UNITE Seminar Series Schedule
August 14, 2023 (12 pm ET, 9 am PT; webinar signup)
Samantha Zambuto, University of Illinois
Engineering Biomimetic Materials for Female Reproductive Health
Abstract
Female reproductive health and women’s health research are historically understudied fields that would significantly benefit from engineering expertise due to the unique biomechanical environment in the female reproductive tract and the dynamic tissue changes orchestrated throughout the menstrual cycle by sex hormones. With the synergistic techniques of tissue engineering, biomaterials science, biomechanics, and reproductive biology, we engineer models of the female reproductive system, including the endometrium, decidua, and vagina, to study pregnancy-related disorders and birth injuries. We use these tissue engineering models to understand cell-cell interactions, cell- matrix interactions, and hormone dynamics in the context of early pregnancy and vaginal tearing during childbirth. To mimic, instruct, and define the cellular microenvironment in the female reproductive tract, we use gelatin methacryloyl (GelMA) hydrogels. Derived from gelatin, GelMA hydrogels are biomimetic, biocompatible, and bioactive. Functionalization of gelatin into GelMA renders GelMA stability under physiological temperatures as well as enhanced tunability of mechanical properties. We fabricated a library of GelMA hydrogels and composites that capture a range of biomechanical properties specifically designed to mimic tissue biomechanical properties. We then construct GelMA hydrogel composites by combining GelMA hydrogels with other materials, including electrospun fibers and hyaluronic acid methacrylate. We perform sophisticated material characterization with spherical nanoindentation and define the effects of biomechanical properties on cellular behavior and the effect of cells on hydrogel mechanical properties. We demonstrated that GelMA hydrogel platforms are adaptable for studying dynamic endometrial processes, including endometrial angiogenesis, hormone responsiveness (e.g., decidualization of endometrial stromal cells), epithelial monolayer formation in a stratified tissue model, and trophoblast invasion. We also established a three-dimensional model of the vaginal epithelium by incorporating primary human vaginal epithelial cells in gelatin-elastin fiber composites impregnated with GelMA hydrogels. Our ongoing studies seek to advance these existing model systems into complex, three-dimensional tissue mimics of the endometrium and vagina for not only basic science purposes but also for regenerative medicine applications. Finally, we inform our engineering studies by performing systematic reviews and meta- analyses of the medical literature to identify health issues in female reproductive health, to assess the quality of existing literature, and to highlight future directions of the field that can be informed with basic science research using engineering models.
Gabriel Rodriguez-Rivera, University of Colorado
Engineering hydrogels for cardiac applications
Abstract
Injectable hydrogel for treating ventricular arrhythmias (VA): The only effective treatment for VA is cardiac defibrillation, where a high-energy shock extinguishes the reentrant circuits that initiate and sustain VA. However, these high-energy shocks exceed the pain threshold. The primary goal of this research is to develop new painless strategies to extinguish reentrant VA. The current treatment requires large energy because the current leads capture the tissue from a single point far from the heterogeneous scarred tissue responsible for the electrical disruptions. We hypothesized that flexible electrodes that can access midmyocardium near the scarred area via the cardiac veins, we could terminate arrhythmias with low-energy shocks. However, there were no pacing electrodes small enough to navigate these tributaries to test this hypothesis. To the best of our knowledge, we were the first to report an injectable electrode used to successfully pace the midmyocardium and mimic physiologic conduction. As such, this injectable hydrogel electrode developed during my Ph.D. work provides a novel way to improve current defibrillation strategies and opens opportunities for new therapeutic approaches. By capturing a larger area and deeper into the midmyocardium, this technology enhances new ways to study tissue activation that were not possible with current pacing leads. From microspheres to rods: Prior work with injectable, acellular bulk hydrogels for cardiac repair resulted in improved angiogenesis and cardiac function, even without potent angiogenic cues; however, the lack of macroporosity of bulk hydrogel structures limits rapid cellular infiltration. This limitation is mitigated by granular hydrogels, which exhibit an inherent porosity to support cell infiltration and activity. Widely studied granular hydrogels consist of spherical particles. In contrast, our lab recently developed granular hydrogels from rod-like microgels of aspect ratio 2.2 for improved cellular invasions in both in vitro and in vivo studies. However, it is unclear how increased aspect ratios affect granular hydrogel packing, injectability, cell invasion, and tissue reconstruction, which are crucial for delivery, mechanics, and angiogenesis. To address this, we fabricated rod-like microgels with increased aspect ratios and compared these to control spherical microgels that matched the volumes of rods. To monitor cellular invasion in vitro, spheroids of endothelial/mesenchymal cells were introduced to the granular materials and cultured for 3 days to assess cells sprouting in the granular material. I uncovered that the sprout displacements were larger when the spheroids were placed in the granular hydrogels from microgels with higher aspect ratio rods when compared to spheres of similar volume. This suggests that rods of higher aspect ratios have higher porosity and less tortuous path to enable cell sprouting, providing a key design consideration for engineering granular materials in biomedical applications. Ongoing work includes the assessment of granular hydrogels in a rat heart infarct model.
Russell Urie, University of Michigan
Sentinel Biomaterials Identify Transplant Rejection and Prenatal Complications
Abstract
Introduction: As there is no assay to predict alloimmunity in transplant or fetal rejection, clinicians rely on invasive tissue biopsy and aggressive immunosuppression. Immunosuppression protects transplants but increases systemic toxicities. Also, nearly half of all cases of prenatal complication have an undefined immune basis. This immune cascade inhibits placenta development, yet the clinic focuses on later disease stages. Primary tissue histology is a flawed standard for alloimmunity surveillance and diagnostics, as histological evidence of rejection inherently lags behind molecular biomarkers and suffers from variability. Noninvasive alternatives, including gene profiling and cell-free DNA, also measure lagging indicators of rejection. A minimally invasive surveillance method is urgently needed to identify early risk of rejection for minimizing invasive procedures and personalizing interventions. I have developed porous biomaterial implants (“scaffolds”) for minimally-invasive sampling. These scaffolds amass immune cells producing biomarkers of disease as an engineered immunological niche, and gene expression in biopsied scaffolds predicts disease onset. In this work, I employ microporous scaffolds as a synthetic immunological niche to capture the longitudinal immune domain of healthy and rejecting transplants and healthy and miscarriage-prone rodent pregnancies without needing to disrupt the primary tissue and with greater specificity than blood. Methods: Biomaterial scaffolds accumulate immune cells producing biomarkers of rejection as an engineered immunological niche. We implanted subcutaneous poly-caprolactone scaffolds in murine heart transplant recipients and miscarriage-prone pregnancies. Scaffolds were biopsied and analyzed for differential gene expression by RNA sequencing using elastic net regularization for differential expression across mice, tissue, and day to generate a biomarker signature of rejection. We performed singular value decomposition and supervised machine learning (Random Forest) to derive single-metric scores and a predictive model for graft or fetus rejection. Results and Conclusions: Gene expression in the cell-capture scaffold identified biomarker signatures of early rejection in heart transplant (Fig 1) and miscarriage prone pregnancies, without invasive biopsy. This implantable scaffold enables minimally invasive histological evaluation and molecular calculation of the early risk of rejection to reduce the frequency of invasive biopsy and personalize treatment to prevent alloinjury. In healthy and preeclamptic-like pregnancies, the scaffold implant recapitulates the immune microenvironment of the placenta with greater tissue specificity than blood. Gene expression in the scaffold can distinguish between gestation at different stages and immunological states. We identified 8 genes that differentiate between allogeneic and syngeneic pregnancies at embryonic day 5, prior to fetal or placental organogenesis. We have developed an implant to remotely monitor immunological markers of alloimmunity in transplantation and pregnancy. Scaffold gene expression can differentiate immune state across time and disease progression prior to the onset of symptoms, creating an early, novel therapeutic window to prevent transplant or fetal injury.
August 28, 2023 (12 pm ET, 9 am PT; webinar signup)
Olivia Lanier, University of Texas, Austin
Leveraging Nanotechnology and Drug Delivery for Improved Health Equity
Abstract
Many variables contribute to the perpetuation of health disparities: environmental factors, social contributions, patient compliance, quality of care, and access to care. Access to care is affected by the delivery route of the therapeutic. Biologic (protein, RNA) therapeutics have revolutionized the care of multiple chronic autoimmune conditions but must be delivered parenterally via infusions from medical professionals, which further perpetuates health disparities. For patients for whom transportation constraints, poverty, mental illness, and limited hospital access – to name a few – are obstacles to their care, infusion-based therapies are not accessible. Nanotechnologies can be used to address health equity concerns by creating non-invasive delivery systems that utilize oral or vaginal routes that improve patient access and compliance to therapies. I aim to replace infusions by creating nanotechnologies that protect therapeutics from degradation and bypass biological barriers (e.g. mucus and cell layers, pH, enzymes) associated with these routes. Additionally, this technology will control release to reduce dosing requirements and enable less complex treatment regimens. I will develop nanotechnology platforms to deliver biologics (RNA, proteins), with a particular focus on diseases that disproportionately affect underserved populations, and I will also analyze the role of biological sex, age, and ancestry on the performance of the developed nanotechnologies. My talk will focus on one example of this work from my postdoctoral work at University of Texas at Austin. My project develops a pH sensitive nanotechnology platform for the oral delivery of small interfering RNA (siRNA) as a replacement for infusion therapy for treatment of inflammatory bowel disease. Challenges associated with the oral delivery of siRNA include the harsh pH of the stomach, enzymatic degradation, uptake of siRNA into macrophages in the intestines, and the need to undergo endosomal escape following intracellular delivery. To achieve this, a multi-layered system is proposed and will be developed with an anionic coating that protects its payload through the stomach and expands to release siRNA-loaded cationic nanogels under neutral pH conditions in the intestines. This dual layered platform can be applied to other autoimmune diseases in the future. Additionally, the role of sex is being explored in vitro on gene transfection and cytotoxicity.
Gary Liu, Massachusetts Institute of Technology
Biomaterials across length scales: a patient-scientist’s perspective
Abstract
Factors that may deter patient compliance with their medications include toxic side effects and administration discomfort. Biomaterials may address some of these urgent patient needs by altering pharmacokinetic profiles and enabling new methods of drug administration. In this talk I will share my 20+ years’ experience as a kidney disease patient, and how navigating a chronic disease has provided insight into the constraints, design, and development of new biomaterials. I will share how working with materials and animal models across length scales can address these patient challenges, and the opportunities of working at each length scale. Chronic disease patients face long-term drug courses that can result in persistent side effects. As a kidney disease patient navigating many such side effects, I sought to engineer new materials for renal-specific drug delivery. My Ph.D. sought to identify the materials properties of polymers and nanoparticles, two widely used classes of drug carriers, that drive their renal tropism. We synthesized a panel of polymers of similar size but varying anionic charge, and found that greater anionic charge augmented polymer accumulation into renal tissue. In contrast, nanoparticles of size 20- and 100-nm, but not 200-nm, accumulate in renal glomeruli but not tubules. Both materials types exhibit greater renal accumulation during renal disease. These findings provide insight into how materials properties can be tuned to drive accumulation into specified renal cell types, and how disease state may be leveraged to augment distribution. In the second part of my talk, I will highlight my postdoctoral work at the macroscale. Orally administered enzymes and bacteria can modulate disease through activity in the stomach and intestines, but are quickly inactivated in the harsh gastrointestinal environment. Strategies to stabilize these therapeutics use solid, excipient-containing formulations, which are inaccessible for pediatric and geriatric patients who have difficulty swallowing solids. To address this challenge, we developed LIFT (liquid in situ-forming and tough) hydrogels, which transition from a drinkable liquid to a tough, solid drug depot within the stomach. Comprising biocompatible poly(ethylene glycol) and alginate double polymer networks, LIFT rapidly forms a tough hydrogel in vivo in porcine stomachs, and can sustain multiple compressions compared to single-network hydrogels, which permanently deform after one compression. These materials were further examined for their multifunctionality. LIFT hydrogels can modulate small molecule release and protect the activity of various enzymes and therapeutic bacteria in rat and porcine stomachs. Thus, LIFT hydrogels present a new platform capable of modulating and sustaining the activity of various drug types in the harsh gastrointestinal environment, enabling access to and oral delivery of advanced therapeutics for vulnerable patient populations.
Adrienne Scott, Washington University, St. Louis
Mechanically induced cell fate changes in pregnancy
Abstract
Severe maternal morbidity and maternal mortality has been steadily increasing over time in the United States. Globally, ten percent of all pregnancies result in preterm birth and 2 million pregnancies worldwide result in stillbirth. Critical maternal health issues leading to this growing crisis have been underexplored in the field of engineering. Our research strives to improve maternal health by using engineering and molecular biology tools to understand multiscale observations through biological mechanisms. Specifically, we are inspired to explore how adaptations to changing mechanical environments alter cellular responses and cell fate during and after pregnancy. During pregnancy, the uterus expands to one thousand times the original size and the physical properties of uterine and cervical tissues change drastically due to tissue remodeling. Overall, we hypothesize that understanding how cells respond to mechanical signals in pregnancy will elucidate therapeutic strategies to prevent high risk pregnancies, such as preterm birth. Our previous work demonstrates that changing mechanical environments induce remodeling of epigenetically marked chromatin, causing alterations in gene expression and the overall phenotype of the cell. Furthermore, we found that mechanically induced remodeling of epigenetically marked chromatin can persist, even after the initial mechanical stimulus is removed. In other words, cells retain a mechanical memory encoded in the chromatin architecture. Specifically, we found that the architecture of H3K9me3 marked chromatin changes in response to the mechanical environment, in both cardiomyocytes in the heart and chondrocytes in articular cartilage. Future work could apply similar methods to study the extent adaptations of uterine smooth muscle cells or cervical fibroblasts to changing mechanical signals in pregnancy may also induce long term memory encoded in the chromatin architecture of these cells. Our current research focuses on using engineering tools to model and understand how the mechanical environment changes in pregnancies with complications, such as with uterine scaring from a previous C-section or with Fetal Growth Restriction. Using finite element modeling, we have found that the placement of a uterine scar influences uterine mechanics in a subsequent pregnancy, which may have implications for an increased risk of pre-term birth or uterine rupture. Additionally, we are studying tissue remodeling and the micromechanical environment in the placenta of Fetal Growth Restriction pregnancies to inform computational models of oxygen transport and blood flow. In the future, these computational models will be used to understand how the mechanical environment changes during pregnancy to inform the design of mechanobiology experiments. With these tools, we are now poised to explore the underlying mechanotransduction mechanisms that result in multiscale short and long-term adaptations of the female reproductive system.
September 11, 2023 (12 pm ET, 9 am PT; webinar signup)
Kolade Adebowale, Harvard University
Abstract
Circulating monocytes are recruited to tumors, where they can differentiate into macrophages that mediate tumor progression. To reach the tumor microenvironment, monocytes extravasate out of the vasculature and migrate through type-1 collagen rich stromal matrix. The viscoelastic stromal matrix around tumors not only stiffens relative to normal stromal matrix, but often exhibits enhanced viscous characteristics, as indicated by faster stress relaxation rate. Stress relaxation refers to a decrease in internal stresses in viscoelastic materials because of applied deformation. Despite clinically observed changes in matrix properties, the potential impact of changes in matrix stiffness or stress relaxation on monocyte migration is not understood. To address this research gap, we studied how changes in matrix stiffness and viscoelasticity impact the three-dimensional migration of monocytes through stromal-like matrices. We developed interpenetrating networks (IPNs) of type-1 collagen and alginate with independent tunability of stiffness and stress relaxation over physiologically relevant ranges. IPNs provide a confining stromal-like matrices and a three-dimensional context experienced by monocytes in vivo. Collagen fiber architecture was quantified by measuring collagen fiber length and width. Importantly, IPN stress relaxation properties are tuned independent of polymer concentration, Young’s modulus, and collagen fiber architecture, allowing for independent assessment of matrix stress relaxation. We tuned the characteristic stress relaxation times from ~100 seconds (fast relaxing) to 1,000 seconds (slow relaxing) while keeping the initial Young’s modulus of all the materials at ~1 kPa or ~2.5 kPa. Faster stress relaxation and higher Young’s modulus independently enhanced the 3D migration of monocytes. Migrating monocytes have an ellipsoidal or rounded wedge-like morphology, reminiscent of amoeboid migration, with accumulation of actin at the trailing edge. Surprisingly, monocytes could migrate without matrix adhesion and Rho-mediated contractility but are dependent on actin polymerization for migration. Our mechanistic studies indicate that actin polymerization at the leading edge generates protrusive forces that generate a path to migrate in the confining viscoelastic matrices. In summary, our findings implicate matrix stiffness and stress relaxation as key mediators of migration. More broadly, the tunable nature of the material developed could enable mechanistic insights into the role of changes in the stromal matrix in the promotion of health and disease. Specifically, it provides a platform to study the role of viscoelasticity on migration of normal leukocytes and diseased leukocytes such as those with Leukocyte Adhesion Deficiency-1. Taken together, our data raises the possibility that ECM stiffness and viscoelasticity could determine immune cell recruitment and ultimately shape the immune response under normal and pathological conditions.
Gurneet Sangha, University of Maryland
Going with the Flow: The Evolving Role of Red Blood Cell Mechanosignaling in Vascular Health and Disease
Abstract
Red blood cells (RBCs), once thought to solely transport O2 and CO2, are now recognized to actively contribute to vascular health and disease. In addition to carrying hemoglobin, RBCs contain enzymes, metabolites, antioxidants, cytokines, and miRNAs that affect vascular function. RBCs are also mechanosensitive, releasing these molecular signals as they deform while traversing the microcirculation. Yet, we do not understand how biomolecules released by mechanostimulated RBCs affect endothelial dysfunction, the initial hallmark of vascular disease. As a result, the use of RBCs to diagnose and treat vascular disease remains limited. My current research investigates how mechanostimulated RBC production and release of nitric oxide and extracellular vesicles (EVs) impact endothelial function. Nitric oxide is an atheroprotective signaling molecule crucial to maintaining endothelial function, while RBC-EVs are lipid-bound particles that protect and then systemically transport RBC cargo to endothelial cells throughout the vasculature. In this talk, I will first highlight my mechanistic in vitro studies showing that stimulation of the mechanosensitive Ca2+ ion channel piezo1 triggers RBC nitric oxide and RBC-EV production. I will then share my in silico simulations using HemoCell to understand the dynamic forces RBCs experience in circulation that may activate mechanosensitive signaling. Finally, I will conclude with my preliminary research using exercise as an in vivo model to study how increased blood flow and exercise-induced adaptative mechanisms affect RBC mechanosignaling.
Sarvenaz Sarabipour, Johns Hopkins University
Mechanistic models of receptor trafficking dynamics
Abstract
Vascular endothelial growth factor (VEGF) controls the growth and regression of blood vessels. While some successes have been achieved in inhibition of VEGF to disrupt blood vessel growth in cancer and retinopathy, over a dozen clinical trials of VEGF delivery to increase vascular growth in patients with ischemic diseases have failed. The inability to successfully bridge treatment from animals to humans demonstrates that our understanding of the VEGF system is far from complete. We have developed and validated a molecularly-detailed computational model of the trafficking in endothelial cells of the key VEGF receptors: VEGFR1, VEGFR2, and Neuropilin-1. The model uses coupled, nonlinear, deterministic ordinary differential equations simulating receptor dimerization, ligand-receptor binding, and the trafficking of transmembrane receptors. Crucially, the model is parameterized using new in vitro experiments of human endothelial cell culture treated with ligands, drugs, and targeted shRNAs that perturb trafficking, including experiments predicted by the model to be most informative. Our simulations and experiments show that VEGFR1 is less stable than VEGFR2 and NRP1 in endothelial cells – due to a faster internalization rate constant, resulting in increased overall degradation. In addition, the differential trafficking results in differential localization of the receptors: on the cell surface VEGFR2 is in excess over VEGFR1; while inside the cell, the reverse is true. This alters both the sensing of extracellular ligands and which receptors form signaling complexes and ligand decoys at the cell surface vs inside the cell. The presence of ligands and hypoxic conditions (both relevant to physiological and pathological conditions) further alter receptor trafficking and stability, and can be quantitatively accounted for in computational predictions of therapeutics.
September 25, 2023 (12 pm ET, 9 am PT; webinar signup)
Jenna Moore-Ott, Princeton University
Abstract
A promising approach for many environmental and human health crises can be found in our smallest factories: bacteria. Since the discovery of microbes over 300 years ago, we have developed tools to not only understand microbial functions, but to engineer them for specific applications. Synthetic biology has developed tools to engineer inside bacteria by editing genetic material, resulting in control over protein synthesis and gene expression. Biophysics has developed tools to engineer the outside environment that bacterial communities interact with, including bioprinting defined community spatial structure and composition. However, the interplay between microbial behavior at the genetic scale and community scale remains poorly understood; further, there are very few methods to predict these behaviors a priori. My future research group will address this gap in knowledge by combining tools from synthetic biology and biophysics to unravel the complex dynamics between microbial genetic expression and community behavior with experimental and theoretical work. I am currently finishing my PhD at Princeton University, advised by Prof. Sujit Datta. For my dissertation, I am studying how spatial organization plays a role in microbial communities, including their phenotype, interactions with their environment, and multispecies composition, using both theoretical and experimental techniques. A particular highlight—and inspiration for my independent research vision—of my dissertation is my recent publication in eLife, in which I developed the first minimal model that captures the transition from the free-swimming, planktonic bacterial community to the immobilized biofilm. The addition of such minimal models allows us new ways to predict and control these microbial communities in our favor. I have extended such minimal models to predict the symbiotic organization of aerobic and anaerobic bacterial communities. Using novel experimental techniques related to bioprinting and granular media, I have validated my theoretical predictions. However, for my future career, I do not currently have the experimental expertise to probe the complex communities I envision; to resolve this issue, I will be joining Prof. Mark Blenner and Prof. Kevin Solomon at the University of Delaware as a postdoctoral researcher upon my graduation. I will study the spatial organization of plastic-degrading microbial consortia, which will provide the experimental expertise in synthetic biology that I seek. With my biophysical background from my PhD and my anticipated background in synthetic biology from my incoming postdoctoral research, I will have the scientific foundation to lead the Inside-Out Lab: Engineering Microbial Communities from the Inside-Out. Specifically, we will utilize the spatial control of bioprinting with the microbial classification tools from synthetic biology to probe (1) enhanced biofilm formation in multispecies communities, (2) division of labor within biofilms, and (3) biofilm-enhanced plastic degradation. With all research areas, we will develop minimal biophysical models to capture the essential physics of these complex systems, underlying our overarching goal of harnessing these communities in our environment and human health.
Mykel Green, University of Texas, Austin
Health Equity Focused Strategies for Biomaterial-Based Therapies in Sickle Cell Disease and Beyond
Abstract
Sickle cell disease (SCD) is a complex and devastating blood disorder affecting nearly 20 million people globally and has been overlooked by the greater scientific community for the past 20 years. Despite being the focus of gene-editing technology development, public perception of gene therapy has created a misconception that new treatments for SCD are no longer necessary. Understanding the physiology of bone marrow and stem cell engraftment, especially in SCD, remains insufficient. To tackle this, my research program will expand on my doctoral work to investigate how bone and marrow mechanobiology influences the regulation of the hematopoietic niche, particularly concerning age and biological sex. This knowledge will enhance the development of bone marrow transplantation technology I'm working on during my postdoctoral position, specifically tailored to address SCD-related complications. Moreover, the biomaterial platform developed in this research can potentially treat myeloma, leukemia, and aplastic anemia and manage clinical implications associated with bone marrow transplantation.
Grace Bushnell, University of Michigan
Immunologic regulation of dormancy in breast cancer stem cells