Deconstructing the Mechanics of Bone Marrow Disease

by Katherine Unger Baillie

Acollaborative team developed an alginate-based hydrogel system that mimics the viscoelasticity of the natural extracellular matrix in bone marrow. By tweaking the balance between elastic and viscous properties in these artificial ECMs, they could recapitulate the viscoelasticity of healthy and scarred fibrotic bone marrow, and study the effects on human monocytes placed into these artificial ECMs. (Image: Adam Graham/Harvard CNS/Wyss Institute at Harvard University)

Fibrosis is the thickening of various tissues caused by the deposition of fibrillar extracellular matrix (ECM) in tissues and organs as part of the body’s wound healing response to various forms of damage. When accompanied by chronic inflammation, fibrosis can go into overdrive and produce excess scar tissue that can no longer be degraded. This process causes many diseases in multiple organs, including lung fibrosis induced by smoking or asbestos, liver fibrosis induced by alcohol abuse, and heart fibrosis often following heart attacks. Fibrosis can also occur in the bone marrow, the spongy tissue inside some bones that houses blood-producing hematopoietic stem cells (HSCs) and can lead to scarring and the disruption of normal functions.

Chronic blood cancers known as “myeloproliferative neoplasms” (MPNs) are one example, in which patients can develop fibrotic bone marrow, or myelofibrosis, that disrupts the normal production of blood cells. Monocytes, a type of white blood cell belonging to the group of myeloid cells, are overproduced from HSCs in neoplasms and contribute to the inflammation in the bone marrow environment, or niche. However, how the fibrotic bone marrow niche itself impacts the function of monocytes and inflammation in the bone marrow was unknown.

Now, a collaborative team from PennHarvard, the Dana-Farber Cancer Institute (DFCI), and Brigham and Women’s Hospital has created a programmable hydrogel-based in vitro model mimicking healthy and fibrotic human bone marrow. Combining this system with mouse in vivo models of myelofibrosis, the researchers demonstrated that monocytes decide whether to enter a pro-inflammatory state and go on to differentiate into inflammatory dendritic cells based on specific mechanical properties of the bone marrow niche with its densely packed ECM molecules. Importantly, the team found a drug that could tone down these pathological mechanical effects on monocytes, reducing their numbers as well as the numbers of inflammatory myeloid cells in mice with myelofibrosis. The findings are published in Nature Materials.

“We found that stiff and more elastic slow-relaxing artificial ECMs induced immature monocytes to differentiate into monocytes with a pro-inflammatory program strongly resembling that of monocytes in myelofibrosis patients, and the monocytes to differentiate further into inflammatory dendritic cells,” says co-first author Kyle Vining, who recently joined Penn’s School of Dental Medicine and School of Engineering and Applied Science as an assistant professor of preventive and restorative sciences. “More viscous fast-relaxing artificial ECMs suppressed this myelofibrosis-like effect on monocytes. This opened up the possibility of a mechanical checkpoint that could be disrupted in myelofibrotic bone marrow and also may be at play in other fibrotic diseases.”

Vining worked on the study as a postdoctoral fellow at Harvard in the lab of David Mooney. “Our study shows that the differentiation state of monocytes, which are key players in the immune system, is highly regulated by mechanical changes in the ECM they encounter,” says Mooney, who co-led the study with DFCI researcher Kai Wucherpfennig. “Specifically, the ECM’s viscoelasticity has been a historically under-appreciated aspect of its mechanical properties that we find correlates strongly between our in vitro and the in vivo models and human disease. It turns out that myelofibrosis is a mechano-related disease that could be treated by interfering with the mechanical signaling in bone marrow cells.”

Continue reading at Penn Today

Center for Innovation & Precision Dentistry Welcomes Inaugural Class to Training Program

The inaugural class of the CiPD NIDCR T90/R90 Postdoctoral Training Program Fellows with Dean Mark Wolff (center); Dr. Michel Koo, Founding Director of CiPD (far right); and CiPD Co-Director Dr. Kathleen Stebe of Penn’s School of Engineering and Applied Science (far left).

With one of its key missions to develop a new generation of scientists at the interface of dental medicine and engineering, the Center for Innovation & Precision Dentistry (CiPD) has selected its inaugural class of fellows for its new postdoctoral training program.

The CiPD was awarded a $2.5 million T90/R90 grant from the National Institute of Dental and Craniofacial Research (NIDCR) last summer to establish the program, recently naming this first cohort of fellows that includes Justin Burrell,  Marshall Padilla,  Zhi Ren, and Dennis Sourvanos.

“We’re hoping this program will promote cross-pollination and create a culture between these two fields to help dentists develop innovative strategies with engineers,” says Penn Dental Medicine’s Michel Koo, Co-Director of CiPD, who launched the Center in 2021 with Co-Director Kathleen Stebe, Richer & Elizabeth Goodwin Professor in Penn Engineering’s Department of Chemical and Biomolecular Engineering. “Dentists can learn from engineering principles and tools, and engineers can understand more about the needs of the dental and craniofacial fields. We’re providing a platform for them to work together to address unmet clinical needs and develop careers in that interface.”

The NIDCR T90/R90 Postdoctoral Training Program aims to specifically focus on the oral microbiome, host immunity, and tissue regeneration, each of which ties into different aspects of oral health, from tooth decay and periodontal disease to the needs of head and neck cancer patients. To advance these areas, emerging approaches, from advanced materials, robotics, and artificial intelligence to tissue engineering, chloroplast- and nanoparticle-based technologies, will be leveraged.

As part of the two-year training, each postdoc will receive co-mentorship from faculty from each school in conjunction with a career development committee of clinicians, basic scientists, as well as engineers. These mentorships will be focused on research outcomes and readying participants to submit grants and compete for positions in academia or industry.

The inaugural class of fellows includes Justin Burrell, a postdoctoral student in the lab of D. Kacy Cullen, Associate Professor of Neurosurgery; Marshall Padilla, a postdoc in the lab of Michael J. Mitchell, Skirkanich Assistant Professor of Innovation in Bioengineering; and Zhi Ren, a postdoc in the lab of Michael Koo; and Dennis Sourvanos, an Advanced Graduate Dental Education resident at Penn Dental Medicine whose research has been co-directed by Timothy C. Zhu, Professor of Radiation Oncology in the Perelman School of Medicine. Cullen, Mitchell, Koo and Zhu are all members of the Penn Bioengineering Graduate Group.

Read more about the inaugural class of postdocs at Penn Dental Medicine News

Shapeshifting Microrobots Can Brush and Floss Teeth

by Katherine Unger Baillie

In a proof-of-concept study, researchers from the School of Dental Medicine and School of Engineering and Applied Science shows that a hands-free system could effectively automate the treatment and removal of tooth-decay-causing bacteria and dental plaque. (Illustration: Melissa Pappas)

A shapeshifting robotic microswarm may one day act as a toothbrush, rinse, and dental floss in one.

The technology, developed by a multidisciplinary team at the University of Pennsylvania, is poised to offer a new and automated way to perform the mundane but critical daily tasks of brushing and flossing. It’s a system that could be particularly valuable for those who lack the manual dexterity to clean their teeth effectively themselves.

The building blocks of these microrobots are iron oxide nanoparticles that have both catalytic and magnetic activity. Using a magnetic field, researchers could direct their motion and configuration to form either bristlelike structures that sweep away dental plaque from the broad surfaces of teeth, or elongated strings that can slip between teeth like a length of floss. In both instances, a catalytic reaction drives the nanoparticles to produce antimicrobials that kill harmful oral bacteria on site.

Experiments using this system on mock and real human teeth showed that the robotic assemblies can conform to a variety of shapes to nearly eliminate the sticky biofilms that lead to cavities and gum disease. The Penn team shared their findings establishing a proof-of-concept for the robotic system in the journal ACS Nano.

“Routine oral care is cumbersome and can pose challenges for many people, especially those who have hard time cleaning their teeth” says Hyun (Michel) Koo, a professor in the Department of Orthodontics and divisions of Community Oral Health and Pediatric Dentistry in Penn’s School of Dental Medicine and co-corresponding author on the study. “You have to brush your teeth, then floss your teeth, then rinse your mouth; it’s a manual, multistep process. The big innovation here is that the robotics system can do all three in a single, hands-free, automated way.”

Read the full story in Penn Engineering Today.

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

Edward Steager is a senior research investigator in Penn’s School of Engineering and Applied Science.

Koo and Steager’s coauthors on the paper are Penn Dental Medicine’s Min Jun Oh, Alaa Babeer, Yuan Liu, and Zhi Ren and Penn Engineering’s Jingyu Wu, David A. Issadore, Kathleen J. Stebe, and Daeyeon Lee.

This work was supported in part by the National Institute for Dental and Craniofacial Research (grants DE025848 and DE029985), Procter & Gamble, and the Postdoctoral Research Program of Sungkyunkwan University.

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 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.

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.

Penn Dental, Penn Engineering Unite to Form Center for Innovation & Precision Dentistry

by Beth Adams

With the shared vision to transform the future of oral health care, Penn Dental Medicine and Penn’s School of Engineering and Applied Sciences have united to form the Center for Innovation & Precision Dentistry (CiPD). The new Center marked its official launch on January 22 with a virtual program celebrating the goals and plans of this unique partnership. Along with the Deans from both schools, the event gathered partners from throughout the University of Pennsylvania and invited guests, including the National Institute of Dental and Craniofacial Research Director (NIDCR) Dr. Rena D’Souza and IADR Executive Director Chris Fox.

Conceived and brought to fruition by co-directors Dr. Michel Koo of Penn Dental Medicine and Dr. Kathleen Stebe of Penn Engineering, the CiPD is bridging the two schools through cutting-edge research and technologies to accelerate the development of new solutions and devices to address unmet needs in oral health, particularly in the areas of dental caries, periodontal disease, and head and neck cancer. The CiPD will also place a high priority on programs to train the next generation of leaders in oral health care innovation.

“We have a tremendous global health challenge. Oral diseases and craniofacial disorders affect 3.5 billion people, disproportionately affecting the poor and the medically and physically compromised,” says Dr. Koo, Professor in the Department of Orthodontics and Divisions of Community Oral Health and Pediatric Dentistry, in describing their motivation to form the Center. “There is an urgent need to find better ways to diagnose, prevent, and treat these conditions, particularly in ways that are affordable and accessible for the most susceptible populations. That is our driving force for putting this Center together.”

“We have united our schools around this mission,” adds Dr. Stebe, Richer & Elizabeth Goodwin Professor in the Department of Chemical and Biomolecular Engineering. “We have formed a community of scholars to develop and harness new engineering paradigms, to generate new knowledge, and to seek new approaches that are more effective, precise, and affordable to address oral health. More importantly, we will train a new community of scholars to impact this space.”

Born through Interdisciplinary Research

A serendipitous connection born through Penn’s interdisciplinary research environment itself brought Drs. Koo and Stebe together more than five years ago, an introduction that would eventually lead to creating the CiPD.

Dr. Tagbo Niepa, now assistant professor at the University of Pittsburgh, came to Penn Engineering in 2014 as part of Penn’s Postdoctoral Fellowship for Academic Diversity, an initiative from the office of the Vice Provost for Research. His studies on the microbiome led him to reach out to Dr. Stebe and Dr. Daeyeon Lee (also at Penn Engineering), and to connect them to Dr. Koo, initiating collaboration between their labs.

“Tagbo embodies what we are trying to do with the CiPD,” recalls Dr. Stebe. “He had initiative, he identified new tools and important context, and he did good science that may help us understand how to interrupt the disease process and identify new underlying mechanisms that can inspire new therapies.” Dr. Niepa worked on applying microfluidics and engineering to study the oral microbiome and better understand how the interactions between fungi and bacteria could impact dental caries.

“Upon meeting Michel, we became excited about the possibilities of bringing talent from the two schools together,” notes Dr. Stebe. A 2018 workshop organized by Drs. Koo and Stebe and funded by Penn’s Vice Provost of Research explored the potential for expanding cross-school research. “We invited researchers from dental medicine and engineering as well as relevant people from the arts and sciences to see if we could find a way to collaborate to advance oral and craniofacial health,” says Dr. Koo. “That was the catalyst for the Center; after the workshop, we put together a task force which would become the core members of the CiPD.”

In addition to Drs. Koo and Stebe, the CiPD Executive Committee includes Associate Directors Dr. Henry Daniell, Vice-Chair and W.D. Miller Professor, Department of Basic & Translational Sciences, Penn Dental Medicine, and Dr. Anh Le, Chair and Norman Vine Endowed Professor of Oral Rehabilitation, Department of Oral and Maxillofacial Surgery / Pharmacology, Penn Dental Medicine; as well as Dr. Andrew Tsourkas, Professor, Department of Bioengineering, Co-Director, Center for Targeted Therapeutics & Translational Nanomedicine (CT3N) and Chemical and Nanoparticle Synthesis Core, Penn Engineering; and Dr. Jason Moore, Edward Rose Professor of Informatics, Director of the Penn Institute for Biomedical Informatics. The core members of CiPD include 26 faculty from across both Penn Dental Medicine and Penn Engineering, and also from the Schools of Medicine and Arts & Sciences.

Read the full story in Penn Today.