Tag: publication

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Penn Dental Medicine Collaboration Identifies New Bacterial Species Involved in Tooth Decay

S. sputigena cells form a honeycomb-like structure that encapsulates S. mutans to greatly increase and concentrate acid production that boost caries development and severity.
Image: Courtesy of Penn Dental Medicine

Collaborating researchers from the University of Pennsylvania School of Dental Medicine and the Adams School of Dentistry and Gillings School of Global Public Health at the University of North Carolina have discovered that a bacterial species called Selenomonas sputigena can have a major role in causing tooth decay.

Scientists have long considered another bacterial species, the plaque-forming, acid-making Streptococcus mutans, as the principal cause of tooth decay—also known as dental caries. However, in the study, published in Nature Communications, the Penn Dental Medicine and UNC researchers showed that S. sputigena, previously associated only with gum disease, can work as a key partner of S. mutans, greatly enhancing its cavity-making power.

“This was an unexpected finding that gives us new insights into the development of caries, highlights potential future targets for cavity prevention, and reveals novel mechanisms of bacterial biofilm formation that may be relevant in other clinical contexts,” says study co-senior author Hyun (Michel) Koo, a professor in the Department of Orthodontics and Divisions of Pediatrics and Community Oral Health and co-director of the Center for Innovation & Precision Dentistry at Penn Dental Medicine.

The other two co-senior authors of the study were Kimon Divaris, professor at UNC’s Adams School of Dentistry, and Di Wu, associate professor at the Adams School and at the UNC Gillings School of Global Public Health.

“This was a perfect example of collaborative science that couldn’t have been done without the complementary expertise of many groups and individual investigators and trainees,” Divaris says.

Read the full story in Penn Today.

Michel Koo is a professor in the Department of Orthodontics and divisions of Community Oral Health and Pediatric Dentistry in Penn Dental Medicine and co-director of the Center for Innovation & Precision Dentistry. He is a member of the Penn Bioengineering Graduate Group.

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RNA Nanoparticle Therapy Stops the Spread of Incurable Bone Marrow Cancer

by Melissa Pappas

Myeloma cells producing monoclonal proteins of varying types, created by Scientific Animations under the Creative Commons Attributions-Share Alike International 4.0 License

Multiple myeloma is an incurable bone marrow cancer that kills over 100,000 people every year. Known for its quick and deadly spread, this disease is one of the most challenging to address. As these cancer cells move through different parts of the body, they mutate, outpacing possible treatments. People diagnosed with severe multiple myeloma that is resistant to chemotherapy typically survive for only three to six months. Innovative therapies are desperately needed to prevent the spread of this disease and provide a fighting chance for those who suffer from it.

Michael Mitchell, J. Peter and Geri Skirkanich Assistant Professor of Innovation in Bioengineering (BE), and Christian Figueroa-Espada, doctoral student in BE at the University of Pennsylvania School of Engineering and Applied Science, created an RNA nanoparticle therapy that makes it impossible for multiple myeloma to move and mutate. The treatment, described in their study published in PNAS, turns off a cancer-attracting function in blood vessels, disabling the pathways through which multiple myeloma cells travel.

By shutting down this “chemical GPS” that induces the migration of cancer cells, the team’s therapy stops the spread of multiple myeloma, helping to eliminate it altogether.

Read the full story in Penn Engineering Today.

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Engineered White Blood Cells Eliminate Cancer

by Melissa Pappas

“Macrophages killing cancer cell” photographed by Susan Arnold.

By silencing the molecular pathway that prevents macrophages from attacking our own cells, Penn Engineers have manipulated these white blood cells to eliminate solid tumors.

Cancer remains one of the leading causes of death in the U.S. at over 600,000 deaths per year. Cancers that form solid tumors such as in the breast, brain or skin are particularly hard to treat. Surgery is typically the first line of defense for patients fighting solid tumors. But surgery may not remove all cancerous cells, and leftover cells can mutate and spread throughout the body. A more targeted and wholistic treatment could replace the blunt approach of surgery with one that eliminates cancer from the inside using our own cells.

Dennis Discher, Robert D. Bent Professor in Chemical and Biomolecular Engineering, Bioengineering, and Mechanical Engineering and Applied Mechanics, and postdoctoral fellow, Larry Dooling, provide a new approach in targeted therapies for solid tumor cancers in their study, published in Nature Biomedical Engineering. Their therapy not only eliminates cancerous cells, but teaches the immune system to recognize and kill them in the future.

“Due to a solid tumor’s physical properties, it is challenging to design molecules that can enter these masses,” says Discher. “Instead of creating a new molecule to do the job, we propose using cells that ‘eat’ invaders – macrophages.”

Macrophages, a type of white blood cell, immediately engulf and destroy – phagocytize – invaders such as bacteria, viruses, and even implants to remove them from the body. A macrophage’s innate immune response teaches our bodies to remember and attack invading cells in the future. This learned immunity is essential to creating a kind of cancer vaccine.

But, a macrophage can’t attack what it can’t see.

“Macrophages recognize cancer cells as part of the body, not invaders,” says Dooling. “To allow these white blood cells to see and attack cancer cells, we had to investigate the molecular pathway that controls cell-to-cell communication. Turning off this pathway – a checkpoint interaction between a protein called SIRPa on the macrophage and the CD47 protein found on all ‘self’ cells – was the key to creating this therapy.”

Read the full story in Penn Engineering Today.

Multiple members in the biophysical engineering lab lead by Dennis Discher, including co-lead author and postdoctoral fellow and Penn Bioengineering alumnus Jason Andrechak and Bioengineering Ph.D. student Brandon Hayes, contributed to this study. The research was funded by grants from the National Heart, Lung, and Blood Institute and the National Cancer Institute, including the Physical Sciences Oncology Network, of the US National Institutes of Health.

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Nanorobotic Systems Presents New Options for Targeting Fungal Infections

by Nathi Magubane

Candida albicans is a species of yeast that is a normal part of the human microbiota but can also cause severe infections that pose a significant global health risk due to their resistance to existing treatments, so much so that the World Health Organization has highlighted this as a priority issue. The picture above shows a before (left) and after (right) fluorescence image of fungal biofilms being precisely targeted by nanozyme microrobots without bonding to or disturbing the tissue sample. (Image: Min Jun Oh and Seokyoung Yoon)

Infections caused by fungi, such as Candida albicans, pose a significant global health risk due to their resistance to existing treatments, so much so that the World Health Organization has highlighted this as a priority issue.

Although nanomaterials show promise as antifungal agents, current iterations lack the potency and specificity needed for quick and targeted treatment, leading to prolonged treatment times and potential off-target effects and drug resistance.

Now, in a groundbreaking development with far-reaching implications for global health, a team of researchers jointly led by Hyun (Michel) Koo of the University of Pennsylvania School of Dental Medicine and Edward Steager of Penn’s School of Engineering and Applied Science has created a microrobotic system capable of rapid, targeted elimination of fungal pathogens.

“Candida forms tenacious biofilm infections that are particularly hard to treat,” Koo says. “Current antifungal therapies lack the potency and specificity required to quickly and effectively eliminate these pathogens, so this collaboration draws from our clinical knowledge and combines Ed’s team and their robotic expertise to offer a new approach.”

The team of researchers is a part of Penn Dental’s Center for Innovation & Precision Dentistry, an initiative that leverages engineering and computational approaches to uncover new knowledge for disease mitigation and advance oral and craniofacial health care innovation.

For this paper, published in Advanced Materials, the researchers capitalized on recent advancements in catalytic nanoparticles, known as nanozymes, and they built miniature robotic systems that could accurately target and quickly destroy fungal cells. They achieved this by using electromagnetic fields to control the shape and movements of these nanozyme microrobots with great precision.

“The methods we use to control the nanoparticles in this study are magnetic, which allows us to direct them to the exact infection location,” Steager says. “We use iron oxide nanoparticles, which have another important property, namely that they’re catalytic.”

Read the full story in Penn Today.

Hyun (Michel) Koo is a professor in the Department of Orthodontics and in the divisions of Pediatric Dentistry and Community Oral Health and is the co-founder of the Center for Innovation & Precision Dentistry in the School of Dental Medicine at the University of Pennsylvania. He is a member of the Penn Bioengineering Graduate Group.

Edward Steager is a research investigator in the School of Engineering and Applied Science’s General Robotics, Automation, Sensing & Perception Laboratory at Penn.

Other authors include Min Jun Oh, Alaa Babeer, Yuan Liu, Zhi Ren, Zhenting Xiang, Yilan Miao, and Chider Chen of Penn Dental; and David P. Cormode and Seokyoung Yoon of the Perelman School of Medicine. Cormode also holds a secondary appointment in Bioengineering.

This research was supported in part by the National Institute for Dental and Craniofacial Research (R01 DE025848, R56 DE029985, R90DE031532 and; the Basic Science Research Program through the National Research Foundation of Korea of the Ministry of Education (NRF-2021R1A6A3A03044553).

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Study Reveals New Insights on Brain Development Sequence Through Adolescence

by Eric Horvath

3D illustration of a human brain
Image: Courtesy of Penn Medicine News

Brain development does not occur uniformly across the brain, but follows a newly identified developmental sequence, according to a new Penn Medicine study. Brain regions that support cognitive, social, and emotional functions appear to remain malleable—or capable of changing, adapting, and remodeling—longer than other brain regions, rendering youth sensitive to socioeconomic environments through adolescence. The findings are published in Nature Neuroscience.

Researchers charted how developmental processes unfold across the human brain from the ages of 8 to 23 years old through magnetic resonance imaging (MRI). The findings indicate a new approach to understanding the order in which individual brain regions show reductions in plasticity during development.

Brain plasticity refers to the capacity for neural circuits—connections and pathways in the brain for thought, emotion, and movement—to change or reorganize in response to internal biological signals or the external environment. While it is generally understood that children have higher brain plasticity than adults, this study provides new insights into where and when reductions in plasticity occur in the brain throughout childhood and adolescence.

The findings reveal that reductions in brain plasticity occur earliest in “sensory-motor” regions, such as visual and auditory regions, and occur later in “associative” regions, such as those involved in higher-order thinking (problem solving and social learning). As a result, brain regions that support executive, social, and emotional functions appear to be particularly malleable and responsive to the environment during early adolescence, as plasticity occurs later in development.

“Studying brain development in the living human brain is challenging. A lot of neuroscientists’ understanding about brain plasticity during development actually comes from studies conducted with rodents. But rodent brains do not have many of what we refer to as the association regions of the human brain, so we know less about how these important areas develop,” says corresponding author Theodore D. Satterthwaite, the McLure Associate Professor of Psychiatry in the Perelman School of Medicine, and director of the Penn Lifespan Informatics and Neuroimaging Center (PennLINC).

Read the full story in Penn Medicine News.

N.B.: Theodore Satterthwaite in a member of the Penn Bioengineering Graduate Group.

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This Patterned Surface Solves Equations at the Speed of Light

by Devorah Fischler

A tailored silicon nanopattern coupled with a semi-transparent gold mirror can solve a complex mathematical equation using light. (Image credit: Ella Maru studio)

Researchers at the University of Pennsylvania, AMOLF, and the City University of New York (CUNY) have created a surface with a nanostructure capable of solving mathematical equations.

Powered by light and free of electronics, this discovery introduces exciting new prospects for the future of computing.

Nader Engheta, H. Nedwill Ramsey Professor of Electrical and Systems Engineering at the University of Pennsylvania School of Engineering and Applied Science, is a visionary figure in optics and in electromagnetic platforms. For the last two decades, he has created theory and designed experiments to make electromagnetic and optical devices that operate at the fastest rate in the universe.

Engheta is the founder of the influential field of “optical metatronics.” He creates materials that interact with photons to manipulate data at the speed of light. Engheta’s contribution to this study marks an important advance in his quest to use light-matter interactions to surpass the speed and energy limitations of digital electronics, bringing analog computing out of the past and into the future.

“I began the work on optical metatronics in 2005,” says Engheta, “wondering if it were possible to recreate the elements of a standard electronic circuit at nanoscale. At this tiny size, it would be possible to manipulate the circuit with light, rather than electricity. After achieving this, we became more ambitious, envisioning collections of these nanocircuits as processors. In 2014, we were designing materials that used these optical nanostructures to perform mathematical operations, and in 2019, we anted up to entire mathematical equations using microwaves. Now, my collaborators and I have created a surface that can solve equations using light waves, a significant step closer to our larger goals for computing materials.”

The study, recently published in Nature Nanotechnology, demonstrates the possibility of solving complex mathematical problems and a generic matrix inversion at speeds far beyond those of typical digital computing methods.

The solution converges in about 349 femtoseconds (less than one trillionth of a second), orders of magnitude faster than the clock speed of a conventional processor.

Read the full story in Penn Engineering Today.

Nader Engheta is the H. Nedwill Ramsey Professor in the Departments of Electrical and Systems Engineering and in Bioengineering in the School of Engineering and Applied Science and Professor in Physics and Astronomy in the School of Arts & Sciences at the University of Pennsylvania.

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More Cancers May be Treated with Drugs than Previously Believed

by Alex Gardner

3D illustration of cancer cells
nucleus and membrane of pathogen micro organisms in blue background

Up to 50 percent of cancer-signaling proteins once believed to be immune to drug treatments due to a lack of targetable protein regions may actually be treatable, according to a new study from the Perelman School of Medicine at the University of Pennsylvania. The findings, published this month in Nature Communications, suggest there may be new opportunities to treat cancer with new or existing drugs.

Researchers, clinicians, and pharmacologists looking to identify new ways to treat medical conditions—from cancer to autoimmune diseases—often focus on protein pockets, areas within protein structures to which certain proteins or molecules can bind. While some pockets are easily identifiable within a protein structure, others are not. Those hidden pockets, referred to as cryptic pockets, can provide new opportunities for drugs to bind to. The more pockets scientists and clinicians have to target with drugs, the more opportunities they have to control disease.

The research team identified new pockets using a Penn-designed neural network, called PocketMiner, which is artificial intelligence that predicts where cryptic pockets are likely to form from a single protein structure and learns from itself. Using PocketMiner—which was trained on simulations run on the world’s largest super computer—researchers simulated single protein structures and successfully predicted the locations of cryptic pockets in 35 cancer-related protein structures in thousands of areas of the body. These once-hidden targets, now identified, open up new approaches for potentially treating existing cancer.

What’s more, while successfully predicting the cryptic pockets, the method scientists used in this study was much faster than previous simulation or machine-learning methods. The network allows researchers to nearly instantaneously decide if a protein is likely to have cryptic pockets before investing in more expensive simulations or experiments to pursue a predicted pocket further.

“More than half of human proteins are considered undruggable due to an apparent lack of binding proteins in the snapshots we have,” said Gregory R. Bowman, PhD, a professor of Biochemistry and  Biophysics and Bioengineering at Penn and the lead author of the study. “This PocketMiner research and other research like it not only predict druggable pockets in critical protein structures related to cancer but suggest most human proteins likely have druggable pockets, too. It’s a finding that offers hope to those with currently untreatable diseases.”

Read the full story in Penn Medicine News.

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New Insights into the Mechanisms of Tumor Growth

by Nathi Magubane

3d render of cells secreting exosomes
A team of researchers led by the School of Arts & Science’s Wei Guo offers new insights into a mechanism that promotes tumor growth. “This information could be used to help clinicians diagnose cancers earlier in the future,” says Guo.

In many instances, the physical manifestation of cancers and the ways they are subsequently diagnosed is via a tumor, tissue masses of mutated cells and structures that grow excessively. One of the major mysteries in understanding what goes awry in cancers relates to the environments within which these structures grow, commonly known as the tumor microenvironment.

These microenvironments play a role in facilitating tumor survival, growth, and spread. Tumors can help generate their own infrastructure in the form of vasculature, immune cells, signaling molecules, and extracellular matrices (ECMs), three-dimensional networks of collagen-rich support scaffolding for a cell. ECMs also help regulate cellular communications, and in the tumor microenvironment ECMs can be a key promoter of tumor growth by providing structural support for cancerous cells and in modulating signaling pathways that promote growth.

Now, new research led by the School of Arts & Science’s Wei Guo and published in the journal Nature Cell Biology has bridged the complex structural interactions within the tumor microenvironment to the signals that trigger tumor growth. The researchers studied cancerous liver cells grown on ECMs of varying stiffness and discovered that the stiffening associated with tumor growth can initiate a cascade that increases the production of small lipid-encapsulated vesicles known as exosomes.

“Think of these exosomes as packages that each cell couriers out, and, depending on the address, they get directed to other cells,” says Ravi Radhakrishnan, professor of bioengineering in the School of Engineering and Applied Science and a co-author of the paper.

“By recording the number of packages sent, the addresses on these packages, their contents, and most importantly, how they’re regulated and generated, we can better understand the relationship between a patient’s tumor microenvironment and their unique molecular signaling signatures, hinting at more robust personalized cancer therapies,” Radhakrishnan says.

While studying exosomes in relation to tumor growth and metastasis has been well-documented in recent years, researchers have mostly focused on cataloging their characteristics rather than investigating the many processes that govern the creation and shuttling of exosomes between cells. As members of Penn’s Physical Sciences Oncology Center (PSOC), Guo and Radhakrishnan have long collaborated on projects concerning tissue stiffness. For this paper, they sought to elucidate how stiffening promotes exosome trafficking in cancerous intracellular signaling.

“Our lab previously found that high stiffness promotes the secretion of exosomes,” says Di-Ao Liu, co-first author of the paper and a graduate student in the Guo Lab. “Now, we were able to model the stiffening processes through experiments and identify molecular pathways and protein networks that cause this, which better links ECM stiffening to cancerous signaling.”

Read the full story in Penn Today.

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Targeted Prenatal Therapy for Mothers and Their Babies Addresses Longstanding Gap in Health Equity

by Melissa Pappas

The research team from left to right includes Kelsey Swingle, Hannah Safford, Alex Hamilton, Ajay Thatte, Hannah Geisler, and Mike Mitchell.

New research on reproductive health demonstrates the first successful delivery of mRNA to placental cells to treat pre-eclampsia at its root.

Pre-eclampsia is a leading cause of stillbirths and prematurity worldwide, occurring in 3 – 8 % of pregnancies. A disorder characterized by high maternal blood pressure, it results from insufficient vasodilation in the placenta, restricting blood flow from the mother to the fetus.

Currently, a health-care plan for someone with pre-eclampsia involves diet and movement changes, frequent monitoring, blood pressure management, and sometimes early delivery of the baby. These standards of care address symptoms of the condition, not the root cause, and further perpetuate health inequity.

Now, Penn engineers are addressing this longstanding gap in reproductive health care with targeted RNA therapy.

The COVID vaccines demonstrated how lipid nanoparticles (LNPs) efficiently deliver mRNA to target cells. The success of LNPs is opening doors for a variety of RNA therapies aiming to treat the root causes of illness and disease. However, drug development and health care have consistently neglected a portion of the population in need of targeted care the most – pregnant people and their babies.

Targeted Treatment for Pre-eclampsia. Current treatment: Early delivery. Results in high maternal blood pressure, restricted blood flow to the fetus. New treatment: Targeted RNA therapy and blood pressure monitoring. Strategically designed Lipid Nanoparticles deliver mRNA to placental cells. Vascular endothelial growth factor expands blood vessels, restores blood flow.In one of the first studies of its kind, published in the Journal of the American Chemical Society, Michael Mitchell, J. Peter and Geri Skirkanich Assistant Professor of Innovation in Bioengineering, and Kelsey Swingle, Ph.D. student in the Mitchell Lab and lead author, describe their development of an LNP with the ability to target and deliver mRNA to trophoblasts, endothelial cells, and immune cells in the placenta.

Once these cells receive the mRNA, they create vascular endothelial growth factor (VEGF), a protein that helps expand the blood vessels in the placenta to reduce the mother’s blood pressure and restore adequate circulation to the fetus. The researchers’ successful trials in mice may lead to promising treatments for pre-eclampsia in humans.

Read the full story in Penn Engineering Today.

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New Single Cell Analysis Tool

by Nathi Magubane

Researchers at Penn and colleagues have developed a tool to analyze single cells that assesses both the patterns of gene activation within a cell and which sibling cells shared a common progenitor.

3D illustration of a cell held by a pipet and a needle
Arjun Raj of the School of Engineering and Applied Science and the Perelman School of Medicine, former postdoc Lee Richman, now of Brigham and Women’s Hospital, and colleagues have developed a new analysis tool that combines a cell’s unique gene expression data with information about the cell’s origins. The method can be applied to identify new cell subsets throughout development and better understand drug resistance.

Recent advances in analyzing data at the single-cell level have helped biologists make great strides in uncovering new information about cells and their behaviors. One commonly used approach, known as clustering, allows scientists to group cells based on characteristics such as the unique patterns of active or inactive genes or by the progeny of duplicating cells, known as clones, over several generations.

Although single-cell clustering has led to many significant findings, for example, new cancer cell subsets or the way immature stem cells mature into “specialized” cells, researchers to this point had not been able to marry what they knew about gene-activation patterns with what they knew about clone lineages.

Now, research published in Cell Genomics led by University of Pennsylvania professor of bioengineering Arjun Raj has resulted in the development of ClonoCluster, an open-source tool that combines unique patterns of gene activation with clonal information. This produces hybrid cluster data that can quickly identify new cellular traits; that can then be used to better understand resistance to some cancer therapies.

“Before, these were independent modalities, where you would cluster the cells that express the same genes in one lot and cluster the others that share a common ancestor in another,” says Lee Richman, first paper author and a former postdoc in the Raj lab who is now at Brigham and Women’s Hospital in Boston. “What’s exciting is that this tool allows you to draw new lines around your clusters and explore their properties, which could help us identify new cell types, functions, and molecular pathways.”

Researchers in the Raj Lab use a technique known as barcoding to assign labels to cells they are interested in studying, particularly useful for tracking cells, clustering data based on cells’ offspring, and following lineages over time. Believing they could parse more valuable information out of this data by incorporating the cell’s unique patterns of gene activation, the researchers applied ClonoCluster to six experimental datasets that used barcoding to track dividing cells’ offspring. Specifically, they looked at the development of chemotherapy resistance and of stem cells into specialized tissue types.

Read the full story in Penn Today.