In vitro M-like cells genesis through a tissue-engineered triple-culture intestinal model.

Although fewer in number, M-cells are considered antigen sampling cells, acting as a gateway for antigens from the gut lumen and presenting an impressive aptitude for particle transcytosis. These features make M-cells attractive targets for oral drug delivery studies, but this has been poorly explored. New and reproducible tissue-like in vitro models for studying intestinal sampling and permeability mechanisms are needed. The combination of different cell players in such models offers improved microenvironments with higher physiologic relevance. Here, a tissue-engineered model was established, by co-culturing Caco-2 absorptive cells, HT29-MTX mucus-producing cells and Raji B lymphocytes. After 3 weeks of cell co-culture, the presence of M-like cells was evidenced by the loss of brush-border organization, detected by the lack of microvilli. The triple-culture model showed to be efficient for insulin transport, a process that was influenced by the tightness of junctions between epithelial cells and the presence of mucus and M-like cells. Ultimately, the proposed tissue-engineered model provides a more complete and reliable tool to perform drug permeability tests, as compared to traditional models, and may also find applicability as an in vitro system to study transdifferentiation mechanisms of M cells.