A New Model for How the Brain Perceives Unique Odors

by Erica K. Brockmeier

Cathy and Marc Lasry Professor Vijay Balasubramanian at Penn’s BioPond.

A study published in PLOS Computational Biology describes a new model for how the olfactory system discerns unique odors. Researchers from the University of Pennsylvania found that a simplified, statistics-based model can explain how individual odors can be perceived as more or less similar from others depending on the context. This model provides a starting point for generating new hypotheses and conducting experiments that can help researchers better understand the olfactory system, a complex, crucial part of the brain.

The sense of smell, while crucial for things like taste and hazard avoidance, is not as well studied as other senses. Study co-author Vijay Balasubramanian, a theoretical physicist with an interest in how living systems process information, says that olfaction is a prime example of a complex information-processing system found in nature, as there are far more types of volatile molecules—on the scale of tens or hundreds of thousands—than there are receptor types in the nose to detect them, on the scale of tens to hundreds depending on the species.

“Every molecule can bind to many receptors, and every receptor can bind to many molecules, so you get this combinatorial mishmash, with the nose encoding smells in a way that involves many receptor types to collectively tell you what a smell is,” says Balasubramanian. “And because there are many fewer receptor types than molecular species, you basically have to compress a very high dimensional olfactory space into a much lower dimensional space of neural responses.”

Read the full story in Penn Today.

Vijay Balasubramanian is the Cathy and Marc Lasry Professor in the Department of Physics & Astronomy in the School of Arts & Sciences at the University of Pennsylvania and a member of the Penn Bioengineering Graduate Group.

This research was supported by the Simons Foundation Mathematical Modeling of Living Systems (Grant 400425) and the Swartz Foundation.

Carl June Highlighted for Success in Gene Therapy

Carl June, MD

Scientific American recently featured two gene therapies that were invented at Penn, including research from Carl June, MD, the Richard W. Vague Professor in Immunotherapy in Pathology and Laboratory Medicine, director of the Center for Cellular Immunotherapies, and member of the Penn Bioengineering Graduate Group, which led to the FDA approval for the CAR T therapy (sold by Novartis as Kymriah) for treating acute lymphoblastic leukemia (ALL), one of the most common childhood cancers.

Read “Four Success Stories in Gene Therapy” in Scientific American.

Nerve Repair, With Help From Stem Cells

A cross-disciplinary Penn team is pioneering a new approach to peripheral nerve repair.

In a new publication in the journal npj Regenerative Medicine, a team of Penn researchers from the School of Dental Medicine and the Perelman School of Medicine “coaxed human gingiva-derived mesenchymal stem cells (GMSCs) to grow Schwann-like cells, the pro-regenerative cells of the peripheral nervous system that make myelin and neural growth factors,” addressing the need for regrowing functional nerves involving commercially-available scaffolds to guide nerve growth. The study was led by Anh Le, Chair and Norman Vine Endowed Professor of Oral Rehabilitation in the Department of Oral and Maxillofacial Surgery/Pharmacology at the University of Pennsylvania School of Dental Medicine, and was co-authored by D. Kacy Cullen, Associate Professor in Neurosurgery at the Perelman School of Medicine at Penn and the Philadelphia Veterans Affairs Medical Center and member of the Bioengineering Graduate Group:

D. Kacy Cullen (Image: Eric Sucar)

“To get host Schwann cells all throughout a bioscaffold, you’re basically approximating natural nerve repair,” Cullen says. Indeed, when Le and Cullen’s groups collaborated to implant these grafts into rodents with a facial nerve injury and then tested the results, they saw evidence of a functional repair. The animals had less facial droop than those that received an “empty” graft and nerve conduction was restored. The implanted stem cells also survived in the animals for months following the transplant.

“The animals that received nerve conduits laden with the infused cells had a performance that matched the group that received an autograft for their repair,” he says. “When you’re able to match the performance of the gold-standard procedure without a second surgery to acquire the autograft, that is definitely a technology to pursue further.”

Read the full story and view the full list of collaborators in Penn Today.

Penn Engineers Will Use NSF Grant to Develop ‘DReAM’ for On-demand, On-site mRNA Manufacturing

by Melissa Pappas

Daeyeon Lee, Kathleen Stebe and Michael Mitchell

COVID-19 vaccines are just the beginning for mRNA-based therapies; enabling a patient’s body to make almost any given protein could revolutionize care for other viruses, like HIV, as well as various cancers and genetic disorders. However, because mRNA molecules are very fragile, they require extremely low temperatures for storage and transportation. The logistical challenges and expense of maintaining these temperatures must be overcome before mRNA therapies can become truly widespread.

With these challenges in mind, Penn Engineering researchers are developing a new manufacturing technique that would be able to produce mRNA sequences on demand and on-site, isolating them in a way that removes the need for cryogenic temperatures. With more labs able to make and store mRNA-based therapeutics on their own, the “cold chain” between manufacturer and patient can be made shorter, faster and less expensive.

The National Science Foundation (NSF) is supporting this project, known as Distributed Ribonucleic Acid Manufacturing, or DReAM, through a four-year, $2 million grant from its Emerging Frontiers in Research and Innovation (EFRI) program.

The project will be led by Daeyeon Lee, Evan C Thompson Term Chair for Excellence in Teaching and Professor in the Department of Chemical and Biomolecular Engineering (CBE), along with Kathleen Stebe, Richer and Elizabeth Goodwin Professor in CBE and in the Department of Mechanical Engineering and Applied Mechanics. They will collaborate with Michael Mitchell, Skirkanich Assistant Professor of Innovation in the Department of Bioengineering, Drexel University’s Masoud Soroush and Michael Grady, the University of Oklahoma’s Dimitrios Papavassiliou and the University of Colorado Boulder’s Joel Kaar.

Read the full story in Penn Engineering Today.

Penn Dental Medicine, Penn Engineering Award First IDEA Prize to Advance Oral Health Care Innovation

Henry Daniell and Daeyeon Lee

by Beth Adams

Penn Dental Medicine and Penn Engineering, which teamed earlier this year to launch the Center for Innovation and Precision Dentistry (CiPD), recently awarded the Center’s first IDEA (Innovation in Dental Medicine and Engineering to Advance Oral Health) Prize. Dr. Henry Daniell, W.B. Miller Professor and Vice Chair in the Department of Basic & Translational Sciences at Penn Dental Medicine, and his collaborator, Dr. Daeyeon Lee, Professor of Chemical and Biomolecular Engineering at Penn Engineering, are the inaugural recipients, awarded the Prize for a project titled “Engineered Chewing Gum for Debulking Biofilm and Oral SARS-CoV-2.”

“The IDEA Prize was created to support Penn Dental and Penn Engineering collaboration, and this project exemplifies the transformative potential of this interface to develop new solutions to treat oral diseases,” says Dr. Michel Koo, Professor in the Department of Orthodontics and Divisions of Pediatric Dentistry and Community Oral Health at Penn Dental Medicine and Co-Director of the CiPD.

“The prize is an exciting opportunity to unite Drs. Lee and Daniell and their vision to bring together state-of-the-art functional materials and drug-delivery platforms,” adds Dr. Kathleen Stebe, CiPD Co-Director and Goodwin Professor of Engineering and Applied Science at Penn Engineering.

Open to faculty from Penn Dental Medicine and Penn Engineering, the IDEA Prize, to be awarded annually, supports collaborative teams investigating novel ideas using engineering approaches to kickstart competitive proposals for federal funding and/or private sector/industry for commercialization. Awardees are selected based on originality and novelty; the impact of the proposed innovation of oral/craniofacial health; and the team composition with complementary expertise. Indeed, the project of Drs. Daniell and Lee reflects all three.

The collaborative proposal combines Dr. Daniell’s novel plant-based drug development/delivery platform with Dr. Lee’s novel polymeric structures to create an affordable, long-lasting way to reduce dental biofilms (plaque) and oral SARS-CoV-2 transmission using a uniquely consumer-friendly delivery system — chewing gum.

“Oral diseases afflict 3.5 billion people worldwide, and many of these conditions are caused by microbes that accumulate on teeth, forming difficult to treat biofilms,” says Dr. Daniell. “In addition, saliva is a source of pathogenic microbes and aerosolized particles transmit disease, including COVID-19, so there is an urgent need to develop new methods to debulk pathogens in the saliva and decrease their aerosol transmission.”

Continue reading at Penn Dental Medicine News.

N.B. Henry Daniell and Daeyeon Lee are members of the Penn Bioengineering Graduate Group.

Decoding How the Brain Accurately Depicts Ever-changing Visual Landscapes

A collaborative study finds that deeper regions of the brain encode visual information more slowly, enabling the brain to identify fast-moving objects and images more accurately and persistently.

by Erica K. Brockmeier

Busy pedestrian crossing at Hong Kong

New research from the University of Pennsylvania, the Scuola Internazionale Superiore de Studi Avanzati (SISSA), and KU Leuven details the time scales of visual information processing across different regions of the brain. Using state-of-the-art experimental and analytical techniques, the researchers found that deeper regions of the brain encode visual information slowly and persistently, which provides a mechanism for explaining how the brain accurately identifies fast-moving objects and images. The findings were published in Nature Communications.

Understanding how the brain works is a major research challenge, with many theories and models developed to explain how complex information is processed and represented. One area of particular interest is vision, a major component of neural activity. In humans, for example, there is evidence that around half of the neurons in the cortex are related to vision.

Researchers are eager to understand how the visual cortex can process and retain information about objects in motion in a way that allows people to take in dynamic scenes while still retaining information about and recognizing the objects around them.

“One of the biggest challenges of all the sensory systems is to maintain a consistent representation of our surroundings, despite the constant changes taking place around us. The same holds true for the visual system,” says Davide Zoccolan, director of SISSA’s Visual Neuroscience Laboratory. “Just look around us: objects, animals, people, all on the move. We ourselves are moving. This triggers rapid fluctuations in the signals acquired by the retina, and until now it was unclear whether the same type of variations apply to the deeper layers of the visual cortex, where information is integrated and processed. If this was the case, we would live in tremendous confusion.”

Experiments using static stimuli, such as photographs, have found that information from the sensory periphery are processed in the visual cortex according to a finely tuned hierarchy. Deeper regions of the brain then translate this information about visual scenes into more complex shapes, objects, and concepts. But how this process works in more dynamic, real-world settings is not well understood.

To shed light on this, the researchers analyzed neural activity patterns in multiple visual cortical areas in rodents while they were being shown dynamic visual stimuli. “We used three distinct datasets: one from SISSA, one from a group in KU Leuven led by Hans Op de Beeck and one from the Allen Institute for Brain Science in Seattle,” says Zoccolan. “The visual stimuli used in each were of different types. In SISSA, we created dedicated video clips showing objects moving at different speeds. The other datasets were acquired using various kinds of clips, including from films.”

Next, the researchers analyzed the signals registered in different areas of the visual cortex through a combination of sophisticated algorithms and models developed by Penn’s Eugenio Pasini and Vijay Balasubramanian. To do this, the researchers developed a theoretical framework to help connect the images in the movies to the activity of specific neurons in order to determine how neural signals evolve over different time scales.

“The art in this science was figuring out an analysis method to show that the processing of visual images is getting slower as you go deeper and deeper in the brain,” says Balasubramanian. “Different levels of the brain process information over different time scales; some things could be more stable, some quicker. It’s very hard to tell if the time scales across the brain are changing, so our contribution was to devise a method for doing this.”

Read the full story in Penn Today.

Vijay Balasubramanian is the Cathy and Marc Lasry Professor in the Department of Physics and Astronomy in the School of Arts & Sciences and a member of the Penn Bioengineering Graduate Group at the University of Pennsylvania.

The Pioneering Career of Norman Badler

by Ebonee Johnson

The retiring CIS professor chats about his recent ACM SIGGRAPH election and his expansive computer graphics path.

Norman Badler, Ph.D. (Image credit: Penn CIS)

Norman Badler’s election into the 2021 ACM SIGGRAPH Academy Class is right on time. After nearly five decades of teaching and trailblazing in the Penn community, the Rachleff Family Professor in the Department of Computer and Information Sciences retired at the end of the spring semester.

When he arrived at the University in 1974, CIS itself was only about 2 years old, and there was virtually no computer graphics focus or program at all. Badler had no intention to teach it.

“At that time, I was actually a computer vision researcher, but I was also working a little bit in natural language,” says Badler. “So I was literally brought in to fit between the chair, Aravind Joshi, who was a natural language person, and the computer vision person. It wasn’t until about three or four years after I came here that I switched over to computer graphics. Mostly because there was a vacuum and a need and an excitement.”

Several years after completing his dissertation in computer vision and forming a career path to head in that direction, Badler “started getting serious about computer graphics.” An organization that was getting its start around the same time as his Penn career would play a major role: ACM SIGGRAPH (the Association for Computing Machinery’s Special Interest Group on Computer Graphics and Interactive Techniques).

Read the full story in the CIS Blog.

N.B.: Badler was a member of the Penn Bioengineering Graduate Group.

New Grant Aims to Broaden Participation in Cutting-Edge Materials Research

University of Puerto Rico’s Edgardo Sánchez (left) and Penn graduate Zhiwei Liao working in the lab of Daeyeon Lee. Via the Advancing Device Innovation through Inclusive Research and Education program, researchers from Penn and the University of Puerto Rico will continue their materials science collaboration while supporting STEM career pathways for underrepresented groups. (Image credit: Felice Macera).

The National Science Foundation (NSF) has awarded grants to eight research teams to support partnerships that will increase diversity in cutting-edge materials research, education, and career development. One of those teams is Penn’s Laboratory for Research on the Structure of Matter (LRSM) and the University of Puerto Rico (UPR), whose long-running collaboration has now received an additional six years of support.

With the goal of supporting partnerships between minority-serving educational institutions and leading materials science research centers, NSF’s Partnership for Research & Education in Materials (PREM) program funds innovative research programs and provides institutional support to increase recruitment, retention, and graduation by underrepresented groups as well as providing underserved communities access to materials research and education.

‘Research at the frontier’

With this PREM award, known as the Advancing Device Innovation through Inclusive Research and Education (ADIIR) program, researchers from Penn and UPR’s Humacao and Cayey campuses will conduct research on the properties of novel carbon-based materials with unique properties, and will study the effects of surface modification in new classes of sensors, detectors, and purification devices.

Thanks to this collaboration of more than 20 years, both institutions have made significant scientific and educational progress aided by biannual symposia and regular pre-pandemic travel between both institutions before the pandemic, resulting in a rich portfolio of publications, conference presentations, patents, students trained, and outreach programs.

“Together we have been publishing good papers that have impact, and we’ve really cultivated a culture of collaboration and friendship between our institutions,” says Penn’s Arjun Yodh, former director of the LRSM. “Our goal is to carry out research at the frontier and, in the process, nurture promising students from Puerto Rico and Penn.”

Ivan Dmochowski, a chemistry professor at Penn who has been involved with PREM for several years, says that this program has helped his group connect with experts in Puerto Rico whose skills complement his group’s interests in protein engineering. Dmochowski has also hosted UPR faculty members and students in his lab and also travelled to Puerto Rico before the pandemic to participate in research symposia, seminars, and outreach events.

“I’ve had students who have benefitted from being a co-author on a paper or having a chance to mentor students, and the faculty we’ve interacted with are exceptional,” Dmochowski says. “There’s a lot of benefit for both me and my students, and I’ve enjoyed our interactions both personally and scientifically.”

Penn’s Daeyeon Lee, a chemical and biomolecular engineering professor who has been involved with PREM for several years, regularly hosts students and faculty from UPR while working on nanocarbon-based composite films for sensor applications. The success of this collaboration relies on unique materials made by researchers at UPR combined with a method for processing them into composite structures developed in Lee’s lab.

“What I really admire about people at PREM, both faculty and students, is their passion,” says Lee. “I think that’s had a really positive impact on my students and postdocs who got to interact with them because they got to see the passion that the students brought.”

Read the full story in Penn Today.

Daeyeon Lee is a professor and the Evan C Thompson Term Chair for Excellence in Teaching in the Department of Chemical and Biomolecular Engineering and a member of the Bioengineering Graduate Group in Penn’s School of Engineering and Applied Science.

Arjun Yodh is the James M. Skinner Professor of Science in the Department of Physics & Astronomy in Penn’s School of Arts & Sciences and a member of the Bioengineering Graduate Group in Penn’s School of Engineering and Applied Science.

“’Electronic Nose’ Accurately Sniffs Out Hard-to-Detect Cancers”

A.T. Charlie Johnson, Ph.D.

A.T. Charlie Johnson, Rebecca W. Bushnell Professor of Physics and Astronomy at the Penn School of Arts & Sciences, and member of the Penn Bioengineering Graduate Group has been working with a team of researchers on a new “electronic nose” that could help track the spread of COVID-19 based on the disease’s unique odor profile. Now, similar research shows that vapors emanating from blood samples can be tested to distinguish between benign and cancerous pancreatic and ovarian cells. Johnson presented the results at the annual American Society of Clinical Oncology meeting on June 4 (Abstract # 5544):

“It’s an early study but the results are very promising,” Johnson said. “The data shows we can identify these tumors at both advanced and the earliest stages, which is exciting. If developed appropriately for the clinical setting, this could potentially be a test that’s done on a standard blood draw that may be part of your annual physical.”

Read the full story in Penn Medicine News.

How HIV Infection Shrinks the Brain’s White Matter

by Katherine Unger Baillie

Researchers from Penn and CHOP detail the mechanism by which HIV infection blocks the maturation process of brain cells that produce myelin, a fatty substance that insulates neurons.

A confocal microscope image shows an oligodendrocyte in cell culture, labeled to show the cell nucleus in blue and myelin proteins in red, green, and yellow. Researchers from Penn and CHOP have shown that HIV infection prevents oligodendrocytes from maturing, leading to a reduction in white matter in the brain. (Image: Raj Putatunda)

It’s long been known that people living with HIV experience a loss of white matter in their brains. As opposed to gray matter, which is composed of the cell bodies of neurons, white matter is made up of a fatty substance called myelin that coats neurons, offering protection and helping them transmit signals quickly and efficiently. A reduction in white matter is associated with motor and cognitive impairment.

Earlier work by a team from the University of Pennsylvania and Children’s Hospital of Philadelphia (CHOP) found that antiretroviral therapy (ART)—the lifesaving suite of drugs that many people with HIV use daily—can reduce white matter, but it wasn’t clear how the virus itself contributed to this loss.

In a new study using both human and rodent cells, the team has hammered out a detailed mechanism, revealing how HIV prevents the myelin-making brain cells called oligodendrocytes from maturing, thus putting a wrench in white matter production. When the researchers applied a compound blocking this process, the cells were once again able to mature.

The work is published in the journal Glia.

“Even when people with HIV have their disease well-controlled by antiretrovirals, they still have the virus present in their bodies, so this study came out of our interest in understanding how HIV infection itself affects white matter,” says Kelly Jordan-Sciutto, a professor in Penn’s School of Dental Medicine and co-senior author on the study. “By understanding those mechanisms, we can take the next step to protect people with HIV infection from these impacts.”

“When people think about the brain, they think of neurons, but they often don’t think about white matter, as important as it is,” says Judith Grinspan, a research scientist at CHOP and the study’s other co-senior author. “But it’s clear that myelination is playing key roles in various stages of life: in infancy, in adolescence, and likely during learning in adulthood too. The more we find out about this biology, the more we can do to prevent white matter loss and the harms that can cause.”

Jordan-Sciutto and Grinspan have been collaborating for several years to elucidate how ART and HIV affect the brain, and specifically oligodendrocytes, a focus of Grinspan’s research. Their previous work on antiretrovirals had shown that commonly used drugs disrupted the function of oligodendrocytes, reducing myelin formation.

In the current study, they aimed to isolate the effect of HIV on this process. Led by Lindsay Roth, who recently earned her doctoral degree within the Biomedical Graduate Studies group at Penn and completed a postdoctoral fellowship working with Jordan-Sciutto and Grinspan, the investigation began by looking at human macrophages, one of the major cell types that HIV infects.

Read the full story in Penn Today.

Kelly Jordan-Sciutto is vice chair and professor in the University of Pennsylvania School of Dental Medicine’s Department of Basic & Translational Sciences and is director of Biomedical Graduate Studies. She is a member of the Penn Bioengineering Graduate Group.