查看更多>>摘要:NR4A2 is a transcription factor belonging to the steroid orphan nuclear receptor superfamily.It was originally considered to be essential in the generation and maintenance of dopaminergic neurons,and associated with neurological disorders such as Parkinson's disease.Recently,NR4A2 has been found to play a critical role in some inflammatory diseases and cancer.NR4A2 can be efficiently trans-activated by some proinflammatory cytokines,such as tumor necrosis factor-α,interleukin-1β,and vascular endothelial growth factor (VEGF).The nuclear factor-κB signaling pathway serves as a principal regulator of inducible NR4A expression in immune cells.NR4A2 can trans-activate Foxp3,a hallmark specifically expressed in regulatory T (Treg) cells,and plays a critical role in the differentiation,maintenance,and function of Treg cells.NR4A2 in T lymphocytes is pivotal for Treg cell induction and suppression of aberrant induction of Th1 under physiological and pathological conditions.High density of Foxp3+ Treg cells is significantly associated with gastrointestinal inflammation,tumor immune escape,and disease progression.NR4A2 is produced at high levels in CD133+ colorectal carcinoma (CRC) cells and significantly upregulated by cyclooxygenase-2-derived prostaglandin E2 in a cyclic adenosine monophosphate (cAMP)/protein kinase A (PKA)-dependent manner in CRC cells.The cAMP/PKA signaling pathway is the common pathway of NR4A2-related inflammation and cancer.NR4A2 trans-activates osteopontin,a direct target of the Wnt/β-catenin pathway associated with CRC invasion,metastasis,and poor prognosis.Knockdown of endogenous NR4A2 expression attenuates VEGF-induced endothelial cell proliferation,migration and in vivo angiogenesis.Taken together,NR4A2 emerges as an important nuclear factor linking gastrointestinal inflammation and cancer,especially CRC,and should serve as a candidate therapeutic target for inflammation-related gastrointestinal cancer.
查看更多>>摘要:This special issue of World Journal of Gastroenterology has been conceived to illustrate to gastroenterology operators the role that regenerative medicine (RM) will have in the progress of gastrointestinal (GI) medicine.RM is a multidisciplinary field aiming to replace,regenerate or repair diseased tissues or organs.The past decade has been marked by numerous ground-breaking achievements that led experts in the field to manufacture functional substitutes of relatively simple organs.This progress is paving the ground for investigations that aims to the bioengineering and regeneration of more complex organs like livers,pancreas and intestine.In this special issue,the reader will be introduced,hand-in-hand,to explore the field of RM and will be educated on the progress,pitfalls and promise of RM technologies as applied to GI medicine.
查看更多>>摘要:If only at a small scale,islet transplantation has successfully addressed what ought to be the primary endpoint of any cell therapy:the functional replenishment of damaged tissue in patients.After years of less-thanoptimal approaches to immunosuppression,recent advances consistently yield long-term graft survival rates comparable to those of whole pancreas transplantation.Limited organ availability is the main hurdle that stands in the way of the widespread clinical utilization of this pioneering intervention.Progress in stem cell research over the past decade,coupled with our decades-long experience with islet transplantation,is shaping the future of cell therapies for the treatment of diabetes.Here we review the most promising avenues of research aimed at generating an inexhaustible supply of insulin-producing cells for islet regeneration,including the differentiation of pluripotent and multipotent stem cells of embryonic and adult origin along the beta cell lineage and the direct reprogramming of non-endocrine tissues into insulin-producing cells.
查看更多>>摘要:Although allogeneic islet transplantation can successfully cure type 1 diabetes,it has limited applicability.For example,organs are in short supply; several human pancreas donors are often needed to treat one diabetic recipient; the intrahepatic site may not be the most appropriate site for islet implantation; and immunosuppressive regimens,which are associated with side effects,are often required to prolong survival of the islet graft.An altemative source of insulinproducing cells would therefore be of major interest.Pigs represent a possible alternative source of beta cells.Grafting of pig islets may appear difficult because of the immunologic species barrier,but pig islets have been shown to function in primates for at least 6 mo with clinically incompatible immunosuppression.Therefore,a bioartificial pancreas made of encapsulated pig islets may resolve issues associated with islet allotransplantation.Although several groups have shown that encapsulated pig islets are functional in small-animal models,less is known about the use of bioartificial pancreases in large-animal models.In this review,we summarize current knowledge of encapsulated pig islets,to determine obstacles to implantation in humans and possible solutions to overcome these obstacles.
Ricardo LondonoBlair A JobeToshitaka HoppoStephen F Badylak...
6894-6899页
查看更多>>摘要:In addition to squamous cell carcinoma,the incidence of Barrett's esophagus with high-grade dysplasia and esophageal adenocarcinoma is rapidly increasing worldwide.Unfortunately,the current standard of care for esophageal pathology involves resection of the affected tissue,sometimes involving radical esophagectomy.Without exception,these procedures are associated with a high morbidity,compromised quality of life,and unacceptable mortality rates.Regenerative medicine approaches to functional tissue replacement include the use of biological and synthetic scaffolds to promote tissue remodeling and growth.In the case of esophageal repair,extracellular matrix (ECM) scaffolds have proven to be effective for the reconstruction of small patch defects,anastomosis reinforcement,and the prevention of stricture formation after endomucosal resection (EMR).More so,esophageal cancer patients treated with ECM scaffolds have shown complete restoration of a normal,functional,and disease-free epithelium after EMR.These studies provide evidence that a regenerative medicine approach may enable aggressive resection of neoplastic tissue without the need for radical esophagectomy and its associated complications.
Giorgia TotonelliPanagiotis MaghsoudlouJonathan M FishmanGiuseppe Orlando...
6900-6907页
查看更多>>摘要:A number of congenital and acquired disorders require esophageal tissue replacement.Various surgical techniques,such as gastric and colonic interposition,are standards of treatment,but frequently complicated by stenosis and other problems.Regenerative medicine approaches facilitate the use of biological constructs to replace or regenerate normal tissue function.We review the literature of esophageal tissue engineering,discuss its implications,compare the methodologies that have been employed and suggest possible directions for the future.Medline,Embase,the Cochrane Library,National Research Register and ClinicalTrials.gov databases were searched with the following search terms:stem cell and esophagus,esophageal replacement,esophageal tissue engineering,esophageal substitution.Reference lists of papers identified were also examined and experts in this field contacted for further information.All full-text articles in English of all potentially relevant abstracts were reviewed.Tissue engineering has involved acellular scaffolds that were either transplanted with the aim of being repopulated by host cells or seeded prior to transplantation.When acellular scaffolds were used to replace patch and short tubular defects they allowed epithelial and partial muscular migration whereas when employed for long tubular defects the results were poor leading to an increased rate of stenosis and mortality.Stenting has been shown as an effective means to reduce stenotic changes and promote cell migration,whilst omental wrapping to induce vascularization of the construct has an uncertain benefit.Decellularized matrices have been recently suggested as the optimal choice for scaffolds,but smart polymers that will incorporate signalling to promote cell-scaffold interaction may provide a more reproducible and available solution.Results in animal models that have used seeded scaffolds strongly suggest that seeding of both muscle and epithelial cells on scaffolds prior to implantation is a prerequisite for complete esophageal replacement.Novel approaches need to be designed to allow for peristalsis and vascularization in the engineered esophagus.Although esophageal tissue engineering potentially offers a real alternative to conventional treatments for severe esophageal disease,important barders remain that need to be addressed.
查看更多>>摘要:The increasing shortage of donors and the adverse effects of immunosuppression have restricted the impact of solid organ transplantation.Despite the initial promising developments in xenotransplantation,roadblocks still need to be overcome and this form of organ support remains a long way from clinical practice.While hepatocyte transplantation may be effectively correct metabolic defects,it is far less effective in restoring liver function than liver transplantation.Tissue engineering,using extracellular matrix scaffolds with an intact but decellularized vascular network that is repopulated with autologous or allogeneic stem cells and/or adult cells,holds great promise for the treatment of failure of organs within gastrointestinal tract,such as endstage liver disease,pancreatic insufficiency,bowel failure and type 1 diabetes.Particularly in the liver field,where there is a significant mortality of patients awaiting transplant,human bioengineering may offer a source of readily available organs for transplantation.The use of autologous cells will mitigate the need for long term immunosuppression thus removing a major hurdle in transplantation.
查看更多>>摘要:The digestive tract is designed for the optimal processing of food that nourishes all organ systems.The esophagus,stomach,small bowel,and colon are sophisticated neuromuscular tubes with specialized sphincters that transport ingested food-stuffs from one region to another.Peristaltic contractions move ingested solids and liquids from the esophagus into the stomach; the stomach mixes the ingested nutrients into chyme and empties chyme from the stomach into the duodenum.The to-and-fro movement of the small bowel maximizes absorption of fat,protein,and carbohydrates.Peristaltic contractions are necessary for colon function and defecation.
Christopher BoothTom SokerPedro BaptistaChristina L Ross...
6926-6934页
查看更多>>摘要:The present review aims to illustrate the strategies that are being implemented to regenerate or bioengineer livers for clinical purposes.There are two general pathways to liver bioengineering and regeneration.The first consists of creating a supporting scaffold,either synthetically or by decellularization of human or animal organs,and seeding cells on the scaffold,where they will mature either in bioreactors or in vivo.This strategy seems to offer the quickest route to clinical translation,as demonstrated by the development of liver organoids from rodent livers which were repopulated with organ specific cells of animal and/or human origin.Liver bioengineering has potential for transplantation and for toxicity testing during preclinical drug development.The second possibility is to induce liver regeneration of dead or resected tissue by manipulating cell pathways.In fact,it is well known that the liver has peculiar regenerative potential which allows hepatocyte hyperplasia after amputation of liver volume.Infusion of autologous bone marrow cells,which aids in liver regeneration,into patients was shown to be safe and to improve their clinical condition,but the specific cells responsible for liver regeneration have not yet been determined and the underlying mechanisms remain largely unknown.A complete understanding of the cell pathways and dynamics and of the functioning of liver stem cell niche is necessary for the clinical translation of regenerative medicine strategies.As well,it will be crucial to elucidate the mechanisms through which cells interact with the extracellular matrix,and how this latter supports and drives cell fate.
查看更多>>摘要:AIM:To investigate the suppressive activity of MUTYH variant proteins against mutations caused by oxidative lesion,8-hydroxyguanine (8OHG),in human cells.METHODS:p.R154H,p.M255V,p.L360P,and p.P377L MUTYH variants,which were previously found in patients with colorectal polyposis and cancer,were selected for use in this study.Human H1299 cancer cell lines inducibly expressing wild-type (WT) MUTYH (type 2) or one of the 4 above-mentioned MUTYH variants were established using the piggyBac transposon vector system,enabling the genomic integration of the transposon sequence for MUTYH expression.MUTYH expression was examined after cumate induction using Western blotting analysis and immunofiuorescence analysis.The intracellular localization of MUTYH variants tagged with FLAG was also immunofluorescently examined.Next,the mutation frequency in the supF of the shuttle plasmid pMY189 containing a single 8OHG residue at position 159 of the supFwas compared between empty vector cells and cells expressing WT MUTYH or one of the 4 MUTYH variants using a supF forward mutation assay.RESULTS:The successful establishment of human cell lines inducibly expressing WT MUTYH or one of the 4 MUTYH variants was concluded based on the detection of MUTYH expression in these cell lines after treatment with cumate.All of the MUTYH variants and WT MUTYH were localized in the nucleus,and nuclear localization was also observed for FLAG-tagged MUTYH.The mutation frequency ofsupFwas 2.2 x 102in the 8OHG-containing pMY189 plasmid and 2.5× 10-4 in WT pMY189 in empty vector cells,which was an 86-fold increase with the introduction of 8OHG.The mutation frequency (4.7 × 10-3) of supF in the 8OHG-containing pMY189 plasmid in cells overexpressing WT MUTYH was significantly lower than in the empty vector cells (P < 0.01).However,the mutation frequencies of the supF in the 8OHG-containing pMY189 plasmid in cells overexpressing the p.R154H,p.M255V,p.L360P,or p.P377L MUTYH variant were 1.84 × 10-2,1.55 ×x 102,1.91 × 102,and 1.96 × 10-2,respectively,meaning that no significant difference was observed in the mutation frequency between the empty vector cells and cells overexpressing MUTYH mutants.CONCLUSION:The suppressive activities of p.R154H,p.M255V,p.L360R and p.P377L MUTYH variants against mutations caused by 8OHG are thought to be severely impaired in human cells.