Notice and Invitation
Oral Defense of Doctoral Proposal

Department of Bioengineering
College of Engineering and Computing, George Mason University

Chih-Hsiang (Sean) Hu

Bachelor of Science, Chemical and Biomolecular Engineering, Lafayette College, 2019

Spatiotemporal release in hydrogel system for studying and modeling the CD4⁺ T Cell differentiation

Tuesday, June 28, 2022, 10:00 am

IABR 1004, SciTech Campus

Or via Zoom here

Meeting ID: 979 6480 0142

Passcode: 200274

Committee
Dr. Remi Veneziano, Director

Dr. Caroline Hoemann, Chair
Dr. Lee Solomon
Dr. Pilgyu Kang

Abstract

Cancer immunotherapy, which includes adoptive T cell therapy (ACT) and immune checkpoint inhibitors, has shown great potentials in clinical trials over various tumor types. However, the efficacy of cancer immunotherapy be positively or negatively impacted by CD4⁺ T cells depending on the specific CD4⁺ T cell subtypes, which includes helper T cells type 1 (Th1), 2 (Th2), 17 (Th17), and regulatory T cells (Treg). The current method for studying the differentiation of CD4⁺ naïve T cells typically involves the use of artificial antigen presenting cells (APCs), such as Dynabeads, along with addition of specific cytokines to induce the differentiation. While the current methodologies successfully induce differentiation of specific CD4⁺ T cell subtypes, it does not fully mimic the extracellular matrix and the temporal distribution of cytokines within. Therefore, be able to understand and control the specific differentiation of CD4⁺ T cells subtype based on the temporal distribution of cytokines would contribute towards improving the efficacy of cancer immunotherapy, specifically ACT. Hydrogel system has emerged as a potential method to mimic the extracellular matrix (ECM) due to its tunable mechanical properties and composition. However, hydrogel systems without specific modifications like controlled release system is unable to replicate the temporal distribution of cytokine found in the ECM environment. A potential solution is DNA nanotechnology, which allows creations of nanostructures that are highly programmable, actuatable with various stimuli, and orthogonal modification with multiplexing of biomolecules. Therefore, we will utilize both DNA nanotechnology tools, such as multiplex design and strand displacement reaction, and 3D bioprinting to fabricate a dynamic hydrogel environment and study the effect of cytokine dosage, release rate, and pattern on T cell differentiation in a high-throughput manner. To achieve this objective, we will first design and characterize the multiplexed DNA-based controlled release system, study the effect of mismatched bases within the trigger strands on release rate/quantity, and develop a computational model for the release profile within solution. The designed multiplexed controlled release system will be incorporated into the hydrogel system, which will be fabricated using 3D bioprinting technique. We will characterize the hydrogel properties and study how the release profile of the system is affected after the incorporation into the hydrogel. The data gathered will be incorporated into the computational model developed prior and use to predict the release profile within the hydrogel system. CD4⁺ T naïve cells will be cultured on the designed hydrogel system and we will generate specific temporal distribution of cytokine to study how it affects the CD4⁺ T naïve cell differentiation. The purposed studies can enhance our understanding of how CD4⁺ T naïve cells differentiate in response to the temporal distribution of specific cytokines (IL-2, IL-6 and TGFβ), which better mimic the ECM environment. This can potentially improve the efficacy of ACT by preferentially generate desirable CD4⁺ T cell population with desirable subtypes.