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TISSUE ENGINEERED MYELINATION AND THE STRETCH REFLEX ARC SENSORY CIRCUIT: DEFINED MEDIUM FORMULATION, INTERFACE DESIGN AND MICROFABRICATION
Title
TISSUE ENGINEERED MYELINATION AND THE STRETCH REFLEX ARC SENSORY CIRCUIT: DEFINED MEDIUM FORMULATION, INTERFACE DESIGN AND MICROFABRICATION.
Creator
Rumsey, John, Hickman, James, University of Central Florida
Abstract / Description
The overall focus of this research project was to develop an in vitro tissue-engineered system that accurately reproduced the physiology of the sensory elements of the stretch reflex arc as well as engineer the myelination of neurons in the systems. In order to achieve this goal we hypothesized that myelinating culture systems, intrafusal muscle fibers and the sensory circuit of the stretch reflex arc could be bioengineered using serum-free medium formulations, growth substrate interface...
Show moreThe overall focus of this research project was to develop an in vitro tissue-engineered system that accurately reproduced the physiology of the sensory elements of the stretch reflex arc as well as engineer the myelination of neurons in the systems. In order to achieve this goal we hypothesized that myelinating culture systems, intrafusal muscle fibers and the sensory circuit of the stretch reflex arc could be bioengineered using serum-free medium formulations, growth substrate interface design and microfabrication technology. The monosynaptic stretch reflex arc is formed by a direct synapse between motoneurons and sensory neurons and is one of the fundamental circuits involved in motor control. The circuit serves as a proprioceptive feedback system, relaying information about muscle length and stretch to the central nervous system (CNS). It is composed of four elements, which are split into two circuits. The efferent or motor circuit is composed of an α-motoneuron and the extrafusal skeletal muscle fibers it innervates, while the afferent or sensory circuit is composed of a Ia sensory neuron and a muscle spindle. Structurally, the two muscular units are aligned in parallel, which plays a critical role modulating the system's performance. Functionally, the circuit acts to maintain appropriate muscle length during activities as diverse as eye movement, respiration, locomotion, fine motor control and posture maintenance. Myelination of the axons of the neuronal system is a vertebrate adaptation that enables rapid conduction of action potentials without a commensurate increase in axon diameter. In vitro neuronal systems that reproduce these effects would provide a unique modality to study factors influencing sensory neuronal deficits, neuropathic pain, myelination and diseases associated with myelination. In this dissertation, results for defined in vitro culture conditions resulting in myelination of motoneurons by Schwann cells, pattern controlled myelination of sensory neurons, intrafusal fiber formation, patterned assembly of the mechanosensory complex and integration of the complex on bio-MEMS cantilever devices. Using these systems the stretch sensitive sodium channel BNaC1 and the structural protein PICK1 localized at the sensory neuron terminals associated with the intrafusal fibers was identified as well as the Ca2+ waves associated with sensory neuron electrical activity upon intrafusal fiber stretch on MEMS cantilevers. The knowledge gained through these multi-disciplinary approaches could lead to insights for spasticity inducing diseases like Parkinson's, demyelinating diseases and spinal cord injury repair. These engineered systems also have application in high-throughput drug discovery. Furthermore, the use of biomechanical systems could lead to improved fine motor control for tissue-engineered prosthetic devices.
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Date Issued
2009
Identifier
CFE0002904, ucf:48013
Format
Document (PDF)
PURL
http://purl.flvc.org/ucf/fd/CFE0002904
SURVIVAL OF MYCOBACTERIUM AVIUM SUBSPECIES PARATUBERCULOSIS IN THE POLYMORPHONUCLEAR LEUKOCYTES OF A CROHN'S DISEASE PATIENT
Title
SURVIVAL OF MYCOBACTERIUM AVIUM SUBSPECIES PARATUBERCULOSIS IN THE POLYMORPHONUCLEAR LEUKOCYTES OF A CROHN'S DISEASE PATIENT.
Creator
Rumsey, John, Naser, Saleh, University of Central Florida
Abstract / Description
Mycobacterium avium subspecies paratuberculosis (map) is an intracellular pathogen that is known to parasitize macrophages and monocytes. Map infiltrates gastrointestinal tract host tissue where it is the known etiological agent of johne's disease in ruminants and implicated in the etiology of crohn's disease in humans. Map's ability to survive within macrophages enables it to disseminate throughout the rest of the host, possibly infecting other circulating blood leukocytes. In this study,...
Show moreMycobacterium avium subspecies paratuberculosis (map) is an intracellular pathogen that is known to parasitize macrophages and monocytes. Map infiltrates gastrointestinal tract host tissue where it is the known etiological agent of johne's disease in ruminants and implicated in the etiology of crohn's disease in humans. Map's ability to survive within macrophages enables it to disseminate throughout the rest of the host, possibly infecting other circulating blood leukocytes. In this study, the survival and fate of map strain atcc 43015 (human isolate) following phagocytosis was determined using in vitro murine macrophage cell line j774a.1 and polymorphonuclear cells (pmnc's) from five crohn's disease patients. Pmnc's from three healthy individuals and two ulcerative colitis patients, as well as escherichia coli (atcc 11303) and mycobacterium tuberculosis strain h37ra (atcc 25177), were included as controls (moi 10:1). Maturation of the phagosome was determined by evaluating the presence of stage specific markers on the surface of the phagosomal membrane. The endosomal protein, transferrin receptor, and the lysosomal marker, lamp-1, were then immunostained with cy-5 conjugated secondary antibodies, and colocalization of bacteria with each marker was evaluated separately using confocal scanning laser microscopy (cslm). In both tissue models, colocalization of viable map and m. Tuberculosis with the early endosomal marker, transferrin receptor occurred with an estimated five fold higher frequency than did association with the late lysosomal marker, lamp-1, as compared to live e. Coli, and all dead bacterial species. Using differential live/dead staining and fluorescent microscopy, survival of m. Tuberculosis and map was estimated at 85% and 79%, respectively compared to only 14% for e. Coli. The outcome was similar for both tissue culture and pmncs from all patients tested, suggesting that map and m. Tuberculosis can survive readily in both cell types, and regardless of the disease state of the host or the killing power of the cell. Map's survival appears to mimic m. Tuberculosis', suggesting the ability to resist phagolysosome fusion, by maintaining association with the early endosomes. Overall, the data confirms map virulence in host human blood leukocytes.
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Date Issued
2004
Identifier
CFE0000184, ucf:52838
Format
Document (PDF)
PURL
http://purl.flvc.org/ucf/fd/CFE0000184