Engineering Commons^™

The Cooperative Effects Of Channel Length-Bias, Width Asymmetry, Gradient Steepness, And Contact-Guidance On Fibroblasts’ Directional Decision Making, Quang Long Pham

Dissertations

Cell migration in complex micro-environments, that are similar to tissue pores, is important for predicting locations of tissue nucleation and optimizing scaffold architectures. Firstly, how fibroblast cells - relevant to tissue engineering, affect each other’s directional decisions when encountered with a bifurcation of different channel lengths was investigated. It was found that cell sequence and cell mitosis influence the directional choices that the cells made while chemotaxing. Specifically, the fibroblasts chose to alternate between two possible paths - one longer and the other shorter - at a bifurcation. This finding was counter-intuitive given that the shorter path had a steeper …

Overcoming Conventional Modeling Limitations Using Image- Driven Lattice-Boltzmann Method Simulations For Biophysical Applications, Olufemi E. Kadri

Dissertations

The challenges involved in modeling biological systems are significant and push the boundaries of conventional modeling. This is because biological systems are distinctly complex, and their emergent properties are results of the interplay of numerous components/processes. Unfortunately, conventional modeling approaches are often limited by their inability to capture all these complexities. By using in vivo data derived from biomedical imaging, image-based modeling is able to overcome this limitation.

In this work, a combination of imaging data with the Lattice-Boltzmann Method for computational fluid dynamics (CFD) is applied to tissue engineering and thrombogenesis. Using this approach, some of the unanswered questions …

Consistent And Reproducible Cultures Of Large-Scale 3d Mammary Epithelial Structures Using An Accessible Bioprinting Platform, John A. Reid, Peter M. Mollica, Robert D. Bruno, Patrick C. Sachs

School of Medical Diagnostics & Translational Sciences Faculty Publications

Background: Standard three-dimensional (3D) in vitro culture techniques, such as those used for mammary epithelial cells, rely on random distribution of cells within hydrogels. Although these systems offer advantages over traditional 2D models, limitations persist owing to the lack of control over cellular placement within the hydrogel. This results in experimental inconsistencies and random organoid morphology. Robust, high-throughput experimentation requires greater standardization of 3D epithelial culture techniques.

Methods: Here, we detail the use of a 3D bioprinting platform as an investigative tool to control the 3D formation of organoids through the "self-assembly" of human mammary epithelial cells. Experimental bioprinting procedures …

Fabrication And In Vitro Characterization Of An Implant For The Detection Of Metastatic Cancer Cells, Carlos Martin Cantu

Bioengineering Theses

Greater than 90% of cancer related deaths are due to metastasis (Hayes & Wicha, 2011). Since current conventional techniques detect the disease by the time that it has become systemic, our lab has developed a hydrogel based cancer trap that can attract metastatic cancer cells via cytokine release. However, for continual monitoring and accessibility to the gel, an implant is needed for delivery, retention, and retrieval of the gel. The research undergone in this thesis seeks to develop such a method. Namely, the objective was to develop a polylactide (PLA) based implant that is capable of delivering and retaining a …

Developmental Steps For A Functional Three-Dimensional Cell Culture System For The Study Of Asymmetrical Division Of Neural Stem Cells, Martina Zamponi

Biomedical Engineering Theses & Dissertations

Stem cells are a cell type present during and following development, which possess self- renewal properties, as well as the ability to differentiate into specific cells. Asymmetrical division is the cellular process that allows stem cells to produce one differentiated and one un-differentiated daughter cell during the same mitotic event. Insights in the molecular mechanisms of such process are minimal, due to the absence of effective methods for its targeted study. Currently, traditional methods of investigation include monolayer cell culture and animal models. The first poses structural limitations to the accurate representation of human tissue and cell structures, while animal …

Preparation And Characterization Of Electrospun Rgo-Poly(Ester Amide) Tissue Engineering Scaffolds, Hilary Stone

Electronic Thesis and Dissertation Repository

Tissue engineering scaffolds should support tissue maturation through exposure to biologically relevant stimuli and through successful cell infiltration. External electrical stimulation is particularly relevant for cardiac and neural applications, and requires conductive scaffolds to propagate electrical signals; cell infiltration is only possible with scaffolds that have sufficient porosity. The aim of this study was to impart conductivity and increased porosity of electrospun poly(ester amide) (PEA) scaffolds. Reduced graphene oxide (rGO) was incorporated into blend PEA and coaxial PEA-chitosan fibrous scaffolds, which increased scaffold conductivity and supported cardiac differentiation. The novel combination of ultrasonication and leaching of a sacrificial polymer was …

Application Of Composite Hydrogels To Control Physical Properties In Tissue Engineering And Regenerative Medicine, Cassidy Sheffield, Kaylee Meyers, Emil Johnson, Rupak Rajachar

Michigan Tech Publications

The development of biomaterials for the restoration of the normal tissue structure–function relationship in pathological conditions as well as acute and chronic injury is an area of intense investigation. More recently, the use of tailored or composite hydrogels for tissue engineering and regenerative medicine has sought to bridge the gap between natural tissues and applied biomaterials more clearly. By applying traditional concepts in engineering composites, these hydrogels represent hierarchical structured materials that translate more closely the key guiding principles required for improved recovery of tissue architecture and functional behavior, including physical, mass transport, and biological properties. For tissue-engineering scaffolds in …

Recent Developments In Tough Hydrogels For Biomedical Applications, Yuan Liu, Weilue He, Zhongtian Zhang, Bruce P. Lee

Department of Biomedical Engineering Publications

A hydrogel is a three-dimensional polymer network with high water content and has been attractive for many biomedical applications due to its excellent biocompatibility. However, classic hydrogels are mechanically weak and unsuitable for most physiological load-bearing situations. Thus, the development of tough hydrogels used in the biomedical field becomes critical. This work reviews various strategies to fabricate tough hydrogels with the introduction of non-covalent bonds and the construction of stretchable polymer networks and interpenetrated networks, such as the so-called double-network hydrogel. Additionally, the design of tough hydrogels for tissue adhesive, tissue engineering, and soft actuators is reviewed.

3d Printed Pla Scaffolds To Promote Healing Of Large Bone Defects, Jacob W. Cole, Tiera Martinelli, Mitchell T. Ryan, Sarah G. Seman, Daniel Sidle, Stephen R. Smith, Rocco J. Rotello, Timothy L. Norman

The Research and Scholarship Symposium (2013-2019)

One challenge modern medicine faces is the ability to repair large bone defects and stimulate healing. Small defects typically heal naturally, but large bone defects do not and current solutions are to replace the missing tissue with biologically inert materials such as titanium. This limits the amount of bone healing as the defect is not repaired but rather replaced. The focus of our research is to develop a method of using 3D printing to create biodegradable scaffolds which promote bone in-growth and replacement. To accomplish this we used poly lactic acid (PLA) filament and a desktop 3D printer. To promote …

Osteon Mimetic Scaffolding, Janay Clytus

Senior Theses

The purpose of this research is to provide an alternative to naturally derived bone grafts. There is a gap in the supply of donors and the demand of bone tissue. Artificial scaffold creation can work as an implant and decrease the shortage of bone grafts and increase the range of injuries that can be repaired. Current research focuses on optimizing mechanical properties such as porosity, improving vascularization using cells, and generating osteoconductivity. For osteodifferentiation, mesenchymal stem cells (MSCs) can differentiate into mesodermal lineages such as chondrocytes, osteoblasts, adipocytes, and tenocytes by supplementing cultures with lineage-specific soluble factors (Marchetti). Co-culturing ECFCs …

3d Bioprinting Systems For The Study Of Mammary Development And Tumorigenesis, John Reid

Electrical & Computer Engineering Theses & Dissertations

Understanding the microenvironmental factors that control cell function, differentiation, and stem cell renewal represent the forefront of developmental and cancer biology. To accurately recreate and model these dynamic interactions in vitro requires both precision-controlled deposition of multiple cell types and well-defined three-dimensional (3D) extracellular matrix (ECM). To achieve this goal, we hypothesized that accessible bioprinting technology would eliminate the experimental inconsistency and random cell-organoid formation associated with manual cell-matrix embedding techniques commonly used for 3D, in vitro cell cultures. The first objective of this study was to adapt a commercially-available, 3D printer into a 3D bioprinter. Goal-based computer simulations were …

3d Tissue Engineering, An Emerging Technique For Pharmaceutical Research, Gregory Jensen, Christian Morrill, Yu Huang

Biological Engineering Faculty Publications

Tissue engineering and the tissue engineering model have shown promise in improving methods of drug delivery, drug action, and drug discovery in pharmaceutical research for the attenuation of the central nervous system inflammatory response. Such inflammation contributes to the lack of regenerative ability of neural cells, as well as the temporary and permanent loss of function associated with neurodegenerative diseases such as Alzheimer's disease, Parkinson's disease, and traumatic brain injury. This review is focused specifically on the recent advances in the tissue engineering model made by altering scaffold biophysical and biochemical properties for use in the treatment of neurodegenerative diseases. …

Visible Light Crosslinkable Human Hair Keratin Hydrogels, Kan Yue, Yanhui Liu, Batzaya Byambaa, Vaishali Singh, Wanjun Liu, Xiuyu Li, Yunxia Sun, Yu Shrike Zhang, Ali Tamayol, Peihua Zhang, Kee Woei Ng, Nasim Annabi, Ali Khademhosseini

Department of Mechanical and Materials Engineering: Faculty Publications

Keratins extracted from human hair have emerged as a promising biomaterial for various biomedical applications, partly due to their wide availability, low cost, minimal immune response, and the potential to engineer autologous tissue constructs. However, the fabrication of keratin-based scaffolds typically relies on limited crosslinking mechanisms, such as via physical interactions or disulfide bond formation, which are time-consuming and result in relatively poor mechanical strength and stability. Here, we report the preparation of photocrosslinkable keratin-polyethylene glycol (PEG) hydrogels via the thiol-norbornene “click” reaction, which can be formed within one minute upon irradiation of visible light. The resulting keratin-PEG hydrogels showed …

Engineering Hyaluronic Acid Carbon Nanotube Nanofibers: A Peripheral Nerve Interface To Electrically Stimulate Regeneration, Elisabeth M. Steel

Wayne State University Dissertations

Peripheral nerve injuries annually affect hundreds of thousands of people globally. Current treatments like the gold standard autograft and commercially available nerve guide conduits (NGC) are insufficient to repair long gap peripheral nerve injuries. NGCs can aid recovery but lack key microenvironment cues that promote nerve regeneration. We hypothesized that providing topographical, mechanical, and electrical guidance cues through a nanofibrous composite biopolymer would result in improved neuron growth metrics using an in vitro model. We embedded hydrophilic carbon nanotubes (CNT) within hyaluronic acid (HA) nanofibers by electrospinning. The aims of this study were (1) to define the topographical, nanomechanical, and …

Radial And Longitudinal Motion Of The Arterial Wall: Their Relation To Pulsatile Pressure And Flow In The Artery, Dan Wang, Linda Vahala, Zhili Hao

Mechanical & Aerospace Engineering Faculty Publications

The aim of this paper is to analyze the radial and longitudinal motion of the arterial wall in the context of pulsatile pressure and flow, and to understand their physiological implications for the cardiovascular system. A reexamination of the well-established one-dimensional governing equations for axial blood flow in the artery and the constitutive equation for the radial dilation of the arterial wall shows that two waves—a pulsatile pressure wave in the artery and a radial displacement wave in the arterial wall—propagate simultaneously along the arterial tree with the same propagation velocity, explaining why this velocity combines the physical properties and …

An Integrated Study Towards Curing Neurodegenerative Disorders Using Materials Science And Stem Cell-Based Tissue Engineering Approaches, Nishat Tasnim

Open Access Theses & Dissertations

Neurodegenerative diseases affect around one billion people globally that are characterized by irreversible degeneration of brain tissues. These diseases cause serious effects on patients degrading their brain functions and causing enormous physical and mental health issues. Parkinson's disease (PD) is one of the most common neurodegenerative disorder affecting millions of people worldwide which results from loss of dopaminergic (DA) neurons in the mid-brain. Unfortunately, no medical treatment is effective to date for these significant brain disorders, except some symptomatic therapies only focusing on improving the quality of patient's life.

Two current approaches hold great promise in targeting PD as well …

A Novel Supercritical Co2-Based Decellularization Method For Maintaining Scaffold Hydration And Mechanical Properties, Michael A. Matthews, Tarek Shazly, Rachel M. Handleton, Dominic M. Casali

Faculty Publications

Decellularized tissues are commonly utilized as tissue engineering scaffolds. Decellularization by extended exposure to aqueous detergents can damage the microstructure or deposit cytotoxic residue. Supercritical carbon dioxide (scCO2) has been proposed for decellularization, but reportedly causes dehydration and scaffold embrittlement.

Presented herein is a novel decellularization method that preserves matrix hydration state and mechanical properties. Over 97% of the water in porcine aorta is maintained by presaturating scCO2 with water; however, complete decellularization was not attained by any process utilizing only scCO2. Instead, a novel hybrid method is presented that combines a brief (48 h) exposure of tissue to aqueous …

Molded Features In Pdms For Fabricating Bacterial Cellulose For Various Geometries, Mitchell Habegger

Williams Honors College, Honors Research Projects

The purpose of producing features on bacterial cellulose (BC) is to facilitate the elongation and alignment for cells, in this case Normal Human Dermal Fibroblast (NHDF) cells. The elongated cells have applications in wound healing, tissue engineering, disease diagnostics, and many other fields. Experiments were run to test the effectiveness of transferring features to BC sheets from features induced by fracturing on polydimethylsiloxane (PDMS) and those duplicated from molds with existing features. The features were duplicated to BC sheets by either air drying or Guided Assembly-Based Biolithography (GAB). The research results showed that fracture inducing on PDMS produced very small …