Fetal bone engraftment reconstitutes the immune system in pigs with severe combined immunodeficiency

Authors: MONARCH, KAYLYNN - University Of Missouri; YOON, JUNCHUL - University Of Missouri; UH, KYUNGJUN - University Of Missouri; REESE, EMILY - University Of Missouri; CANAVERAL RESTREPO, DIANA - University Of Missouri; MADRE, MELANY - University Of Missouri; TOUCHARD, LAURIE - University Of Missouri; SPATE, LEE - University Of Missouri; SAMUEL, MELLISA - University Of Missouri; DRIVER, JOHN - University Of Missouri; LIM, JI-HEY - University Of Missouri; SCHLINK, SARAH - University Of Missouri; WHITWORTH, KRISTIN - University Of Missouri; WELLS, KEVIN - University Of Missouri; PRATHER, RANDALL - University Of Missouri; Chen, Paula; LEE, KIHO - University Of Missouri

Submitted to: Lab Animal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/21/2024
Publication Date: N/A
Citation: N/A

Interpretive Summary: Generating animals models of immunodeficiency is critical for understanding immune development, immune-related disorders, and to be recipients of organs for transplantation studies. Pigs displaying immunodeficiency have been generated through genome editing, but they fail-to-thrive and typically die within the first few weeks of life. The goal of this study was to reestablish an immune system in the immunodeficient pig models by transplanting bone from a healthy pig that would repopulate the immune cells. Successful transplantation of healthy bone was achieved in the immunodeficient pigs, and new immune cells were detected in many immune-related tissues. Most importantly, the transplantation recipients thrived and had signs of puberty, therefore expanding the utility of this model for immune system research.

Technical Abstract: Genetic modification of genes such as recombination activating gene 2 (RAG2) or interleukin 2 receptor gamma (IL2RG) results in pigs exhibiting severe combined immunodeficiency (SCID). Pig models presenting a SCID phenotype are important animal models that can be utilized to establish xenografts, study pathogenesis, and understand immune development. However, due to their immunocompromised nature, SCID pigs are notoriously difficult to maintain and have shortened lifespans. The fail-to-thrive phenotype makes the establishment of a breeding population of RAG2/IL2RG double knockout pigs virtually impossible. To overcome this challenge, we performed a novel alloengraftment of fetal bone into SCID piglets to extend lifespan. In this trial, we found that allografts originated from fetal bones provided lymphocytes that enter circulation and engrafted within the SCID host. Lymphocytes expressing markers including CD3+, CD4+ and CD8+ T cells, CD79a+ B cell lineage, and CD335+ natural killer cells were detected in recipient animals. The lymphocytes were detected in circulation as well as organs including the spleen, liver, bone marrow, and thymic tissues, indicating broad engraftment of donor cells in the recipient SCID pigs. Unlike control SCID pigs, the recipient animals thrived and reached puberty under standard housing conditions. This study demonstrates a novel method to extend the life of SCID pigs, and therefore, improving the availability and use of SCID pigs as a laboratory animal in biomedicine.