A Dynamic WNT/β-CATENIN Signaling Environment Leads to WNT-Independent and WNT-Dependent Proliferation of Embryonic Intestinal Progenitor Cells.

Much of our understanding about how intestinal stem and progenitor cells are regulated comes from studying the late fetal stages of development and the adult intestine. In this light, little is known about intestine development prior to the formation of stereotypical villus structures with columnar epithelium, a stage when the epithelium is pseudostratified and appears to be a relatively uniform population of progenitor cells with high proliferative capacity. Here, we investigated a role for WNT/β-CATENIN signaling during the pseudostratified stages of development (E13.

Generation of tissue-engineered small intestine using embryonic stem cell-derived human intestinal organoids.

Short bowel syndrome (SBS) is characterized by poor nutrient absorption due to a deficit of healthy intestine. Current treatment practices rely on providing supportive medical therapy with parenteral nutrition; while life saving, such interventions are not curative and are still associated with significant co-morbidities. As approaches to lengthen remaining intestinal tissue have been met with only limited success and intestinal transplants have poor survival outcomes, new approaches to treating SBS are necessary.

Transcriptome-wide Analysis Reveals Hallmarks of Human Intestine Development and Maturation In Vitro and In Vivo.

Human intestinal organoids (HIOs) are a tissue culture model in which small intestine-like tissue is generated from pluripotent stem cells. By carrying out unsupervised hierarchical clustering of RNA-sequencing data, we demonstrate that HIOs most closely resemble human fetal intestine. We observed that genes involved in digestive tract development are enriched in both fetal intestine and HIOs compared to adult tissue, whereas genes related to digestive function and Paneth cell host defense are expressed at higher levels in adult intestine.

An in vivo model of human small intestine using pluripotent stem cells.

Differentiation of human pluripotent stem cells (hPSCs) into organ-specific subtypes offers an exciting avenue for the study of embryonic development and disease processes, for pharmacologic studies and as a potential resource for therapeutic transplant. To date, limited in vivo models exist for human intestine, all of which are dependent upon primary epithelial cultures or digested tissue from surgical biopsies that include mesenchymal cells transplanted on biodegradable scaffolds. Here, we generated human intestinal organoids (HIOs) produced in vitro from human embryonic stem cells (ESCs) or induced pluripotent stem cells (iPSCs) that can engraft in vivo.

De novo formation of insulin-producing "neo-β cell islets" from intestinal crypts.

The ability to interconvert terminally differentiated cells could serve as a powerful tool for cell-based treatment of degenerative diseases, including diabetes mellitus. To determine which, if any, adult tissues are competent to activate an islet β cell program, we performed an in vivo screen by expressing three β cell "reprogramming factors" in a wide spectrum of tissues. We report that transient intestinal expression of these factors-Pdx1, MafA, and Ngn3 (PMN)-promotes rapid conversion of intestinal crypt cells into endocrine cells, which coalesce into "neoislets" below the crypt base.

A gutsy task: generating intestinal tissue from human pluripotent stem cells.

Many significant advances in our understanding of intestine development, intestinal stem cell homeostasis and differentiation have been made in recent years. These advances include novel techniques to culture primary human and mouse intestinal epithelium in three-dimensional matrices, and de novo generation of human intestinal tissue from embryonic and induced pluripotent stem cells. This short review will focus on the directed differentiation of human pluripotent stem cells into intestinal tissue, highlight novel uses of this tissue, and compare and contrast this system to primary intestinal epithelial cultures.

Stem cell-derived human intestinal organoids as an infection model for rotaviruses.

Unlabelled: Directed differentiation of stem cell lines into intestine-like tissue called induced human intestinal organoids (iHIOs) is now possible (J. R. Spence, C.

Human stool contains a previously unrecognized diversity of novel astroviruses.

Human astroviruses are a leading cause of gastrointestinal disease. Since their discovery in 1975, 8 closely related serotypes have been described in humans, and more recently, two new astrovirus species, astrovirus MLB1 and astrovirus VA1, were identified in diarrhea patients. In this study, we used consensus astrovirus primers targeting the RNA polymerase to define the diversity of astroviruses present in pediatric patients with diarrhea on two continents.

Detection of novel sequences related to african Swine Fever virus in human serum and sewage.

The family Asfarviridae contains only a single virus species, African swine fever virus (ASFV). ASFV is a viral agent with significant economic impact due to its devastating effects on populations of domesticated pigs during outbreaks but has not been reported to infect humans. We report here the discovery of novel viral sequences in human serum and sewage which are clearly related to the asfarvirus family but highly divergent from ASFV.

Identification of a novel astrovirus (astrovirus VA1) associated with an outbreak of acute gastroenteritis.

The etiology of a large proportion of gastrointestinal illness is unknown. In this study, random Sanger sequencing and pyrosequencing approaches were used to analyze fecal specimens from a gastroenteritis outbreak of unknown etiology in a child care center. Multiple sequences with limited identity to known astroviruses were identified.

Klassevirus 1, a previously undescribed member of the family Picornaviridae, is globally widespread.

Background: Diarrhea is the third leading infectious cause of death worldwide and is estimated to be responsible for approximately 2 million deaths a year. While many infectious causes of diarrhea have been established, approximately 40% of all diarrhea cases are of unknown etiology. In an effort to identify novel viruses that may be causal agents of diarrhea, we used high throughput mass sequencing to analyze stool samples collected from patients with acute diarrhea.

Detection of newly described astrovirus MLB1 in stool samples from children.

The prevalence of the recently identified astrovirus MLB1 in a cohort of children with diarrhea in St. Louis, Missouri, USA, was defined by reverse transcription-PCR. Of 254 stool specimens collected in 2008, 4 were positive for astrovirus MLB1.

Identification of a novel picornavirus related to cosaviruses in a child with acute diarrhea.

Diarrhea, the third leading infectious cause of death worldwide, causes approximately 2 million deaths a year. Approximately 40% of these cases are of unknown etiology. We previously developed a metagenomic strategy for identification of novel viruses from diarrhea samples.

Complete genome sequence of a highly divergent astrovirus isolated from a child with acute diarrhea.

Background: Astroviruses infect a variety of mammals and birds and are causative agents of diarrhea in humans and other animal hosts. We have previously described the identification of several sequence fragments with limited sequence identity to known astroviruses in a stool specimen obtained from a child with acute diarrhea, suggesting that a novel virus was present.

Results: In this study, the complete genome of this novel virus isolate was sequenced and analyzed.

Metagenomic analysis of human diarrhea: viral detection and discovery.

Worldwide, approximately 1.8 million children die from diarrhea annually, and millions more suffer multiple episodes of nonfatal diarrhea. On average, in up to 40% of cases, no etiologic agent can be identified.