UNITE Seminar Series Schedule
August 12, 2024 (12 pm ET, 9 am PT; webinar signup)
Roberto Alonso Matilla, University of Minnesota
Mechanics of T Cell Migration and Plasma Membrane Accumulation at the Cytokinetic Furrow of Dividing Cells
Abstract
T cell migration: Despite recent progress in understanding amoeboid-mesenchymal migratory balance, it remains largely unknown how T cells mechanically move through tumors and what factors set their migration capabilities. To address this, we have developed a biophysical T cell migration model that elucidates the potential physical principles and molecular components modulating their movement. The model results are complemented by preliminary data obtained from in vitro T cell migration studies. We first examined the potential for adhesion-free bleb-based migration and show that cells only inefficiently migrate in the absence of adhesion-based forces, i.e., cell swimming. However, our model suggests that T cells can employ a hybrid bleb- and adhesion-based migration mechanism for rapid cell motility and identifies conditions for optimality. Leukemia cell cytokinesis: The actomyosin-based machinery that drives cell division is widely studied, but how actomyosin impacts the plasma membrane during cytokinesis is poorly understood. By using a combination of imaging and biophysical modeling, we found an extensive accumulation and folding of the plasma membrane at the cleavage furrow and the intercellular bridge. This is caused by actomyosin pulling the plasma membrane toward the cleavage furrow and by local cell surface area changes driven by the radial constriction of the furrow. Our work reveals that actomyosin-based mechanisms responsible for cytokinesis can also decrease membrane tension at the intercellular bridge. This could promote cytokinetic fidelity and locally alter endocytosis, exocytosis, and cell signaling.
Camilo Duarte-Cordon, Columbia University
An anisotropic viscoelastic model of the macaque rhesus cervix to quantify cervical remodeling
Abstract
Through pregnancy, the cervix, a collagenous and hydrated tissue, undergoes a remarkable transformation from a rigid/closed structure that keeps the fetus inside the uterus to a more compliant/extensible one that opens to facilitate delivery at parturition. This process, known as cervical remodeling, involves complex changes in the cervix's equilibrium and dynamic mechanical properties, such as stiffness, viscoelasticity, and permeability. Constitutive models of the cervix extracellular matrix (ECM) calibrated with experimental data at equilibrium and obtained from animal cervical tissue, primarily rodents, have proven helpful in studying how the cervix softens through gestation. Recently, a poro-viscoelastic model of the human cervix was used to describe the human cervix's time-dependent behavior but limited to compressive strains and two gestational points (pregnant and nonpregnant). The variations in the cervix's intrinsic viscoelastic properties under tension at different pregnancy stages have not yet been thoroughly studied, which is crucial for understanding better cervical remodeling. Building upon these previous constitutive models, we implemented an anisotropic viscoelastic model of the cervix ECM, which captures the viscoelastic behavior of the cervix under tensile deformation. To calibrate our model, we used force-displacement experimental data from spherical indentation and uniaxial tension tests in cervix samples from Rhesus Macaques, chosen because of their homology to humans, and collected at four relevant gestational time points. We observed that Rhesus Macaque cervical tissue is non-linear elastic, and the stiffness of the toe and linear region decreases with gestational age. Furthermore, the time relaxation properties of cervical tissue differ significantly between nonpregnant/early pregnant and late pregnant stages. This work gives insights into normal cervical remodeling, which is crucial to developing diagnostic methods and treatments for preterm birth (birth before 37 weeks).
Chia-Wen Chang, University of Illinois Urbana-Champaign
Probing cancer-immune crosstalk in glioblastoma using microengineered models
Abstract
Glioblastoma (GBM) is the most common and aggressive form of primary brain cancer, with a median survival of less than 15 months. Highly infiltration of microglia, primary brain-resident immune cells, is associated with poor prognosis and immunosuppression of GBM. Advancing our physicochemical understanding of the GBM-microglia crosstalk, such as microglia activation and matrix invasion, is pivotal for developing novel GBM therapeutic strategies for improving longterm drug efficacy. To this end, we developed microfluidic systems integrated with 3-D tunable collagen hydrogels to systematically investigate the activation, matrix invasion, cellular contractility, and cytokine release in response to GBM-microglia crosstalk. Our results show that GBM inflammatory biomolecules significantly promote the activation and matrix invasion of microglia. Interestingly, microglia invasion is unaffected by inhibitions of both matrix metalloproteinase (MMP) activity and cellular glycolysis. In contrast, ROCK-pathway inhibition significantly impedes microglia matrix invasion in GBM. Infrared spectra acquisition confirms that the GBM treatments did not alter the levels of lipid contents inside microglia. Our results also found that GBM significantly increased collagen hydrogel contraction, verifying microglia cellular contractility to physically remodel the extracellular matrix (ECM). Cytokine arrays reveal a suite of soluble proteins that may contribute to the chemotactic effects of microglia invasion. Collectively, this study refines our biophysical understanding that GBM enhances microglia matrix invasion through increasing cellular contractility, independent of MMP activity and cellular glycolysis. Furthermore, the microfluidic platform developed in this research also provides future applications in the exploration of vascular-immune interaction (e.g., microglia-mediated angiogenesis) during GBM progression.
August 26, 2024 (12 pm ET, 9 am PT; webinar signup)
Stephanie Fung, Children’s Hospital of Philadelphia
Hydrogel Tissue Expanders for Stimulating Facial Growth in Congenital Microphthalmia Patients
Abstract
Microphthalmia and anophthalmia, congenital conditions where a child is born with at least one abnormally small or missing eyeball, puts the afflicted at risk for abnormal facial development. Absence of an eyeball hinders normal orbital and facial growth, which leads to deformities that impede social interactions. Early intervention is critical to maintain symmetrical development and enable implantation of a permanent prosthetic eye later in life. Currently, the standard of care is a self-inflating osmotic expander to guide bone and soft tissue expansion. These hydrogel devices have several limitations. They expand rapidly, which can lead to pain and inflammation of the surrounding tissue. They are composed of a singular material that expands isotropically, which does not produce the spatially differential pressures required to properly expand a composite tissue like the orbital socket. Furthermore, the expanders are typically left in for weeks or months at a time, and biofilm formation on this device is a source of concern. The goal of this work is to identify a biomaterial formulation that promotes soft tissue and bone tissue expansion while mitigating the disadvantages of the current product used in the clinic. We achieved this goal by modulating chemical composition to control swelling potential and by utilizing an interpenetrating network of chitosan within the synthetic hydrogel. Chitosan has antimicrobial properties and is degraded by lysozyme, an enzyme that occurs naturally in human tears. We hypothesized that this interpenetrating network would control the initial rate of expansion, and degradation of the network under physiological conditions would result in a linear rate of swelling over an extended period of time. Hydrogels with varying ratios of methyl methacrylate, n-vinyl pyrrolidone (NVP), and crosslinker were synthesized via bulk free radical polymerization using azobisisobutyronitrile (AIBN) as a thermal initiator. Saponification of the gels produced an ionic hydrogel. Swelling potential of the base hydrogel was controlled by monomer percentage, percent ionization, initiator concentration, and crosslinker concentration. Percent mass change at equilibrium ranged from 150-800%, and this range included formulations with swelling behavior comparable to the industry standard. While the base hydrogel, like the industry standard, exhibited a rapid swelling rate, the chitosan interpenetrating network mitigated this limitation by providing a means of restricting and controlling network expansion. The chitosan network degraded in the presence of lysozyme, leading to a linear, crosslinker concentrationdependent increase in hydrogel swelling over time. When implanted subcutaneously in rats, the hydrogels expanded to a similar degree as they did ex vivo. The explanted hydrogels were surrounded by a thin, loose fibrous capsule, and no signs of inflammation were observed after 14 days. This work produced a library of hydrogel formulations that exert a broad range of osmotic pressures when implanted. Consequently, we are now capable of rationally designing multi-formulation devices to spatially control pressure exertion tailored to patient-specific craniofacial geometries.
William Moscoso Barrera, University of Texas at Austin
Application of Low Intensity Focused Ultrasound for Peripheral Nerve Pain
Abstract
Pain, as defined by the International Association for the Study of Pain (IASP), is an unpleasant bodily signal associated with immediate or potential tissue damage, universally experienced but uniquely perceived by everyone. In 2021, the Centers for Disease Control and Prevention conducted a study revealing that approximately 21% of adults in the United States experience chronic pain, defined as pain occurring every day or most days for at least three months. Direct consequences of severe pain include loss of strength, reliance on medication, and disrupted sleep. Pain can induce significant changes in both the central and peripheral nervous systems. Some of these changes are adaptive and short-lived, while others may become maladaptive and lead to the development of chronic pain. Low-Intensity Focused Ultrasound (LIFU) is a novel, non-invasive method with the advantage of precise stimulation in deep tissues. This seminar presents the context of LIFU use and some preliminary results related to its potential for treating peripheral nerve pain through neurostimulation.
Sahar Jalal, University of Minnesota
The Role of Biomechanics in Diagnosis and Evaluation of Coronary Artery Disease
Abstract
While there is a strong need to assess the safety and efficacy of novel therapies prior to evaluation in human patients, the ability to accurately model the complexities of coronary disease in-vitro and/or animal models is somewhat limited. Animal models, even those with genetic predispositions toward coronary disease do not exhibit high grade stenoses, similar to those that require treatment in human patients. At the same time, most in-vitro models and simulations of fluid-structure interactions cannot simultaneously capture the complex geometries, hemodynamics, and biomechanical response of human coronary disease. Here, we introduce a robust workflow to replicate an in-vitro platform incorporating compliant, realistic diseased coronary arteries in a flow loop under physiological conditions. Through ex-vivo imaging of cadaveric specimens, coupled with co-registered measurements of coronary biomechanics, we developed protocols that allow for fabrication and testing of highly realistic 3D printed models. The anatomical and biomechanical features of the coronary arteries, including local variations associated with the observed disease burdens were extracted and 3D printed, in high spatial resolution, using commercially available printers, making this methodology conveniently reproducible. Subsequently, the models were incorporated in a testing platform made of flow loops and valve resistance to mimic circulation and microvascular resistance respectively. Under physiological boundary conditions, we successfully collected measurements along the length of the vessels that exhibit a range of biomechanical characteristics from low to high values of modulus and assessed the impact of biomechanics on gold standard diagnostic and prognostic measures such as Fractional Flow Reserve. We demonstrated that incorporating the effects of local biomechanics significantly improves the predicted hemodynamics metrics with respect to ex-vivo coronaries.
September 9, 2024 (12 pm ET, 9 am PT; webinar signup)
Nzinga Mack, Johns Hopkins University
Abstract
My research interests lie at the intersections between cancer, autoimmunity, and hyperinflammation, applying both wet lab and computational tools to unlock potential treatments for these disorders. I am uniquely situated to delve into these areas using a diverse set of methodologies, building on my doctoral work which focused on biochemical experiments related to cancer treatment, and my postdoctoral work which is focused on applying computational tools to immunological research. My current research focuses on Interleukin-2 (IL-2), which stimulates the survival, activation, and expansion of T lymphocytes. Due to its critical role in immune function, the IL-2 cytokine has been FDA-approved for the treatment of certain metastatic cancers and used clinically for the treatment of autoimmune conditions such as type 1 diabetes and for the prevention of transplant rejection. However, the off-target effects of IL-2 and its vanishingly short half-life have hampered clinical progress. To circumvent the therapeutic shortcomings of natural cytokines, our lab has tethered IL-2 to anti-IL-2 antibodies to form immunocytokines, which enhance target specificity and significantly prolong serum persistence of IL-2. To advance therapeutic translation, we are building a computational pharmacological model that mechanistically characterizes the activity of IL-2 and IL-2-based immunocytokines. Our model incorporated ligand-receptor binding, trafficking dynamics, and signaling in two cell types (T-effector and T-regulatory lymphocytes). The level of IL-2 signaling induction (represented in the model as ligand-receptor binding) was used as a predictor of downstream signaling and validated against experimental measurements of signaling induced by IL-2 and IL-2-based immunocytokines. To replicate the experimental data, we introduced an intermediate signaling step between the ligand-receptor activation and the signaling readout, using a Hill function to permit amplification of the receptor activation. This transformation allowed for the previously measured binding affinities to reproduce the observed cell-type-specific and ligand-specific responses to IL-2 and IL-2-based immunocytokines using a consistent set of parameters. We are next translating the mechanistic model to a computational pharmacological model to simulate IL-2 and IL-2-based immunocytokines as therapeutics in the body, to help accelerate therapeutic regimen development. Looking further in the future, my vision is to have my lab - the Mack Lab – build upon the cancer and immunology expertise that I have gained throughout my training to focus on the intersections between cancer, autoimmunity and hyperinflammation. On the wet lab side, I would like my lab to explore the alterations in energy metabolism that is characteristic of both cancer cells and activated immune cells to unlock potential treatments. In addition, I’d like my lab to explore the biology of the links between these three areas. On the translational side, I intend to have my lab build computational mechanistic models of cancer and autoimmune treatments and expand them to computational pharmacokinetic/(PK/PD) models to inform clinical trials and lay the foundation for personalized medicine. In addition, my lab would also use artificial intelligence to build machine learning models to determine which clinical indicators are most important in determining disease severity and therefore should be prioritized for intervention. I envision the Mack Lab driving forward our understanding of the overlaps between cancer, autoimmunity and hyperinflammation, while using both wet lab and computational tools simultaneously to unlock potential treatments for these disorders.
Ishita Jain, Stanford University
Computational Modeling in Tissue Engineering: A Multi-Omics and Machine Learning Perspective
Abstract
The bioengineering field faces a next-generation challenge: systematically analyzing the vast data generated daily. In tissue engineering and regenerative medicine, optimizing multiple parameters and analyzing cellular behavior is crucial. High-throughput technologies and next-generation sequencing enable testing numerous parameters and gaining detailed insights into cellular behavior. However, novel analysis pipelines and complex algorithms are needed to choose parameters and innovatively analyze cellular behavior. This talk presents three stories demonstrating how these pipelines led to new findings in liver and cardiovascular regenerative medicine. First, I will discuss my past work using high-throughput technologies and multi-omics to identify new target genes in hepatic stellate cells for non-alcoholic fatty liver disease. Next, I will share my current work developing novel 3D hydrogels to study endothelial to mesenchymal transition in atherosclerosis and using single-cell transcriptomics to analyze cellular behavior. Additionally, I will discuss a collaboration with the FDA on designing an AI model to predict optimal culture properties for mesenchymal stem cell manufacturing and developing a clinical benchmark for in vitro manufacturing of MSCs. Finally, I will outline my plans to integrate computational approaches to understand in vitro blood vessel development and design artificial in vitro blood vessels with varied structural and functional properties. More specifically, I will showcase the integration of multi-omics and machine learning to build in silico tissues for mechanistic studies that will iteratively guide the design of next generation therapeutics.
Tania Lopez Silva, National Cancer Institute
Abstract
Material-based immunomodulation using nanofibrous peptide hydrogels Material-based strategies to elicit specific immune responses can be transformative in developing more effective immunotherapies. Common strategies using materials for immunomodulation rely on the delivery of drugs, biomolecules, or cells. However, materials have intrinsic properties that can be exploited to recruit specific cell types and activate or suppress the immune system. A unique class of materials exhibiting immunomodulatory effects is self-assembling peptide hydrogels. These materials comprise short peptides that assemble into nanofibers and form highly hydrated 3D networks. They offer high versatility for material design as we can tune their sequence, structure, and mechanical properties. To fully harness the potential of peptide materials for immunomodulation, it is critical to understand how peptide design affects the immune response and to elucidate the relevant factors and cell-nanofiber interactions responsible for those responses. This work focuses on the comprehensive characterization of the immune response to a family of peptide hydrogels with a range of highly positive, neutral (zwitterionic), and negative charges. These materials have similar viscoelastic properties and nanofibrous structure, which ensures that the net charge and charge distribution are the main determining factors eliciting the observed immune responses. We evaluated the immune response to this family of peptide gels using a subcutaneous injection model combined with ultrasound imaging, tissue analyses, flow cytometry, and multiplex immunoassays. We observed distinct and divergent host responses elicited by the differentially charged peptide gels, indicating the influence of material attributes on the immune response. In particular, we found that material charge can be used to control the recruitment of neutrophils and Neutrophil Extracellular Trap (NET) formation. Our system facilitates anatomical and locoregional control of NET formation directly within a hydrogel implant, and we can fine-tune inflammation and the degree of NET formation in vivo by employing composites of gels with different charges. This project contributes to elucidating basic principles for peptide material design that we can use to control the immune system without the need for exogenous additives. Harnessing the power of the immune system using peptide materials will allow us to enhance current therapies, particularly for cancer.
September 23, 2024 (12 pm ET, 9 am PT; webinar signup)
Sade Williams Clayton, Washington University in St. Louis
Abstract
The spinal column is an invaluable structure of the musculoskeletal system and the defining characteristic of vertebrate animals. An essential component of the spinal column is the intervertebral disc (IVD), a connective tissue that provides the shock absorption and weight distribution biomechanical properties of the spine. IVDs are complex, heterogeneous structures that are prone to cumulative damage due to a limited regenerative capacity. The accrual of IVD injuries leads to tissue degeneration, which is a leading contributor to debilitating back pain and a reduction in quality of life. Successful healing of connective tissue injuries relies on temporally regulated immune cells that rapidly infiltrate damaged tissues and initiate regenerative signaling cascades. These immune cells rapidly migrate into injured tissues and function as critical mediators of tissue regeneration and healing. However, the identity of these immune cell subtypes, their temporal coordination, and their effect on the IVD repair after injury remain understudied. The objective of this study is to prevent IVD degeneration by defining the role of infiltrating immune cells during injury to improve tissue repair. The importance of immune cells in facilitating healing has been well characterized in musculoskeletal (MSK) tissues such as bone and muscle. Cd3+ T lymphocytes have been shown to be critical mediators of repair, but their role in IVD healing is unknown. To determine the role of immune cells during IVD damage, we utilized a needle puncture model to induce the robust infiltration of Cd45+ immune cells by causing a severe injury to IVD tissue. Our findings show a sex divergent response of anti-inflammatory Cd3+ γδ T cells during the acute IVD injury response and a dysregulation in IVD tissue mechanics in mice lacking lymphocytes. We hypothesize that Cd3+ γδ T cells are essential for IVD tissue repair. By utilizing methodologies such as quantitative polymerase chain reaction, bulk RNA sequencing, flow cytometry, and drug therapy, this study offers a targeted approach to modulate IVD repair by elucidating the types and temporal regulation of key immune cell subtypes important during IVD repair.
Kristen Jakubowski, Emory University and Georgia Institute of Technology
Restoring, maintaining, and augmenting neuromuscular health and mobility through targeted rehabilitation and personalized wearable robotic devices
Abstract
Preserving mobility is a key public health challenge. Lower limb robotic exoskeletons have been developed as a tool for improving mobility. Yet, it remains an open question on how exoskeletons should be designed and controlled to best elicit positive, rehabilitative benefits. Contributing to this gap is 1) a limited understanding of the individual-specific mechanisms driving impaired mobility to determine what component of the neuromuscular system a rehabilitative exoskeleton should target, and 2) devices lack feedback on how the human neuromuscular system reacts and adapts to the device to ensure the device is eliciting the desired rehabilitative effect while also working seamlessly with the wearer. In this seminar, I will highlight my work to address these gaps by: 1) identifying the underlying mechanisms contributing to mobility impairments using joint and whole-body measurements, 2) developing neuromechanics-informed exoskeleton control paradigms, and 3) quantifying how the human neuromuscular system reacts and adapts to exoskeletons. In combination, this work provides a framework for the development of lower limb robotic exoskeletons that are rehabilitative tools for maintaining mobility across an individual's life.
Lena Gamboa, Emory University and Georgia Institute of Technology
Programming synthetic immunity against solid tumors