Intestinal organoids in farm animals

Abstract

In livestock species, the monolayer of epithelial cells covering the digestive mucosa plays an essential role for nutrition and gut barrier function. However, research on farm animal intestinal epithelium has been hampered by the lack of appropriate in vitro models. Over the past decade, methods to culture livestock intestinal organoids have been developed in pig, bovine, rabbit, horse, sheep and chicken. Gut organoids from farm animals are obtained by seeding tissue-derived intestinal epithelial stem cells in a 3-dimensional culture environment reproducing in vitro the stem cell niche. These organoids can be generated rapidly within days and are formed by a monolayer of polarized epithelial cells containing the diverse differentiated epithelial progeny, recapitulating the original structure and function of the native epithelium. The phenotype of intestinal organoids is stable in long-term culture and reflects characteristics of the digestive segment of origin. Farm animal intestinal organoids can be amplified in vitro, cryopreserved and used for multiple experiments, allowing an efficient reduction of the use of live animals for experimentation. Most of the studies using livestock intestinal organoids were used to investigate host-microbe interactions at the epithelial surface, mainly focused on enteric infections with viruses, bacteria or parasites. Numerous other applications of farm animal intestinal organoids include studies on nutrient absorption, genome editing and bioactive compounds screening relevant for agricultural, veterinary and biomedical sciences. Further improvements of the methods used to culture intestinal organoids from farm animals are required to replicate more closely the intestinal tissue complexity, including the presence of non-epithelial cell types and of the gut microbiota. Harmonization of the methods used to culture livestock intestinal organoids will also be required to increase the reproducibility of the results obtained in these models. In this review, we summarize the methods used to generate and cryopreserve intestinal organoids in farm animals, present their phenotypes and discuss current and future applications of this innovative culture system of the digestive epithelium.

Intestinal organoid-based 2D monolayers mimic physiological and pathophysiological properties of the pig intestine

“…This finding can be explained by the composition of the differentiation medium containing the gamma-secretase inhibitor DAPT, leading to increased formation of goblet cells [ 25 ]. Expression of villin shows mature enterocytes indicating the formation of the typical intestinal brush boarder membrane [ 9 , 26 ]. Chromogranin A allowed the identification of single enteroendocrine cells in our organoid-based 2D model [ 9 , 26 ].…”

Generation of equine enteroids and enteroid-derived 2D monolayers that are responsive to microbial mimics

“…While enteroid cultures are starting to become standardized in human and mouse [ 3 ], there are less studies published on enteroids from farm animals as recently reviewed [ 4 , 5 ] and only two studies describing equine enteroids [ 6 , 7 ]. Several of the horse’s most common diseases are linked to the gastro-intestinal tract, such as colic, laminitis, diarrhoea and parasite infections.…”

Porcine small intestinal organoids as a model to explore ETEC–host interactions in the gut

“…These enteroids are complex 3D structures composed of intestinal epithelial cells and more closely resemble the intestinal architecture and cellular diversity seen in vivo as compared to frequently used intestinal epithelial cell lines, such as the Caco-2 (human) or IPEC-J2 (porcine) cell lines. In contrast to human and mouse, a handful of papers describe the culture and development of porcine enteroids [ 14 , 17 – 20 , 27 ]. These reports mainly focussed on identifying different cell lineages present in enteroid cultures and the optimization of culture conditions.…”

“…However, in contrast to human and murine studies, literature on porcine enteroids is scarce. The development and cellular composition of the porcine enteroids has been described [ 14 , 17 – 20 ], but to the best of our knowledge functional responses of enteroids towards porcine pathogens have only recently been reported [ 21 – 25 ]. Here, we build further on previous studies to report the development of porcine enteroids from all segments of the small intestine in different culture media, the generation of enteroid monolayers and focus on the functional responses elicited by ETEC-derived enterotoxins.…”