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; DE CARVALHO MADRID, DARLING MELANY - University Of Missouri; TOUCHARD, LAURIE - University Of Missouri; SPATE, LEE - University Of Missouri; SAMUEL, MELISSA - 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: 9/17/2024
Citation: Monarch, K., Yoon, J., Uh, K., Reese, E., Canaveral Restrepo, D., De Carvalho Madrid, D., Touchard, L., Spate, L.D., Samuel, M.S., Driver, J.P., Lim, J., Schlink, S., Whitworth, K.M., Wells, K.D., Prather, R.S., Chen, P.R., Lee, K. 2024. Fetal bone engraftment reconstitutes the immune system in pigs with severe combined immunodeficiency. Lab Animal. 53:276-286. https://doi.org/10.1038/s41684-024-01439-7.
DOI: https://doi.org/10.1038/s41684-024-01439-7

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-' (IL2RG) results in pigs exhibiting severe combined immunodeficiency (SCID). Pigs presenting a SCID phenotype are important animal models that can be used to establish xenografts and to study immune system development and various immune-related pathologies. However, due to their immunocompromised nature, SCID pigs have shortened lifespans and are notoriously difficult to maintain. The failure-to-thrive phenotype makes the establishment of a breeding population of RAG2/IL2RG double-knockout pigs virtually impossible. Here, to overcome this limitation, we investigated whether reconstituting the immune system of SCID piglets with a fetal bone allograft would extend their lifespan. Following intramuscular transplantation, allografts gave rise to lymphocytes expressing T cell (CD3, CD4 and CD8), B cell (CD79a) and natural killer cell (CD335) lineage markers, which were detected in circulation as well in the spleen, liver, bone marrow and thymic tissues. The presence of lymphocytes indicates broad engraftment of donor cells in the recipient SCID pigs. Unlike unreconstituted SCID pigs, the engrafted animals thrived and reached puberty under standard housing conditions. This study demonstrates a novel method to extend the survival of SCID pigs, which may improve the availability and use of SCID pigs as a biomedical animal model.