Research Experience

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August 2023 - Present

Research Assistant (PhD Student)

Jennifer Barton, PhD, Director of the BIO5 Institute, Professor of Biomedical Engineering and Optical Sciences

University of Arizona

Developing an endoscopic imaging system for early detection of gastric cancer using optical coherence tomography (OCT), doppler OCT (DOCT), and optical coherence elastography (OCE)

• Designing and constructing endoscope, including optical system and piezoelectric scanning mechanism 
• Conducting ex vivo preliminary studies with a benchtop OCT system for proof-of-concept

July 2020 - May 2022

Graduate Researcher

Duke University

Nirmala Ramanujam, PhD, Robert W. Carr Professor of Engineering and Professor of Cancer Pharmacology and Global Health 

Targeting Tumor Acidosis and Regulatory T Cells Unmasks Anti-Metastatic Potential of Local Tumor Ablation in Triple-Negative Breast Cancer

Triple-negative breast cancer (TNBC) is an immunologically heterogenous disease that lacks clinically actionable targets and is more likely to progress to metastatic disease than other types of breast cancer. Tumor ablation has been used to increase response rates to checkpoint inhibitors, which remain low for TNBC patients. We hypothesized that tumor ablation could produce an anti-tumor response without using checkpoint inhibitors if immunosuppression (i.e., Tregs, tumor acidosis) was subdued. Tumors were primed with sodium bicarbonate (200 mM p.o.) to reduce tumor acidosis and low-dose cyclophosphamide (100–200 mg/kg i.p.) to deplete regulatory T cells, as has been shown independently in previous studies. A novel injectable ablative was then used to necrose the tumor, release tumor antigens, and initiate an immune event that could create an abscopal effect. This combination of bicarbonate, cyclophosphamide, and ablation, called “BiCyclA”, was tested in three syngeneic models of TNBC: E0771 (C57BL/6), 67NR (BALB/c), and 4T1-Luc (BALB/c). In E0771 and 67NR, BiCyclA therapy significantly reduced tumor growth and cured 5/7 and 6/10 mice 50 days after treatment respectively. In the metastatic 4T1-Luc tumors, for which surgery and checkpoint inhibitors fail, BiCyclA cured 5/10 mice of primary tumors and lung metastases. Notably, CD4+ and CD8+ T cells were found to be crucial for the anti-metastatic response, and cured mice were able to resist tumor rechallenge, suggesting production of immune memory. Reduction of tumor acidity and regulatory T cells with ablation is a simple yet effective therapy for local and systemic tumor control with broad applicability as it is not limited by expensive supplies.  

• Conducted longitudinal studies in mice to assess survival, tumor growth, and anti-tumor immune response following breast tumor polymer-assisted ethanol ablation
• Quantified tumor growth over time with in vivo bioluminescence imaging 

Nief, Corrine, Alana Gonzales, Erika Chelales, Júlia Sroda Agudogo, Brian T. Crouch, Smita Nair, Nirmala Ramanujam (2022). “Targeting tumor acidosis and regulatory T cells unmasks anti-metastatic potential of local tumor ablation in triple-negative breast cancer,” International Journal of Molecular Sciences, vol. 23, 8479.

Summer 2019

MSRP Intern

Massachusetts Institute of Technology

Roger Kamm, PhD, Professor of Biological and Mechanical Engineering

Modeling T Cell and Vascular Interactions In Vitro

Immunotherapy drugs have become a widespread cancer treatment. Researchers are developing methods to predict patient-specific responses, but these have not examined the influence of the vascular endothelium in immune cell migration to tumors. We aim to model this interaction using in vitro systems by evaluating T cell migration and adhesion to human endothelial cells (ECs). Initial 2D experiments used conditioned media from four cancer cell lines to provide cytokine stimulus. Porous membranes were used to quantify T cell migration in response to a cytokine gradient, while adhesion was measured by treating EC monolayers with conditioned media prior to incubation with T cells. There was a significant difference in T cell adhesion across the four cell lines (p=1.8×10-5) and in T cell migration in response to cytokine gradients (p=2.5×10-3). Results showed a nearly 3-fold increase in T cell adhesion to ECs (p=3×10-5) and a 3-fold increase in T cell migration (p=0.0017) in response to MDA-MB-231 conditioned media compared to the negative controls. Therefore, this model demonstrates that cytokine stimulus affects T cell migration and adhesion to EC monolayers. Future experiments aim to examine migration and adhesion profiles in more detail using vascularized 3D microfluidic devices to model the tumor microenvironment. 

• Designed two experimental setups to model T cell adhesion and migration relative to human endothelial cells using a Transwell migration assay, 2D cell culture, and fluorescence microscopy
• Wrote scripts in ImageJ and RStudio to analyze microscopy data

Learn more about the unique MSRP experience and my incredible fellow interns.

Spring 2017

Student Researcher

Institute of Sports Medicine, Bispebjerg Hospital, Copenhagen, Denmark

Abigail Mackey, PhD

Determining Skeletal Muscle Fiber Type in Regenerating Muscle after Injury Induced by Electrical Stimulation of the Vastus Lateralis  

The purpose of this study was to characterize injured skeletal muscle fibers regenerating post-injury. Based on discoveries in previous research studying the mechanisms of muscle regeneration, we wanted to look further into the interactions between the cells involved in this process. One study done by Abigail Mackey and colleagues (2011) observed that after induced injury, multiple muscle fiber membranes on serial sections of human gastrocnemius muscle biopsies encroached into one fiber, fusing what was observed as two or more fibers in other locations on the biopsy. We hypothesized that only those fibers which are type II myosin are effected by the electrical stimulation, exhibiting signs of regeneration indicated by fusing and the presence of embryonic and/or neonatal myosin. However, a second hypothesis stated that if a fiber expresses immature myosin, ATPase stains cannot be relied on to determine fiber type. To test the hypotheses, we analyzed serial sections from skeletal muscle biopsies collected following electrically induced eccentric contractions in the vastus lateralis muscle. Methods included imaging of the prepared slides and characterization of the fibers by measuring the size and length of regenerating fibers and determining their myosin type. The results, which showed that none of the type I fibers and most of the type II fibers expressed neonatal myosin, led us to conclude that only type II fibers were affected by the electrical stimulation. We were also able to confirm that the ATPase stain analysis could accurately determine fiber type for those positive for neonatal myosin, but not those expressing embryonic myosin. 

• Quantified amounts of different fiber types in injured skeletal muscle tissue using fluorescence microscopy 

Højfeldt, Grith, Trent Sorenson, Alana Gonzales, Michael Kjaer, Jesper L Andersen, Abigail L Mackey (2023). “Fusion of myofibre branches is a physiological feature of healthy human skeletal muscle regeneration,” Skeletal Muscle, vol. 13, 13.

Summer 2015

Research Assistant

University of Arizona

David Armstrong, PhD, DPM and Bijan Najafi, PhD

Gait and Balance Assessment and Training Program for Patients with or At Risk for Peripheral Neuropathy  

HIV patients and cancer patients undergoing neurotoxic chemotherapy often experience symptoms of peripheral neuropathy. These include pain, tingling, and numbness in the hands and feet as well as weakness and trouble with walking and balance. Patients with peripheral neuropathy commonly experience falls and often require the use of walking assist devices such as canes or wheelchairs. This project tested the effectiveness of a virtual reality-based exercise program for improving gait and balance in HIV and cancer patients affected by peripheral neuropathy. Using wearable sensors, patients completed walking and balance tasks such as a virtual obstacle course, for which the patient steps over virtual objects they see on the screen.

• Directed patients through virtual reality-based exercises
• Collected exercise data using MATLAB and wearable motion sensors
• Obtained patient demographics and health history using IRB-approved surveys