<p> Human breast cancer is currently the highest diagnosed form of cancer and the second leading cause of cancer-related deaths in American women. Triple negative breast cancer is of the basal subtype and displays the worst prognosis owing to its highly metastatic properties. Current treatments focused on eradicating breast tumors in lieu of or following local therapy include chemotherapy, hormonal therapy, and targeted therapy. Hormonal therapy is not an option for triple negative breast cancer as it does not contain hormone receptors and there are currently no approved biological targeted therapies. Chemotherapy has proven unsuccessful because triple negative breast cancer is highly drug resistant. Here we report that metastatic human breast cancer cells (BCCs) were converted to a less aggressive phenotype and overcame chemotherapeutic drug resistance following exposure to embryonic stem cells (ESCs) encapsulated in alginate microstrands. We also demonstrate that the 3D ESC model restores proper EGFR and canonical Wnt/&beta;-catenin signaling pathway regulation in metastatic BCCs and can be applied to identify a biological treatment for triple negative breast cancer. This study establishes the feasibility of inhibiting highly aggressive human BCCs with 3D cultured ESCs as demonstrated through decreases in metastatic BCC proliferation, abnormal metabolism, migration, invasiveness, chemotherapeutic drug resistance, and survival <i>in vitro. </i> ESCs and BCCs display signaling pathway convergence, which is highly and precisely regulated in ESCs and dysregulated in BCCs. Gene expression at the mRNA and protein level within restricted human BCCs indicates inhibition of the oncogenic EGFR and canonical Wnt/&beta;-catenin signaling pathways. Naked cuticle 2 (NKD2) is a potential point of cross-talk between these two pathways and its increased expression suggests a role in restored regulation of these pathways. Application of this model for mechanistic studies will enable development of a targeted treatment for triple negative human breast cancer.</p>

<p> Endothelial cells form the innermost lining of blood vessels throughout the circulatory system. They exhibit a remarkable ability to adapt rapidly to biomechanical and biochemical stimuli from their microenvironment. Vascular endothelial cells play an essential role during the onset of inflammatory conditions and sepsis. Sepsis accounts for the highest number of mortalities in non-cardiac intensive care units and is linked to numerous other underlying conditions including cancer, inflammatory conditions and diabetes. Cancer patients, in particular, are especially susceptible to infections that lead to sepsis and show significantly higher mortality rates due to the immunocompromised nature of the host defense system. Currently, there are no available treatments for sepsis. Furthermore, TNF&alpha; has been implicated as one of the major pro-inflammatory cytokines in sepsis. In the current work, we used physiologically relevant shear stress rates and translated them into a well-controlled <i> in vitro</i> system applying fluid shear stress onto primary endothelial microvascular endothelial cells. We identified a complex formed by the active form of the small GTPase R-Ras and the cytoskeletal scaffold protein filamin A (FLNa) that can regulate TNF&alpha;-mediated activation of endothelial cells under fluid shear stress conditions. R-Ras binds directly to repeat 3 of FLNa forming a complex that is necessary for endothelial barrier integrity. We show here that activated GTP-bound R-Ras blocks vascular permeability. Permeability is monitored using the electrical cell impedance spectroscopy (ECIS) method that acquires real-time transendothelial electrical resistance (TEER) values. From the electrical resistance, impedance and capacitance, endothelial permeability can be derived by employing the ECIS model and quantified at nanoscale precision levels concurrently with endothelial cells subjected to fluid shear stress. We also demonstrate a novel platform comprised of ECIS and physiologically relevant fluid shear stress levels to test novel inhibitors or compounds that block TNF&alpha;-mediated vascular permeability. Thus, we show that the R-Ras/FLNa complex is important in regulating vascular endothelial permeability under fluid shear stress conditions. This work may offer insights into the regulation of endothelial permeability by providing novel targets to block vascular hyperpermeability or leakiness.</p>

<p> With Athletes and individuals developing osteoarthritis and chondral defects at younger ages, long term treatments are in high demand. Total knee replacements only last for 10-15 years, so younger individuals would need to have multiple knee replacements within their lifetime. Allograft transplantation has shown to last long term and have high success rates, but the lack of donors and the possibility of damaging other areas of the knee to obtain tissue grafts has become a large concern. &nbsp;Xenografts derived from porcine cartilage is cost effective and the supply is abundant. Two antigen removal processes were examined: a short term antigen removal process to maintain the mechanical stability of the tissue, and a long antigen removal process to minimize the risk of triggering an immune response. The antigen removal processes were compared, and the future precautions were determined to enhance the probability of creating a viable osteochondral xenograft preparation technique. </p>

Thesis (Ph.D.)--Brown University, 2008. / Vita. Advisor: Anubhav Tripathi. Includes bibliographical references (leaves 224-254).

Thesis (M.S.)--State University of New York at Binghamton, Thomas J. Watson School of Engineering and Applied Science, Department of Bioengineering, Biomedical Engineering, 2009. / Includes bibliographical references.