Poster C4 - Polymeric artificial antigen presenting cells for CD8+ T cell activation and phenotypic skewing

Friday, October 25, 2024

3:30 PM – 4:30 PM EST

Location: Exhibit Hall E, F & G

Presenting Author(s)

Zoe T. Hsieh

Undergraduate Student
Johns Hopkins University, United States

Co-Author(s)

SS

Sydney R. Shannon

PhD Candidate
Johns Hopkins School of Medicine, United States
Stephany Y. Tzeng, PhD

Assistant Research Professor
Johns Hopkins University, United States
Jonathan P. Schneck, MD, PhD (he/him/his)

Professor
Johns Hopkins University, United States

Primary Investigator(s)

Jordan J. Green, PhD (he/him/his)

Professor
Johns Hopkins University, Maryland, United States

Introduction: Generations of developing promising (yet limited) immunotherapies based on cytotoxic T cell modulation have encouraged extensive research on integrating this concept into an artificial antigen-presenting cell (aAPC) platform that is extremely adaptive, stable, and economically efficient. This platform mimics the signal delivery framework of a natural antigen-presenting cell, namely a signal 1 (antigen recognition), signal 2 (costimulatory effector direction protein), and a signal 3 protein (cytokines and chemokines for further T-cell stimulation). [1] A novel biodegradable combination of poly(lactic-co-glycolic acid) (PLGA) and a hydrophobic poly(beta-amino-ester) (PBAE) has been established as an aAPC with improved T cell efficacy, and the objective of this study is to optimize the established platform with the most optimal combination of the signal 3 protein for maximal T cell activation, memory phenotype, and exhaustion minimization.

Materials and

Methods: To analyze T-cell proliferation and phenotype/exhaustion markers, we have recently developed a micro-scale PLGA/PBAE aAPC platform, named “Formulation 5,” which was deemed the most suitable candidate for this study. Formulation 5 was synthesized via emulsion-based synthesis, and its size and spherical shape was confirmed with Transmission Electron Microscopy (TEM) (Figure 1A). The particle was conjugated with signal 1 (anti-CD3) and signal 2 (anti-CD28) antibodies at a concentration of 1.33 mg of particle per ml of PBS and 5 µg primary signals per mg particles (Figure 1B). Cytokine stimulations were performed by utilizing variations of soluble cytokine combinations with Formulation 5 to quantify B6 CD8+ T cell fold proliferation over the course of 7 days (Figure 1C).

Results, Conclusions, and Discussions: The synthesis of spherical Formulation 5 particles was characterized via TEM, showing an average size of 1279 nm via DLS (Figure 1A). An average of 0.239 µg of signal 1 (anti-CD3) per mg of particle and 0.155 µg of signal 2 (anti-CD28) per particle were bound to the Formulation 5 platform (Figure 2A). Soluble tri-cytokine combinations showed comparable B6 CD8+ T cell fold proliferation to the positive control (Dynabeads) and had significantly higher T cell proliferation as compared to the IL2, IL7, IL15, and IL21 cytokine combination bases (Figure 3A).

We have shown the development and optimization of a novel PLGA/PBAE microparticle that encapsulates signal 1 and signal 2 and can be combined with soluble signal 3. In ongoing studies, we are enhancing this particle with the most promising soluble tri-cytokine combinations to modify T cell proliferation, maximize memory cell phenotype, and minimize/rescue T cell exhaustion. We are characterizing these goals with in vitro soluble cytokine stimulations and hope to ultimately create a novel biodegradable and robust aAPC platform on the microscale that expands immunotherapy research and fosters the discovery of new avenues in the field of immunoengineering.

Acknowledgements (Optional):