Bone marrow transplantation ameliorates pathology in interleukin-10 knockout colitic mice

Inflammatory bowel disease-associated intestinal fibrosis

Fibrosis is characterized by a proliferation of fibroblasts and excessive extracellular matrix following chronic inflammation, and this replacement of organ tissue with fibrotic tissue causes a loss of function. Inflammatory bowel disease (IBD) is a chronic inflammation of the gastrointestinal tract, and intestinal fibrosis is common in IBD patients, resulting in several complications that require surgery, such as a stricture or penetration. This review describes the pathogenesis and various factors involved in intestinal fibrosis in IBD, including cytokines, growth factors, epithelial-mesenchymal and endothelial-mesenchymal transitions, and gut microbiota. Furthermore, histopathologic findings and scoring systems used for stenosis in IBD are discussed, and differences in the fibrosis patterns of ulcerative colitis and Crohn's disease are compared. Biomarkers and therapeutic agents targeting intestinal fibrosis are briefly mentioned at the end.

A Systematic Review of the Evidence of Hematopoietic Stem Cell Differentiation to Fibroblasts

Fibroblasts have an important role in the maintenance of the extracellular matrix of connective tissues by producing and remodelling extracellular matrix proteins. They are indispensable for physiological processes, and as such also associate with many pathological conditions. In recent years, a number of studies have identified donor-derived fibroblasts in various tissues of bone marrow transplant recipients, while others could not replicate these findings. In this systematic review, we provide an overview of the current literature regarding the differentiation of hematopoietic stem cells into fibroblasts in various tissues. PubMed, Embase, and Web of Science (Core Collection) were systematically searched for original articles concerning fibroblast origin after hematopoietic stem cell transplantation in collaboration with a medical information specialist. Our search found 5421 studies, of which 151 were analysed for full-text analysis by two authors independently, resulting in the inclusion of 104 studies. Only studies in animals and humans, in which at least one marker was used for fibroblast identification, were included. The results were described per organ of fibroblast engraftment. We show that nearly all mouse and human organs show evidence of fibroblasts of hematopoietic stem cell transfer origin. Despite significant heterogeneity in the included studies, most demonstrate a significant presence of fibroblasts of hematopoietic lineage in non-hematopoietic tissues. This presence appears to increase after the occurrence of tissue damage.

The Role of the Anti-Inflammatory Cytokine Interleukin-10 in Tissue Fibrosis

Significance: Fibrosis is the endpoint of chronic disease in multiple organs, including the skin, heart, lungs, intestine, liver, and kidneys. Pathologic accumulation of fibrotic tissue results in a loss of structural integrity and function, with resultant increases in morbidity and mortality. Understanding the pathways governing fibrosis and identifying therapeutic targets within those pathways is necessary to develop novel antifibrotic therapies for fibrotic disease. Recent Advances: Given the connection between inflammation and fibrogenesis, Interleukin-10 (IL-10) has been a focus of potential antifibrotic therapies because of its well-known role as an anti-inflammatory mediator. Despite the apparent dissimilarity of diseases associated with fibrotic progression, pathways involving IL-10 appear to be a conserved molecular theme. More recently, many groups have worked to develop novel delivery tools for recombinant IL-10, such as hydrogels, and cell-based therapies, such as ex vivo activated macrophages, to directly or indirectly modulate IL-10 signaling. Critical Issues: Some efforts in this area, however, have been stymied by IL-10's pleiotropic and sometimes conflicting effects. A deeper, contextual understanding of IL-10 signaling and its interaction with effector cells, particularly immune cells, will be critical to future studies in the field. Future Directions: IL-10 is clearly a gatekeeper of fibrotic/antifibrotic signaling. The development of novel therapeutics and cell-based therapies that capitalize on targets within the IL-10 signaling pathway could have far-reaching implications for patients suffering from the consequences of organ fibrosis.

Participation of Somatic Stem Cells, Recognized by a Unique A3 Antibody, in Mucosal Epithelial Regeneration in Dextran Sulfate Sodium (DSS)-Induced Rat Colonic Lesions

A3, generated as a monoclonal antibody against rat malignant fibrous histiocytoma cells, recognizes somatic stem cells in rats. We analyzed the distribution of A3-positive cells in dextran sulfate sodium (DSS)-induced colonic lesions consisting of regenerating mucosa and fibrosis. Male 6-week-old F344 rats were administered 5% DSS in drinking water for 5 to 7 days, and lesions at recovery stage were also examined. In untreated control adult colons, A3-positive cells are localized around the crypts where stem cell niche is formed. Histopathologically, in colons of DSS-administered rats, mucosal atrophy, inflammatory cell infiltration, and fibrosis were observed in the lamina propria; thereafter, mucosal epithelia were desquamated, and crypts were decreased gradually with decrease in surrounding A3-positive cells. At the early recovery stage, crypts showed regeneration with reappearance of A3-positive cells. Interestingly, A3-positive cells aggregated in desquamated mucosa surface of fibrosis. Aggregated A3-positive cells coexpressed with vimentin, Thy-1, and partly CK19 but did not react simultaneously with α-SMA. Likely, aggregated A3-positive cells may be rescue cells with nature of both mesenchymal and epithelial cells to maintain self-renewal after injury in the colon. A3 antibody would become a useful tool to investigate the participation of stem cells in rat colonic lesions.

Mechanism and therapeutic effect of umbilical cord mesenchymal stem cells in inflammatory bowel disease

Inflammatory bowel disease (IBD) is a persistent and chronic disease that is characterized by destructive gastrointestinal (GI) inflammation. Researchers are trying to identify and develop new and more effective treatments with no side effects. Acute and chronic mouse models of IBD were established using dextran sulfate sodium (DSS) solution. To evaluate the efficacy and mechanism, umbilical cord mesenchymal stem cells (UCMSCs) were obtained from Kunming (KM) mice and humans. In the chronic IBD study, the survival rates of the normal control, model, mouse UCMSC (mUCMSC) and human UCMSC (hUCMSC) groups were 100%, 40%, 86.7%, and 100%, respectively. The histopathological scores of the normal control, intraperitoneal injection, intravenous treatment, and model groups were 0.5 ± 0.30, 5.9 ± 1.10, 8.7 ± 1.39, and 8.8 ± 1.33 (p = 0.021). UCMSCs promoted the expression of the intestinal tight junction protein occludin, downregulated the protein expression of the autophagy marker LC3A/B in colon tissue, and upregulated the expression of VEGF-A and VEGFR-1 at the injured site. This study provides an experimental model for elucidating the therapeutic effects of UCMSCs in IBD. We provide a theoretical basis and method for the clinical treatment of IBD using UCMSCs.

Differentiation and roles of bone marrow-derived cells on the tumor microenvironment of oral squamous cell carcinoma

The stroma affects the properties and dynamics of the tumor. Previous studies have demonstrated that bone marrow-derived cells (BMDCs) possess the capability of differentiating into stromal cells. However, the characteristics and roles of BMDCs in oral squamous cell carcinoma remain unclear. The current study therefore investigated their locations and features by tracing green fluorescent protein (GFP)-labeled BMDCs in a transplantation mouse model. After irradiation, BALB-c nu-nu mice were injected with bone marrow cells from C57BL/6-BALB-C-nu/nu-GFP transgenic mice. These recipient mice were then injected subcutaneously in the head with human squamous cell carcinoma-2 cells. Immunohistochemistry for GFP, Vimentin, CD11b, CD31 and α-smooth muscle actin (SMA), and double-fluorescent immunohistochemistry for GFP-Vimentin, GFP-CD11b, GFP-CD31 and GFP-α-SMA was subsequently performed. Many round-shaped GFP-positive cells were observed in the cancer stroma, which indicated that BMDCs served a predominant role in tumorigenesis. Vimentin(+) GFP(+) cells may also be a member of the cancer-associated stroma, originating from bone marrow. Round or spindle-shaped CD11b(+) GFP(+) cells identified in the present study may be macrophages derived from bone marrow. CD31(+)GFP(+) cells exhibited a high tendency towards bone marrow-derived angioblasts. The results also indicated that spindle-shaped α-SMA(+) GFP(+) cells were not likely to represent bone marrow-derived cancer-associated fibroblasts. BMDCs gathering within the tumor microenvironment exhibited multilineage potency and participated in several important processes, such as tumorigenesis, tumor invasion and angiogenesis.

Characterization and potential roles of bone marrow-derived stromal cells in cancer development and metastasis

Background: The tumor microenvironment and its stromal cells play an important role in cancer development and metastasis. Bone marrow-derived cells (BMDCs), a rich source of hematopoietic and mesenchymal stem cells, putatively contribute to this tumoral stroma. However their characteristics and roles within the tumor microenvironment are unclear. In the present study, BMDCs in the tumor microenvironment were traced using the green fluorescent protein (GFP) bone marrow transplantation model. Methods: C57BL/6 mice were irradiated and rescued by bone marrow transplantation from GFP-transgenic mice. Lewis lung cancer cells were inoculated into the mice to generate subcutaneous allograft tumors or lung metastases. Confocal microscopy, immunohistochemistry for GFP, α-SMA, CD11b, CD31, CD34 and CD105, and double-fluorescent immunohistochemistry for GFP-CD11b, GFP-CD105 and GFP-CD31 were performed. Results: Round and dendritic-shaped GFP-positive mononuclear cells constituted a significant stromal subpopulation in primary tumor peripheral area (PA) and metastatic tumor area (MA) microenvironment, thus implicating an invasive and metastatic role for these cells. CD11b co-expression in GFP-positive cells suggests that round/dendritic cell subpopulations are possibly BM-derived macrophages. Identification of GFP-positive mononuclear infiltrates co-expressing CD31 suggests that these cells might be BM-derived angioblasts, whereas their non-reactivity for CD34, CD105 and α-SMA implies an altered vascular phenotype distinct from endothelial cells. Significant upregulation of GFP-positive, CD31-positive and GFP/CD31 double-positive cell densities positively correlated with PA and MA (P<0.05). Conclusion: Taken together, in vivo evidence of traceable GFP-positive BMDCs in primary and metastatic tumor microenvironment suggests that recruited BMDCs might partake in cancer invasion and metastasis, possess multilineage potency and promote angiogenesis.

Inflammatory hypoxia induces syndecan-2 expression through IL-1β-mediated FOXO3a activation in colonic epithelia

Chronic inflammation is known to be a key causative factor in tumor progression, but we do not yet fully understand the molecular mechanism through which inflammation leads to cancer. Here, we report that the dextran sulfate sodium (DSS)-induced mouse model of chronic colitis is associated with increases in the serum level of IL-1β and the colonic epithelial expression of the cell-surface heparan sulfate proteoglycan, syndecan-2. We further show that IL-1β stimulated the transcription of syndecan-2 via NF-κB-dependent FOXO3a activation in CCD841CoN normal colonic epithelial cells and early-stage HT29 colon cancer cells. Inflammatory hypoxia was observed in the colonic epithelia of mice with chronic colitis, suggesting that hypoxic stress is involved in the regulation of syndecan-2 expression. Consistently, experimental inflammatory hypoxia induced hypoxia inducible factor-1α-dependent FOXO3a expression and the p38 MAPK-mediated nuclear localization of FOXO3a. FOXO3a directly mediated syndecan-2 expression in both cell lines and the colonic epithelia of mice with DSS-induced colitis. Moreover, syndecan-2 expression was detected in azoxymethane/DSS-induced colon tumors. Together, these data demonstrate that inflammatory hypoxia up-regulates syndecan-2 via the IL-1β-NF-κB-FOXO3a pathway. These findings provide new mechanistic insights into inflammatory hypoxia-mediated syndecan-2 expression to connect chronic inflammation and the development of colon cancer.-Choi, S., Chung, H., Hong, H., Kim, S. Y., Kim, S.-E., Seoh, J.-Y., Moon, C. M., Yang, E. G., Oh, E.-S. Inflammatory hypoxia induces syndecan-2 expression through IL-1β-mediated FOXO3a activation in colonic epithelia.

The Influence of Bone Marrow-Secreted IL-10 in a Mouse Model of Cerulein-Induced Pancreatic Fibrosis

This study aimed to understand the role of IL-10 secreted from bone marrow (BM) in a mouse model of pancreatic fibrosis. The severity of cerulein-induced inflammation, fibrosis, and the frequency of BM-derived myofibroblasts were evaluated in the pancreas of mice receiving either a wild-type (WT) BM or an IL-10 knockout (KO) BM transplantation. The area of collagen deposition increased significantly in the 3 weeks after cerulein cessation in mice with an IL-10 KO BM transplant (13.7 ± 0.6% and 18.4 ± 1.1%, p < 0.05), but no further increase was seen in WT BM recipients over this time. The percentage of BM-derived myofibroblasts also increased in the pancreas of the IL-10 KO BM recipients after cessation of cerulein (6.7 ± 1.1% and 11.9 ± 1.3%, p < 0.05), while this figure fell in WT BM recipients after cerulein withdrawal. Furthermore, macrophages were more numerous in the IL-10 KO BM recipients than the WT BM recipients after cerulein cessation (23.2 ± 2.3 versus 15.3 ± 1.7 per HPF, p < 0.05). In conclusion, the degree of fibrosis, inflammatory cell infiltration, and the number of BM-derived myofibroblasts were significantly different between IL-10 KO BM and WT BM transplanted mice, highlighting a likely role of IL-10 in pancreatitis.

Amniotic fluid stem cells improve survival and enhance repair of damaged intestine in necrotising enterocolitis via a COX-2 dependent mechanism

OBJECTIVE

Necrotising enterocolitis (NEC) remains one of the primary causes of morbidity and mortality in neonates and alternative strategies are needed. Stem cells have become a therapeutic option for other intestinal diseases, which share some features with NEC. We tested the hypothesis that amniotic fluid stem (AFS) cells exerted a beneficial effect in a neonatal rat model of NEC.

DESIGN

Rats intraperitoneally injected with AFS cells and their controls (bone marrow mesenchymal stem cells, myoblast) were analysed for survival, behaviour, bowel imaging (MRI scan), histology, bowel absorption and motility, immunofluorescence for AFS cell detection, degree of gut inflammation (myeloperoxidase and malondialdehyde), and enterocyte apoptosis and proliferation.

RESULTS

AFS cells integrated in the bowel wall and improved rat survival and clinical conditions, decreased NEC incidence and macroscopic gut damage, improved intestinal function, decreased bowel inflammation, increased enterocyte proliferation and reduced apoptosis. The beneficial effect was achieved via modulation of stromal cells expressing cyclooxygenase 2 in the lamina propria, as shown by survival studies using selective and non-selective cyclooxygenase 2 inhibitors. Interestingly, AFS cells differentially expressed genes of the Wnt/β-catenin pathway, which regulate intestinal epithelial stem cell function and cell migration and growth factors known to maintain gut epithelial integrity and reduce mucosal injury.

CONCLUSIONS

We demonstrated here for the first time that AFS cells injected in an established model of NEC improve survival, clinical status, gut structure and function. Understanding the mechanism of this effect may help us to develop new cellular or pharmacological therapies for infants with NEC.

Interleukin 10 receptor signaling: master regulator of intestinal mucosal homeostasis in mice and humans

Interleukin 10 (IL10) is a key anti-inflammatory cytokine that can inhibit proinflammatory responses of both innate and adaptive immune cells. An association between IL10 and intestinal mucosal homeostasis became clear with the discovery that IL10 and IL10 receptor (IL10R)-deficient mice develop spontaneous intestinal inflammation. Similarly, patients with deleterious mutations in IL10, IL10RA, or IL10RB present with severe enterocolitis within the first months of life. Here, we review recent findings on how IL10- and IL10R-dependent signaling modulates innate and adaptive immune responses in the murine gastrointestinal tract, with implications of their role in the prevention of inflammatory bowel disease (IBD). In addition, we discuss the impact of IL10 and IL10R signaling defects in humans and their relationship to very early-onset IBD (VEO-IBD).

Stem cells as a potential therapy for necrotizing enterocolitis

INTRODUCTION

Necrotizing enterocolitis (NEC) is a severe gastrointestinal disease of neonates, especially those born prematurely, that remains an important cause of morbidity and mortality. Although current treatments such as inotropes, antibiotics and ventilation are supportive, there is an urgent need for novel therapies that specifically target the affected intestine.

AREAS COVERED

We briefly introduce the disease and the effects on intestinal epithelia. We provide a brief description of amniotic fluid stem (AFS) cells, and then describe some recent data in which AFS cells were beneficial in an animal model of NEC and a potential mechanism is described. The effects of AFS cells are compared with data on bone marrow mesenchymal stem cells. The potential implications of these findings for therapy are discussed.

EXPERT OPINION

The current data are promising and demonstrate that stem cells do have an effect in rodent models of NEC. However, the short timescale, limited ability for longitudinal evaluation and uncertain clinical relevance of these models means that there are considerable challenges to be overcome before attempting stem cell therapy in clinical trials. Nevertheless, these data open up novel areas of research into a prevention or therapy for this devastating disease.

Bone marrow mesenchymal stem cells repair colonic vascular endothelium in rats with ulcerative colitis

AIM: To investigate whether bone marrow mesenchymal stem cells (MSCs) can repair colonic vascular endothelium in rats with ulcerative colitis (UC).

METHODS: Monocytes were purified from bone marrow, amplified and identified as MSCs in vitro. Thirty female Wistar rats were randomly and equally divided into three groups: a normal control, a model group and a MSC group. Colitis was induced with trinitro-benzene-sulfonic acid in rats of the model and MSC groups. Rats of the MSC group were injected with 1 mL of MSC suspension via the tail vein, while the rats of the normal control group and model group were injected with equal volume of normal saline. After two weeks, colon tissue samples were analyzed for histopathology, and serial sections of the colon tissue were made for determining the distribution of Y chromosome and CD34 double positive cells. The protein expression of CD34 was detected by immunohistochemisty. The mRNA expression of CD34 was determined by RT-PCR. The contents of interleukin-6 (IL-6) and interleukin-10 (IL-10) in colon tissue were determined by ELISA.

RESULTS: Y chromosome and CD34 double positive cells could be seen in colon tissue of rats injected with MSCs. Compared to the normal control group, the expression of CD34 and IL-6 was increased (1.629 ± 0.067 vs 1.000 ± 0.113, P < 0.05; 238.304 pg/mL ± 0.019 pg/mL vs 81.439 pg/mL ± 0.120 pg/mL, P < 0.01) and the expression of IL-10 was decreased (87.531 pg/mL ± 0.101 pg/mL vs 289.413 pg/mL ± 0.039 pg/mL, P < 0.01) in the model group. Compared to the model group, the expression of CD34 and IL-10 was increased (2.502 ± 0.189 vs 1.629 ± 0.067, P < 0.05; 158.185 pg/mL ± 0.033 pg/mL vs 87.531 pg/mL ± 0.115 pg/mL, P < 0.01) and the expression of IL-6 was decreased (160.95 pg/mL ± 0.116 pg/mL vs 238.304 pg/mL ± 0.109 pg/mL, P < 0.01) in the MSC group.

CONCLUSION: MSCs may exert a therapeutic effect on colitis by differentiating into vascular cell endothelial cells and inhibiting inflammation.

Interleukin-10 and interleukin-10-receptor defects in inflammatory bowel disease

Inflammatory bowel disease (IBD) is a chronic inflammatory disease characterized by abdominal pain, bloody diarrhoea, and malabsorption leading to weight loss. It is considered the result of inadequate control of an excessive reaction of the immune system to the resident flora of the gut. Like other primary immunodeficiencies, IL-10 and IL-10 receptor (IL10R) deficiency present with IBD and demonstrate the sensitivity of the intestine to any changes of the immune system. Both IL-10 and IL10R deficiency cause severe early-onset enterocolitis and can be successfully treated by hematopoietic stem cell transplantation (HSCT).

Immunomodulatory properties of the protein fraction from Phorphyra columbina

The phycobiliproteins from Rhodophyta , R-phycoerythrin (R-PE) and C-phycocyanin (C-PC), have been shown to exert immunomodulatory effects. This study evaluated the effects of a Phorphyra columbina protein fraction (PF) and R-PE and C-PC on rat primary splenocytes, macrophages, and T-lymphocytes in vitro. PF featured various protein species, including R-PE and C-PC. PF showed mitogenic effects on rat splenocytes and was nontoxic to cells except at 1 g L(-1) protein. IL-10 secretion was enhanced by PF in rat splenocytes, macrophages, and especially T-lymphocytes, whereas it was markedly diminished by R-PE and C-PC. The production of pro-inflammatory cytokines by macrophages was inhibited. The effect of PF on IL-10 was evoked by JNK/p38 MAPK and NF-κB-dependent pathways in macrophages and T-lymphocytes. It was concluded that PF has immunomodulatory effects on macrophages and lymphocytes that appear to be predominantly anti-inflammatory via up-regulated IL-10 production and cannot be accounted for by R-PE and C-PC.

Matrix metalloproteinases in the restorative proctocolectomy pouch of pediatric ulcerative colitis

AIM: To investigate matrix metalloproteinases (MMPs) and their tissue inhibitors (TIMPs) in pouch mucosa of pediatric onset ulcerative colitis (UC).

METHODS: In this cross-sectional study, 28 patients with pediatric onset UC underwent ileal pouch biopsy 13 years (median) after proctocolectomy. Expression of MMPs-3, -7, -8, -9, -12 and -26 and TIMPs-1, -2 and -3 in samples was examined using immunohistochemichal methods, and another biopsy was used to evaluate the grade of histological inflammation. Two investigators independently graded the immunohistochemical specimens in a semiquantitative fashion, using a scale marking staining intensity as follows: 0 = less than 20 positive cells; 1 = 20-50 positive cells; 2 = 50-200 positive cells; 3 = over 20 positive cells. Fecal calprotectin and blood inflammatory markers [serum C-reactive protein (CRP) and erythrocyte sedimentation rate] were determined during a follow-up visit to examine correlations between these markers and the expression of MMPs and TIMPs.

RESULTS: Of the 28 patients with pediatric onset UC, nine had not experienced pouchitis, whereas thirteen reported a single episode, and six had recurrent pouchitis (≥ 4 episodes). At the time of the study, six patients required metronidazole. In all of the others, the most recent episode of pouchitis had occurred over one month earlier, and none were on antibiotics. Only four samples depicted no sign of inflammation, and these were all from patients who had not had pouchitis. Two samples were too small to determine the grade of inflammation, but both had suffered pouchitis, the other recurrent. No sample depicted signs of colonic metaplasia. Most pouch samples showed expression of epithelial (e) and stromal (s) MMP-3 (e, n = 22; s, n = 20), MMP-7 (e, n = 28; s, n = 27), MMP-12 (e, n = 20; s, n =24), TIMP-2 (e, n = 23; s, n = 23) and MMP-3 (e, n = 23; s, n = 28) but MMP-8 (e, n = 0; s, n = 1), MMP-9 (e, n = 0; s, n = 9) and MMP-26 (e, n = 0; s, n = 3) and TIMP-1 (n = 0, both) were lacking. In samples with low grade of inflammatory activity, the epithelial MMP-3 and MMP-7 expression was increased (r = -0.614 and r = -0.472, respectively, P < 0.05 in both). MMPs and TIMPs did not correlate with the markers of inflammation, fecal calprotectin, erythrocyte sedimentation rate, or CRP, with the exception of patients with low fecal calprotectin (< 100 μg/g) in whom a higher expression of epithelial MMP-7 was found no differences in MMP- or TIMP-profiles were seen in patients with a history of pouchitis compared to ones with no such episodes. Anastomosis with either straight ileoanal anastomosis or ileoanal anastomosis with J-pouch did depict differences in MMP- or TIMP-expression.

CONCLUSION: The expression of MMPs pediatric UC pouch in the long-term shares characteristics with inflammatory bowel disease, but inflammation cannot be classified as a reactivation of the disease.

Localized colonic stem cell transplantation enhances tissue regeneration in murine colitis

Many patients suffer from chronic gastrointestinal diseases characterized by chronic inflammation, increased intestinal permeability and visceral pain in which there is no definitive treatment. Adult stem cells have recently been used in various disease states to contribute wound-healing processes. In the current study we investigated the ability of intra-colonic adult stem cells application to heal colonic inflammation in IL-10(-/-) mice with active colitis. The aims of this study were to determine whether intra-colonic infusion of adult colonic stem cells (CSCs) (local stem cell transplantation): (i) restores intestinal permeability; (ii) attenuates visceral hypersensitivity; (iii) heals murine colitis. IL-10(-/-) mice with active colitis were transplanted with adult stem cells. Mice received either a single intracolonic infusion of CSCs or colonic epithelial cells. Two weeks after transplantation, we measured visceral hypersensitivity and intestinal permeability and correlated these with histological improvement of colitis. IL-10(-/-) mice that received stem cell transplantation showed histopathologic evidence of recovery from colitis. Improvement in colitis as graded by pathology scores correlated with restoration of intestinal permeability and decreased visceral hypersensitivity. Intra-colonic administration of CSCs is a potential therapeutic method for treating refractory symptoms in patients with chronic gastrointestinal diseases associated with chronic inflammation and visceral hypersensitivity. This method may be safer and should have far fewer side effects than systemic stem cell administration.

Bone marrow-derived cells contribute to cerulein-induced pancreatic fibrosis in the mouse

Bone marrow (BM) cells may transdifferentiate into circulating fibrocytes and myofibroblasts in organ fibrosis. In this study, we investigated the contribution and functional roles of BM-derived cells in murine cerulein-induced pancreatic fibrosis. C57/BL6 female mice wild-type (WT) or Col 1α1(r/r) male BM transplant, received supraphysiological doses of cerulein to induce pancreatic fibrosis. The CD45(+)Col 1(+) fibrocytes isolated from peripheral blood (PB) and pancreatic tissue were examined by in situ hybridization for Y chromosome detection. The number of BM-derived myofibroblasts, the degree of Sirius red staining and the levels of Col 1α1 mRNA were quantified. The Y chromosome was detected in the nuclei of PB CD45(+)Col 1(+) fibrocytes, confirming that circulating fibrocytes can be derived from BM. Co-expression of α-smooth muscle actin illustrated that fibrocytes can differentiate into myofibroblasts. The number of BM-derived myofibroblasts, degree of collagen deposition and pro-collagen I mRNA expression were higher in the mice that received Col 1α1(r/r) BM, (cells that produce mutated, collagenase-resistant collagen) compared to WT BM, indicating that the genotype of BM cells can alter the degree of pancreatic fibrosis. Our data indicate that CD45(+)Col 1(+) fibrocytes in the PB can be BM-derived, functionally contributing to cerulein-induced pancreatic fibrosis in mice by differentiating into myofibroblasts.

The ailing gut: a therapeutic role for bone marrow cells?

It is obvious that the BM does more than simply supply the GIT with cells of the innate and adaptive immune system. A growing number of studies suggest that BMCs can differentiate into ISEMFs (Lee et al., PLOS ONE 2011;6:e26082) and in the setting of inflammation can be contributors to all lineages of the neovasculature. The role of BMCs in epithelial turnover is more problematic; their contribution after transient mucosal injury seems negligible, but a number of studies in both rodents and man suggest that small numbers of BMCs can be incorporated into the epithelial compartment with more chronic injury (e.g., GvHD in man and chemically induced colitis in rodents); commonly cell fusion seems to be responsible for this. Significantly, this engraftment does not seem to occur in the stem-cell compartment, with the notable single report of the chronically infected murine gastric mucosa, where the BM origin of the stem cells can be the only rational explanation for the complete colonization of the mucosa by BMDCs. In the clinical setting, a role for MSCs in ameliorating colitis seems promising, though the mechanisms by which this is achieved remain somewhat unclear, though both immunomodulatory and regenerative effects of BMCs are likely to be important.

Intraperitoneal but not intravenous cryopreserved mesenchymal stromal cells home to the inflamed colon and ameliorate experimental colitis

BACKGROUND AND AIMS

Mesenchymal stromal cells (MSCs) were shown to have immunomodulatory activity and have been applied for treating immune-mediated disorders. We compared the homing and therapeutic action of cryopreserved subcutaneous adipose tissue (AT-MSCs) and bone marrow-derived mesenchymal stromal cells (BM-MSCs) in rats with trinitrobenzene sulfonic acid (TNBS)-induced colitis.

METHODS

After colonoscopic detection of inflammation AT-MSCs or BM-MSCs were injected intraperitoneally. Colonoscopic and histologic scores were obtained. Density of collagen fibres and apoptotic rates were evaluated. Cytokine levels were measured in supernatants of colon explants. For cell migration studies MSCs and skin fibroblasts were labelled with Tc-99m or CM-DiI and injected intraperitonealy or intravenously.

RESULTS

Intraperitoneal injection of AT-MSCs or BM-MSCs reduced the endoscopic and histopathologic severity of colitis, the collagen deposition, and the epithelial apoptosis. Levels of TNF-α and interleukin-1β decreased, while VEGF and TGF-β did not change following cell-therapy. Scintigraphy showed that MSCs migrated towards the inflamed colon and the uptake increased from 0.5 to 24 h. Tc-99m-MSCs injected intravenously distributed into various organs, but not the colon. Cm-DiI-positive MSCs were detected throughout the colon wall 72 h after inoculation, predominantly in the submucosa and muscular layer of inflamed areas.

CONCLUSIONS

Intraperitoneally injected cryopreserved MSCs home to and engraft into the inflamed colon and ameliorate TNBS-colitis.

Inflammatory bowel disease and colon cancer

The inflammatory bowel diseases (IBD); Crohn's and Ulcerative colitis, result from an altered host response to intestinal flora. Recurrent inflammation with ulceration and tissue restitution confers an increased risk of cancer in both UC and Crohns, and genome wide searches have identified a number of disease susceptibility alleles. The carcinogenesis pathway in colitis-associated colorectal cancer (CACRC) is less clearly understood than it's sporadic counterpart. Clonal ordering experiments have indicated the order and timing of chromosomal instability and common genetic mutations. Epigenetic changes such as DNA methylation and histone modification are thought to play an increasingly important role in inflammation induced carcinogenesis. Clonal expansion of procarcinogenic mutations can lead to large fields of mutant tissue from which colitis associated cancers can arise (field cancerisation). Endoscopic screening is the mainstay of surveillance in high-risk patients although the development of appropriate, clinically applicable biomarkers remains a research priority. Despite the expanding field of biological therapy in inflammatory bowel disease the ASA compounds remain the best-studied and most efficacious chemopreventive agents. Colitis associated CRC appears to have a different aetiology, carcinogenesis pathway and clinical course to its sporadic counterpart. Further research including long-term follow up of patient cohorts taking biological therapies will improve the detection and treatment of these important, inflammation-induced malignancies.

Bone marrow cells in murine colitis: multi-signal analysis confirms pericryptal myofibroblast engraftment without epithelial involvement

Background

The contribution of bone marrow-derived cells to epithelial tissues in the inflamed gut remains controversial. Recent reports have suggested that cell fusion between bone marrow-derived cells and the intestinal epithelium takes place in inflammatory conditions.

Methods

In attempts to confirm this, we have undertaken gender mis-matched bone marrow (BM) transplants from male Swiss Webster (SWR) mice to B and T cell-deficient female Rag2 KO mice which, 4 weeks later, were given 5% dextran sodium sulphate in drinking water to induce acute colitis. A further BM-treated group of animals with a graft versus host-like condition was also studied. We developed a new method to combine up to three brightfield or fluorescent lectin- or immuno-histochemical signals with fluorescent in situ hybridisation for the Y and X chromosomes to enable us unequivocally to identify BM-derived male cells which presented as different cell types in the gastrointestinal tract.

Principal Findings

In rolled preparations of whole intestines we scanned around 1.5 million crypts at many tissue levels. In no instance did we see a Y chromosome-positive cell in the epithelial compartment, which was not also CD45-positive. We saw no evidence of cell fusion, based on combined X and Y chromosome analysis. Levels of CD45-positive stromal and lymphoid cells and pericryptal myfibroblasts (positive for α-smooth muscle actin) increased with time up to a plateau, which resembled the level seen in untreated control grafted animals. We saw very few Y chromosome-positive endothelial cells in intestinal stromal vessels.

Conclusions

We conclude that whole BM transplantation does not result in intestinal epithelial engraftment in this model. Our new methods can usefully assist in multi-signal analyses of cell phenotypes following BM transplant and in models of chimaerism and regenerative medicine.

Myogenic lineage differentiated mesenchymal stem cells enhance recovery from dextran sulfate sodium-induced colitis in the rat

BACKGROUND

Although mounting evidence implicates mesenchymal stem cells (MSCs) in intestinal tissue repair, uncertainty remains concerning the distribution, function, and fate of repopulating MSCs in recipient colonic tissues. Therefore, we investigated the role of transplanted MSCs in the repair phase of DSS colitis.

METHODS

LacZ-labeled rat MSCs were transplanted into rats with colitis induced by 4% DSS on day 2. Regular water replaced the DSS solution on day 6. Therapeutic effect was evaluated on day 9 by clinicopathologic and growth factor/cytokine expression profiles. We analyzed the Notch signaling pathway by Western blotting and characterized immunofluorescence of lacZ-labeled MSCs with confocal laser microscopy. In vivo differentiation of MSC was confirmed by transmission electron microscopy (TEM).

RESULTS

Recovery of colitis was modestly but significantly promoted by MSC transplantation due to proceeding cell cycle and inhibiting apoptosis in the epithelia. Tgfa mRNA expression increased significantly, while Notch signaling was inhibited in the colonic tissues with MSC transplantation. β-Galactosidase-positive cells, which expressed α-SMA, desmin, and vimentin, were infrequently detected in the lamina propria stroma. DSS exposure in vitro proved to be the most potent inducer for α-SMA in MSCs where TEM demonstrated myogenic lineage differentiation.

CONCLUSIONS

We found that MSCs transplantation modestly promoted the repair of DSS colitis. The donor-derived MSCs were likely reprogrammed to differentiate to myogenic lineage cells by cues from the micro milieu. Further characterization of these cells is warranted as a basis for applying cell-based therapy for inflammatory bowel disease.

KSR1 protects from interleukin-10 deficiency-induced colitis in mice by suppressing T-lymphocyte interferon-γ production

BACKGROUND & AIMS

Immunological disorders of the gastrointestinal tract such as inflammatory bowel disease often result in recurrent and persistently elevated levels of proinflammatory cytokines. Kinase suppressor of Ras 1 (KSR1) is involved in tumor necrosis factor-mediated colon epithelial cell survival, yet its role in chronic inflammation has not been defined. In this study, we tested the hypothesis that KSR1 is protective against spontaneous experimental colitis.

METHODS

KSR1(-/-)Interleukin-10 (Il10)(-/-) mice were generated and histolopathologic parameters of intestinal inflammation were scored. Bone marrow transplants performed on wild-type and KSR1(-/-)Il10(-/-) mice determined the contribution of KSR1 in hematopoietic lineages. Mucosal T helper (Th) 1 and Th17 cytokine were also examined. In vitro Th1 and Th17 polarization assays were conducted and interleukin (IL)-17A and interferon-γ (IFN-γ) production analyzed by flow cytometry. Neutralizing antibodies against IgG, IL-17A, or IFN-γ were administered to 3-week-old KSR1(-/-)Il10(-/-) mice for 3 weeks and scored for colitis.

RESULTS

KSR1(-/-)Il10(-/-) mice developed accelerated and severe spontaneous colitis by 4 weeks of age. KSR1 expression in hematopoietic lineages was protective against colitis. Both IFN-γ and IL-17A transcripts were elevated in colons of KSR1(-/-) and KSR1(-/-)Il10(-/-) mice. IFN-γ production was increased in lamina propria T cells isolated from KSR1(-/-) and KSR1(-/-)Il10(-/-) mice. Additionally, in vitro Th1 polarization was increased while Th17 polarization was impaired in KSR1-deficient naïve T cells. Finally, administration of IFN-γ neutralizing antibodies attenuated colitis in KSR1(-/-)Il10(-/-) mice.

CONCLUSIONS

Mice lacking both KSR1 and IL-10 develop exacerbated colitis due to dysregulated IFN-γ production in T lymphocytes.

Expression profiles of matrix metalloproteinases and their inhibitors in colonic inflammation related to pediatric inflammatory bowel disease

OBJECTIVE

The differential diagnosis of chronic colitis in inflammatory bowel disease (IBD) is challenging and a distinction between Crohn's disease (CD) and ulcerative colitis (UC) is not always possible. Matrix metalloproteinases (MMPs) cleave components of the extracellular matrix and their dysregulation leads to damage to the mucosa. They are involved in inflammation in IBD, as well as in eventual tissue repair. We aimed to examine putative differences in the profiles of MMPs and their tissue inhibitors [tissue inhibitors of metalloproteinase (TIMPs)] in pediatric IBD to find better tools for differential diagnosis of various IBD subgroups at the tissue level in the colon.

MATERIAL AND METHODS

Expression of MMPs -1, -7, -8, -9, -10, -12 and -26 and TIMPs -1 and -3 was studied by immunohistochemistry in colonic tissue samples of 32 pediatric patients with IBD and 11 non-IBD cases.

RESULTS

In the colon, expression of MMP-7 in epithelium was greater in CD samples compared to UC samples (1.09 versus 0.33; P = 0.010). Furthermore, epithelial MMP-10 expression was elevated in CD and UC samples compared to non-IBD samples (1.55 versus 1.00; P = 0.041 and 1.58 versus 1.00; P = 0.025, respectively). TIMP-3 expression in the stroma was higher in both the CD and UC groups when compared to non-IBD samples (2.18 versus 1.36; P = 0.026 and 2.50 versus 1.36; P = 0.002, respectively), but differences between UC and CD could not be observed.

CONCLUSIONS

Increased expression of epithelial MMP-10 and stromal TIMP-3 could serve as histological indicators of IBD etiology. Epithelial MMP-7 expression, on the other hand, could help to differentiate between CD-related colitis and UC.

Inflammatory bowel disease and mutations affecting the interleukin-10 receptor

BACKGROUND

The molecular cause of inflammatory bowel disease is largely unknown.

METHODS

We performed genetic-linkage analysis and candidate-gene sequencing on samples from two unrelated consanguineous families with children who were affected by early-onset inflammatory bowel disease. We screened six additional patients with early-onset colitis for mutations in two candidate genes and carried out functional assays in patients' peripheral-blood mononuclear cells. We performed an allogeneic hematopoietic stem-cell transplantation in one patient.

RESULTS

In four of nine patients with early-onset colitis, we identified three distinct homozygous mutations in genes IL10RA and IL10RB, encoding the IL10R1 and IL10R2 proteins, respectively, which form a heterotetramer to make up the interleukin-10 receptor. The mutations abrogate interleukin-10-induced signaling, as shown by deficient STAT3 (signal transducer and activator of transcription 3) phosphorylation on stimulation with interleukin-10. Consistent with this observation was the increased secretion of tumor necrosis factor alpha and other proinflammatory cytokines from peripheral-blood mononuclear cells from patients who were deficient in IL10R subunit proteins, suggesting that interleukin-10-dependent "negative feedback" regulation is disrupted in these cells. The allogeneic stem-cell transplantation performed in one patient was successful.

CONCLUSIONS

Mutations in genes encoding the IL10R subunit proteins were found in patients with early-onset enterocolitis, involving hyperinflammatory immune responses in the intestine. Allogeneic stem-cell transplantation resulted in disease remission in one patient.

Novel cell-based therapeutic strategy for ischemic colitis with use of bone marrow-derived mononuclear cells in rats

PURPOSE

Ischemic colitis is a common disorder of the large bowel. In the clinical setting, some patients suffer refractory ischemic colitis regardless of conventional treatment. Meanwhile, bone marrow-derived mononuclear cells are known to accelerate neovascularization. The purpose of this study was to verify the effects of bone marrow-derived mononuclear cells on ischemic colitis in rats.

METHODS

An ischemic colitis model was established by partial obstruction of the rectum and interruption of the marginal vessel in the immunodeficient rat. Bone marrow-derived mononuclear cells from a Wistar rat were injected into the ischemic area one day later than the ischemia (Group MNC). As a control, phosphate-buffered saline was injected in the same manner (Group PBS). Seven days after cell transplantation, each rat was evaluated for histology and colic motility.

RESULTS

Compared with Group PBS scores, the Group MNC macroscopic and microscopic colitis severity scores were significantly reduced. Moreover, the density of the capillary and myenteric plexus was significantly higher in Group MNC than in Group PBS (9.55 +/- 0.74 vs. 4.61 +/- 0.22, respectively, P < 0.01; and 8.57 +/- 0.41 vs. 5.93 +/- 0.31, respectively, P < 0.02). The whole-gut transit time was significantly shorter in Group MNC compared with Group PBS (472.7 +/- 17.6 vs. 584.8 +/- 24.0 minutes, respectively, P < 0.01). Transplanted cells were detected in all layers of the intestinal wall; however, these cells did not differentiate into vascular or neural cells.

CONCLUSIONS

These results suggest that transplantation of bone marrow-derived mononuclear cells might enhance not only tissue regeneration and angiogenesis but also neurogenesis. Transplantation of bone marrow-derived mononuclear cells may be a useful therapeutic strategy for ischemic colitis.

[Therapeutic effect of allogenic bone marrow transplantation in acute TNBS-induced colitis]

BACKGROUND/AIMS

Bone marrow-derived cells (BMDC) contribute to tissue maintenance under many kinds of pathologic conditions. We carried out a study to see how BMDC play a role in the treatment of experimental murine colitis.

METHODS

We divided the animals into 3 groups and treated them with 50% ethanol (control group), 2,4,6-trinitrobenzene sulfinic acid colitis (TNBS group), and TNBS+bone marrow transplant (BMT group). To induce colitis, TNBS (5.0 mg/mouse) dissolved in 50% ethanol was injected into anus weekly for two weeks. Bone marrow transplantations were performed using bone marrow of male transgenic mouse (donor) with green fluorescence protein (GFP) into female wild type mouse (recipient) three weeks before TNBS instillation. All animals were sacrificed, and colons were extracted one week after the last TNBS instillation. We measured microscopic scores of mucosal injury and investigated the GFP expression for bone marrow engraftment. The immunostaining of vimentin and alpha-smooth muscle actin (alpha-SMA) for myofibroblasts was performed.

RESULTS

The score of mucosal injury in the TNBS group was much more severe than those in control, and reduced significantly by BMT (p<0.05). GFP-positive cells were almost deposited in pericryptal niche of BMT group but not at all in both control and TNBS group. Most of myofibroblasts stained with both vimentin and SMA also infiltrated into pericryptal niche. But, the number of myofibroblasts stained with vimentin and SMA in both control and TNBS group was smaller than that in BMT group.

CONCLUSIONS

BMDC deposited on pericryptal niche might have a significant role in repairing acute experimental murine colitis.

Intestinal fibrosis in IBD--a dynamic, multifactorial process

Intestinal fibrosis is a common and potentially serious complication of IBD that results from the reaction of intestinal tissue to the damage inflicted by chronic inflammation. The traditional view that fibrosis is inevitable or irreversible in patients with IBD is progressively changing in light of improved understanding of the cellular and molecular mechanisms that underlie the pathogenesis of fibrosis in general, and, in particular, intestinal fibrosis. These mechanisms are complex and dynamic, and involve multiple cell types, interconnected cellular events and a large number of soluble factors. In addition, owing to a breakdown of the epithelial barrier during inflammation of the gut, luminal bacterial products induce an innate immune response, which is triggered by activation of immune and nonimmune cells alike. Comprehension of the mechanisms of intestinal fibrosis will create a conceptual and practical framework that could achieve the specific blockade of fibrogenic pathways, allow for the estimation of risk of fibrotic complications, permit the detection of early fibrotic changes and, eventually, enable the development of treatments customized to the type and stage of each patient's IBD.

Inflammatory bowel disease: Moving toward a stem cell-based therapy

The incidence and prevalence of Crohn's disease (CD) and ulcerative colitis (UC), the two major forms of inflammatory bowel diseases (IBD), are rising in western countries. The modern hygienic lifestyle is probably at the root of a disease where, in genetically susceptible hosts, the intestinal commensal flora triggers dysregulated immune and inflammatory responses. Current therapies ranging from anti-inflammatory drugs to immunosuppressive regimens, remain inadequate. Advances in our understanding of the cell populations involved in the pathogenetic processes and recent findings on the regenerative, trophic and immunoregulatory potential of stem cells open new paths in IBD therapy. Hematopoietic and mesenchymal stem cells are catalyzing the attention of IBD investigators. This review highlights the pivotal findings for stem cell-based approaches to IBD therapy and collects the encouraging results coming in from clinical trials.

Intestinal fibrosis in inflammatory bowel disease - Current knowledge and future perspectives

BACKGROUND AND AIMS

Intestinal fibrosis is a common complication of IBD that can become seriously symptomatic and may require surgical intervention if stricture formation ensues. This review discusses existing and developing knowledge of intestinal fibrosis and its implications for therapy.

METHODS

Review of the literature, personal communications, unpublished observations.

RESULTS

Known mechanisms of intestinal fibrosis include fibroblast proliferation and migration, activation of stellate cells, and extraintestinal fibroblast recruitment. However, novel mechanisms are being uncovered, including epithelial-to-mesenchymal transition, endothelial-to-mesenchymal transition, pericyte differentiation, and fibrocyte recruitment. Most of the traditional and novel mechanisms underlying intestinal fibrosis are associated to the presence of chronic inflammation, but is also possible that fibrosis develops independently of persistent immune activation in the gut. At the moment, the development of preventive, non-interventional, and more effective management of intestinal fibrosis is hampered by the lack of a greater knowledge of its basic pathophysiology and predisposing factors.

CONCLUSIONS

It is reasonable to expect that therapy of IBD-associated fibrosis will radically improve once the underlying mechanisms are better understood, and therapeutic modalities will emerge that prevent or reverse this complication of IBD.

Involvement of bone marrow-derived stromal cells in gastrointestinal cancer development and metastasis

BACKGROUND

The involvement of bone marrow (BM) in tumor-stroma reactions or tumor development has not been examined in a cancer allograft, which has otherwise been appropriate for assessing therapeutic modalities. We investigated the fate of BM-derived cells in colon cancer allografts and liver metastases in mice.

METHODS

C57BL/6 mice were irradiated and rescued by BM transplantation from green fluorescent protein (GFP)-transgenic mice. MC38 colon cancer cells were stably transfected with the pDsRed gene in order to identify tumor cells by fluorescence. These were inoculated into the mice to generate subcutaneous allografted tumors or liver metastases. The tumors were observed under confocal microscopy and fluorescent immunohistochemistry to determine the fate of tumor versus BM-derived cells.

RESULTS

GFP-positive (GFP(+)) cells were consistently identified as vimentin(+), alpha-smooth muscle actin (alphaSMA)(+), spindle-shaped stromal cells in both the subcutaneous tumors and the liver metastases. GFP(+) cells of leukocyte lineage also infiltrated the tumors. Neither GFP(+) CD31(+) endothelial cells nor GFP(+) DsRed(+) cells were detected in the tumor.

CONCLUSIONS

BM-derived cells frequently and consistently infiltrated the tumor allografts and metastases as interstitial cells and leukocytes. Cells derived from the fusion of BM cells and tumor cells were not observed. This model may be appropriate for the clarification of the effects of anticancer therapies and the study of BM-derived cells in tumor-host interactions.

Exogenous administration of mesenchymal stem cells ameliorates dextran sulfate sodium-induced colitis via anti-inflammatory action in damaged tissue in rats

AIMS

Mesenchymal stem cells (MSCs) may modulate inflammatory responses resulting in improvement in inflammatory diseases, as well as tissue regeneration via cellular differentiation. We examined the therapeutic effects of exogenously administered MSCs in dextran sulfate sodium (DSS)-induced colitis in rats.

MAIN METHODS

Experimental colitis was produced in inbred male Lewis rats by administration of 4% DSS in drinking water for 7 days. MSCs (5x10(6) cells) which were isolated from whole marrow cells and cultured in an optimal medium for MSC outgrowth were administered to the treated rats via the tail vein on days 0, 2, and 4. On day 7, we evaluated colon length, histological changes, and colonic various mRNA expressions by RT-PCR. Localization of MSCs was evaluated using a green-fluorescent cell linker dye. To evaluate the anti-inflammatory action of MSCs, we assayed LPS-induced TNF-alpha secretion in a co-culture of MSCs and monocytes (THP-1 cells) using ELISA.

KEY FINDINGS

MSCs reduced in bloody stools, weight loss, colon shortening, and microscopic injuries. In the rectum of MSCs-treated rats, mRNA expression of TNF-alpha, IL-1beta, and COX-2 decreased to 40, 15, and 15% of their respective control levels. MSCs significantly suppressed mRNA expression of VEGF, HGF, and b-FGF to 40, 25, and 25% of their respective control levels. Green-fluorescent-labeled MSCs were found only within the lamina propria in inflamed regions. LPS-induced TNF-alpha secretion by THP-1 cells was significantly suppressed by co-culture with MSCs dose-dependently.

SIGNIFICANCE

We conclude that exogenous MSCs accumulated in inflamed tissues and ameliorated DSS-induced colitis via a local anti-inflammatory action.

Inflammatory bowel disease: Moving toward a stem cell-based therapy

The incidence and prevalence of Crohn's disease (CD) and ulcerative colitis (UC), the two major forms of inflammatory bowel diseases (IBD), are rising in western countries. The modern hygienic lifestyle is probably at the root of a disease where, in genetically susceptible hosts, the intestinal commensal flora triggers dysregulated immune and inflammatory responses. Current therapies ranging from anti-inflammatory drugs to immunosuppressive regimens, remain inadequate. Advances in our understanding of the cell populations involved in the pathogenetic processes and recent findings on the regenerative, trophic and immunoregulatory potential of stem cells open new paths in IBD therapy. Hematopoietic and mesenchymal stem cells are catalyzing the attention of IBD investigators. This review highlights the pivotal findings for stem cell-based approaches to IBD therapy and collects the encouraging results coming in from clinical trials.

Topical implantation of mesenchymal stem cells has beneficial effects on healing of experimental colitis in rats

Mesenchymal stem cells (MSCs) are attractive cell sources in regenerative medicine. We examined the effects of topical MSCs implantation on an experimental model of inflammatory bowel disease. Putative MSCs, isolated from bone marrow aspirates of male rats by dish adherence and expanded in vitro, were characterized by flow cytometry, reverse transcription-polymerase chain reaction, enzyme-linked immunosorbent assay, and differentiation assays. Experimental colitis was induced by intraluminal instillation of 2,4,6-trinitrobonzene sulfonic acid (TNBS) in the colons of male rats. The putative MSCs and unselected fresh bone marrow cells were injected into the colonic submucosa surrounding the area exposed to TNBS. The healing process of the injury was examined macroscopically and immunohistologically. Multipotent MSCs positive for CD29 and CD90, and negative for CD31 and CD34, were implanted into colon tissue surrounding the lesion; a majority of the engrafted cells were positive for vimentin. The implantation significantly accelerated healing of the damaged mucosa compared with vehicle-injected controls. The MSCs expressed vascular endothelial growth factor (VEGF) and transforming growth factor (TGF)-beta1 in vitro and after the implantation. In conclusion, we found that MSCs were successfully topically implanted in the colon and that they were associated with accelerated healing of TNBS-induced colitis. The beneficial effects of the MSCs might be mediated, at least in part, by their ability to differentiate into colonic interstitial cells and by their ability to provide VEGF and TGF-beta1 to the injured area.

Matrix metalloproteinase-7 (matrilysin) controls neutrophil egress by generating chemokine gradients

Matrilysin [matrix metalloproteinase 7 (MMP7)] is induced by mucosal injury of many tissues. To assess function of this proteinase, we subjected wild-type and Mmp7(-/-) mice to acute colon injury. When matrilysin expression was increasing, 73% of wild-type mice died, whereas only 32% of Mmp7(-/-) mice succumbed. Although re-epithelialization was delayed in Mmp7(-/-) mice, overall injury did not differ markedly between genotypes. We hypothesized that differences in acute inflammation caused increased mortality in wild-type mice. Indeed, whereas overall neutrophil influx into tissue was similar in wild-type and Mmp7(-/-) mice, their location and extent of migration differed between genotypes. Neutrophils were dispersed throughout the mucosa and within the lumen of wild-type mice, but these leukocytes were largely confined to the submucosa in Mmp7(-/-) mice. The levels of neutrophil chemokines, keratinocyte-derived chemokine and MIP-2, increased in the colon tissue of both genotypes, but these factors were detected only in lumenal lavages of wild-type mice. Our findings indicate that matrilysin mediates beneficial and deleterious effects in response to injury. On one hand, it promotes re-epithelialization, but it also controls the transepithelial influx of neutrophils, which if excessive, can lead to tissue damage.

The role of bone marrow-derived cells in fibrosis

There is a growing realization that bone marrow-derived cells (BMDCs) are a potential therapy for many diseases including ischemic heart disease, arterial stenosis and osteogenesis imperfecta. On the other hand, the fact that BMDCs may also contribute to fibrosis in many solid organs as well as to fibrosis surrounding tumours suggests that BMDCs are also involved in disease progression. This review focuses on the contribution of bone marrow cells to organ and tumour fibrosis, noting the utility of BMDCs as a potential new portal through which to direct anti-tumour therapies. Conversely, bone marrow cell therapy has been claimed to reduce fibrosis in some organs, highlighting a seemingly beneficial as opposed to a detrimental effect of BMDCs on organ fibrosis.

Butein blocks tumor necrosis factor alpha-induced interleukin 8 and matrix metalloproteinase 7 production by inhibiting p38 kinase and osteopontin mediated signaling events in HT-29 cells

In this study, we evaluated whether butein can inhibit the effects of tumor necrosis factor alpha (TNF-alpha), an inflammatory mediator, in intestinal epithelial HT-29 cells. Butein significantly inhibited TNF-alpha-induced interleukin 8 (IL-8) secretion and mRNA expression. Moreover, butein suppressed the expression of matrix metalloproteinase 7 (MMP-7) mRNA and extracellular pro-MMP-7 secretion. The signal transduction study revealed that butein significantly attenuates p38 phosphorylation and inhibits osteopontin (OPN) mediated inhibitory factor kappaBalpha (I-kappaBalpha) phosphorylation in TNF-alpha-stimulated HT-29 cells. Using specific kinase inhibitors, we also found that blocking the p38 pathway is critical for, and blocking of OPN-mediated I-kappaBalpha phosphorylation pathway is at least for, the inhibitory effect by butein on TNF-alpha-induced IL-8 and MMP-7 expression. Furthermore, using an MMP inhibitor, we showed that IL-8 lies upstream of MMP-7 in the TNF-alpha-induced signaling process in HT-29 cells. Collectively, these results suggest that butein may be an effective agent for the treatment of intestinal inflammation.

Nonmyeloablative stem cell therapy enhances microcirculation and tissue regeneration in murine inflammatory bowel disease

BACKGROUND AND AIMS

Reduced microcirculation has been implicated in the pathogenesis of inflammatory bowel disease (IBD). Stem cells or endothelial progenitor cells are thought to contribute to tissue regeneration through neoangiogenesis or vasculogenesis in ischemia- or inflammatory-related diseases. We therefore hypothesized that adult stem cells facilitate epithelial repair in IBD.

METHODS

Moderate-severe colitis in mice was induced by dextran sulfate sodium (DSS) and 2.0 x 10(6) immortalized CD34(-) stem cells infused twice via the tail vein during an observation period of 35 days in a nonmyeloablative setting.

RESULTS

Here, we demonstrate that adult stem cells home to the damaged digestive tract in the large intestine and facilitate mucosal repair in moderate-severe colitis. Nonmyeloablative stem cell therapy resulted in increased survival in severe colitis (P < .0001). Moreover, clinical activity and histologic evaluation of the colitis severity score were reduced significantly in moderate (P = .0003 or P = .03) and severe (P < .0001 or P < .03) colitis after 35 days, in addition to the DSS-induced shortening of colon length (P = .002 and P < .0002). Genetically marked stem cells were detected predominantly in the submucosa of the damaged colon epithelium. Epithelial repair in experimental IBD was mediated either by induction of improved vasculogenesis or by the differentiation of the transplanted stem cells into endothelial cells, as demonstrated by the promotion of Tie2 activity in the infused cells at the site of the damaged mucosa.

CONCLUSIONS

Our findings indicate that systemically administered adult stem cells respond to an adequate tissue lesion in murine IBD by enhancing microcirculation, resulting in accelerated tissue repair.

Role of intestinal subepithelial myofibroblasts in inflammation and regenerative response in the gut

Inflammatory bowel disease (IBD) is characterized by an ongoing mucosal inflammation caused by a dysfunctional host immune response to commensal microbiota and dietary factors. In the pathophysiology of IBD, mesenchymal cells such as intestinal subepithelial myofibroblasts (ISEMF) affect the recruitment, retention and activation of immune cells. Mesenchymal cells also promote resolution of inflammatory activity accompanied with balanced repair processes. The transient appearance of mesenchymal cells is a feature of normal wound healing, but the persistence of these cells is associated with tissue fibrosis. Recent studies suggest that mesenchymal cells derived from bone marrow (BM) stem cells play a crucial role in intestinal repair and fibrosis. This article focuses on recent knowledge about ISEMF in the field of immune response inflammation and repair. Two major topics were documented: interaction between interleukin (IL)-17-secreting CD4+ cells (Th-17 cells) and about role of BM-derived stem cells in mucosal regenerative response via differentiation to ISEMF. Recent therapeutic strategies targeting BM stem cells for IBD patients were also documented.

Matrix metalloproteinases in inflammatory bowel disease: boon or a bane?

Matrix metalloproteinases (MMPs) are a family of Zn(2+)-dependent extracellular matrix (ECM) degrading endopeptidases that share common functional domains, activation mechanisms, and collectively have the capacity to degrade all types of ECM proteins. In addition to playing a central role in ECM turnover, MMPs proteolytically activate or degrade a variety of nonmatrix substrates including chemokines, cytokines, growth factors, and junctional proteins. Thus, they are increasingly recognized as critical players in inflammatory response. Indeed, accumulating data from several studies indicate that they are the predominant proteases involved in the pathogenesis of inflammatory bowel disease (IBD) via their influence on the function and migration of inflammatory cells, mucosal ulceration, as well as matrix deposition and degradation. Some MMPs are constitutively expressed and play a protective role in IBD through their effect on cellular homeostasis, while others are induced during inflammation-mediated tissue damage. This article focuses on the role of the various MMPs in IBD, discussing their physiologic and pathogenetic role in the context of intestinal defense, mucosal inflammatory response, and immune cell-epithelial interaction.

The gastrointestinal tract stem cell niche

The gastrointestinal epithelium is unique in that cell proliferation, differentiation, and apoptosis occur in an orderly fashion along the crypt-villus axis. The intestinal crypt is mainly a proliferative compartment, is monoclonal and is maintained by stem cells. The villus represents the differentiated compartment, and is polyclonal as it receives cells from multiple crypts. In the small intestine, cell migration begins near the base of the crypt, and cells migrate from here emerging onto the villi. The basal crypt cells at position 5 are candidate stem cells. As the function of stem cells is to maintain the integrity of the intestinal epithelium, it must self-renew, proliferate, and differentiate within a protective niche. This niche is made up of proliferating and differentiating epithelial cells and surrounding mesenchymal cells. These mesenchymal cells promote the epithelial- mesenchymal crosstalk required to maintain the niche. A stochastic model of cell division has been proposed to explain how a single common ancestral stem cell exists from which all stem cells in a niche are descended. Our group has argued that these crypts then clonally expand by crypt fission, forming two daughters' crypts, and that this is the mechanism by which mutated stem cells or even cancer stem cell clones expand in the colon and in the entire gastrointestinal tract. Until recently, the differentiation potential of stem cells into adult tissues has been thought to be limited to cell lineages in the organ from which they were derived. Bone marrow cells are rare among adult stem cells regarding their abundance and role in the continuous, lifelong, physiological replenishment of circulating cells. In human and mice experiments, we have shown that bone marrow can contribute to the regeneration of intestinal myofibroblasts and thereby after epithelium following damage, through replacing the cells, which maintain the stem cells niche. Little is known about the markers characterizing the stem and transit amplifying populations of the gastrointestinal tract, although musashi-1 and hairy and enhancer of split homolog-1 have been proposed. As the mammalian gastrointestinal tract develops from the embryonic gut, it is made up of an endodermally-derived epithelium surrounded by cells of mesoderm origin. Cell signaling between these two tissue layers plays a critical role in coordinating patterning and organogenesis of the gut and its derivatives. Many lines of evidence have revealed that Wnt signaling is the most dominant force in controlling cell proliferation, differentiation, and apoptosis along the crypt-villus axis. We have found Wnt messenger RNAs expression in intestinal subepithelial myofibroblasts and frizzled messenger RNAs expression in both myofibroblasts and crypt epithelium. Moreover, there are many other factors, for example, bone morphogenetic protein, homeobox, forkhead, hedgehog, homeodomain, and platelet-derived growth factor that are also important to stem cell signaling in the gastrointestinal tract.