Biomedical Engineering and Bioengineering Commons^™

3-Dimensional Muscle Constructs: Using Hydrogels In Order To Model The Effects Of Exercise In Disease Conditions, Mark Mchargue

Theses and Dissertations--Biomedical Engineering

Currently, there is no standard in vitro model for studying the effects of mechanical stimulation on muscle in type II diabetes. Existing models primarily utilize electrical stimulation, which does not fully recapitulate the effects of exercise. In this thesis, we create a standardized in vitro model of murine muscle that can recapitulate the benefits seen in exercise when mechanically stimulated. Moreover, we show that a type II diabetes environment has similar effects on the muscle in vitro as well as in vivo.

Optimization Of Gelatin-Based Cellular Coating Of Msc For Myocardial Infarction Therapy, Kara Amelle Davis

Theses and Dissertations--Chemical and Materials Engineering

Cardiovascular disease remains the number one threat to American lives. During an acute myocardial infarction (AMI), blood flow is blocked and results in the formation of scar tissue. As the body’s immune system responds, inflammatory signaling causes an increase in both scar tissue size and the patient’s risk for further chronic heart failure. In order to reduce the risk of continued heart disease inflammatory signaling must be reduced. Stem cell therapies have the ability to alter the immune system’s pro-inflammatory signal. However, stem cell retention is limited due to blood flow shear. Gelatin methacrylate (GelMA) based coatings have been shown …

A Framework For Heterologous Biosynthesis Of Natural Products In Mammalian Cells Via Polymer-Mediated Transfections, Logan Warriner

Theses and Dissertations--Chemical and Materials Engineering

With the promise to treat a multi-faceted list of serious inherited and acquired diseases, such as cancer, neurodegenerative and infectious diseases, and inherited genetic indications, gene therapy has continued to push the boundaries of traditional medicine since its earliest implementation. While much progress has been made, clinical success has largely remained elusive. Immunogenicity, difficulty producing commercially relevant quantities, and having a limited genetic payload still limits the ability of viruses to act as directed delivery agents for genetic material. As such, researchers have turned to cationic synthetic materials as a means of delivering nucleic acids, which can circumvent the immune …

Cell Surface Coatings For Mammalian Cell-Based Therapeutic Delivery, Pei-Jung Wu

Theses and Dissertations--Chemical and Materials Engineering

The cell plasma membrane is an interactive interface playing an important role in regulating cell-to-cell, cell-to-tissue contact, and cell-to-environment responses. This environment-responsive phospholipid layer consisting of multiple dynamically balanced macromolecules, such as membrane proteins, carbohydrate and lipids, is regarded as a promising platform for various surface engineering strategies. Through different chemical modification routes, we are able to incorporate various artificial materials into the cell surface for biomedical applications in small molecule and cellular therapeutics.

In this dissertation, we establish two different cell coating techniques for applications of cell-mediated drug delivery and the localization of cell-based therapies to specific tissues. The …

Comparison Of Eosin And Fluorescein Conjugates For The Photoinitiation Of Cell-Compatible Polymer Coatings, Jacob L. Lilly, Anuhya Gottipati, Calvin F. Cahall, Mohamed Agoub, Brad J. Berron

Chemical and Materials Engineering Faculty Publications

Targeted photopolymerization is the basis for multiple diagnostic and cell encapsulation technologies. While eosin is used in conjunction with tertiary amines as a water-soluble photoinitiation system, eosin is not widely sold as a conjugate with antibodies and other targeting biomolecules. Here we evaluate the utility of fluorescein-labeled bioconjugates to photopolymerize targeted coatings on live cells. We show that although fluorescein conjugates absorb approximately 50% less light energy than eosin in matched photopolymerization experiments using a 530 nm LED lamp, appreciable polymer thicknesses can still be formed in cell compatible environments with fluorescein photosensitization. At low photoinitiator density, eosin allows more …

Surface Functionalization Via Photoinitiated Radical Polymerization For Rare Cell Isolation And Mechanical Protection, Calvin Frank Cahall

Theses and Dissertations--Chemical and Materials Engineering

Surface functionalization of living cells for cell therapeutics has gained substantial momentum in the last two decades. From encapsulating islets of Langerhans, to cell laden gels for tissue scaffolds, to individual cell encapsulation in thin hydrogels, to surface adhesives and inert surface camouflage, modification of living cell surfaces has a wide array of important applications. Here we use hydrogel encapsulation of individual cells as a mode of protection from mechanical forces for high throughput cell printing, and chemical stimuli for the isolation of rare cells in blood.

In the first study, we review methods of surface functionalization and establish a …

Subject-Independent Emotion Recognition Based On Physiological Signals: A Three-Stage Decision Method, Jing Chen, Bin Hu, Yue Wang, Philip Moore, Yongqiang Dai, Lei Feng, Zhijie Ding

Biomedical Engineering Faculty Publications

Background: Collaboration between humans and computers has become pervasive and ubiquitous, however current computer systems are limited in that they fail to address the emotional component. An accurate understanding of human emotions is necessary for these computers to trigger proper feedback. Among multiple emotional channels, physiological signals are synchronous with emotional responses; therefore, analyzing physiological changes is a recognized way to estimate human emotions. In this paper, a three-stage decision method is proposed to recognize four emotions based on physiological signals in the multi-subject context. Emotion detection is achieved by using a stage-divided strategy in which each stage deals with …

Reducing Biomass Recalcitrance By Heterologous Expression Of A Bacterial Peroxidase In Tobacco (Nicotiana Benthamiana), Ayalew Ligaba-Osena, Bertrand Hankoua, Kay Dimarco, Robert Pace, Mark Crocker, Jesse Mcatee, Nivedita Nagachar, Ming Tien, Tom L. Richard

Center for Applied Energy Research Faculty and Staff Publications

Commercial scale production of biofuels from lignocellulosic feed stocks has been hampered by the resistance of plant cell walls to enzymatic conversion, primarily owing to lignin. This study investigated whether DypB, the lignin-degrading peroxidase from Rodococcus jostii, depolymerizes lignin and reduces recalcitrance in transgenic tobacco (Nicotiana benthamiana). The protein was targeted to the cytosol or the ER using ER-targeting and retention signal peptides. For each construct, five independent transgenic lines were characterized phenotypically and genotypically. Our findings reveal that expression of DypB in the cytosol and ER does not affect plant development. ER-targeting increased protein accumulation, and …

Quantifying The Effects Of Hydrostatic Pressure On Fibroblast Growth Factor-2 Binding By The Human Endothelium, Taylor R. Mckenty

Theses and Dissertations--Biomedical Engineering

Fluid pressures regulate endothelial cell (EC) tubulogenic activity involving fibroblast growth factor 2 (FGF-2) and its receptor, FGF receptor 2 (FGFR2). Our lab has recently shown that sustained 20 mmHg hydrostatic pressure (HP) upregulates EC sprout formation in a FGF2-dependent fashion. This upregulation of sprout formation may be due to enhanced FGF-2 / FGFR2 interactions in the presence of 20 mmHg HP. We hypothesize that exposure of ECs to 20 mmHg sustained HP enhances FGF-2 binding kinetics. We used a custom hydrostatic pressure system, immunofluorescence, and FACS to quantify FGF-2 binding by ECs in the absence or presence of a …

The Effect Of Cholesterol On The Osteoblast Responsiveness To Hydrodynamic Pressure Stimulation, Kristen Lough

Theses and Dissertations--Biomedical Engineering

Hypercholesterolemia is a risk factor for osteoporosis but the underlying mechanism is unknown. Previous evidence suggests that osteoporosis results from an impaired regulation of osteoblasts by fluid pressure fluctuations in the bone matrix. Recently, our laboratory showed that enhanced cholesterol in the cell membrane, due to hypercholesterolemia, alters leukocyte mechanosensitivity. We predict a similar link between osteoblasts and hypercholesterolemia leading to osteoporosis. Specifically, we hypothesize that extracellular cholesterol modifies the osteoblast sensitivity to pressure. MC3T3-E1 cells were exposed to hydrodynamic pressures regimes (mean=40mmHg, amplitude=0-20mmHg, frequency=1Hz) for 1-12 hours. To assess the impact of membrane cholesterol enrichment, cells were pre-treated with …

Up Regulation Of Heat Shock Protein 70b (Hsp70b) And Ssa1 In Chlamydomonas Reinhardtii Via Hsp70a-Rbcs2 And Psad Promoter, B. Kirtley Amos

Theses and Dissertations--Biosystems and Agricultural Engineering

Fabrication of effective algae cultivation systems adjacent to coal-fired power plants to fixate waste CO₂ would represent a sizable step towards achieving a carbon neutral energy cycle. However, emission gas would elevate the algal cultivation system temperature and decreases its pH without expensive preprocessing. Increased temperature and acidity constitutes a profound stress on the algae. Although stressed algae produce heat shock proteins (HSPs) that promote protein folding and protect against stress, the ordinary biological response is insufficient to protect against coal flue gas. Experimental upregulation of HSPs could make algae respond to the stress caused by high temperatures and …

Bioerodible Calcium Sulfate Bone Grafting Substitutes With Tailored Drug Delivery Capabilities, Bryan R. Orellana

Theses and Dissertations--Biomedical Engineering

Bone regeneration or augmentation is often required prior to or concomitant with implant placement. With the limitations of many existing technologies, a biologically compatible synthetic bone grafting substitute that is osteogenic, bioerodible, and provides spacing-making functionality while acting as a drug delivery vehicle for bioactive molecules could provide an alternative to ‘gold standard’ techniques.

In the first part of this work, calcium sulfate (CS) space-making synthetic bone grafts with uniformly embedded poly(β-amino ester) (PBAE) biodegradable hydrogel particles was developed to allow controlled release of bioactive agents. The embedded gel particles’ influence on the physical and chemical characteristics of CS was …

The Effects Of Hydrostatic Pressure On Early Endothelial Tubulogenic Processes, Ryan M. Underwood

Theses and Dissertations--Biomedical Engineering

The effects of mechanical forces on endothelial cell function and behavior are well documented, but have not been fully characterized. Specifically, fluid pressure has been shown to elicit physical and chemical responses known to be involved in the initiation and progression of endothelial cell-mediated vascularization. Central to the process of vascularization is the formation of tube-like structures. This process—tubulogenesis—is essential to both the physiological and pathological growth of tissues. Given the known effects of pressure on endothelial cells and its ubiquitous presence in the vasculature, we investigated pressure as a magnitude-dependent parameter for the regulation of endothelial tubulogenic activity. To …

Growth Plate Regeneration Using Polymer-Based Scaffolds Releasing Growth Factor, Amanda Clark

Theses and Dissertations--Biomedical Engineering

Currently growth plate fractures account for nearly 18.5% of fractures in children and can lead to stunted bone growth or angular deformation. If the body is unable to heal itself a bony bar forms, preventing normal bone growth. Clinical treatment involves removing the bony bar and replacing it with a filler substance, which causes poor results 60% of the time.

Using primarily poly(lactic-co-glycolic acid) (PLGA) as the scaffold material, the goal was to develop an implant that would support to the implant site, allow for cell ingrowth, and degrade away over time. Porous scaffolds were fabricated from PLGA microspheres using …