Postnatal development of the mucosal plexus in the porcine small and large intestine

Neonatal intestinal organoids as an ex vivo approach to study early intestinal epithelial disorders

BACKGROUND

Adult intestinal organoids have been used to study ex vivo intestinal injury in adulthood. However, the neonatal intestinal epithelium has many unique features that are different from adult mature intestine. Establishing a neonatal ex vivo organoid model is essential to study the epithelial physiology in early postnatal development and to investigate derangements associated with disease processes during the neonatal period like necrotizing enterocolitis (NEC).

METHODS

Fresh and frozen terminal ileum was harvested from mice pups on postnatal day 9. Crypts were isolated and organoids were cultured. Organoids were exposed to hypoxia and lipopolysaccharide (LPS) for 48 h to induce epithelial injury. Inflammatory cytokines and tight junction proteins were evaluated.

RESULTS

Robust intestinal organoids can be formed from both fresh and frozen intestinal tissue of neonatal mice pups. Hypoxia and LPS administration induced intestinal inflammation and disrupted tight junctions in these neonatal intestinal organoids.

CONCLUSIONS

We have established a novel method to grow organoids from neonatal intestine. We demonstrated that these organoids respond to the injury occurring during neonatal intestinal diseases such as NEC by increasing the organoid inflammation and by disrupting the organoid barrier function. Organoids provide an ex vivo platform to study intestinal physiology and pathology during the neonatal period.

Impaired intestinal barrier function and relapsing digestive disease: Lessons from a porcine model of early life stress

Within this issue of Neurogastroenterology and Motility, an article by Pohl et al highlights new insights from a powerful porcine model of the link between early life adversity and relapsing functional gastrointestinal disorders. Early weaning stress closely mimics the early life psychosocial stressors that have been linked to adult onset gastrointestinal dysfunction. This early weaning model provides reproducible and highly translatable outcomes in young stress-challenged pigs. Due to the convincingly comparable neurological and gastroenterological anatomy and physiology between pigs and human beings, gastrointestinal stress and injury studies utilizing swine models will provide invaluable insights to improve our understanding and treatment of gastrointestinal disease in human beings. Future studies to examine mechanisms underlying this link between early life adversity and functional gastrointestinal disorders will explore the roles of gender and hypomaturity in gastrointestinal responses to stress.

Early-life stress origins of gastrointestinal disease: animal models, intestinal pathophysiology, and translational implications

Early-life stress and adversity are major risk factors in the onset and severity of gastrointestinal (GI) disease in humans later in life. The mechanisms by which early-life stress leads to increased GI disease susceptibility in adult life remain poorly understood. Animal models of early-life stress have provided a foundation from which to gain a more fundamental understanding of this important GI disease paradigm. This review focuses on animal models of early-life stress-induced GI disease, with a specific emphasis on translational aspects of each model to specific human GI disease states. Early postnatal development of major GI systems and the consequences of stress on their development are discussed in detail. Relevant translational differences between species and models are highlighted.

Classification and diagnostic criteria of variants of Hirschsprung's disease

"Variants of Hirschsprung's disease" are conditions that clinically resemble Hirschsprung's disease (HD), despite the presence of ganglion cells in rectal suction biopsies. The diagnosis and management of these patients can be challenging. Specific histological, immunohistochemical and electron microscopic investigations are required to characterize this heterogeneous group of functional bowel disorders. Variants of HD include intestinal neuronal dysplasia, intestinal ganglioneuromatosis, isolated hypoganglionosis, immature ganglia, absence of the argyrophil plexus, internal anal sphincter achalasia and congenital smooth muscle cell disorders such as megacystis microcolon intestinal hypoperistalsis syndrome. This review article systematically classifies variants of HD based on current diagnostic criteria with an additional focus on pathogenesis, epidemiology, clinical presentation, management and outcome.

Nerve growth factor content is increased in the rectal mucosa of children with diarrhea-predominant irritable bowel syndrome

BACKGROUND

The enteric nervous system is a complex network that includes, in the digestive mucosa, neuronal bodies and fibers interacting with the immune system and mucosal mast cells (MC). These interactions involve the secretion of messengers, such as the neurotrophin nerve growth factor (NGF), which influence colonic motility and sensitivity, both affected in irritable bowel syndrome (IBS). This study was designed to test the hypothesis that, in children with IBS, colonic mucosal innervation, NGF content, and MC infiltration are altered. We aimed to measure MC infiltration, number of neuronal bodies, distance from MC to nerve fibers, inflammation, and NGF content in rectal mucosa of pediatric patients with IBS as compared with controls.

METHODS

Rectal biopsies from children (median age: 14 years) with diarrhea-predominant IBS (n = 11) and controls (n = 14) were studied. MC and neuronal mucosal structures were identified by tryptase, CD117 and PGP9.5 immunoreactivity. Inflammatory cells (neutrophils, eosinophils, and lymphocytes) were counted. NGF was quantified in situ by ELISA.

KEY RESULTS

No mucosal inflammation was detected in IBS. MC infiltration and number of neuronal bodies were not significantly different between IBS and controls. The distance between MC and nerve fibers was not different in IBS compared with controls (5.2 ± 0.3 vs 5.0 ± 0.3 μm). Number of MC in close proximity to nerve fibers (<5 μm) was not different in the two groups. However, in IBS, NGF content was higher than controls (0.93 ± 0.3 vs 0.62 ± 0.3 pg mg(-1) protein, P < 0.05) and significantly correlated with MC number.

CONCLUSIONS & INFERENCES

Regardless of inflammation, NGF content is increased in rectal mucosa of diarrhea-predominant IBS children.

Development of enteric neuron diversity

The mature enteric nervous system (ENS) is composed of many different neuron subtypes and enteric glia, which all arise from the neural crest. How this diversity is generated from neural crest-derived cells is a central question in neurogastroenterology, as defects in these processes are likely to underlie some paediatric motility disorders. Here we review the developmental appearance (the earliest age at which expression of specific markers can be localized) and birthdates (the age at which precursors exit the cell cycle) of different enteric neuron subtypes, and their projections to some targets. We then focus on what is known about the mechanisms underlying the generation of enteric neuron diversity and axon pathfinding. Finally, we review the development of the ENS in humans and the etiologies of a number of paediatric motility disorders.

Enteric nervous system stem cells derived from human gut mucosa for the treatment of aganglionic gut disorders

BACKGROUND & AIMS

Enteric nervous system stem cells (ENSSCs) provide potential therapeutic tools to replenish absent ganglia in Hirschsprung's disease. Although full-thickness human postnatal gut tissue can be used to generate ENSSCs, reliance on its harvesting from surgical resection poses significant practical limitations. This study aimed to explore whether gut tissue obtained utilizing minimally invasive routine endoscopy techniques could be used to generate ENSSCs and whether such cells retain the potential to generate an ENS upon transplantation into aganglionic gut.

METHODS

Postnatal human gut mucosal tissue obtained from children undergoing gastrointestinal endoscopy was used to generate cell cultures in which ENSSCs were contained within neurosphere-like bodies (NLBs). These NLBs were characterized by immunostaining, and their potential to generate components of the ENS, in vitro and upon transplantation into models of aganglionic gut, was examined.

RESULTS

Gut mucosal biopsy specimens were obtained from 75 children (age, 9 months-17 years). The biopsy specimens contained neural cells and ENSSCs and, on culturing, generated characteristic NLBs at all ages examined. Postnatal mucosa-derived NLBs contained cells that, akin to their embryonic counterparts, were proliferating, expressed ENSSC markers, were bipotent, and capable of generating large colonies in clonogenic cultures and multiple ENS neuronal subtypes. Upon transplantation, cells from NLBs colonized cultured recipient aganglionic chick and human hindgut to generate ganglia-like structures and enteric neurons and glia.

CONCLUSIONS

The results represent a significant practical advance toward the development of definitive cell replenishment therapies for ENS disorders such as Hirschsprung's disease.

Postnatal and diet-dependent increases in enteric glial cells and VIP-containing neurones in preterm pigs

A mature enteric nervous system (ENS) is required to ensure a normal pattern of intestinal motility in order to regulate digestion after birth. We hypothesized that neuronal and glial components of the ENS would mature during the first postnatal days in preterm pigs that are a sensitive animal model of food intolerance and necrotizing enterocolitis (NEC). Stereological volume densities of the general neuronal population [assessed by betaIII-tubulin immunoreactivity (IR)] and subsets of neuronal (VIP-IR and nitrergic IR) and glial cells (GFAP-IR and S100-IR) were determined in the small intestine of newborn preterm piglets (93% gestation), after 3 days of receiving total parenteral nutrition (TPN) and after 3 days of TPN plus 2 days of enteral feeding with sow's colostrum or milk formula. Following TPN, VIP in the myenteric and inner submucous plexus and GFAP in the inner submucous plexus increased, while the relative volume of the total neuronal population remained constant. Introduction of enteral food induced variable degrees of food intolerance and NEC, especially after formula feeding, a diet that gave rise to a higher myenteric VIP and GFAP content in the inner submucous plexus than colostrum feeding. However, the ENS seemed unaffected by the presence of NEC-like intestinal lesions. Nevertheless, this study shows that the ENS is highly plastic during the first days after premature birth and adapts in an age- and diet-dependent manner. The observed postnatal adaptation in enteric VIP and GFAP may help to maintain intestinal homeostasis during suboptimal feeding regimens in preterm neonates.