PhD, University of Cincinnati, 2016, Medicine: Molecular and Developmental Biology

Calcific Aortic Valve Disease (CAVD) is the most prevalent type of heart valve disease, affecting ~2% of the US population. The risk for developing CAVD increases with age, and CAVD is becoming more common with increased average lifespan. Currently, the standard of care involves aortic valve (AoV) replacement surgery, which is often contraindicated for the elderly. Importantly, the pathogenic mechanisms driving CAVD, which could serve as potential therapeutic targets, are not well understood. Studies of human diseased AoV provide initial evidence that the Bone Morphogenetic Proteins (BMPs), essential for normal bone formation, play a critical role during CAVD. However, the function of BMP signaling during osteochondrogenic gene induction and AoV calcification, both CAVD features, remain unknown. Here, studies are directed towards the understanding of molecular pathways involved in CAVD using a combination of a murine model of premature aging in vivo and directed mechanistic studies of porcine aortic valve interstitial cells (VICs) in vitro.

Committee: Katherine Yutzey Ph.D. (Committee Chair); Burns Blaxall Ph.D. (Committee Member); Rolf Stottman PhD (Committee Member); James Wells Ph.D. (Committee Member); Yana Zavros Ph.D. (Committee Member) Subjects: Molecular Biology

Doctor of Philosophy, Case Western Reserve University, 2014, Molecular Biology and Microbiology

Glioblastoma Multiforme (GBM) and other cancers are challenging to treat due to their intertumoral and intratumoral heterogeneity. The hierarchical model of intratumoral heterogeneity describes the existence of a cellular hierarchy in glioblastoma with a cancer stem cell (CSC) population at the apex. These CSCs can initiate tumors and are resistant to therapies, suggesting that they are responsible for tumor recurrence. CSCs give rise to differentiated cells, which have limited tumor initiation abilities but provide a supportive CSC niche. Here, I examine the cellular cues that maintain both CSCs and the niche by tuning the relative levels of differentiation and self-renewal in GBM. I suggest Bone Morphogenetic Proteins (BMPs) as a driver of differentiation, as BMPs have been shown to promote CSC differentiation and are strongly expressed in GBM. Extrapolating from existing paradigms in development and in cancer, I then hypothesize that extracellular BMP antagonists could be the parallel drivers of CSC self-renewal.I subsequently demonstrate that a BMP antagonist, Gremlin1, is secreted specifically by CSCs, supporting CSCs in the context of the endogenous differentiation signals provided by BMP. I promote self-renewal and increase growth of non-CSCs by overexpression of Gremlin1, and drive differentiation and slow growth of CSCs by Gremlin1 knockdown. Finally, I examine the mechanisms downstream of Gremlin1 that drive its effects on growth and self-renewal, as well as the mechanisms upstream of Gremlin1 that promote its differential secretion by CSCs. Downstream of Gremlin1, cell proliferation effects are mediated by p21 inhibition, and self-renewal is partly mediated by activation of Wnt signaling. Upstream of Gremlin1, I identify XBP1, a pro-survival factor in the unfolded protein response, as a CSC-specific signal that might be promoting Gremlin1 expression. In the course of this thesis, I identify a novel molecular target, Gremlin1, as well as severa (open full item for complete abstract)

Committee: Jeremy Rich (Advisor); Thomas Egelhoff (Committee Chair); Eric Arts (Committee Member); William Schiemann (Committee Member); Paul Tesar (Committee Chair) Subjects: Biology; Biomedical Research; Cellular Biology

Doctor of Philosophy, The Ohio State University, 2006, Veterinary Clinical Sciences

Complicated healing of articular fractures represents a clinical challenge and a financial burden on the health care system. Bone marrow-derived mesenchymal stem cells (BMDMSC) hold promise for targeted osteogenic differentiation and can be augmented by delivery of genes encoding bone morphogenetic proteins (BMP). Osteogenic differentiation of BMDMSC was investigated using two BMP genes. Cultured BMDMSC were transduced with adenoviral vectors containing human BMP2 or BMP6 in either sustained in monolayer or suspended in alginate for 22 days. Adenovirus (Ad)-BMP-2 and Ad-BMP-6 transduction resulted in abundant BMP-2 and BMP-6 mRNA and ligand expression in monolayer culture and BMP-2 ligand expression in alginate. Ad-BMP-2 and Ad-BMP-6 transduced BMDMSC in monolayer had earlier alkaline phosphatase-positive staining and mineralization and were sustained for a longer duration than untransduced or Ad-ß-galactosidase-transduced cells. Gene expression studies at day 2 confirmed an inflammatory response to the gene delivery process. Up-regulation of genes consistent with response to BMP exposure and osteogenic differentiation occurred in BMP-transduced cells. These data support that transduction of BMDMSC with Ad-BMP-2 or Ad-BMP-6 can accelerate osteogenic differentiation and mineralization of stem cells. BMP-2-transduced stem cells suspended in alginate culture may be a practical carrier system to support bone formation in vivo. A distal femoral articular osteotomy model was created in the nude rat to study articular fracture healing. Osteotomies were treated with BMDMSC, wild-type (NoAd) or transduced with Ad-BMP-2. Cells were delivered in alginate (ALG) or injected in saline. Controls were empty ALG, saline injections, direct Ad-BMP-2 injection, and untreated osteotomies. Healing was compared using quantitative micro-computed tomography, fluorescent labeling, and histology. At day 14, osteotomy gap area in the Ad-BMP-2 ALG group was significantly greater than other grou (open full item for complete abstract)

Committee: Alicia Bertone (Advisor) Subjects: