A type of white blood cells called B cells play a critical role in our immune system by producing antibodies to combat various infections. However, B cells are not on alert all the time; they need to be selectively activated to proliferate and change (differentiate) to become antibody-producing cells in a special physiological microenvironment called the germinal center (GC). Due to its complicated structure, function, and dynamically evolving nature, creating a fully functional GC model ex vivo (outside the body) is extremely challenging, and thus requires an interdisciplinary and comprehensive engineering approach. This CAREER project seeks to develop a purely artificial GC model system by recreating the most critical components of the GC capable of inducing a full array of B cell reactions. Using the ex-vivo model system with precise and independent control over each critical parameter, the roles of these GC components in producing B cell reactions will be investigated in unprecedented detail compared to using conventional in-vivo (inside the body) observations. These outcomes will enable critical advancement of various fields, including vaccination, immunotherapy, autoimmune diseases, and cancers. As complementary educational and outreach plans of the highly interdisciplinary project, focus has been made on three aspects: 1) the development of effective curricula for immunoengineering that teaches the topics at the interface between immunology and engineering, 2) the creation of uniquely collaborative environment for education and research among academia, local research institutes, and industry partners, and 3) the promotion of underrepresented high school and college students in Northern Alabama to be engaged in immunoengineering and general STEM fields.
The investigator’s long-term research goal is to develop translational cellular and molecular immunotherapies for cancers, infections, and autoimmune diseases through the unconventional amalgamation of biomaterials engineering and immunology, namely immunoengineering. Towards this goal, this CAREER project will develop an artificial ex-vivo model system that enables the mimicry of the most important functional feature of the geminal center (GC): to create B cells that can produce affinity-matured antigen-specific antibodies. Despite tremendous achievements in B-cell biology and immunology, no artificial model system has yet been fully capable of recapitulating all the critical features of the GCs ex vivo. Motivated by findings from state-of-the-art GC models, this project hypothesizes that there are three critical components of the GC microenvironments, without the correct mimicry of which, the recapitulation of ex-vivo GC reactions would be impossible: 1) the optimal CD40L-CD40 signaling that requires help signals from T-follicular helper (TFH) cells, 2) the zonal structure of the GC and interzonal migration between the light zone (LZ) and the dark (DZ) of the GC B cells, and 3) the temporally controlled on-and-off B cell receptor (BCR) signals that require antigen presentations from follicular dendric cells (FDCs). The Research Plan is organized under three objectives that address each of the identified critical components. Each objective includes development of systematically controllable biomaterial platforms that will provide critical biological signals and microenvironments to artificially developing GC B cells. The FIRST Objective is to control the quality and quantity of the CD40 signaling provided by follicular helper T (TFH) cells, by providing CD40 ligand (CD40L or CD154) molecules on bio-mimetic/bio-responsive viscoelastic hydrogels that have tunable modulus and stress relaxation characteristics. The expected outcome is enhanced understanding of how to control the quantity and quality of signaling events by designing mechanical properties of biomaterials platforms for the presentation of ligands to cell-surface receptors, especially to various molecules of the tumor necrosis factor (TNF) superfamily to which CD40L belongs. The SECOND Objective is to provide a microenvironment mimicking the zonal structures of GC (DZ and LZ) by creating controlled chemokine gradients within a microfluidic device for the artificial GC B Cells. By providing a controlled chemokine gradient using microfluidic devices, a systematic study about the conditions that enable artificially activated B cells to migrate and the consequences of the interzonal migrations in terms of GC reactions will be enabled. The THIRD Objective is to introduce On and Off temporal regulation of BCR signaling via reversible surface conjugation of model antigens to microbead-based artificial FDCs, hypothesizing that the BCR signaling needs to be temporally regulated on-and-off in order to enable an extended proliferation of GC B cells The expected outcome is a clearer understanding of the role of BCR signaling in GC reactions. Finally, the outcomes of this project are expected to enable realization of a functional artificial ex-vivo GC model that could: 1) facilitate the development of novel vaccines against major pathogens for which no effective vaccines are yet available by enabling recognition of novel B-cell epitopes without T-cell dependency, 2) be developed as a linearly scalable cell-manufacturing platform for generation of antigen-specific effector B cells as adoptive cell therapy, and 3) serve as a better-controlled and more cost-effective model system in biomedical sciences that studies B-cell biology and B-cell malignancies.
This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.
