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Goldenberg D, McLaughlin C, Koduru SV, Ravnic DJ. Regenerative Engineering: Current Applications and Future Perspectives. Front Surg 2021; 8:731031. [PMID: 34805257 PMCID: PMC8595140 DOI: 10.3389/fsurg.2021.731031] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2021] [Accepted: 10/13/2021] [Indexed: 12/12/2022] Open
Abstract
Many pathologies, congenital defects, and traumatic injuries are untreatable by conventional pharmacologic or surgical interventions. Regenerative engineering represents an ever-growing interdisciplinary field aimed at creating biological replacements for injured tissues and dysfunctional organs. The need for bioengineered replacement parts is ubiquitous among all surgical disciplines. However, to date, clinical translation has been limited to thin, small, and/or acellular structures. Development of thicker tissues continues to be limited by vascularization and other impediments. Nevertheless, currently available materials, methods, and technologies serve as robust platforms for more complex tissue fabrication in the future. This review article highlights the current methodologies, clinical achievements, tenacious barriers, and future perspectives of regenerative engineering.
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Affiliation(s)
- Dana Goldenberg
- Irvin S. Zubar Plastic Surgery Research Laboratory, Penn State College of Medicine, Hershey, PA, United States
- Department of Surgery, Penn State Health Milton S. Hershey Medical Center, Hershey, PA, United States
| | - Caroline McLaughlin
- Irvin S. Zubar Plastic Surgery Research Laboratory, Penn State College of Medicine, Hershey, PA, United States
- Department of Surgery, Penn State Health Milton S. Hershey Medical Center, Hershey, PA, United States
| | - Srinivas V. Koduru
- Irvin S. Zubar Plastic Surgery Research Laboratory, Penn State College of Medicine, Hershey, PA, United States
- Department of Surgery, Penn State Health Milton S. Hershey Medical Center, Hershey, PA, United States
| | - Dino J. Ravnic
- Irvin S. Zubar Plastic Surgery Research Laboratory, Penn State College of Medicine, Hershey, PA, United States
- Department of Surgery, Penn State Health Milton S. Hershey Medical Center, Hershey, PA, United States
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2
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Stewart AS, Schaaf CR, Luff JA, Freund JM, Becker TC, Tufts SR, Robertson JB, Gonzalez LM. HOPX + injury-resistant intestinal stem cells drive epithelial recovery after severe intestinal ischemia. Am J Physiol Gastrointest Liver Physiol 2021; 321:G588-G602. [PMID: 34549599 PMCID: PMC8616590 DOI: 10.1152/ajpgi.00165.2021] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Intestinal ischemia is a life-threatening emergency with mortality rates of 50%-80% due to epithelial cell death and resultant barrier loss. Loss of the epithelial barrier occurs in conditions including intestinal volvulus and neonatal necrotizing enterocolitis. Survival depends on effective epithelial repair; crypt-based intestinal epithelial stem cells (ISCs) are the source of epithelial renewal in homeostasis and after injury. Two ISC populations have been described: 1) active ISC [aISC; highly proliferative; leucine-rich-repeat-containing G protein-coupled receptor 5 (LGR5+)-positive or sex-determining region Y-box 9 -antigen Ki67-positive (SOX9+Ki67+)] and 2) reserve ISC [rISC; less proliferative; homeodomain-only protein X positive (HOPX+)]. The contributions of these ISCs have been evaluated both in vivo and in vitro using a porcine model of mesenteric vascular occlusion to understand mechanisms that modulate ISC recovery responses following ischemic injury. In our previously published work, we observed that rISC conversion to an activated state was associated with decreased HOPX expression during in vitro recovery. In the present study, we wanted to evaluate the direct role of HOPX on cellular proliferation during recovery after injury. Our data demonstrated that during early in vivo recovery, injury-resistant HOPX+ cells maintain quiescence. Subsequent early regeneration within the intestinal crypt occurs around 2 days after injury, a period in which HOPX expression decreased. When HOPX was silenced in vitro, cellular proliferation of injured cells was promoted during recovery. This suggests that HOPX may serve a functional role in ISC-mediated regeneration after injury and could be a target to control ISC proliferation.NEW & NOTEWORTHY This paper supports that rISCs are resistant to ischemic injury and likely an important source of cellular renewal following near-complete epithelial loss. Furthermore, we have evidence that HOPX controls ISC activity state and may be a critical signaling pathway during ISC-mediated repair. Finally, we use multiple novel methods to evaluate ISCs in a translationally relevant large animal model of severe intestinal injury and provide evidence for the potential role of rISCs as therapeutic targets.
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Affiliation(s)
- Amy Stieler Stewart
- 1College of Veterinary Medicine, North Carolina State University, Raleigh, North Carolina
| | - Cecilia Renee Schaaf
- 1College of Veterinary Medicine, North Carolina State University, Raleigh, North Carolina
| | - Jennifer A. Luff
- 1College of Veterinary Medicine, North Carolina State University, Raleigh, North Carolina
| | - John M. Freund
- 1College of Veterinary Medicine, North Carolina State University, Raleigh, North Carolina
| | - Thomas C. Becker
- 2Duke Molecular Physiology Institute and Sarah W. Stedman Nutrition and Metabolism Center, Duke University Medical Center, Durham, North Carolina
| | - Sara R. Tufts
- 1College of Veterinary Medicine, North Carolina State University, Raleigh, North Carolina
| | - James B. Robertson
- 1College of Veterinary Medicine, North Carolina State University, Raleigh, North Carolina
| | - Liara M. Gonzalez
- 1College of Veterinary Medicine, North Carolina State University, Raleigh, North Carolina
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3
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Zhou J, Hou C, Chen H, Qin Z, Miao Z, Zhao J, Wang Q, Cui M, Xie C, Wang R, Li Q, Zuo G, Miao D, Jin J. P16 I NK 4a Deletion Ameliorates Damage of Intestinal Epithelial Barrier and Microbial Dysbiosis in a Stress-Induced Premature Senescence Model of Bmi-1 Deficiency. Front Cell Dev Biol 2021; 9:671564. [PMID: 34712655 PMCID: PMC8545785 DOI: 10.3389/fcell.2021.671564] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2021] [Accepted: 08/31/2021] [Indexed: 12/21/2022] Open
Abstract
This study aimed to determine whether Bmi-1 deficiency leads to intestinal epithelial barrier destruction and microbiota dysfunction, which members of the microbial community alter barrier function with age, and whether p16INK4a deletion could reverse the damage of intestinal epithelial barrier and microbial dysbiosis. Intestines from Bmi-1–deficient (Bmi-1–/–), Bmi-1 and p16INK4a double-knockout (Bmi-1–/–p16INK4a–/–), and wild-type mice were observed for aging and inflammation. Duolink Proximity Ligation Assay, immunoprecipitation, and construction of p16INK4a overexpressed adenovirus and the overexpressed plasmids of full-length, mutant, or truncated fragments for occludin were used for analyzing the interaction between p16INK4a and occludin. High-throughput sequencing of V4 region amplicon of 16S ribosomal RNA was conducted using intestinal microbiota. We found Bmi-1 deficiency destructed barrier structure, barrier function, and tight junction (TJ) in intestinal epithelium; decreased the TJ proteins; increased tumor necrosis factor α (TNF-α)–dependent barrier permeability; and up-regulated proinflammatory level of macrophages induced by intestinal microbial dysbiosis. The transplantation of fecal microbiota from wild-type mice ameliorated TJ in intestinal epithelium of Bmi-1–/– and Bmi-1–/–p16INK4a–/– mice. Harmful bacteria including Desulfovibrio, Helicobacter, and Oscillibacter were at a higher level in Bmi-1–/– mice. More harmful bacteria Desulfovibrio entered the epithelium and promoted macrophages-secreted TNF-α and caused TNF-α–dependent barrier permeability and aging. Accumulated p16INK4a combined with occludin at the 1st–160th residue in cytoplasm of intestinal epithelium cells from Bmi-1–/– mice, which blocked formation of TJ and the repair of intestinal epithelium barrier. P16INK4a deletion could maintain barrier function and microbiota balance in Bmi-1–/– mice through strengthening formation of TJ and decreasing macrophages-secreted TNF-α induced by Desulfovibrio entering the intestinal epithelium. Thus, Bmi-1 maintained intestinal TJ, epithelial barrier function, and microbiota balance through preventing senescence characterized by p16INK4a accumulation. The clearance of p16INK4a-positive cells in aging intestinal epithelium would be a new method for maintaining barrier function and microbiota balance. The residues 1–160 of occludin could be a novel therapeutic target for identifying small molecular antagonistic peptides to prevent the combination of p16INK4a with occludin for protecting TJ.
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Affiliation(s)
- Jiawen Zhou
- Research Center for Bone and Stem Cells, Department of Human Anatomy, Key Laboratory for Aging and Disease, The State Key Laboratory of Reproductive Medicine, Nanjing Medical University, Nanjing, China
| | - Chenxing Hou
- Research Center for Bone and Stem Cells, Department of Human Anatomy, Key Laboratory for Aging and Disease, The State Key Laboratory of Reproductive Medicine, Nanjing Medical University, Nanjing, China
| | - Haiyun Chen
- Anti-Aging Research Laboratory, Friendship Plastic Surgery Hospital, Nanjing Medical University, Nanjing, China
| | - Ziyue Qin
- Research Center for Bone and Stem Cells, Department of Human Anatomy, Key Laboratory for Aging and Disease, The State Key Laboratory of Reproductive Medicine, Nanjing Medical University, Nanjing, China
| | - Zi'an Miao
- Research Center for Bone and Stem Cells, Department of Human Anatomy, Key Laboratory for Aging and Disease, The State Key Laboratory of Reproductive Medicine, Nanjing Medical University, Nanjing, China
| | - Jingyu Zhao
- Research Center for Bone and Stem Cells, Department of Human Anatomy, Key Laboratory for Aging and Disease, The State Key Laboratory of Reproductive Medicine, Nanjing Medical University, Nanjing, China
| | - Qiuyi Wang
- Research Center for Bone and Stem Cells, Department of Human Anatomy, Key Laboratory for Aging and Disease, The State Key Laboratory of Reproductive Medicine, Nanjing Medical University, Nanjing, China
| | - Min Cui
- Research Center for Bone and Stem Cells, Department of Human Anatomy, Key Laboratory for Aging and Disease, The State Key Laboratory of Reproductive Medicine, Nanjing Medical University, Nanjing, China
| | - Chunfeng Xie
- Department of Nutrition and Food Safety, School of Public Health, Nanjing Medical University, Nanjing, China
| | - Rong Wang
- Research Center for Bone and Stem Cells, Department of Human Anatomy, Key Laboratory for Aging and Disease, The State Key Laboratory of Reproductive Medicine, Nanjing Medical University, Nanjing, China
| | - Qing Li
- Department of Science and Technology, Jiangsu Jiankang Vocational College, Nanjing, China
| | - Guoping Zuo
- Research Center for Bone and Stem Cells, Department of Human Anatomy, Key Laboratory for Aging and Disease, The State Key Laboratory of Reproductive Medicine, Nanjing Medical University, Nanjing, China
| | - Dengshun Miao
- Research Center for Bone and Stem Cells, Department of Human Anatomy, Key Laboratory for Aging and Disease, The State Key Laboratory of Reproductive Medicine, Nanjing Medical University, Nanjing, China.,Anti-Aging Research Laboratory, Friendship Plastic Surgery Hospital, Nanjing Medical University, Nanjing, China
| | - Jianliang Jin
- Research Center for Bone and Stem Cells, Department of Human Anatomy, Key Laboratory for Aging and Disease, The State Key Laboratory of Reproductive Medicine, Nanjing Medical University, Nanjing, China
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Calibasi-Kocal G, Mashinchian O, Basbinar Y, Ellidokuz E, Cheng CW, Yilmaz ÖH. Nutritional Control of Intestinal Stem Cells in Homeostasis and Tumorigenesis. Trends Endocrinol Metab 2021; 32:20-35. [PMID: 33277157 DOI: 10.1016/j.tem.2020.11.003] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/22/2020] [Revised: 10/31/2020] [Accepted: 11/01/2020] [Indexed: 02/06/2023]
Abstract
Food and nutrition have a profound impact on organismal health and diseases, and tissue-specific adult stem cells play a crucial role in coordinating tissue maintenance by responding to dietary cues. Emerging evidence indicates that adult intestinal stem cells (ISCs) actively adjust their fate decisions in response to diets and nutritional states to drive intestinal adaptation. Here, we review the signaling mechanisms mediating the dietary responses imposed by caloric intake and nutritional composition (i.e., macronutrients and micronutrients), fasting-feeding patterns, diet-induced growth factors, and microbiota on ISCs and their relevance to the beginnings of intestinal tumors.
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Affiliation(s)
- Gizem Calibasi-Kocal
- David H. Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology (MIT), Cambridge, MA, USA; Department of Translational Oncology, Institute of Oncology, Dokuz Eylul University, Izmir, Turkey
| | - Omid Mashinchian
- Nestlé Research, Ecole Polytechnique Fédérale de Lausanne (EPFL) Innovation Park, Lausanne, Switzerland; School of Life Sciences, EPFL, Lausanne, Switzerland
| | - Yasemin Basbinar
- Department of Translational Oncology, Institute of Oncology, Dokuz Eylul University, Izmir, Turkey
| | - Ender Ellidokuz
- Department of Gastroenterology, Faculty of Medicine, Dokuz Eylul University, Izmir, Turkey
| | - Chia-Wei Cheng
- David H. Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology (MIT), Cambridge, MA, USA.
| | - Ömer H Yilmaz
- David H. Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology (MIT), Cambridge, MA, USA; Department of Biology, MIT, Cambridge, MA, USA; Broad Institute of Harvard and MIT, Cambridge, MA, USA; Departments of Pathology, Gastroenterology, and Surgery, Massachusetts General Hospital and Harvard Medical School, Boston, USA.
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5
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Abstract
The gastrointestinal microbiome plays a pivotal role in physiological homeostasis of the intestine as well as in the pathophysiology of diseases including inflammatory bowel diseases (IBD) and colorectal cancer (CRC). Emerging evidence suggests that gut microbiota signal to the mitochondria of mucosal cells, including epithelial cells and immune cells. Gut microbiota signaling to mitochondria has been shown to alter mitochondrial metabolism, activate immune cells, induce inflammasome signaling, and alter epithelial barrier function. Both dysbiosis of the gut microbiota and mitochondrial dysfunction are associated with chronic intestinal inflammation and CRC. This review discusses mitochondrial metabolism of gut mucosal cells, mitochondrial dysfunction, and known gut microbiota-mediated mitochondrial alterations during IBD and CRC.
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Affiliation(s)
- Dakota N. Jackson
- Department of Internal Medicine, Division of Gastroenterology, Baylor Scott & White Research Institute, Baylor University Medical Center, Dallas, TX, USA
| | - Arianne L. Theiss
- Department of Internal Medicine, Division of Gastroenterology, Baylor Scott & White Research Institute, Baylor University Medical Center, Dallas, TX, USA,CONTACT Arianne L. Theiss Division of Gastroenterology, Baylor Research Institute, Baylor University Medical Center, 250 Hoblitzelle, 3500 Gaston Avenue, Dallas, TX75246, USA
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6
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Wells AI, Coyne CB. Enteroviruses: A Gut-Wrenching Game of Entry, Detection, and Evasion. Viruses 2019; 11:E460. [PMID: 31117206 PMCID: PMC6563291 DOI: 10.3390/v11050460] [Citation(s) in RCA: 53] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2019] [Revised: 05/08/2019] [Accepted: 05/19/2019] [Indexed: 12/13/2022] Open
Abstract
Enteroviruses are a major source of human disease, particularly in neonates and young children where infections can range from acute, self-limited febrile illness to meningitis, endocarditis, hepatitis, and acute flaccid myelitis. The enterovirus genus includes poliovirus, coxsackieviruses, echoviruses, enterovirus 71, and enterovirus D68. Enteroviruses primarily infect by the fecal-oral route and target the gastrointestinal epithelium early during their life cycles. In addition, spread via the respiratory tract is possible and some enteroviruses such as enterovirus D68 are preferentially spread via this route. Once internalized, enteroviruses are detected by intracellular proteins that recognize common viral features and trigger antiviral innate immune signaling. However, co-evolution of enteroviruses with humans has allowed them to develop strategies to evade detection or disrupt signaling. In this review, we will discuss how enteroviruses infect the gastrointestinal tract, the mechanisms by which cells detect enterovirus infections, and the strategies enteroviruses use to escape this detection.
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Affiliation(s)
- Alexandra I Wells
- Department of Pediatrics, University of Pittsburgh School of Medicine, Pittsburgh, PA 15213, USA.
- Center for Microbial Pathogenesis, UPMC Children's Hospital of Pittsburgh, Pittsburgh, PA 15224, USA.
| | - Carolyn B Coyne
- Department of Pediatrics, University of Pittsburgh School of Medicine, Pittsburgh, PA 15213, USA.
- Center for Microbial Pathogenesis, UPMC Children's Hospital of Pittsburgh, Pittsburgh, PA 15224, USA.
- Richard K. Mellon Institute for Pediatric Research, UPMC Children's Hospital of Pittsburgh, Pittsburgh, PA 15224, USA.
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7
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Bankaitis ED, Ha A, Kuo CJ, Magness ST. Reserve Stem Cells in Intestinal Homeostasis and Injury. Gastroenterology 2018; 155:1348-1361. [PMID: 30118745 PMCID: PMC7493459 DOI: 10.1053/j.gastro.2018.08.016] [Citation(s) in RCA: 116] [Impact Index Per Article: 19.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/13/2018] [Revised: 07/17/2018] [Accepted: 08/01/2018] [Indexed: 02/07/2023]
Abstract
Renewal of the intestinal epithelium occurs approximately every week and requires a careful balance between cell proliferation and differentiation to maintain proper lineage ratios and support absorptive, secretory, and barrier functions. We review models used to study the mechanisms by which intestinal stem cells (ISCs) fuel the rapid turnover of the epithelium during homeostasis and might support epithelial regeneration after injury. In anatomically defined zones of the crypt stem cell niche, phenotypically distinct active and reserve ISC populations are believed to support homeostatic epithelial renewal and injury-induced regeneration, respectively. However, other cell types previously thought to be committed to differentiated states might also have ISC activity and participate in regeneration. Efforts are underway to reconcile the proposed relatively strict hierarchical relationships between reserve and active ISC pools and their differentiated progeny; findings from models provide evidence for phenotypic plasticity that is common among many if not all crypt-resident intestinal epithelial cells. We discuss the challenges to consensus on ISC nomenclature, technical considerations, and limitations inherent to methodologies used to define reserve ISCs, and the need for standardized metrics to quantify and compare the relative contributions of different epithelial cell types to homeostatic turnover and post-injury regeneration. Increasing our understanding of the high-resolution genetic and epigenetic mechanisms that regulate reserve ISC function and cell plasticity will help refine these models and could affect approaches to promote tissue regeneration after intestinal injury.
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Affiliation(s)
- Eric D. Bankaitis
- Department of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC,Center for Gastrointestinal Biology & Disease, University of North Carolina at Chapel Hill, Chapel Hill, NC
| | - Andrew Ha
- Department of Medicine, Hematology Division, and Stanford Cancer Institute, Stanford University School of Medicine, Stanford, CA 94305,Department of Biology, Stanford University, Stanford, CA 94305
| | - Calvin J. Kuo
- Department of Medicine, Hematology Division, and Stanford Cancer Institute, Stanford University School of Medicine, Stanford, CA 94305,Co-Corresponding Authors: Calvin J. Kuo: , Scott T. Magness: , Calvin J. Kuo: Stanford University School of Medicine, Lokey Stem Cell Research Building G2034A, 265 Campus Drive, Stanford, CA 94305; Scott T. Magness, University of North Carolina at Chapel Hill, 111 Mason Farm Rd. CB# 7032, MBRB Rm 4337, Chapel Hill, NC, 27599
| | - Scott T. Magness
- Department of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC,Joint Departments of Biomedical Engineering, University of North Carolina at Chapel Hill/North Carolina State University, Chapel Hill, NC,Department of Cell Biology & Physiology, University of North Carolina at Chapel Hill, Chapel Hill, NC,Center for Gastrointestinal Biology & Disease, University of North Carolina at Chapel Hill, Chapel Hill, NC,Co-Corresponding Authors: Calvin J. Kuo: , Scott T. Magness: , Calvin J. Kuo: Stanford University School of Medicine, Lokey Stem Cell Research Building G2034A, 265 Campus Drive, Stanford, CA 94305; Scott T. Magness, University of North Carolina at Chapel Hill, 111 Mason Farm Rd. CB# 7032, MBRB Rm 4337, Chapel Hill, NC, 27599
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8
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Schoenborn AA, von Furstenberg RJ, Valsaraj S, Hussain FS, Stein M, Shanahan MT, Henning SJ, Gulati AS. The enteric microbiota regulates jejunal Paneth cell number and function without impacting intestinal stem cells. Gut Microbes 2018; 10:45-58. [PMID: 29883265 PMCID: PMC6363071 DOI: 10.1080/19490976.2018.1474321] [Citation(s) in RCA: 38] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/27/2017] [Revised: 04/06/2018] [Accepted: 05/01/2018] [Indexed: 02/03/2023] Open
Abstract
Paneth cells (PCs) are epithelial cells found in the small intestine, next to intestinal stem cells (ISCs) at the base of the crypts. PCs secrete antimicrobial peptides (AMPs) that regulate the commensal gut microbiota. In contrast, little is known regarding how the enteric microbiota reciprocally influences PC function. In this study, we sought to characterize the impact of the enteric microbiota on PC biology in the mouse small intestine. This was done by first enumerating jejunal PCs in germ-free (GF) versus conventionally raised (CR) mice. We next evaluated the possible functional consequences of altered PC biology in these experimental groups by assessing epithelial proliferation, ISC numbers, and the production of AMPs. We found that PC numbers were significantly increased in CR versus GF mice; however, there were no differences in ISC numbers or cycling activity between groups. Of the AMPs assessed, only Reg3γ transcript expression was significantly increased in CR mice. Intriguingly, this increase was abrogated in cultured CR versus GF enteroids, and could not be re-induced with various bacterial ligands. Our findings demonstrate the enteric microbiota regulates PC function by increasing PC numbers and inducing Reg3γ expression, though the latter effect may not involve direct interactions between bacteria and the intestinal epithelium. In contrast, the enteric microbiota does not appear to regulate jejunal ISC census and proliferation. These are critical findings for investigators using GF mice and the enteroid system to study PC and ISC biology.
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Affiliation(s)
- Alexi A Schoenborn
- a Center for Gastrointestinal Biology and Disease , University of North Carolina at Chapel Hill , Chapel Hill , NC 27599 , USA
- b Department of Pediatrics, Division of Gastroenterology , University of North Carolina at Chapel Hill , Chapel Hill , NC 27599 , USA
| | - Richard J von Furstenberg
- a Center for Gastrointestinal Biology and Disease , University of North Carolina at Chapel Hill , Chapel Hill , NC 27599 , USA
- c Department of Medicine, Division of Gastroenterology , University of North Carolina at Chapel Hill , Chapel Hill , NC 27599 , USA
| | - Smrithi Valsaraj
- a Center for Gastrointestinal Biology and Disease , University of North Carolina at Chapel Hill , Chapel Hill , NC 27599 , USA
- b Department of Pediatrics, Division of Gastroenterology , University of North Carolina at Chapel Hill , Chapel Hill , NC 27599 , USA
| | - Farah S Hussain
- a Center for Gastrointestinal Biology and Disease , University of North Carolina at Chapel Hill , Chapel Hill , NC 27599 , USA
- c Department of Medicine, Division of Gastroenterology , University of North Carolina at Chapel Hill , Chapel Hill , NC 27599 , USA
| | - Molly Stein
- a Center for Gastrointestinal Biology and Disease , University of North Carolina at Chapel Hill , Chapel Hill , NC 27599 , USA
- b Department of Pediatrics, Division of Gastroenterology , University of North Carolina at Chapel Hill , Chapel Hill , NC 27599 , USA
| | - Michael T Shanahan
- a Center for Gastrointestinal Biology and Disease , University of North Carolina at Chapel Hill , Chapel Hill , NC 27599 , USA
- c Department of Medicine, Division of Gastroenterology , University of North Carolina at Chapel Hill , Chapel Hill , NC 27599 , USA
| | - Susan J Henning
- a Center for Gastrointestinal Biology and Disease , University of North Carolina at Chapel Hill , Chapel Hill , NC 27599 , USA
- c Department of Medicine, Division of Gastroenterology , University of North Carolina at Chapel Hill , Chapel Hill , NC 27599 , USA
- d Department of Cellular and Molecular Physiology , University of North Carolina at Chapel Hill , Chapel Hill , NC 27599 , USA
| | - Ajay S Gulati
- a Center for Gastrointestinal Biology and Disease , University of North Carolina at Chapel Hill , Chapel Hill , NC 27599 , USA
- b Department of Pediatrics, Division of Gastroenterology , University of North Carolina at Chapel Hill , Chapel Hill , NC 27599 , USA
- e Department of Pathology and Laboratory Medicine , University of North Carolina at Chapel Hill , Chapel Hill , NC 27599 , USA
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9
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Moorefield EC, Andres SF, Blue RE, Van Landeghem L, Mah AT, Santoro MA, Ding S. Aging effects on intestinal homeostasis associated with expansion and dysfunction of intestinal epithelial stem cells. Aging (Albany NY) 2018; 9:1898-1915. [PMID: 28854151 PMCID: PMC5611984 DOI: 10.18632/aging.101279] [Citation(s) in RCA: 60] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2017] [Accepted: 08/25/2017] [Indexed: 12/12/2022]
Abstract
Intestinal epithelial stem cells (IESCs) are critical to maintain intestinal epithelial function and homeostasis. We tested the hypothesis that aging promotes IESC dysfunction using old (18-22 months) and young (2-4 month) Sox9-EGFP IESC reporter mice. Different levels of Sox9-EGFP permit analyses of active IESC (Sox9-EGFPLow), activatable reserve IESC and enteroendocrine cells (Sox9-EGFPHigh), Sox9-EGFPSublow progenitors, and Sox9-EGFPNegative differentiated lineages. Crypt-villus morphology, cellular composition and apoptosis were measured by histology. IESC function was assessed by crypt culture, and proliferation by flow cytometry and histology. Main findings were confirmed in Lgr5-EGFP and Lgr5-LacZ mice. Aging-associated gene expression changes were analyzed by Fluidigm mRNA profiling. Crypts culture from old mice yielded fewer and less complex enteroids. Histology revealed increased villus height and Paneth cells per crypt in old mice. Old mice showed increased numbers and hyperproliferation of Sox9-EGFPLow IESC and Sox9-EGFPHigh cells. Cleaved caspase-3 staining demonstrated increased apoptotic cells in crypts and villi of old mice. Gene expression profiling revealed aging-associated changes in mRNAs associated with cell cycle, oxidative stress and apoptosis specifically in IESC. These findings provide new, direct evidence for aging associated IESC dysfunction, and define potential biomarkers and targets for translational studies to assess and maintain IESC function during aging.
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Affiliation(s)
- Emily C Moorefield
- Department of Cell Biology and Physiology, University of North Carolina, Chapel Hill, NC 27599, USA
| | - Sarah F Andres
- Division of Gastroenterology, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - R Eric Blue
- Department of Cell Biology and Physiology, University of North Carolina, Chapel Hill, NC 27599, USA
| | - Laurianne Van Landeghem
- Department of Molecular Biomedical Sciences, College of Veterinary Medicine, North Carolina State University, Raleigh, NC 27695, USA
| | - Amanda T Mah
- Department of Hematology, Stanford University, Stanford, CA 94305, USA
| | - M Agostina Santoro
- Massachusetts General Hospital and Harvard Medical School, Boston, MA 02115, USA
| | - Shengli Ding
- Department of Cell Biology and Physiology, University of North Carolina, Chapel Hill, NC 27599, USA
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10
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Dosh RH, Jordan-Mahy N, Sammon C, Le Maitre CL. Tissue Engineering Laboratory Models of the Small Intestine. TISSUE ENGINEERING PART B-REVIEWS 2018; 24:98-111. [DOI: 10.1089/ten.teb.2017.0276] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Affiliation(s)
- Rasha Hatem Dosh
- Biomolecular Sciences Research Centre, Sheffield Hallam University, Sheffield, United Kingdom
- Department of Anatomy and Histology, Faculty of Medicine, University of Kufa, Kufa, Iraq
| | - Nicola Jordan-Mahy
- Biomolecular Sciences Research Centre, Sheffield Hallam University, Sheffield, United Kingdom
| | - Christopher Sammon
- Materials and Engineering Research Institute, Sheffield Hallam University, Sheffield, United Kingdom
| | - Christine Lyn Le Maitre
- Biomolecular Sciences Research Centre, Sheffield Hallam University, Sheffield, United Kingdom
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11
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Zou WY, Blutt SE, Zeng XL, Chen MS, Lo YH, Castillo-Azofeifa D, Klein OD, Shroyer NF, Donowitz M, Estes MK. Epithelial WNT Ligands Are Essential Drivers of Intestinal Stem Cell Activation. Cell Rep 2018; 22:1003-1015. [PMID: 29386123 DOI: 10.1016/j.celrep.2017.12.093] [Citation(s) in RCA: 49] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2017] [Revised: 11/16/2017] [Accepted: 12/24/2017] [Indexed: 12/25/2022] Open
Abstract
Intestinal stem cells (ISCs) maintain and repair the intestinal epithelium. While regeneration after ISC-targeted damage is increasingly understood, injury-repair mechanisms that direct regeneration following injuries to differentiated cells remain uncharacterized. The enteric pathogen, rotavirus, infects and damages differentiated cells while sparing all ISC populations, thus allowing the unique examination of the response of intact ISC compartments during injury-repair. Upon rotavirus infection in mice, ISC compartments robustly expand and proliferating cells rapidly migrate. Infection results specifically in stimulation of the active crypt-based columnar ISCs, but not alternative reserve ISC populations, as is observed after ISC-targeted damage. Conditional ablation of epithelial WNT secretion diminishes crypt expansion and ISC activation, demonstrating a previously unknown function of epithelial-secreted WNT during injury-repair. These findings indicate a hierarchical preference of crypt-based columnar cells (CBCs) over other potential ISC populations during epithelial restitution and the importance of epithelial-derived signals in regulating ISC behavior.
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Affiliation(s)
- Winnie Y Zou
- Department of Molecular Virology and Microbiology, Baylor College of Medicine, Houston, TX 77030, USA
| | - Sarah E Blutt
- Department of Molecular Virology and Microbiology, Baylor College of Medicine, Houston, TX 77030, USA
| | - Xi-Lei Zeng
- Department of Molecular Virology and Microbiology, Baylor College of Medicine, Houston, TX 77030, USA
| | - Min-Shan Chen
- Section of Gastroenterology and Hepatology, Department of Medicine, Baylor College of Medicine, Houston, TX 77030, USA
| | - Yuan-Hung Lo
- Section of Gastroenterology and Hepatology, Department of Medicine, Baylor College of Medicine, Houston, TX 77030, USA
| | - David Castillo-Azofeifa
- Departments of Orofacial Sciences and Pediatrics, University of California, San Francisco, San Francisco, CA 94143, USA
| | - Ophir D Klein
- Departments of Orofacial Sciences and Pediatrics, University of California, San Francisco, San Francisco, CA 94143, USA
| | - Noah F Shroyer
- Section of Gastroenterology and Hepatology, Department of Medicine, Baylor College of Medicine, Houston, TX 77030, USA
| | - Mark Donowitz
- Division of Gastroenterology and Hepatology, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD 21218, USA
| | - Mary K Estes
- Department of Molecular Virology and Microbiology, Baylor College of Medicine, Houston, TX 77030, USA; Section of Gastroenterology and Hepatology, Department of Medicine, Baylor College of Medicine, Houston, TX 77030, USA.
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12
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Samsa LA, Williamson IA, Magness ST. Quantitative Analysis of Intestinal Stem Cell Dynamics Using Microfabricated Cell Culture Arrays. Methods Mol Biol 2018; 1842:139-166. [PMID: 30196407 DOI: 10.1007/978-1-4939-8697-2_10] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Regeneration of intestinal epithelium is fueled by a heterogeneous population of rapidly proliferating stem cells (ISCs) found in the base of the small intestine and colonic crypts. ISCs populations can be enriched by fluorescence-activated cell sorting (FACS) based on expression of combinatorial cell surface markers, and fluorescent transgenes. Conventional ISC culture is performed by embedding single ISCs or whole crypt units in a matrix and culturing in conditions that stimulate or repress key pathways to recapitulate ISC niche signaling. Cultured ISCs form organoid, which are spherical, epithelial monolayers that are self-renewing, self-patterning, and demonstrate the full complement of intestinal epithelial cell lineages. However, this conventional "bulk" approach to studying ISC biology is often semiquantitative, low throughput, and masks clonal effects and ISC phenotypic heterogeneity. Our group has recently reported the construction, long-term biocompatibility, and use of microfabricated cell raft arrays (CRA) for high-throughput analysis of single ISCs and organoids. CRAs are composed of thousands of indexed and independently retrievable microwells, which in combination with time-lapse microscopy and/or gene-expression analyses are a powerful tool for studying clonal ISC dynamics and micro-niches. In this protocol, we describe how CRAs are used as an adaptable experimental platform to study the effect of exogenous factors on clonal stem cell behavior.
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Affiliation(s)
- Leigh A Samsa
- Department of Medicine, Center for Gastrointestinal Biology and Disease, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Ian A Williamson
- Department of Medicine, Center for Gastrointestinal Biology and Disease, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
- NC State/UNC Joint Department of Biomedical Engineering, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Scott T Magness
- Department of Medicine, Center for Gastrointestinal Biology and Disease, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA.
- NC State/UNC Joint Department of Biomedical Engineering, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA.
- Department of Cell Biology and Physiology, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA.
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13
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Hughes KR, Mahida YR. Determination of Histone 2B-Green Fluorescent Protein (GFP) Retention in Intestinal Stem Cells. Methods Mol Biol 2018; 1686:79-89. [PMID: 29030814 DOI: 10.1007/978-1-4939-7371-2_6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
The epithelium of the gastrointestinal tract represents the interface between the luminal contents of the gut and that of the host tissues and plays a central role not only in regulating absorption of dietary nutrients but also in providing a barrier to prevent the entry of bacteria and other pathogens. Repair and replacement of damaged aging cells within the epithelium is modulated by stem cells, which are located in the intestinal crypts of the small intestine.Two distinct populations of intestinal stem cells have been described in the literature, one population at the very base of the crypt and a second population of long-lived stem cells located just above the Paneth cell zone. Herein, we describe a method to label this population of long-lived GFP label retaining cells. This method is free from confounding factors of previous methodologies based on radioactive tracers and also enables functional studies not previously possible using the radioactive tracer techniques described in the literature.
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Affiliation(s)
- Kevin R Hughes
- Nottingham Digestive Diseases Centre, Queen's Medical Centre, Derby Road, Nottingham, NG7 2UH, UK
| | - Yashwant R Mahida
- Nottingham Digestive Diseases Centre, Queen's Medical Centre, Derby Road, Nottingham, NG7 2UH, UK.
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14
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Middelhoff M, Westphalen CB, Hayakawa Y, Yan KS, Gershon MD, Wang TC, Quante M. Dclk1-expressing tuft cells: critical modulators of the intestinal niche? Am J Physiol Gastrointest Liver Physiol 2017; 313:G285-G299. [PMID: 28684459 PMCID: PMC5668570 DOI: 10.1152/ajpgi.00073.2017] [Citation(s) in RCA: 66] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/28/2017] [Revised: 06/20/2017] [Accepted: 06/22/2017] [Indexed: 01/31/2023]
Abstract
Dclk1-expressing tuft cells constitute a unique intestinal epithelial lineage that is distinct from enterocytes, Paneth cells, goblet cells, and enteroendocrine cells. Tuft cells express taste-related receptors and distinct transcription factors and interact closely with the enteric nervous system, suggesting a chemosensory cell lineage. In addition, recent work has shown that tuft cells interact closely with cells of the immune system, with a critical role in the cellular regulatory network governing responses to luminal parasites. Importantly, ablation of tuft cells severely impairs epithelial proliferation and tissue regeneration after injury, implicating tuft cells in the modulation of epithelial stem/progenitor function. Finally, tuft cells expand during chronic inflammation and in preneoplastic tissues, suggesting a possible early role in inflammation-associated tumorigenesis. Hence, we outline and discuss emerging evidence that strongly supports tuft cells as key regulatory cells in the complex network of the intestinal microenvironment.
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Affiliation(s)
- Moritz Middelhoff
- 1Division of Digestive and Liver Diseases, Department of Medicine, Columbia University Medical Center, New York, New York; ,2II. Medizinische Klinik, Klinikum Rechts der Isar, Technische Universität München, Munich, Germany;
| | - C. Benedikt Westphalen
- 3Medizinische Klinik und Poliklinik III, Klinikum der Universität München, Munich, Germany;
| | - Yoku Hayakawa
- 4Department of Gastroenterology, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan;
| | - Kelley S. Yan
- 1Division of Digestive and Liver Diseases, Department of Medicine, Columbia University Medical Center, New York, New York; ,5Department of Genetics and Development, Columbia University Medical Center, New York, New York; and
| | - Michael D. Gershon
- 6Department of Pathology and Cell Biology, Columbia University Medical Center, New York, New York
| | - Timothy C. Wang
- 1Division of Digestive and Liver Diseases, Department of Medicine, Columbia University Medical Center, New York, New York;
| | - Michael Quante
- II. Medizinische Klinik, Klinikum Rechts der Isar, Technische Universität München, Munich, Germany;
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15
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Peck BCE, Shanahan MT, Singh AP, Sethupathy P. Gut Microbial Influences on the Mammalian Intestinal Stem Cell Niche. Stem Cells Int 2017; 2017:5604727. [PMID: 28904533 PMCID: PMC5585682 DOI: 10.1155/2017/5604727] [Citation(s) in RCA: 42] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2017] [Accepted: 08/02/2017] [Indexed: 02/07/2023] Open
Abstract
The mammalian intestinal epithelial stem cell (IESC) niche is comprised of diverse epithelial, immune, and stromal cells, which together respond to environmental changes within the lumen and exert coordinated regulation of IESC behavior. There is growing appreciation for the role of the gut microbiota in modulating intestinal proliferation and differentiation, as well as other aspects of intestinal physiology. In this review, we evaluate the diverse roles of known niche cells in responding to gut microbiota and supporting IESCs. Furthermore, we discuss the potential mechanisms by which microbiota may exert their influence on niche cells and possibly on IESCs directly. Finally, we present an overview of the benefits and limitations of available tools to study niche-microbe interactions and provide our recommendations regarding their use and standardization. The study of host-microbe interactions in the gut is a rapidly growing field, and the IESC niche is at the forefront of host-microbe activity to control nutrient absorption, endocrine signaling, energy homeostasis, immune response, and systemic health.
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Affiliation(s)
- Bailey C. E. Peck
- Department of Surgery, School of Medicine, University of Michigan, Ann Arbor, MI 48105, USA
| | - Michael T. Shanahan
- Department of Biomedical Sciences, College of Veterinary Medicine, Cornell University, Ithaca, NY 14853, USA
| | - Ajeet P. Singh
- Department of Biomedical Sciences, College of Veterinary Medicine, Cornell University, Ithaca, NY 14853, USA
| | - Praveen Sethupathy
- Department of Biomedical Sciences, College of Veterinary Medicine, Cornell University, Ithaca, NY 14853, USA
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16
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von Furstenberg RJ, Li J, Stolarchuk C, Feder R, Campbell A, Kruger L, Gonzalez LM, Blikslager AT, Cardona DM, McCall SJ, Henning SJ, Garman KS. Porcine Esophageal Submucosal Gland Culture Model Shows Capacity for Proliferation and Differentiation. Cell Mol Gastroenterol Hepatol 2017; 4:385-404. [PMID: 28936470 PMCID: PMC5602779 DOI: 10.1016/j.jcmgh.2017.07.005] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/16/2017] [Accepted: 07/13/2017] [Indexed: 02/09/2023]
Abstract
BACKGROUND & AIMS Although cells comprising esophageal submucosal glands (ESMGs) represent a potential progenitor cell niche, new models are needed to understand their capacity to proliferate and differentiate. By histologic appearance, ESMGs have been associated with both overlying normal squamous epithelium and columnar epithelium. Our aim was to assess ESMG proliferation and differentiation in a 3-dimensional culture model. METHODS We evaluated proliferation in human ESMGs from normal and diseased tissue by proliferating cell nuclear antigen immunohistochemistry. Next, we compared 5-ethynyl-2'-deoxyuridine labeling in porcine ESMGs in vivo before and after esophageal injury with a novel in vitro porcine organoid ESMG model. Microarray analysis of ESMGs in culture was compared with squamous epithelium and fresh ESMGs. RESULTS Marked proliferation was observed in human ESMGs of diseased tissue. This activated ESMG state was recapitulated after esophageal injury in an in vivo porcine model, ESMGs assumed a ductal appearance with increased proliferation compared with control. Isolated and cultured porcine ESMGs produced buds with actively cycling cells and passaged to form epidermal growth factor-dependent spheroids. These spheroids were highly proliferative and were passaged multiple times. Two phenotypes of spheroids were identified: solid squamous (P63+) and hollow/ductal (cytokeratin 7+). Microarray analysis showed spheroids to be distinct from parent ESMGs and enriched for columnar transcripts. CONCLUSIONS Our results suggest that the activated ESMG state, seen in both human disease and our porcine model, may provide a source of cells to repopulate damaged epithelium in a normal manner (squamous) or abnormally (columnar epithelium). This culture model will allow the evaluation of factors that drive ESMGs in the regeneration of injured epithelium. The raw microarray data have been uploaded to the National Center for Biotechnology Information Gene Expression Omnibus (accession number: GSE100543).
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Key Words
- 3D Culture
- 3D, 3-dimensional
- ANOVA, analysis of variance
- Acinar Ductal Metaplasia
- Adult Stem Cell
- BE, Barrett’s esophagus
- Barrett’s Esophagus
- CK7, cytokeratin 7
- DMSO, dimethyl sulfoxide
- EAC, esophageal adenocarcinoma
- EGF, epidermal growth factor
- ESMG, esophageal submucosal gland
- EdU, 5-ethynyl-2′-deoxyuridine
- Esophagus
- IHC, immunohistochemistry
- PBS, phosphate-buffered saline
- PCNA, proliferating cell nuclear antigen
- RFA, radiofrequency ablation
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Affiliation(s)
| | - Joy Li
- Division of Gastroenterology, Department of Medicine, Duke University, Durham, North Carolina
| | - Christina Stolarchuk
- Division of Gastroenterology, Department of Medicine, Duke University, Durham, North Carolina
| | - Rachel Feder
- Division of Gastroenterology, Department of Medicine, Duke University, Durham, North Carolina
| | - Alexa Campbell
- Division of Gastroenterology, Department of Medicine, Duke University, Durham, North Carolina
| | - Leandi Kruger
- Department of Clinical Sciences, North Carolina State University, College of Veterinary Medicine, Raleigh, North Carolina
| | - Liara M. Gonzalez
- Department of Clinical Sciences, North Carolina State University, College of Veterinary Medicine, Raleigh, North Carolina
| | - Anthony T. Blikslager
- Department of Clinical Sciences, North Carolina State University, College of Veterinary Medicine, Raleigh, North Carolina
| | - Diana M. Cardona
- Department of Pathology, Duke University, Durham, North Carolina
| | | | - Susan J. Henning
- Division of Gastroenterology, Department of Medicine, University of North Carolina Chapel Hill, Chapel Hill, North Carolina
| | - Katherine S. Garman
- Division of Gastroenterology, Department of Medicine, Duke University, Durham, North Carolina,Correspondence Address correspondence to: Katherine S. Garman, MD, Division of Gastroenterology, Department of Medicine, Duke University Medical Center, Box 3913, Durham, North Carolina 27710. fax: (919) 684-4983.Division of GastroenterologyDepartment of MedicineDuke University Medical CenterBox 3913DurhamNorth Carolina 27710
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17
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Smith NR, Gallagher AC, Wong MH. Defining a stem cell hierarchy in the intestine: markers, caveats and controversies. J Physiol 2016; 594:4781-90. [PMID: 26864260 DOI: 10.1113/jp271651] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2015] [Accepted: 01/06/2016] [Indexed: 12/22/2022] Open
Abstract
The past decade has appreciated rapid advance in identifying the once elusive intestinal stem cell (ISC) populations that fuel the continual renewal of the epithelial layer. This advance was largely driven by identification of novel stem cell marker genes, revealing the existence of quiescent, slowly- and active-cycling ISC populations. However, a critical barrier for translating this knowledge to human health and disease remains elucidating the functional interplay between diverse stem cell populations. Currently, the precise hierarchical and regulatory relationships between these ISC populations are under intense scrutiny. The classical theory of a linear hierarchy, where quiescent and slowly-cycling stem cells self-renew but replenish an active-cycling population, is well established in other rapidly renewing tissues such as the haematopoietic system. Efforts to definitively establish a similar stem cell hierarchy within the intestinal epithelium have yielded conflicting results, been difficult to interpret, and suggest non-conventional alternatives to a linear hierarchy. While these new and potentially paradigm-shifting discoveries are intriguing, the field will require development of a number of critical tools, including highly specific stem cell marker genes along with more rigorous experimental methodologies, to delineate the complex cellular relationships within this dynamic organ system.
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Affiliation(s)
- Nicholas R Smith
- Department of Cell, Developmental and Cancer Biology, Oregon Health & Science University, Portland, OR, 97239, USA
| | - Alexandra C Gallagher
- Department of Cell, Developmental and Cancer Biology, Oregon Health & Science University, Portland, OR, 97239, USA
| | - Melissa H Wong
- Department of Cell, Developmental and Cancer Biology, Oregon Health & Science University, Portland, OR, 97239, USA.,OHSU Stem Cell Center, Oregon Health and Science University, Portland, OR, 97239, USA
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