Biologically Inspired, iterative engineering of a Human Lymphoid Follicle Chip

Abstract

Organs Chips are microengineered, three-dimensional (3D) in vitro models that simulate organ-level pathophysiology and therapeutic responses with high fidelity. Here, we report the development of an in vitro model of lymphoid follicles seen in germinal centers and sites of chronic inflammation. The Human Lymphoid Follicle Chip was designed to mimic lymph flow through the lymph node as well as its cellular and matrix composition. A subcapsular sinus like channel allows the media to flow around the follicles with a fraction of it flowing through the parenchyma. We provide the first known evidence that 3D organization, cellular density and physical forces such as interstitial flow play a role in formation of tertiary lymphoid organs and germinal centers. Like tertiary lymphoid organs, CXCL3 production by lymphocytes is observed in the follicle chip concomitant with the aggregation of T and B cells. The follicles formed in vitro recapitulate the gross expansion and production of antibodies and cytokines seen in vivo in response to bacterial stimulation. While trying to incorporate vasculature into the follicle on chip, we found that our in vitro cultures mimic the killing of allogeneic endothelial cells, a clinically important phenotype in graft rejection that previously couldn’t be modeled without humanized mice.

Mice and conventional two-dimensional (2D) cultures of circulating human immune cells, even together, can fail to replicate human biology, leading to low efficacy and unpredicted, sometimes severe toxicity in clinical trials. In future experiments, the Follicle Chip will enable the assessment of candidate therapeutics, and specifically immunotherapies, in a patient-specific manner in vitro.