Rapid Generation of Hpsc‐Derived High Endothelial Venule Organoids with In Vivo Ectopic Lymphoid Tissue Capabilities

Abstract Bioengineering strategies for the fabrication of implantable lymphoid structures mimicking lymph nodes (LNs) and tertiary lymphoid structures (TLS) could amplify the adaptive immune response for therapeutic applications such as cancer immunotherapy. No method to date has resulted in the consistent formation of high endothelial venules (HEVs), which is the specialized vasculature responsible for naïve T cell recruitment and education in both LNs and TLS. Here we used orthogonal induced differentiation of human pluripotent stem cells (hPSCs) carrying a regulatable ETV2 allele, to rapidly and efficiently induce endothelial differentiation. Assembly of embryoid bodies combining primitive inducible endothelial cells (iEndos) and primary human lymph node fibroblastic reticular cells (FRCs) resulted in the formation of HEV‐like structures that can aggregate into three dimensional organoids (HEVOs). Upon transplantation into immunodeficient mice, HEVOs successfully engrafted and formed lymphatic structures that recruited both antigen‐presenting cells and adoptively‐transferred lymphocytes, therefore displaying basic TLS capabilities. Our results further show that functionally, HEVOs can organize an immune response and promote anti‐tumor activity by adoptively transferred T lymphocytes. Collectively, our experimental approaches represent an innovative and scalable proof‐of‐concept strategy for the fabrication of bioengineered tertiary lymphoid structures that can be deployed in vivo to enhance adaptive immune responses. This article is protected by copyright. All rights reserved