A Pilot Study: Transcriptional Profiling, Functional Analysis, and Organoid Modeling of Intestinal Mucosa in Hirschsprung Disease

BACKGROUND

Hirschsprung disease (HSCR) is a congenital colonic aganglionosis. Many HSCR patients develop enterocolitis despite surgical resection. The pathophysiology of this inflammatory process is poorly understood. We compared transcriptional profiles and function of ganglionic and aganglionic tissue in HSCR patients.

METHODS

RNA sequencing was performed on mucosal tissues from HSCR patients (n = 6) and controls (n = 3). Function of matched ganglionic and aganglionic regions were investigated utilizing organoids generated from these tissues.

RESULTS

Transcriptional differences observed in ganglionic and aganglionic regions of HSCR patients included upregulation of genes involving inflammation, cell differentiation and proliferation as well as decreased expression of genes encoding mucins compared to controls. Organoids derived from ganglionic and aganglionic regions of HSCR patients were similar in epithelial cell differentiation, epithelial barrier formation and response to stimulation with bacterial metabolites and pro-inflammatory cytokines.

CONCLUSIONS

Despite normal ganglionic structure, the section of colon adjacent to the aganglionic region in HSCR patients has perturbed gene expression which resembles the aganglionic segment. Transcriptional and functional changes in colonic epithelium are persevered in the ganglionic colon used for pull-through surgery. This may explain persistence of enterocolitis despite surgical excision of aganglionic colon and subsequent endorectal pull-through performed with ganglionic colon during correction of HSCR.

LEVEL OF EVIDENCE

N/A.

Mapping the adult human esophagus in vivo and in vitro

Many esophageal diseases can arise during development or throughout life. Therefore, well-characterized in vitro models and detailed methods are essential for studying human esophageal development, homeostasis and disease. Here, we (1) create an atlas of the cell types observed in the normal adult human esophagus; (2) establish an ancestrally diverse biobank of in vitro esophagus tissue to interrogate homeostasis and injury; and (3) benchmark in vitro models using the adult human esophagus atlas. We created a single-cell RNA sequencing reference atlas using fresh adult esophagus biopsies and a continuously expanding biobank of patient-derived in vitro cultures (n=55 lines). We identify and validate several transcriptionally distinct cell classes in the native human adult esophagus, with four populations belonging to the epithelial layer, including basal, epibasal, early differentiating and terminally differentiated luminal cells. Benchmarking in vitro esophagus cultures to the in vivo reference using single-cell RNA sequencing shows that the basal stem cells are robustly maintained in vitro, and the diversity of epithelial cell types in culture is dependent on cell density. We also demonstrate that cultures can be grown in 2D or as 3D organoids, and these methods can be employed for modeling the complete epithelial layers, thereby enabling in vitro modeling of the human adult esophagus.