The cellular origin of Barrett’s oesophagus (BO) has been debated for several decades. Current models can be divided into those proposing a cell of origin that is intrinsic to the oesophagus, and those suggesting BO arises from an extra-oesophageal source. Oesophageal intrinsic models include transdifferentiation of squamous epithelial cells and re-programming of stem cells residing in the squamous epithelium or submucosal glands or ducts. Extra-oesophageal models include proximal migration of residual embryonic cells or gastric cardia stem cells, located at the squamocolumnar junction, to competitively replace the damaged squamous epithelium.
Using an innovative in vivo, 3D tissue reconstitution model we reconstituted epithelium from the non-dysplastic, non-transformed, hTERT immortalised Barrett’s cell line, BAR-T over 3 or 6 weeks. Histopathological analysis of the resultant epithelium revealed glandular columnar epithelium (CK7+ and CK8/18+) with goblet cells (Alcian blue+) and expression of intestinal markers (CDX2, Villin) and gastric mucin (MUC5AC), reminiscent of BO epithelium. Surprisingly, we also observed areas of stratified squamous epithelium, reminiscent of the normal oesophageal epithelium, and areas of multi-layered epithelium with mixed phenotype. In contrast, only stratified squamous epithelium is formed when primary human oesophageal epithelial cells are used. Staining with a human specific antibody confirmed reconstitution by BAR-T cells and not cells from the host mouse. FACS and immunocytochemistry of 2D cultures showed that all cells co-expressed CK7 and the squamous marker, CK14, indicating BAR-T are homogeneous with respect to these two markers. In comparison, the hTERT immortalised squamous oesophageal cell line, NES, expressed only CK14. Our findings suggest that BAR-T cells exhibit a level of plasticity that allows differentiation down both squamous and intestinal-type columnar epithelial pathways from the same cell. Thus, our results support the idea of a common cell of origin for both squamous epithelium and BO.