Open Access. Powered by Scholars. Published by Universities.®

Engineering Commons

Open Access. Powered by Scholars. Published by Universities.®

Articles 1 - 11 of 11

Full-Text Articles in Engineering

The Development Of A Mesenchymal Stem Cell Based Bone Graft System, Sarina Sinclair Dec 2009

The Development Of A Mesenchymal Stem Cell Based Bone Graft System, Sarina Sinclair

All Dissertations

Greater than 5.5 million fractures are sustained by Americans each year, accounting for more than 500,000 bone graft surgeries. Bone grafts are the second most transplanted material, surpassed only by blood. The current 'gold standard' for bone grafting involves harvesting bone material from the patient's iliac crest, due to its osteoinductive properties. Unfortunately, the surgery required to harvest material from the iliac crest causes additional pain for the patient, relies on a limited amount of available bone tissue, and results in, on average, a 30% rate of donor site morbidity. Both natural and synthetic substitutes have been developed to avoid …


Hydrogel Compositions For Nonviral Gene Delivery, Eunhee Cho Dec 2009

Hydrogel Compositions For Nonviral Gene Delivery, Eunhee Cho

All Dissertations

The incorporation of nonviral vectors into biomaterial matrices has been employed to improve localization at the implant site and to protect from loss by clearance or extracellular barriers. However, several limitations such as detrimental crosslinking mechanisms, uncontrolled burst release require improved design of matrix-based gene delivery systems that provides sustained and controlled vector release as well as overcomes extracellular barriers to gene transfer in proximity to target cells. The long-term objective of this dissertation project is to provide the basis for the eventual creation of tissue engineering scaffolds that combine structural and biological activity through the creation of composite materials …


Covalent Immobilization Of L1 Neural Cell Adhesion Molecule To Acrylated Tetronicâ® Hydrogels For Neural Regeneration, Rebecca Cribb Dec 2009

Covalent Immobilization Of L1 Neural Cell Adhesion Molecule To Acrylated Tetronicâ® Hydrogels For Neural Regeneration, Rebecca Cribb

All Dissertations

Spinal cord injuries cost the United States $20 billion per year, with an existing patient population of 256,000 growing by an estimated 12,000 each year. Current clinical therapies for spinal cord injury are limited to spinal immobilization and realignment via traction, surgery, administration of methylprednisolone sodium succinate (MPSS) within eight hours post-injury, and rehabilitation exercises. While these therapies are important and may minimize damage and restore limited function, there is a dire clinical need for treatments to address the growing population of chronically-injured patients.
Varying degrees of axonal regeneration and functional recovery following spinal cord injury have been achieved in …


Creation Of Bioactive Surfaces To Modulate Cell Behavior Using Surface Initiated Photoiniferter-Mediated Graft Photopolymerization, Nihar Shah Dec 2009

Creation Of Bioactive Surfaces To Modulate Cell Behavior Using Surface Initiated Photoiniferter-Mediated Graft Photopolymerization, Nihar Shah

All Dissertations

Biomaterials widely used in biomedical applications still face biocompatibility issues arising from non-specific protein adsorption on the foreign surface, and the consequent undesired cell response. Emerging evidence suggests that imparting specific bioactivity to the biomaterial's surface to elicit favorable response from cells, (like osseointegration of joint implants and endothelialization of stents) can yield much better biocompatibility results when combined with passive prevention of protein adsorption. In more complex diseases like spinal cord injury and cardiomyopathy, specific biomolecules are required to elicit desired cell responses for successful regeneration. However, for success of such biomolecule based strategies, the effects of various parameters …


Neomycin Enhances Glutaraldehyde Crosslinking And Glycosaminoglycan Stability In Bioprosthetic Heart Valves, Vincent Friebe Dec 2009

Neomycin Enhances Glutaraldehyde Crosslinking And Glycosaminoglycan Stability In Bioprosthetic Heart Valves, Vincent Friebe

All Theses

The native heart valve will open and close an astonishing 3 billion times in the average lifetime, implicating immense biomechanical ramifications that necessitate near-flawless structure and functional behavior. Deviations from this idyllic function as a result of heart valve disease (HVD) affect millions of individuals worldwide and result in over 275,000 heart valve replacements worldwide every year. Glutaraldehyde (GLUT) cross-linked porcine aortic heart valves, a common type of bioprosthetic heart valve (BHV), are used frequently in these valve replacement surgeries. The native valve leaflets entail a tri-composite design of type I collagen, elastin and glycosaminoglycans (GAGs), each of which are …


Creation Of Defined Single Cell Resolution Neuronal Circuits On Microelectrode Arrays, Russell Pirlo Aug 2009

Creation Of Defined Single Cell Resolution Neuronal Circuits On Microelectrode Arrays, Russell Pirlo

All Dissertations

The way cell-cell organization of neuronal networks influences activity and facilitates function is not well understood. Microelectrode arrays (MEAs) and advancing cell patterning technologies have enabled access to and control of in vitro neuronal networks spawning much new research in neuroscience and neuroengineering. We propose that small, simple networks of neurons with defined circuitry may serve as valuable research models where every connection can be analyzed, controlled and manipulated.
Towards the goal of creating such neuronal networks we have applied microfabricated elastomeric membranes, surface modification and our unique laser cell patterning system to create defined neuronal circuits with single-cell precision …


Adsorption-Induced Changes In Enzyme Bioactivity Correlated With Adsorbed Protein Orientation And Conformation, Kenan Fears May 2009

Adsorption-Induced Changes In Enzyme Bioactivity Correlated With Adsorbed Protein Orientation And Conformation, Kenan Fears

All Dissertations

Systems using immobilized enzymes are attractive for a wide range of industrial and medical applications because they allow for fabrication of stable, reusable substrates with a highly specific functionality. The performance of these systems is greatly influenced by the orientation and conformation of the immobilized enzymes. To investigate these relationships, we have developed and applied methods to quantitatively assess the secondary structure of adsorbed enzyme layers on planar surfaces using circular dichroism (CD) spectropolarimetry and evaluate their bioactivity using colorimetric assays. When combined with knowledge of an enzyme's native structure, these methods provide a means to correlate changes in enzyme …


A Pulsatile Bioreactor For Conditioning Tissue Engineered Heart Valves, Leslie Sierad May 2009

A Pulsatile Bioreactor For Conditioning Tissue Engineered Heart Valves, Leslie Sierad

All Theses

Tissue engineered constructs with autologous adult stem cells capable of self-repair and growth are highly desired replacements for diseased heart valves. However, the current approaches have inadequate mechanical properties to withstand in vivo implantation. Therefore, our group hypothesized that an in vitro environment of physiological intra-cardiac pressures and flow will stimulate stem cells to differentiate and remodel valvular scaffold constructs before implantation.
The group developed a pneumatic-driven conditioning system (Aim I) consisting of a three-chambered heart valve bioreactor, a pressurized compliance tank, a reservoir tank, one-way valves, pressure-retaining valves, and pressure transducers. The system can be sterilized using conventional autoclaving …


Cardiac Cell Mechanics At The Single Cell Level, John Mcrae May 2009

Cardiac Cell Mechanics At The Single Cell Level, John Mcrae

All Theses

The analysis of the cellular microenvironment is an area that has received much
attention recently in the study of the tractions cells use for locomotion. Specifically, the
study of cardiac cell mechanics is of particular interest as cardiac dysfunction is one of
the leading causes of death in America. This progression is fueled by the need to have a
system capable of reproducing mechanical environments before, during and after a
dysfunctional event in order to fully characterize the causes and prevent any permanent
damage. The current study proposes a system capable of providing quantitative
measurements of the cellular microenvironment while …


A Tissue Engineering Approach To Anterior Cruciate Ligament, Kristofer Sinclair May 2009

A Tissue Engineering Approach To Anterior Cruciate Ligament, Kristofer Sinclair

All Dissertations

Ruptures of the anterior cruciate ligament (ACL) are the most frequent of injuries to the knee due to its role in preventing anterior translation of the tibia. It is estimated that as many as 200,000 Americans per year will suffer from a ruptured ACL, resulting in management costs on the order of 5 billion dollars. Without treatment these patients are unable to return to normal activity, as a consequence of the joint instability found within the ACL deficient knee.
Over the last thirty years, a variety of non-degradable, synthetic fibers have been evaluated for their use in ACL reconstruction; however, …


The Effect Of Hydrostatic Pressure On Bladder Smooth Muscle Cell Function, Margaret Drumm May 2009

The Effect Of Hydrostatic Pressure On Bladder Smooth Muscle Cell Function, Margaret Drumm

All Theses

Previous research has demonstrated that bladder smooth muscle cells (BSMC) respond to various forms of mechanical stimuli, including stretch and hydrostatic pressure, by increases of cell proliferation, activation of intracellular signaling pathways, and alteration of contractile and synthetic marker protein expression. These cellular/molecular level changes are all indicative of a BSMC phenotypic shift that can negatively impact the bladder function at the tissue and organ level. The objective of the present study is to test a hypothesis that bladder SMCs shift their phenotype from contractile to synthetic in response to elevated hydrostatic pressure. Rat bladder SMC cultures were exposed to …