Poster Presentation 35th Lorne Cancer Conference 2023

Understanding the cellular origin of Barrett’s metaplasia and its progression (#102)

Ibukun Adejumobi 1 , Elhadi Lich 1 , Wayne Phillips 1 , Nicholas Clemons 1
  1. Cancer Research, Peter MacCallum Cancer Centre, Melbourne, Victoria, Australia

Barrett's metaplasia is the replacement of the squamous epithelium of the oesophagus by a columnar epithelium, which develops after chronic exposure of mucosa to gastrointestinal reflux. Barrett's oesophagus is a precursor of oesophageal adenocarcinoma. The incidence of both has increased dramatically in the last few decades. However, attempts to develop preventive treatment strategies are hindered by the lack of understanding of the natural history of disease development, which is crucial to prevent the onset of Barrett's oesophagus (BE) and its progression to adenocarcinoma. In particular, consensus for the cell of origin for BE is still lacking. Different sources for the cell of origin have been proposed, one of which is the submucosal gland (SMG) and duct cells of the oesophagus. 

Goal: To identify progenitor cells in the oesophageal SMGs/ducts and assess their regenerative and differentiation potential.

Method: Human and porcine esophageal SMG/ducts were characterized using scRNA-seq and multiplex-immunohistochemistry. Organoid cultures were used to assess putative progenitor cells isolated by flow cytometry.

Results: Multiplex-IHC and scRNA-seq analysis demonstrated that pig SMGs/ducts are a good surrogate for studying human SMGS/ducts. Furthermore, pig and human SMGs showed expression of putative stem cell markers in their respective basal duct cells (CD49f and p75) and myoepithelial cells surrounding the glands (CD49f). Thus, suggesting that both the ductal and glandular compartments have their distinct pool of progenitor cells. Culturing of unsorted SMG/duct cells generated two organoid phenotypes: cystic and dense. The cystic spheroids expressed columnar/glandular markers, while the dense spheroids were positive for basal/squamous markers. The type of culturing media favoured the selection/differentiation of a particular phenotype over the other. Organoids were also grown from the different progenitor cell populations (CD49f+/p75+ vs. CD49f+/p75-) isolated using FACS. Subculturing of organoids derived from the glandular compartment (CD49f+/p75-) differentiates into a gastric-type columnar epithelium while those from the ductal compartments (CD49f+/p75+) into the squamous epithelium.

Conclusion: These results lead us to hypothesize that progenitor cells in the duct are responsible for maintaining normal squamous homeostasis. Under chronic reflux exposure, progenitor cells derived from the SMG repair the damaged mucosa with metaplastic epithelium.