A Novel Large Animal Model for Studying the Developmental Potential and Function of LGR5 Stem Cells in Vivo and in Vitro

Project Summary
LGR5, a marker of adult and fetal stem cells in various tissues and organs, has been studied extensively for the
past decades. Cells expressing LGR5 play key roles in organ/tissue development, homeostasis, regeneration,
and disease, including cancer. Therefore, having the ability to identify, track, and manipulate these cells in vitro
and in vivo, will allow their detailed role in normal and pathological organ function. To date, most of the research
on LGR5 cells has been performed using mice, which have significant anatomical, physiological, and molecular
differences from the human. Utilizing a newly developed LGR5-H2B-GFP pig line we have demonstrated its wide
utility for studying the role of these unique cells and have now made seminal observations in a variety of
tissues/organs. However, we have also been unable to address some key aspects due to the inability of the
existing model to analyze the differentiated progeny (lineage tracking) of LGR5 cells during development, after
transplantation, or during the process of injury and repair. In addition, while we have been able to inactivate both
alleles of the LGR5 gene, we do not have the ability to delete the cell itself. Being able to delete the LGR5
expressing cell will increase our understanding of the importance of this unique cell (versus the LGR5 gene itself)
in the phenotypes of interest. Thus, to overcome these two deficiencies, and further increase the value and
impact of the original LGR5-H2B-GFP animal model, we propose to develop a highly improved LGR5 pig line
that will allow labeling of the LGR5 cell, tracking of its progeny after injury, and delete it when desired. The high
concordance between human and pig results to date with respect to LGR5 expression and function, not only
increases the value of this line for basic research, but also for rapidly translating clinical findings to humans,
further increasing the impact of this unique animal model. Successful completion of the proposed aims will
generate a powerful animal model for study of translational aspects of LGR5 stem cells of the gut, lung, skin,
liver, cochlea, and kidney among others.