Tag: postdoc

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Understanding the Physics of Kidney Development

Abstract image of tubules repelling each other and shifting around.
The model of tubule packing developed by the Hughes Lab shows the tubules repelling each other and shifting around.

A recent study by Penn Bioengineering researchers sheds new light on the role of physics in kidney development. The kidney uses structures called nephrons and tubules to filter blood and pass urine to the bladder. Nephron number is set at birth and can vary over an order of magnitude (anywhere from 100,000 to over a million nephrons in an individual kidney). While the reasons for this variability remain unclear, low numbers of nephrons predispose patients to hypertension and chronic kidney disease. 

Now, research published in Developmental Cell led by Alex J. Hughes, Assistant Professor in the Department of Bioengineering, demonstrates a new physics-driven approach to better visualize and understand how a healthy kidney develops to avoid organizational defects that would impair its function. While previous efforts have typically approached this problem using molecular genetics and mouse models, the Hughes Lab’s physics-based approach could link particular types of defects to this genetic information and possibly highlight new treatments to prevent or fix congenital defects.

During embryonic development, kidney tubules grow and the tips divide to make a branched tree with clusters of nephron stem cells surrounding each branch tip. In order to build more nephrons, the tree needs to grow more branches. To keep the branches from overlapping, the kidney’s surface grows more crowded as the number of branches increase. “At this point, it’s like adding more people to a crowded elevator,” says Louis Prahl, first author of the paper and Postdoctoral Fellow in the Hughes Lab. “The branches need to keep rearranging to accommodate more until organ growth stops.”

To understand this process, Hughes, Prahl and their team investigated branch organization in mouse kidneys as well as using computer models and a 3D printed model of tubules. Their results show that tubules have to actively restructure – essentially divide at narrower angles – to accommodate more tubules. Computer simulations also identified ‘defective’ packing, in which the simulation parameters caused tubules to either overlap or be forced beneath the kidney surface. The team’s experimentation and analysis of published studies of genetic mouse models of kidney disease confirmed that these defects do occur.

This study represents a unique synthesis of different fields to understand congenital kidney disease. Mathematicians have studied geometric packing problems for decades in other contexts, but the structural features of the kidney present new applications for these models. Previous models of kidney branching have approached these problems from the perspective of individual branches or using purely geometric models that don’t account for tissue mechanics. By contrast, The Hughes Lab’s computer model demonstrates the physics of how tubule families interact with each other, allowing them to identify ‘phases’ of kidney organization that either relate to normal kidney development or organizational defects. Their 3D printed model of tubules shows that these effects can occur even when one sets the biology aside.

Hughes has been widely recognized for his research in the understanding of kidney development. This new publication is the first fruit of his 2021 CAREER Award from the National Science Foundation (NSF) and he was recently named a 2023 Rising Star by the Cellular and Molecular Bioengineering (CMBE) Special Interest Group. In 2020 he became the first Penn Engineering faculty member to receive the Maximizing Investigators’ Research Award (MIRA) from the National Institutes of Health (NIH) for his forward-thinking work in the creation of new tools for tissue engineering.

Pediatric nephrologists have long worked to understand the cause of these childhood kidney defects. These efforts are often confounded by a lack of evidence for a single causative mutation. The Hughes Lab’s approach presents a new and different application of the packing problem and could help answer some of these unsolved questions and open doors to prevention of these diseases. Following this study, Hughes and his lab members will continue to explore the physics of kidney tubule packing, looking for interesting connections between packing organization, mechanical stresses between neighboring tubule tips, and nephron formation while attempting to copy these principles to build stem cell derived tissues to replace damaged or diseased kidney tissue. Mechanical forces play an important role in developmental biology and there is much scope for Hughes, Prahl and their colleagues to learn about these properties in relation to the kidney.

Read “The developing murine kidney actively negotiates geometric packing conflicts to avoid defects” in Developmental Cell.

Other authors include Bioengineering Ph.D. students and Hughes Lab members John Viola and Jiageng Liu.

This work was supported by NSF CAREER 2047271, NIH MIRA R35GM133380, Predoctoral Training Program in Developmental Biology T32HD083185, and NIH F32 fellowship DK126385.

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RNA Lipid Nanoparticle Engineering Stops Liver Fibrosis in its Tracks, Reverses Damage

by Melissa Pappas

Members of the research team include (from left to right) Xuexiang Han, Michael J. Mitchell, Ningqiang Gong, Lulu Xue, Sarah J. Shepherd, and Rakan El-Mayta.
Members of the research team include (from left to right) Xuexiang Han, Michael J. Mitchell, Ningqiang Gong, Lulu Xue, Sarah J. Shepherd, and Rakan El-Mayta.

Since the success of the COVID-19 vaccine, RNA therapies have been the object of increasing interest in the biotech world. These therapies work with your body to target the genetic root of diseases and infections, a promising alternative treatment method to that of traditional pharmaceutical drugs.

Lipid nanoparticles (LNPs) have been successfully used in drug delivery for decades. FDA-approved therapies use them as vehicles for delivering messenger RNA (mRNA), which prompts the cell to make new proteins, and small interfering RNA (siRNA), which instruct the cell to silence or inhibit the expression of certain proteins.

The biggest challenge in developing a successful RNA therapy is its targeted delivery. Research is now confronting the current limitations of LNPs, which have left many diseases without an effective RNA therapy.

Liver fibrosis occurs when the liver is repeatedly damaged and the healing process results in the accumulation of scar tissue, impeding healthy liver function. It is a chronic disease characterized by the buildup of excessive collagen-rich extracellular matrix (ECM). Liver fibrosis has remained challenging to treat using RNA therapies due to a lack of delivery systems for targeting activated liver-resident fibroblasts. Both the solid fibroblast structure and the lack of specificity or affinity to target these fibroblasts has impeded current LNPs from entering activated liver-resident fibroblasts, and thus they are unable to deliver RNA therapeutics.

To tackle this issue and help provide a treatment for the millions of people who suffer from this chronic disease, Michael Mitchell, J. Peter and Geri Skirkanich Assistant Professor of Innovation in the Department of Bioengineering, and postdoctoral fellows Xuexiang Han and Ningqiang Gong, found a new way to synthesize ligand-tethered LNPs, increasing their selectivity and allowing them to target liver fibroblasts.

Lulu Xue, Margaret Billingsley, Rakan El-Mayta, Sarah J. Shepherd, Mohamad-Gabriel Alameh and Drew Weissman, Roberts Family Professor in Vaccine Research and Director of the Penn Institute for RNA Innovation at the Perelman School of Medicine, also contributed to this work.

Read the full story in Penn Engineering Today.

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Postdoctoral Fellow Marshall Padilla Chosen for AADOCR MIND the Future Program

Marshall Padilla, Ph.D.

Marshall Padilla, a  NIDCR T90 postdoctoral fellow within the Center for Innovation & Precision Dentistry (CiPD) was selected for the American Association for Dental, Oral, and Craniofacial Research (AADOCR)’s Mentoring an Inclusive Network for a Diverse Workforce of the Future (AADOCR MIND the Future) program. CiPD is a collaborative center between Penn Engineering and Penn Dental Medicine and is directed by Hyun Michel Koo, Professor in Orthodontics and member of the Penn Bioengineering Graduate Group:

“Padilla came to the CiPD training program earlier this year with a Ph.D. in Chemistry from the University of Wisconsin-Madison. He is currently a postdoctoral fellow in the lab of Dr. Michael J. Mitchell of Penn’s Department of Bioengineering, where his research focuses on developing new materials to enhance the efficacy and safety of biological therapeutics. While passionate about research, he also has a strong interest in developing mentoring relationships and in teaching. At Wisconsin, Marshall earned a certificate in research, teaching, and learning, in which he conducted a research project on developing positive metacognitive practices in introductory organic chemistry. Additionally, he taught a course on mentoring in a research setting, and is passionate about promoting diversity and inclusiveness in biomedical sciences.”

Read the full story in Penn Dental Medicine News.

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Defining Neural “Representation”

by Marilyn Perkins

Neuroscientists frequently say that neural activity ‘represents’ certain phenomena, PIK Professor Konrad Kording and postdoc Ben Baker led a study that took a philosophical approach to tease out what the term means.

Monitors Show EEG Reading and Graphical Brain Model. In the Background Laboratory Man Wearing Brainwave Scanning Headset Sits in a Chair with Closed Eyes. In the Modern Brain Study Research Laboratory
Neuroscientists use the word “represent” to encompass multifaceted relationships between brain activity, behavior, and the environment.

One of neuroscience’s greatest challenges is to bridge the gaps between the external environment, the brain’s internal electrical activity, and the abstract workings of behavior and cognition. Many neuroscientists rely on the word “representation” to connect these phenomena: A burst of neural activity in the visual cortex may represent the face of a friend or neurons in the brain’s memory centers may represent a childhood memory.

But with the many complex relationships between mind, brain, and environment, it’s not always clear what neuroscientists mean when they say neural activity “represents” something. Lack of clarity around this concept can lead to miscommunication, flawed conclusions, and unnecessary disagreements.

To tackle this issue, an interdisciplinary paper takes a philosophical approach to delineating the many aspects of the word “representation” in neuroscience. The work, published in Trends in Cognitive Sciences, comes from the lab of Konrad Kording, a Penn Integrates Knowledge University Professor and senior author on the study whose research lies at the intersection of neuroscience and machine learning.

“The term ‘representation’ is probably one of the most common words in all of neuroscience,” says Kording, who has appointments in the Perelman School of Medicine and School of Engineering and Applied Science. “But it might mean something very different from one professor to another.”

Read the full story in Penn Today.

Konrad Kording is a Penn Integrates Knowledge University Professor with joint appointments in the Department of Neuroscience the Perelman School of Medicine and in the Department of Bioengineering in the School of Engineering and Applied Science.

Ben Baker is a postdoctoral researcher in the Kording lab and a Provost Postdoctoral Fellow. Baker received his Ph.D. in philosophy from Penn.

Also coauthor on the paper is Benjamin Lansdell, a data scientist in the Department of Developmental Neurobiology at St. Jude Children’s Hospital and former postdoctoral researcher in the Kording lab.

Funding for this study came from the National Institutes of Health (awards 1-R01-EB028162-01 and R01EY021579) and the University of Pennsylvania Office of the Vice Provost for Research.

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Alexander Buffone Appointed Assistant Professor at New Jersey Institute of Technology

Alexander Buffone, Ph.D.

Penn Bioengineering is proud to congratulate Alexander Buffone, Ph.D. on his appointment as Assistant Professor in the Department of Biomedical Engineering at New Jersey Institute of Technology. His appointment began in the Spring of 2022.

Buffone got his Ph.D. in Chemical Engineering from SUNY Buffalo in Buffalo, NY in 2012, working with advisor Sriram Neelamegham, Professor of Chemical and Biological Engineering. Buffone completed previous postdoctoral studies at Roswell Park Comprehensive Cancer Center with Joseph T.Y. Lau, Distinguished Professor of Oncology in the department of Cellular and Molecular Biology. Upon coming to Penn in 2015, Buffone has worked in the Hammer Lab under advisor Daniel A. Hammer, Alfred G. and Meta A. Ennis Professor in Bioengineering and in Chemical and Biomolecular Engineering, first as a postdoc and later a research associate. Buffone also spent a year as a Visiting Scholar in the Center for Bioengineering and Tissue Regeneration, directed by Valerie M. Weaver, Professor at the University of California, San Francisco in 2019.

While at Penn, Buffone was a co-investigator on an R21 grant through the National Institutes of Health (NIH) which supported his time as a research associate. Buffone is excited to start his own laboratory where he plans to train a diverse set of trainees.

Buffone’s research area lies at the intersection of genetic engineering, immunology, and glycobiology and addresses how to specifically tailor the trafficking and response of immune cells to inflammation and various diseases. The work seeks to identify and subsequently modify critical cell surface and intracellular signaling molecules governing the recruitment of various blood cell types to distal sites. The ultimate goal of his research is to tailor and personalize the innate and adaptive immune response to specific diseases on demand.

“None of this would have been possible without the unwavering support of all of my mentors, past and present, and most especially Dan Hammer,” Buffone says. “His support in helping me transition into an independent scientist and his understanding of my outside responsibilities as a dad with two young children is truly the reason why I am standing here today. It’s a testament to Dan as both a person and a mentor.”

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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. 

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Spencer Haws Receives Druckenmiller Fellowship

Spencer Haws, Ph.D.

Spencer Haws, Postdoctoral Research Fellow in the laboratory of Jennifer E. Phillips-Cremins, Associate Professor and Dean’s Faculty Fellow in Bioengineering and in Genetics, was awarded a 2022 Druckenmiller Fellowship from the New York Stem Cell Foundation Research Institute (NYSCF). This prestigious program is the largest dedicated stem cell fellowship program in the world and was developed to train and support young scientists working on groundbreaking research in the field of stem cell research. Haws is one of only five inductees into the 2022 class of fellows.

Haws earned his Ph.D. in Nutritional Sciences in 2021 from the University of Wisconsin-Madison, where he studied metabolism-chromatin connections under the mentorship of John Denu, Professor in Biomolecular Chemistry at the University of Wisconsin-Madison. As a NYSCF – Druckenmiller Fellow in the Cremins Laboratory for Genome Architecture and Spatial Neurobiology, Haws is using this previously developed expertise to frame his investigations into the underlying mechanisms driving the neurodegenerative disorder fragile X syndrome (FXS). “Ultimately, I hope that this work will help guide the development of future FXS-specific therapeutics of which none currently exist,” says Haws.

Read the full list of 2022 Druckenmiller Fellows and view introductory videos on the NYSCF website.

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Taimoor Qazi Appointed Assistant Professor at Purdue University

Taimoor H. Qazi, Ph.D.

The Department of Bioengineering is proud to congratulate Taimoor H. Qazi, Ph.D. on his appointment as Assistant Professor in the Weldon School of Biomedical Engineering at Purdue University. Qazi’s appointment will begin in Fall 2022.

Qazi obtained his Ph.D. at the Technical University of Berlin and the Charité Hospital in Berlin, Germany working on translational approaches for musculoskeletal tissue repair using biomaterials and stem cells under the co-advisement of Georg Duda, Director of the Berlin Institute of Health and David Mooney, Mercator Fellow at Charité – Universitätsmedizin Berlin. After arriving at Penn in 2019, Qazi performed research on microscale granular hydrogels in the Polymeric Biomaterials Laboratory of Jason Burdick, Adjunct Professor in Bioengineering at Penn and Bowman Endowed Professor in Chemical and Biological Engineering at the University of Colorado, Boulder. While conducting postdoctoral research, Qazi also collaborated with the groups of David Issadore, Associate Professor in Bioengineering and in Electrical and Systems Engineering, and Daeyeon Lee, Professor and Evan C. Thompson Term Chair for Excellence in Teaching in Chemical and Biomolecular Engineering and member of the Penn Bioengineering Graduate Group. Qazi’s postdoctoral research was supported through a fellowship from the German Research Foundation, and resulted in several publications in high-profile journals, including Advanced Materials, Cell Stem Cell, Small, and ACS Biomaterials Science and Engineering.

“Taimoor has done really fantastic research as a postdoctoral fellow in the group,” says Burdick. “Purdue has a long history of excellence in biomaterials research and will be a great place for him to build a strong research program.”

Qazi’s future research program will engineer biomaterials to make fundamental and translational advances in musculoskeletal tissue engineering, including the study of how rare tissue-resident cells respond to spatiotemporal signals and participate in tissue repair, and developing modular hydrogels that permit minimally invasive delivery for tissue regeneration. The ultimate goal is to create scalable, translational, and biologically inspired healthcare solutions that benefit a patient population that is expected to grow manifold in the coming years.

Qazi is looking to build a strong and inclusive team of scientists and engineers with diverse backgrounds interested in tackling problems at the interface of translational medicine, materials science, bioengineering, and cell biology, and will be recruiting graduate students immediately. Interested students can contact him directly at thqazi@seas.upenn.edu.

“I am excited to launch my independent research career at a prestigious institution like Purdue,” says Qazi. “Being at Penn and particularly in the Department of Bioengineering greatly helped me prepare for the journey ahead. I am grateful for Jason’s mentorship over the years and the access to resources provided by Jason, Dave Issadore, Ravi, Dave Meany and other faculty which support the training and professional development of postdoctoral fellows in Penn Bioengineering.”

Congratulations to Dr. Qazi from everyone at Penn Bioengineering!

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Moving Away From ‘Average,’ Toward the Individual

by Michele W. Berger

In a course from Annenberg’s David Lydon-Staley, seven graduate students conducted single-participant experiments. This approach, what’s known as an “n of 1,” may better capture the nuances of a diverse population than randomized control trials can.

David Lydon-Staley is an assistant professor of communication and principal investigator of the Addiction, Health, & Adolescence Lab in the Annenberg School for Communication.

To prep for an upcoming course he was teaching, Penn researcher David Lydon-Staley decided to conduct an experiment: Might melatonin gummies—supplements touted to improve sleep—help him, as an individual, fall asleep faster?

For two weeks, he took two gummies on intervention nights and none on control nights. The point, however, wasn’t really to find out whether the gummies worked for him (which they didn’t), but rather to see how an experiment with a single participant played out, what’s known as an “n of 1.”

Randomized control experiments typically include hundreds or thousands of participants. Their aim is to show, on average, how the intervention being studied affects people in the treatment group. But often “there’s a failure to include women and members of minoritized racial and ethnic groups in those clinical trials,” says Lydon-Staley, an assistant professor in the Annenberg School for Communication. “The single-case approach says, instead of randomizing a lot of people, we’re going to take one person at a time and measure them intensively.”

In Lydon-Staley’s spring semester class, Diversity and the End of Average, seven graduate students conducted their own n-of-1 experiments—on themselves—testing whether dynamic stretching might improve basketball performance or whether yoga might decrease stress. One wanted to understand the effect of journaling on emotional clarity. They also learned about representation in science, plus which analytical approaches might best capture the nuance of a diverse population and individuals with many intersecting identities.

“It’s not just an ‘n of 1’ trying to do what the big studies are doing. It’s a different perspective,” says Lydon-Staley. “Though it’s just one person, you’re getting a much more thorough characterization of how they’re changing from moment to moment.”

Read the full story in Penn Today.

David Lydon-Staley is an Assistant Professor of communication and principal investigator of the Addiction, Health, & Adolescence Lab in the Annenberg School for Communication at the University of Pennsylvania. Lydon-Staley is a former postdoctoral research in the Complex Systems Lab of Dani S. Bassett, J. Peter Skirkanich Professor in Bioengineering and in Electrical and Systems Engineering.

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Penn Engineers Secure Wellcome Leap Contract for Lipid Nanoparticle Research Essential in Delivery of RNA Therapies

by Melissa Pappas

The Very Large Scale Microfluidic Integration (VLSMI) platform, a technology developed by the Penn researchers, contains hundreds of mixing channels for mass-producing mRNA-carrying lipid nanoparticles.

Penn Engineering secured a multi-million-dollar contract with Wellcome Leap under the organization’s $60 million RNA Readiness + Response (R3) program, which is jointly funded with the Coalition for Epidemic Preparedness Innovations (CEPI). Penn Engineers aim to create “on-demand” manufacturing technology that can produce a range of RNA-based vaccines.

The Penn Engineering team features Daeyeon Lee, Evan C Thompson Term Chair for Excellence in Teaching and Professor in Chemical and Biomolecular Engineering, Michael Mitchell, Skirkanich Assistant Professor of Innovation in Bioengineering, David Issadore, Associate Professor in Bioengineering and Electrical and Systems Engineering, and Sagar Yadavali, a former postdoctoral researcher in the Issadore and Lee labs and now the CEO of InfiniFluidics, a spinoff company based on their research. Drew Weissman of the Perelman School of Medicine, whose foundational research directly continued to the development of mRNA-based COVID-19 vaccines, is also a part of this interdisciplinary team.

The success of these COVID-19 vaccines has inspired a fresh perspective and wave of research funding for RNA therapeutics across a wide range of difficult diseases and health issues. These therapeutics now need to be equitably and efficiently distributed, something currently limited by the inefficient mRNA vaccine manufacturing processes which would rapidly translate technologies from the lab to the clinic.

Read more in Penn Engineering Today.