Bachelor of Science (BS), Ohio University, 2024, Neuroscience

Duchene muscular dystrophy (DMD) is an X-Linked recessive genetic disorder which occurs in approximately 1/5000 XY births and is caused by a mutation in the human dystrophin gene. DMD causes many physiological defects and drastically shortens the lifespan of those afflicted by it. Gene replacement therapies are in clinical trials, but traditional therapies are still needed whilst those are developed. The C. elegans dys-1 gene is highly conserved compared to human dystrophin, and mutations in C. elegans dys-1 produces a clinically relevant phenotype. By use of the C. elegans DMD model, the pathology of DMD can easily be studied in a laboratory setting, allowing various potential traditional treatments to be tested for effectiveness. Zoledronic Acid (ZA) is approved by the U.S. Food and Drug Administration (FDA) to treat osteoporosis in patients with DMD, and preliminary data suggests that ZA could have positive effects for muscular health in DMD patients without osteoporosis. In the present work, it was found that the drug ZA is effective in improving DMD health in the C. elegans DMD model. Additionally, it was found that ZA improves DMD health through lowering the increased Ca2+ levels classically found in dys-1 mutants, which along with further experimentation informs a potential mechanistic pathway through which ZA acts. With this data, it is hoped that a clinical trial for repurposing ZA for use in for DMD patients is conducted in order to lessen the suffering caused by this disorder whilst gene therapeutics are developed.

Committee: Nathaniel Szewczyk (Advisor); Corinne Nielsen (Advisor) Subjects: Neurosciences

Doctor of Philosophy, University of Akron, 2019, Biomedical Engineering

Bisphosphonate-related osteonecrosis of the jaw (BRONJ) is an elusive disease that presents as exposed necrotic bone following tooth extraction. It occurs in patients undergoing bisphosphonate therapy for metastasizing cancers and osteoporosis. Experts believe the condition is caused by a defect in bone remodeling, the process by which osteoclasts resorb bone and osteoblasts form new bone, within the oral cavity. Its complexity requires a multicellular model to address the net effects of two key risk factors: tooth extraction (overload) and inflammation associated with bacterial infection. In this work, a system comprised of a deformable polymeric chip and mechanical loading device is used to expose bisphosphonate-treated osteocytes, the mechanosensing bone cells, to overload. Osteocyte viability is evaluated as a function of load, and soluble activity is assessed. Effects of these factors on bone resorption by osteoclasts and bone formation by osteoblasts are quantified. Osteoclast activity is also quantified in the presence of inflammatory agents, lipopolysaccharide and interferon gamma. Results support a role for osteocyte mechanotransduction in suppressing osteoblast bone formation within a BRONJ environment. They also suggest inflammation may inhibit resorption of necrotic bone by osteoclasts. These findings provide insights into BRONJ that may contribute to its elucidation. This dissertation also lays the foundation for a biomimetic lab-on-a-chip platform for the study of bone turnover and remodeling-related disease. Fabrication techniques are developed, and osteocyte, osteoclast and osteoblast characterizations are performed on relevant substrates within microfluidic devices. Culture conditions, including seeding densities, feeding requirements and time points for analyses are determined. This work will enable the development of a controlled multicellular lab-on-a-chip capable of quantifying the aggregate response of bone cells to disease cofactors.

Committee: Marnie Saunders PhD (Advisor); Hossein Tavana PhD (Committee Member); Ge Zhang PhD (Committee Member); Jiang Zhe PhD (Committee Member); Sailaja Paruchuri PhD (Committee Member) Subjects: Biomedical Engineering

Doctor of Philosophy, The Ohio State University, 2010, Veterinary Biosciences

Bone invasion negatively effects prognosis for patients with oral squamous cell carcinoma (OSCC). Despite the clinical significance, mechanisms responsible for OSCC invasion into bone are not fully understood. There is limited availability of experimental models which recapitulate the bone invasive behavior of OSCC in which to study disease pathogenesis and treatment. The purpose of this body of work was to develop and characterize models of bone invasive OSCC, to investigate the factors responsible for osteoclastic bone resorption, and to evaluate treatment strategies designed to inhibit bone resorption and tumor growth. The first objective was to characterize a naturally occurring model of bone invasive OSCC in domestic cats, and to determine if expression of parathyroid hormone-related protein (PTHrP) is associated with osteolytic behavior. Bone invasive feline OSCC was characterized by osteoclastic bone resorption and PTHrP expression and nuclear localization was increased in osteolytic tumors; supporting a relationship between PTHrP expression and bone-invasive behavior. The second objective was to investigate the mechanisms responsible for OSCC-associated bone resorption in relevant in vitro and in vivo models of bone invasive OSCC. In bone invasive OSCC cells, PTHrP expression was associated with ability to stimulate in vitro and in vivo bone resorption, in addition to stimulation of receptor activator of nuclear factor κB ligand (RANKL) expression and inhibition of osteoprotegerin (OPG) in murine preosteoblasts. In vitro bone culture released factors which stimulated tumor cell proliferation and PTHrP expression in feline and human OSCC cells, suggesting the existence of a vicious cycle between OSCC growth and osteoclastic bone resorption. The final two objectives were to evaluate the effectiveness of targeting osteoclastic bone resorption in a novel, bioluminescent orthotopic model of maxillary invasive OSCC. Zoledronic acid (ZOL, an aminobisphosphona (open full item for complete abstract)

Committee: Thomas Rosol (Advisor); Steven Weisbrode (Committee Member); Christopher Weghorst (Committee Member); Cheryl London (Committee Member) Subjects: Biomedical Research; Oncology; Veterinary Services

Doctor of Philosophy, The Ohio State University, 2009, Veterinary Biosciences

Prostate cancer (PCa) is the most commonly diagnosed cancer in men accounting for 25% of the new cases every year in the USA. PCa is the second leading cause of cancer-related deaths due to the development of serious skeletal complications in advanced stages of the disease. Bone metastases in PCa are predominantly osteoblastic characterized by formation of excessive low quality woven bone leading to spinal cord compression, paralysis, pathological fractures and severe pain eventually resulting in a poor quality of life. Therefore, bone metastasis represents a major clinical and research interest to investigate and develop therapeutic strategies.Previously, our lab established a canine PCa cell line (Ace-1) that metastasized to bone and caused mixed osteoblastic and osteolytic lesions in nude mice similar to that observed in human patients. We utilized this animal model to investigate the molecular pathogenesis of bone metastasis. First, we investigated the role of osteolytic activity in the development of bone metastasis by inhibiting bone resorption with the bisphosphosphonate, zoledronic acid. We showed that zoledronic acid significantly inhibited osteolysis in this model, but did not affect the PCa growth, incidence and the osteoblastic phenotype of the metastases. These data demonstrated that PCa bone metastases were independent of osteolysis and that PCa secreted factors that directly regulated bone metastasis. To explore the molecular mechanisms involved in metastasis, we investigated the role of Wnt signaling that plays an important role in oncogenesis and osteogenesis in the progression of prostate cancer growth, and incidence and osteoblastic phenotype of bone metastases. Antagonizing Wnt signaling using Dickkopf-1 (Dkk-1) in our model resulted in increased tumor growth although it significantly decreased new woven bone formation in the metastases. In conclusion, these investigations demonstrated PCa secrete factors that induce bone metastasis. Importantl (open full item for complete abstract)

Committee: Thomas Rosol PhD (Advisor) Subjects: Biomedical Research

Master of Science, The Ohio State University, 2013, Comparative and Veterinary Medicine

Bisphosphonates are a class of drug widely used in both human and veterinary medicine for the treatment of pathologies affecting bone remodeling. Currently they represent the most commonly prescribed therapy for osteoporosis, with over 5 million prescriptions filled in the United States every year. Over the last decade the use of high dose nitrogen-containing bisphosphonates (BPs) has become increasingly popular in the multimodal approach to oncologic conditions. This class of medication has been shown to slow the progression of certain tumor cells from penetrating healthy bone tissues as well as slowing tumor cell proliferation. In addition BPs have been shown to significantly reduce the discomfort associated with metastases in some patients. Unfortunately, as the use and dosing of BPs has increased, so has the clinical complication associated with their use. Most notably, a condition known as bisphosphonate related osteonecrosis of the jaw (BRONJ) has emerged over the last ten years. While this condition has been linked to multiple risk factors, high dose BP usage and trauma in the oral cavity have been shown to be the primary events that precede the development of BRONJ lesions. BRONJ is a disabling and painful condition affecting both the maxilla and mandible. To date this condition is poorly understood, and consequently current treatment options are inconsistently effective. The overall purpose of this study was to develop a reliable animal model of BRONJ that can be used by researchers to advance the understanding of the pathophysiology of this disease. Because no grossly visible lesions were observed in these animals, we focused our efforts on exploring the role of two factors that have been implicated in the pathogenesis of BRONJ: periodontal disease and dental trauma. High-resolution micro computed tomography (µCT) was used to quantify the effects of a potent intravenous nitrogen-containing BP, zoledronic acid (ZA), on maxillary alveolar bone loss in an (open full item for complete abstract)

Committee: Matthew Allen (Advisor); Sarandeep Huja (Committee Member); Kimerly Powell (Committee Member) Subjects: Biology; Biomedical Research; Dentistry; Medicine