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Background & aims Preoperative obstructive jaundice is usually associated with higher post-operative mortality. Although external biliary drainage (EBD) has been widely used to relieve obstructive jaundice, the role of bile reinfusion after EBD is still controversial. The aim of our study was to study the effects of biliary obstruction, biliary drainage and bile reinfusion on bile acid metabolism and gut microbiota. Methods Firstly, we created a mice bile drainage collection (BDC) model to simulate the process of biliary obstruction, drainage and bile reinfusion. Then, we analysed the faecal, serum, liver and bile samples to investigate the effects of the process on bile acid profiles and gut microbiota. Finally, we evaluated the clinical effects of bile reinfusion. Results We evaluated the bile acid profiles of faeces, serum, liver and bile of normal mice. During biliary obstruction, secondary bile acids can still be produced, and increased in the liver and serum of mice. Compared with no bile reinfusion, bile reinfusion was beneficial to the recovery of T-ωMCA in the liver and bile, and can restore the colon crypt length shortened by biliary obstruction. Only Ruminococcus_1 proliferated when the biliary obstruction lasted for 12 days. In the clinic, bile reinfusion cannot accelerate the patient's perioperative recovery or prolong long-term survival. Conclusion We have successfully created a mice bile drainage collection model. Short-term bile reinfusion can partially benefit the recovery of the secondary bile acids in the liver and bile, but hardly benefit the patient's perioperative recovery or long-term survival. (247 words).

Simple Summary Colorectal cancer (CRC) is the third most common cause of cancer-related death. Patients suffering inflammatory bowel disease have an increased risk of CRC. It is admitted that CRC found its origin within crypts of the colon mucosa, which host the intestinal stem cells (ISCs) responsible of the tissue renewal. ISC behavior is controlled by the fibroblasts that surround the crypt. During inflammation, the signals delivered by fibroblasts are altered, leading to stem cells’ dysregulation, possibly turning them into cancer-initiating cells. Here, we reviewed the interplays between the fibroblast and the ISCs, possibly leading to the initiation of CRC due to chronic inflammation. Abstract Colorectal cancer (CRC) is the third most common cause of cancer-related death. Significant improvements in CRC treatment have been made for the last 20 years, on one hand thanks to a better detection, allowing surgical resection of the incriminated area, and on the other hand, thanks to a better knowledge of CRC’s development allowing the improvement of drug strategies. Despite this crucial progress, CRC remains a public health issue. The current model for CRC initiation and progression is based on accumulation of sequential known genetic mutations in the colon epithelial cells’ genome leading to a loss of control over proliferation and survival. However, increasing evidence reveals that CRC initiation is more complex. Indeed, chronic inflammatory contexts, such as inflammatory bowel diseases, have been shown to increase the risk for CRC development in mice and humans. In this manuscript, we review whether colon fibroblasts can go from the main regulators of the ISC homeostasis, regulating not only the renewal process but also the epithelial cells’ differentiation occurring along the colon crypt, to the main player in the initiation of the colorectal cancer process due to chronic inflammation.

Colon crypts are recognized as a mechanical and biochemical Turing patterning model. Colon epithelial Caco‐2 cell monolayer demonstrated 2D Turing patterns via force analysis of apical tight junction live cell imaging which illuminated actomyosin meshwork linking the actomyosin network of individual cells. Actomyosin forces act in a mechanobiological manner that alters cell/nucleus/tissue morphology. We observed the rotational motion of the nucleus in Caco‐2 cells that appears to be driven by actomyosin during the formation of a differentiated confluent epithelium. Single‐ to multi‐cell ring/torus‐shaped genomes were observed prior to complex fractal Turing patterns extending from a rotating torus centre in a spiral pattern consistent with a gene morphogen motif. These features may contribute to the well‐described differentiation from stem cells at the crypt base to the luminal colon epithelium along the crypt axis. This observation may be useful to study the role of mechanogenomic processes and the underlying molecular mechanisms as determinants of cellular and tissue architecture in space and time, which is the focal point of the 4D nucleome initiative. Mathematical and bioengineer modelling of gene circuits and cell shapes may provide a powerful algorithm that will contribute to future precision medicine relevant to a number of common medical disorders.

Colorectal cancer (CRC) is a major cause of cancer mortality; loss of the Apc gene is an early step in the formation of CRC. A new computational model of the colonic crypt has been developed to simulate the effects of Apc loss. The model includes a region of flat mucosa, which has not previously been considered in the context of Apc loss. The model suggests that Apc loss confers a survival advantage at the crypt mouth which may be a previously unknown method of mutation fixation.

ObjectiveThe crypt population in the human intestine is dynamic: crypts can divide to produce two new daughter crypts through a process termed crypt fission, but whether this is balanced by a second process to remove crypts, as recently shown in mouse models, is uncertain. We examined whether crypt fusion (the process of two neighbouring crypts fusing into a single daughter crypt) occurs in the human colon.DesignWe used somatic alterations in the gene cytochrome c oxidase (CCO) as lineage tracing markers to assess the clonality of bifurcating colon crypts (n=309 bifurcating crypts from 13 patients). Mathematical modelling was used to determine whether the existence of crypt fusion can explain the experimental data, and how the process of fusion influences the rate of crypt fission.ResultsIn 55% (21/38) of bifurcating crypts in which clonality could be assessed, we observed perfect segregation of clonal lineages to the respective crypt arms. Mathematical modelling showed that this frequency of perfect segregation could not be explained by fission alone (p−20). With the rates of fission and fusion taken to be approximately equal, we then used the distribution of CCO-deficient patch size to estimate the rate of crypt fission, finding a value of around 0.011 divisions/crypt/year.ConclusionsWe have provided the evidence that human colonic crypts undergo fusion, a potential homeostatic process to regulate total crypt number. The existence of crypt fusion in the human colon adds a new facet to our understanding of the highly dynamic and plastic phenotype of the colonic epithelium.

E-cadherin is the core component of epithelial adherens junctions, essential for tissue development, differentiation, and maintenance. It is also fundamental for tissue barrier formation, a critical function of epithelial tissues. The colon or large intestine is lined by an epithelial monolayer that encompasses an E-cadherin-dependent barrier, critical for the homeostasis of the organ. Compromised barriers of the colonic epithelium lead to inflammation, fibrosis, and are commonly observed in colorectal cancer. In addition to its architectural role, E-cadherin is also considered a tumor suppressor in the colon, primarily a result of its opposing function to Wnt signaling, the predominant driver of colon tumorigenesis. Beyond these well-established traditional roles, several studies have portrayed an evolving role of E-cadherin as a signaling epicenter that regulates cell behavior in response to intra- and extra-cellular cues. Intriguingly, these recent findings also reveal tumor-promoting functions of E-cadherin in colon tumorigenesis and new interacting partners, opening future avenues of investigation. In this Review, we focus on these emerging aspects of E-cadherin signaling, and we discuss their implications in colon biology and disease.

Intestinal stem cells are non-quiescent, dividing epithelial cells that rapidly differentiate into progenitor cells of the absorptive and secretory cell lineages. The kinetics of this process is rapid such that the epithelium is replaced weekly. To determine how the transcriptome and proteome keep pace with rapid differentiation, we developed a new cell sorting method to purify mouse colon epithelial cells. Here we show that alternative mRNA splicing and polyadenylation dominate changes in the transcriptome as stem cells differentiate into progenitors. In contrast, as progenitors differentiate into mature cell types, changes in mRNA levels dominate the transcriptome. RNA processing targets regulators of cell cycle, RNA, cell adhesion, SUMOylation, and Wnt and Notch signaling. Additionally, global proteome profiling detected2,800 proteins and revealed RNA:protein patterns of abundance and correlation. Paired together, these data highlight new potentials for autocrine and feedback regulation and provide new insights into cell state transitions in the crypt.

There is a need in biological research for tools designed to manipulate the environment surrounding microscopic regions of tissue. In the current work, a device for the oriented capture of an important and under-studied tissue, the colon crypt, has been designed and tested. The objective of this work is to create a BioMEMs device for biological assays of living colonic crypts. The end goal will be to subject the polarized tissue to user-controlled fluidic microenvironments in a manner that recapitulates the in vivo state. Crypt surrogates, polymeric structures of similar dimensions and shape to isolated colon crypts, were used in the initial design and testing of the device. Successful capture of crypt surrogates was accomplished on a simple device composed of an array of micron-scale capture sites that enabled individual structures to be captured with high efficiency (92 ± 3%) in an ordered and properly oriented fashion. The device was then evaluated using colon crypts isolated from a murine animal model. The capture efficiency attained using the fixed biologic sample was 37 ± 5% due to the increased variability of the colon crypts compared with the surrogate structures, yet 94% ± 3% of the captured crypts were properly oriented. A simple approach to plug the remaining capture sites in the array was performed using inert glass beads. Blockage of unfilled capture sites is an important feature to establish a chemical gradient across the arrayed crypts. A chemical concentration gradient (Cluminal/Cbasal > 10) was demonstrated across the arrayed crypts for over 8 h. Finally unfixed colon crypts were demonstrated to be effectively captured by the micromesh array and to remain viable on the capture sites at 5 h after mouse sacrifice. The present study demonstrates the feasibility and potential for rationally microengineered technologies to address the specific needs of the biologic researcher.

Recently a mucosal pentraxin, Mptx, regulated by heme and calcium was reported in rat gut mucosal scrapings using microarray strategies. Considering the heterogeneity of gut mucosa scrapings and the widespread use of the rat as a model to study colon pathologies this study was undertaken to generate detailed mapping of micro-anatomical locations of Mptx and gain further insight into potential functions of this mucosal pentraxin in rat colon. Differential regulation was also examined in colon from different rat strains and rat models of oxidative stress and in pre-cancerous colon tissue. Different regional patterns of expression and discrete localisation in epithelial cells within transverse and distal colon crypts and an absence of expression in proximal colon were confirmed by regional PCR analysis and in situ hybridisation studies of colon. This study demonstrates that consideration of regional differences in Mptx gene expression and micro-anatomical location is necessary in the interpretation and deciphering of its regulation in colon.

Colons of young adult Sprague-Dawley rats are embedded in paraffin, cut, and stained with Feulgen. The sections are scanned with a Quantimet-system 23 image analyzer under PDP - 11 34 computer control. Each crypt is digitized into 192 × 700 8-bits pixels. The images are stored on magnetic tapes and processed on a PDP - 15 76 computer providing the necessary features for interactive image analysis. The epithelium of each crypt image is separated, and the cells are ordered and numbered according to their position in relation to crypt origin. The location of mitotic figures is also recorded. The progenitor region outer boundary is estimated with the aid of life table analysis. The program also computes the average crypt length and the progenitor/functional ratio, and estimates the epithelial cell production rate.

SummaryThe survival of mouse colon crypts after X-irradiation has been studied by the microcolony technique. The D0 for crypt survival was 266 rad after whole-body irradiation in air, but when the colon alone was irradiated, the D0 was 340 rad. In mice which were breathing 95 per cent oxygen, the D0 values were 238 rad for whole-body and 302 rad for colon irradiation. The survival curves were all extrapolated to the same number, and the DQ was also increased with colon irradiation. There was, therefore an enhancement of colon crypt survival of about 27 per cent by local as opposed to whole-body irradiation. These results might be explained by a circulating repair promoter or by the production of a toxin after whole-body irradiation.

An adequate neoplastic grading system should provide a framework for a precise expression of cell turnover and differentiation. The grading system proposed herewith is applicable to all tissue pathologies associated with changes in cell turnover and differentiation, including neoplasia. It is illustrated on rapidly proliferating tissues known as continuous replicators e.g. the colon crypt epithelium. The enterocyte starts its existence at crypt bottom, during a stem cell division whereupon it gradually advances outward, differentiating as it goes. The typical path covered by the cell, denominated as tissue radius summarizes its life history. The cell is viewed as a point advancing on the radius in a rectlinear motion, defined by two variables: Distance from radius origin ‘x’, defined as the cell location number separating it from origin, and its velocity v(x) defined as the cell location number it covers per unit of time. The path the cell covers is represented by a trajectory in a two dimensional Galilean geometry. The cell's transition from state to state is defined by two transformations: Displacement and shear. Each continuous replicator is represented by a typical trajectory which differs in different pathologies. Neoplastic progression in the continuous replicator may be expressed as a trajectory in the Galilean geometry, which serves also for a unique grading of neoplasia.

Background Normal colon crypts consist of stem cells, proliferating cells, and differentiated cells. Abnormal rates of proliferation and differentiation can initiate colon cancer. We have measured the variation in the number of each of these cell types in multiple crypts in normal human biopsy specimens. This has provided the opportunity to produce a calibrated computational model that simulates cell dynamics in normal human crypts, and by changing model parameter values, to simulate the initiation and treatment of colon cancer. Results An agent-based model of stochastic cell dynamics in human colon crypts was developed in the multi-platform open-source application NetLogo. It was assumed that each cell’s probability of proliferation and probability of death is determined by its position in two gradients along the crypt axis, a divide gradient and in a die gradient. A cell’s type is not intrinsic, but rather is determined by its position in the divide gradient. Cell types are dynamic, plastic, and inter-convertible. Parameter values were determined for the shape of each of the gradients, and for a cell’s response to the gradients. This was done by parameter sweeps that indicated the values that reproduced the measured number and variation of each cell type, and produced quasi-stationary stochastic dynamics. The behavior of the model was verified by its ability to reproduce the experimentally observed monocolonal conversion by neutral drift, the formation of adenomas resulting from mutations either at the top or bottom of the crypt, and by the robust ability of crypts to recover from perturbation by cytotoxic agents. One use of the virtual crypt model was demonstrated by evaluating different cancer chemotherapy and radiation scheduling protocols. Conclusions A virtual crypt has been developed that simulates the quasi-stationary stochastic cell dynamics of normal human colon crypts. It is unique in that it has been calibrated with measurements of human biopsy specimens, and it can simulate the variation of cell types in addition to the average number of each cell type. The utility of the model was demonstrated with in silico experiments that evaluated cancer therapy protocols. The model is available for others to conduct additional experiments.