA is a relatively unstable molecule, distributing these vaccines involves extra logistical challenges. Doses must be transported and stored at ultra-cold temperatures to make sure the mRNA inside doesn’t degrade and lose the genetic information it carries.
Michael Mitchell
As mRNA vaccines and other therapies take off, researchers are looking for other ways to forestall this degradation. One of them is Michael J. Mitchell, Skirkanich Assistant Professor of Innovation in the Department of Bioengineering, who is studying the use of lipid nanoparticles to encapsulate and protect mRNA on its way into the cell. That sort of packaging would be particularly beneficial in proposed mRNA therapies for certain genetic disorders, which aim to deliver the correct protein-making instructions to specific organs, or even a fetus in utero.
But for stabilizing mRNA for vaccine distribution, many other strategies are being explored. In “Keeping covid vaccines cold isn’t easy. These ideas could help,” Wudan Yan of MIT Technology Review reached out to Mitchell for insight on LIONs, or lipid inorganic nanoparticles. These nanoparticles work the opposite way of Mitchell’s organic ones, with the mRNA stabilized by binding to their exteriors.
William H. Peranteau, Michael J. Mitchell, Margaret Billingsley, Meghana Kashyap, and Rachel Riley (Clockwise from top left)
As COVID-19 vaccines roll out, the concept of using mRNA to fend off viruses has become a part of the public dialogue. However, scientists have been researching how mRNA can be used to in life-saving medical treatments well before the pandemic.
The “m” in “mRNA” is for “messenger.” A single-stranded counterpart to DNA, it translates the genetic code into the production of proteins, the building blocks of life. The Moderna and Pfizer COVID-19 vaccines work by introducing mRNA sequences that act as a set of instructions for the body to produce proteins that mimic parts of the virus itself. This prepares the body’s immune response to recognize the real virus and fight it off.
Because it can spur the production of proteins that the body can’t make on its own, mRNA therapies also have the potential to slow or prevent genetic diseases that develop before birth, such as cystic fibrosis and sickle-cell anemia.
However, because mRNA is a relatively unstable molecule that degrades quickly, it needs to be packaged in a way that maintains its integrity as its delivered to the cells of a developing fetus.
To solve this challenge, Michael J. Mitchell, Skirkanich Assistant Professor of Innovation in the Department of Bioengineering, is researching the use of lipid nanoparticles as packages that transport mRNA into the cell. He and William H. Peranteau, an attending surgeon in the Division of General, Thoracic and Fetal Surgery and the Adzick-McCausland Distinguished Chair in Fetal and Pediatric Surgery at Children’s Hospital of Philadelphia, recently co-authored a “proof-of-concept” paper investigating this technique.
In this study, published in Science Advances, Mitchel examined which nanoparticles were optimal in the transport of mRNA to fetal mice. Although no disease or organ was targeted in this study, the ability to administer mRNA to a mouse while still in the womb was demonstrated, and the results are promising for the next stages of targeted disease prevention in humans.
Mitchel spoke with Tom Avril at The Philadelphia Inquirer about the mouse study and its implications for treatment of rare infant diseases through the use of mRNA, ‘the messenger of life.’
Penn bioengineering professor Michael J. Mitchell, the other senior author of the mouse study, tested various combinations of lipids to see which would work best.
The appeal of the fatty substances is that they are biocompatible. In the vaccines, for example, two of the four lipids used to make the delivery spheres are identical to lipids found in the membranes of human cells — including plain old cholesterol.
When injected, the spheres, called nanoparticles, are engulfed by the person’s cells and then deposit their cargo, the RNA molecules, inside. The cells respond by making the proteins, just as they make proteins by following the instructions in the person’s own RNA. (Important reminder: The RNA in the vaccines cannot become part of your DNA.)
Among the different lipid combinations that Mitchell and his lab members tested, some were better at delivering their cargo to specific organs, such as the liver and lungs, meaning they could be a good vehicle for treating disease in those tissues.
William H. Peranteau, Michael J. Mitchell, Margaret Billingsley, Meghana Kashyap, and Rachel Riley (Clockwise from top left)
Researchers at Children’s Hospital of Philadelphia and the School of Engineering and Applied Science at the University of Pennsylvania have identified ionizable lipid nanoparticles that could be used to deliver mRNA as part of fetal therapy. The proof-of-concept study, published today in Science Advances, engineered and screened a number of lipid nanoparticle formulations for targeting mouse fetal organs and has laid the groundwork for testing potential therapies to treat genetic diseases before birth.
“This is an important first step in identifying nonviral mediated approaches for delivering cutting-edge therapies before birth,” said co-senior author William H. Peranteau, MD, an attending surgeon in the Division of General, Thoracic and Fetal Surgery and the Adzick-McCausland Distinguished Chair in Fetal and Pediatric Surgery at CHOP. “These lipid nanoparticles may provide a platform for in utero mRNA delivery, which would be used in therapies like fetal protein replacement and gene editing.”
Michael J. Mitchell, Skirkanich Assistant Professor of Innovation in Penn Engineering’s Department of Bioengineering, is the other co-senior author of the study. The co-first authors are Mitchell Lab members Rachel Riley, a postdoctoral fellow, and Margaret Billingsley, a graduate student, and Peranteau Lab member Meghana Kashyap, a research fellow.
Recent advances in DNA sequencing technology and prenatal diagnostics have made it possible to diagnose many genetic diseases before birth. Some of these diseases are treated by protein or enzyme replacement therapies after birth, but by then, some of the damaging effects of the disease have taken hold. Thus, applying therapies while the patient is still in the womb has the potential to be more effective for some conditions. The small fetal size allows for maximal therapeutic dosing, and the immature fetal immune system may be more tolerant of replacement therapy.
Using specialized nanoparticles, researchers from Penn Engineering and the Massachusetts Institute of Technology (MIT) have developed a way to turn off specific genes in cells of bone marrow, which play an important role in producing blood cells. These particles could be tailored to help treat heart disease or to boost the yield of stem cells in patients who need stem cell transplants.
This type of genetic therapy, known as RNA interference, is usually difficult to target to organs other than the liver, where nanoparticles would tend to accumulate. The researchers were able to modify their particles in such a way that they would accumulate in the cells found in the bone marrow.
In a recent Nature Biomedical Engineering study, conducted in mice, the researchers showed that they could use this approach to improve recovery after a heart attack by inhibiting the release of bone marrow blood cells that promote inflammation and contribute to heart disease.
“If we can get these particles to hit other organs of interest, there could be a broader range of disease applications to explore, and one that we were really interested in in this paper was the bone marrow. The bone marrow is a site for hematopoiesis of blood cells, and these give rise to a whole lineage of cells that contribute to various types of diseases,” says Michael Mitchell, Skirkanich Assistant Professor of Innovation in Penn Engineering’s Department of Bioengineering, one of the lead authors of the study.
Marvin Krohn-Grimberghe, a cardiologist at the Freiburg University Heart Center in Germany, and Maximilian Schloss, a research fellow at Massachusetts General Hospital (MGH), are also lead authors on the paper, which appears today in Nature Biomedical Engineering. The paper’s senior authors are Daniel Anderson, a professor of Chemical Engineering at MIT and a member of MIT’s Koch Institute for Integrative Cancer Research and Institute for Medical Engineering and Science, and Matthias Nahrendorf, a professor of Radiology at MGH.
Mitchell’s expertise is in the design of nanoparticles and other drug delivery vehicles, engineering them to cross biological barriers that normally block foreign agents. In 2018, he received the NIH Director’s New Innovator Award to support research on delivering therapeutics to bone marrow, a key component of this new study.
The researchers have shown they can deliver nanoparticles to the bone marrow, influencing their function with RNA silencing. At top right, the bone marrow is not yet treated with particles that turn off a gene called SDF1. At bottom right, the number of neutrophils (blue) decreases, indicating that they have been released from bone marrow after treatment. At left, treatment with a control nanoparticle does not affect the number of neutrophils before and after treatment.
Originally from Matawan, NJ, Riley has been an NIH Postdoctoral Fellow in the Mitchell Lab since 2018. Her move to a faculty position at Rowan marks a return, as she received her B.S. in Civil and Environmental Engineering there in 2012. Riley went on to receive her Ph.D. in Biomedical Engineering in 2018 at the University of Delaware with Emily Day, Ph.D. before joining the lab of Michael J. Mitchell, Ph.D., Skirkanich Assistant Professor of Innovation, later that year. The Mitchell Lab’s research lies at the interface of biomaterials science, drug delivery, and cellular and molecular bioengineering to fundamentally understand and therapeutically target biological barriers.
“Rachel has had a prolific academic career at the University of Delaware and at Penn, launching several exciting research projects and mentoring the next generation of STEM researchers,” Mitchell says. “I’m very hopeful that her new position as an Assistant Professor of Biomedical Engineering at Rowan University will permit her to engineer new drug delivery technologies for women’s health applications.”
Research in the Riley Lab at Rowan will explore how nanoparticle drug delivery technologies can be engineered specifically for applications in women’s health. They will use nanoparticles as tools to study and treat gynecological cancers, fetal diseases, and pregnancy complications. Riley’s ultimate goal is to gain a fundamental understanding of how nanoparticle structure influences delivery to gynecological tissues to enable them to take an engineering approach to tackle new applications in women’s health.
Riley says that she is committed to supporting women and minorities in STEM disciplines and she looks forward to continuing collaborations with Penn and starting new collaborations with researchers at Cooper Medical School at Rowan University (CMSRU). Congratulations, Dr. Riley!
An artist’s illustration of nanoparticles transporting mRNA into a T cell (blue), allowing the latter to express surface receptors that recognize cancer cells (red). (Credit: Ryan Allen, Second Bay Studios)
New cancer immunotherapies involve extracting a patient’s T cells and genetically engineering them so they will recognize and attack tumors. This type of therapy is not without challenges, however. Engineering a patient’s T cells is laborious and expensive. And when successful, the alterations to the immune system immediately make patients very sick for a short period of time, with symptoms including fever, nausea and neurological effects.
Now, Penn researchers have demonstrated a new engineering technique that, because it is less toxic to the T cells, could enable a different mechanism for altering the way they recognize cancer, and could have fewer side effects for patients.
The technique involves ferrying messenger RNA (mRNA) across the T cell’s membrane via a lipid-based nanoparticle, rather than using a modified HIV virus to rewrite the cell’s DNA. Using the former approach would be preferable, as it only confers a temporary change to the patient’s immune system, but the current standard method for getting mRNA past the cell membrane can be too toxic to use on the limited number of T cells that can be extracted from a patient.
Michael Mitchell, Margaret Billingsley, and Carl June
The researchers demonstrated their technique in a study published in the journal Nano Letters. It was led by Michael Mitchell, Skirkanich Assistant Professor of Innovation of bioengineering in the School of Engineering and Applied Science, and Margaret Billingsley, a graduate student in his lab.
They collaborated with one of the pioneers of CAR T therapy: Carl June, the Richard W. Vague Professor in Immunotherapy and director of the Center for Cellular Immunotherapies in the Abramson Cancer Center and the director of the Parker Institute for Cancer Immunotherapy at the Perelman School of Medicine.
A new approach uses “mechanoceuticals” to treat pain.
Drugs are commonly injected directly into an injury site to speed healing. For chronic pain, clinicians can inject drugs to reduce inflammation in painful joints, or can inject nerve blockers to block the nerve signals that cause pain. In a recent study, a group from UCLA developed a technique to deform a material surrounding nerve fibers to trigger a response in the fibers that would relieve pain. The combination of mechanics and treatment – i.e., ‘mechanoceuticals’ – is a clever way to trick fibers and reverse painful symptoms. Done without any injections and simply controlling magnetic fields outside the body, this approach can be reused as necessary.
The design of this mechanoceutical was completed by Dino Di Carlo, PhD, Professor of Bioengineering, and his team at UCLA’s Sameuli School of Engineering. By encasing tiny, magnetic nanoparticles within a biocompatible hydrogel, the group used magnetic force to stimulate nerve fibers and cause a corresponding decrease in pain signals. This promising development opens up a new approach to pain management, one which can be created with different biomaterials to suit different conditions, and delivered “on demand” without worrying about injections or, for that matter, any prescription drugs.
Understanding the Adolescent Brain
It’s no surprise that adults and adolescents often struggle to understand one another, but the work of neurologists and other researchers provides a possible physical reason for why that might be. Magnetic resonance elastrography (MRE) is a tool used in biomedical imaging to estimate the mechanical properties, or stiffness, of tissue throughout the body. Unexpectedly, a recent study suggests that brain stiffness correlates with cognitive ability, suggesting MRE may provide insight into patients’ behavior, psychology, and psychiatric state.
A new paper in Developmental Cognitive Neuroscience published the results of a study using MRE to track the relative “stiffness” vs. “softness” of adult and adolescent brains. The University of Delaware team, led by Biomedical Engineering Assistant Professor Curtis Johnson, PhD, and his doctoral student Grace McIlvain, sampled 40 living subjects (aged 12-14) and compared the properties to healthy adult brains.
The study found that children and adolescent brains are softer than those of adults, correlating to the overall malleability of childhood development. The team hopes to continue their studies with younger and older children, looking to demonstrate exactly when and how the change from softness to stiffness takes place, and how these properties correspond to individual qualities such as risk-taking or the onset of puberty. Eventually, establishing a larger database of measurements in the pediatric brain will help further studies into neurological and cognitive disorders in children, helping to understand conditions such as multiple sclerosis, autism, and cerebral palsy.
Can Nanoparticles Replace Stents?
Researchers and clinicians have made amazing advances in heart surgery. Stents, in particular, have become quite sophisticated: they are used to both prop open clogged arteries as well as deliver blood-thinning medication slowly over days to weeks in the area of the stent. However, the risk of blood clotting increases with stents and the blood vessels can constrict over time after the stent is placed in the vessel.
A recent NIH grant will support the design of a stent-free solution to unclog blood vessels. Led by Shaoqin Gong, PhD, Vilas Distinguished Professor of Biomedical Engineering at UW-Madison, the team used nanoparticles (or nanoclusters) to directly target the affected blood vessels and prevent regrowth of the cells post-surgery, eliminating the need for a stent to keep the pathways open. These nanoclusters are injected through an intravenous line, further reducing the risks introduced by the presence of the stent. As heart disease affects millions of people worldwide, this new material has far-reaching consequences. Their study is published in the September edition of Biomaterials.
NIST Grant Supports
The National Institute of Standards and Technology (NIST) awarded a $30 million grant to Johns Hopkins University, Binghamton University, and Morgan State University as part of their Professional Research Experience Program (PREP). Over five years, this award will support the collaboration of academics from all levels (faculty, postdoc, graduate, and undergraduate) across the three universities, enabling them to conduct research and attend NIST conferences.
The principal investigator for Binghamton U. is Professor and Chair of the Biomedical Engineering Department, Kaiming Ye, PhD. Dr. Ye is also the Director of the Center of Biomanufacturing for Regenerative Medicine (CBRM), which will participate in this collaborative new enterprise. Dr. Ye hopes that this grant will create opportunities for academics and researchers to network with each other as well as to more precisely define the standards for the fields of regenerative medicine and biomaterial manufacturing.
The gift honors the late A. James Clark, former CEO of Clark Enterprises and Clark Construction Group LLC, one of the country’s largest privately-held general building contractors. It is designed to prepare future engineering and business leaders, with an emphasis on low income families and first-generation college students. Clark never forgot that his business successes began with an engineering scholarship. This has guided the Clark family’s longstanding investments in engineering education and reflects its commitment to ensure college remains accessible and affordable to high-potential students with financial need.
We are proud to say that three incoming Clark Scholars from the Freshman Class of 2022 will be part of the Bioengineering Department here at Penn.
And finally, our congratulations to the new Dean of the School of Engineering at the University of Mississippi: David A. Puleo, PhD. Dr. Puleo earned his bachelor’s degree and doctorate in Biomedical Engineering from Rensselaer Polytechnic Institute. Most recently he served as Professor of Biomedical Engineering and Associate Dean for Research and Graduate Studies at the University of Kentucky’s College of Engineering. Building on his research in regenerative biomaterials, he also founded Regenera Materials, LLC in 2014. Over the course of his career so far, Dr. Puleo received multiple teaching awards and oversaw much departmental growth within his previous institution, and looks poised to do the same for “Ole Miss.”
White fat stories calories and provides the body with insulation.
There are two types of fat in the human body: brown and white. Brown fat, the “good” fat, is rich in mitochondria, which gives it its brown appearance. Whereas white fat stores calories and acts as an insulator, mitochondria-rich brown fat burns energy to produce heat throughout the body and maintains body temperature. White fat, conversely, uses its stored energy to insulate the body and keep its temperature level. While all fat serves a purpose in the body, an excess of white fat cells causes obesity, a condition affecting one in three adults in the U.S. and the root cause of many potential health problems. Finding ways to convert white fat to brown opens a possibility of treating this problem naturally.
A new study in Scientific Reports proposes a clever way to convert fat types. Professor of Biomedical Engineering Samuel Sia, PhD, of the Columbia University School of Engineering and Applied Science, led a team which developed a method of converting white fat into brown using a tissue-grafting technique. After extracting and converting the fat, it can then be transplanted back into the patient. White fat is hard-wired to convert to brown under certain conditions, such as exposure to cold temperatures, so the trick for Dr. Sia’s team was finding a way to make the conversion last for long periods. The studies conducted with mice suggested that using these methods, newly-converted fat stayed brown for a period of two months.
Dr. Sia’s team will proceed to conduct further tests, especially on the subjects’ metabolism and overall weight after undergoing the procedure, and they hope that eventual clinical trials will result in new methods to treat or even prevent obesity in humans.
Cremins Lab Student Appointed Blavatnik Fellow
Linda Zhou is currently pursuing her MD/PhD in Genomics and Computational Biology under the supervision of Dr. Jennifer Phillips-Cremins.
The Perelman School of Medicine named Linda Zhou, a student in BE’s Cremins Laboratory, a Blavatnik Fellow for the 2018-2019 academic year. The selection process for this award is highly competitive, and Linda’s selection speaks to the excellent quality of her scholarship and academic performance. The fellows will be honored in a special ceremony at the Museum of Natural History in New York City.
Linda received her B.S. in Biophysics and Biochemistry from Yale University and is currently pursuing her M.D./Ph.D. in the Genomics and Computational Biology Program at Penn. “I am honored to be named a Blavatnik Fellow and am extremely excited to continue my graduate studies investigating neurological disorders and the 3D genome,” she said. “This support will be integral to achieving my long term goal of driving scientific discovery that will help treat human disease.”
Linda’s research is overseen by Penn Bioengineering Assistant Professor Jennifer Phillips-Cremins, PhD. “Linda is an outstanding graduate student,” said Dr. Cremins. “It is a true delight to work with her. She is hard working, intelligent, kind, and has extraordinary leadership ability. Her unrelenting search for ground-state truth makes her a shining star.”
The Blavatnik Family Fellowship in Biomedical Research is a new award announced by the Perelman School of Medicine in May of this year. This generous gift from the Blavatnik Family Foundation awards $2 million to six recipients in the Biomedical Graduate Studies Program at Penn for each of the next four years.
Growing Lungs in a Lab
As the demand for lung transplants continues to rise, so does the need for safe and effective transplanted lungs. Bioengineered lungs grown or created in labs are one way of meeting this demand. The problem – as is ever the case with transplants – is the high rate of rejection. The results of success are always better when cells from the patient herself (or autologous cells) are used in the transplanted organ.
Recently Joan Nichols, PhD, Professor of Internal Medicine, and Microbiology and Immunology, at the University of Texas Medical Branch at Galveston, successfully bioengineered the first human lung. Her latest study published in Science Translational Medicine describes the next milestone for Dr. Nichols’ lab: successfully transplanting a bioengineered lung into a pig.
These advances are possible due to Dr. Nichols’ work with autologous cells, continuing the trend of “on demand” medicine (i.e. medicine tailor for a specific patient) which we track on this blog. Dr. Nichols’ particular method is to build the structure of a lung (using the harvested organs of dead pigs in this case), de-cellularize the tissue, and then repopulate it with autologous cells from the intended recipient. This way, the host body recognizes the cells as friendly and the likelihood of acceptance increases. While further study is needed before clinical trials can begin, Dr. Nichols and her team see the results as extremely promising and believe that we are on the way to bioengineered human lungs.
Nanoparticles Combat Dental Plaque
Combine a diet high in sugar with poor oral hygiene habits and dental cavities likely result. The sugar triggers the formation of an acidic biofilm (plaque) on the teeth, eroding the surface. Early childhood dental cavities affect one in every four children in the United States and hundreds of millions more globally. It’s a particularly severe problem in underprivileged populations.
Dr. David Cormode is Assistant Professor of Radiology and Secondary Faculty in Bioengineering at Penn. His research includes Bioengineering Therapeutics, Devices and Drug Delivery and Biomaterials.
The flu virus is notoriously contagious, but there may be a way to stop it before it starts. In order for the influenza virus to successfully transport itself into the cells of a human host, it needs a certain protein called hemagglutinin which mediates its entry. By interfering with this vital ingredient, researchers can effectively kill the virus.
A new study in the Proceedings of the National Academy of Sciences discusses a method of disrupting the process by which this protein causes the virus to infect its host cells. This discovery could lead to more effective flu vaccines that target the flu virus at its root, rather than current ones which have to keep up with the ongoing changes and mutations of the virus itself. Indeed, the need for different vaccines to address various “strains” of the flu is moot if a vaccine can stop the virus from infecting people in the first place.
This breakthrough results from grants provided by the NSF, the Welch Foundation, and the NIH to Rice University and Baylor College of Medicine. Lead researchers José Onuchic, PhD, Harry C. and Olga K. Wiess Chair of Physics and Professor of Chemistry and BioSciences at Rice University; Jianpeng Ma, PhD, Professor of Bioengineering at Rice University and Lodwick T. Bolin Professor of Biochemistry at Baylor College of Medicine; and Qinghua Wang, PhD, Assistant Professor of Biochemistry at Baylor College of Medicine. Their team will continue to study the important role proteins play in how the flu virus operates.
People and Places
This week, we congratulate a few new leadership appointments in bioengineering. First, the Georgia Institute of Technology appointed Penn BE alumnus Andréas García, PhD, the new Executive Director of the Parker H. Petit Institute for Bioengineering and Bioscience. In addition to his new role, Dr. García is also the George W. Woodruff School of Mechanical Engineering Regents Professor. He conducts research in biomolecular, cellular, and tissue engineering and collaborates with a number of research centers across Georgia Tech. Dr. García graduated with both his M.S.E. and Ph.D. from the University of Pennsylvania’s Department of Bioengineering.
Secondly, the University of Minnesota Institute for Engineering in Medicine (IEM) named the Distinguished McKnight University Professor John Bischof, PhD, their new director. This follows Dr. Bischof’s recent position as interim director for the IEM. Dr. Bischof earned his Ph.D. in Mechanical Engineering at the University of California at Berkeley, and is currently a faculty member in both the Mechanical Engineering and Biomedical Engineering Departments at the University of Minnesota. Dr. Bischof holds the Carl and Janet Kuhrmeyer Chair in Mechanical Engineering.
At an earlier, but no less impressive, point in his academic career, Tanishq Abraham became the youngest person to graduate with a degree in biomedical engineering. The fifteen year old recently graduated summa cum laude from the University of California, Davis. As part of his graduating research, Abraham – a first-generation Indian-American – designed a device to measure the heart rates of burn victims. Abraham has already been accepted by U.C. Davis for his Ph.D. and plans to continue on to his M.D.
Finally, the work continues to create affordable and well-fitted prosthetics, especially for remote, rural, and underfunded areas both in the U.S. and abroad. Unfortunately, recent studies published by the Centre for Biomedical Engineering at the India Institute of Technology Delhi (IIT) demonstrate the uphill nature of this battle; stating that India alone contains over half a million upper limb amputees. To address this explosive population, researchers and entrepreneurs are using new bioengineering technologies such as digital manufacturing, 3D scanning and printing, and more. The best innovations are those that save time, resources, and money, without sacrificing quality in the prosthetic or patient comfort. Penn Engineering’s Global Biomedical Service (GBS) program similarly responds to this need, as each year students follow an academically rigorous course with a two-week immersive trip to China, where they learn how to create and fit prosthetic limbs for local children in conjunction with Hong Kong Polytechnic University.
