Liara M. Gonzalez

Intestinal epithelial stem cells (ISCs) are responsible for intestinal epithelial barrier renewal; thereby, ISCs play a critical role in intestinal pathophysiology research. While transgenic ISC reporter mice are available, advanced translational studies lack a large animal model. This study validates ISC isolation in a new porcine Leucine Rich Repeat Containing G Protein‐Coupled Receptor 5 (LGR5) reporter line and demonstrates the use of these pigs as a novel colorectal cancer (CRC) model. We applied histology, immunofluorescence, fluorescence‐activated cell sorting, flow cytometry, gene expression quantification, and 3D organoid cultures to whole tissue and single cells from the duodenum, jejunum, ileum, and colon of LGR5‐H2B‐GFP and wild‐type pigs. Ileum and colon LGR5‐H2B‐GFP, healthy human, and murine biopsies were compared by mRNA fluorescent in situ hybridization (FISH). To model CRC, adenomatous polyposis coli ( APC ) mutation was induced by CRISPR/Cas9 editing in porcine LGR5‐H2B‐GFP colonoids. Crypt‐base, green fluorescent protein (GFP) expressing cells co‐localized with ISC biomarkers. LGR5‐H2B‐GFP hi cells had significantly higher LGR5 expression ( p < .01) and enteroid forming efficiency ( p < .0001) compared with LGR5‐H2B‐GFP med/lo/neg cells. Using FISH, similar LGR5, OLFM4, HOPX, LYZ , and SOX9 expression was identified between human and LGR5‐H2B‐GFP pig crypt‐base cells. LGR5‐H2B‐GFP/ APC null colonoids had cystic growth in WNT/R‐spondin‐depleted media and significantly upregulated WNT/β‐catenin target gene expression ( p < .05). LGR5 + ISCs are reproducibly isolated in LGR5‐H2B‐GFP pigs and used to model CRC in an organoid platform. The known anatomical and physiologic similarities between pig and human, and those shown by crypt‐base FISH, underscore the significance of this novel LGR5‐H2B‐GFP pig to translational ISC research.