Tissue Repair Mechanisms Research Articles

Disruption of Skin Stem Cell Homeostasis following Transplacental Arsenicosis; Alleviation by Combined Intake of Selenium and Curcumin.

Of late, a consirable interest has grown in literature on early development of arsenicosis and untimely death in humans after exposure to iAs in drinking water in utero or during the childhood. The mechanism of this kind of intrauterine arsenic poisoning is not known; however it is often suggested to involve stem cells. We looked into this possibility by investigating in mice the influence of chronic in utero exposure to arsenical drinking water preliminarily on multipotent adult stem cell and progenitor cell counts at the beginning of neonatal age. We found that repeated intake of 42.5 or 85ppm iAs in drinking water by pregnant BALB/c mice substantially changed the counts of EpASCs, the progenitor cells, and the differentiated cells in epidermis of their zero day old neonates. EpASCs counts decreased considerably and the differentiated / apoptosed cell counts increased extensively whereas the counts of progenitor cell displayed a biphasic effect. The observed trend of response was dose-dependent and statistically significant. These observations signified a disruption in stem cell homeostasis. The disorder was in parallel with changes in expression of biomarkers of stem cell and progenitor (TA) cell besides changes in expression of pro-inflammatory and antioxidant molecules namely Nrf2, NFkB, TNF-α, and GSH. The biological monitoring of exposure to iAs and the ensuing transplacental toxicity was verifiable correspondingly by the increase in iAs burden in hair, kidney, skin, liver of nulliparous female mice and the onset of chromosomal aberrations in neonate bone marrow cells. The combined intake of selenite and curcumin in utero was found to prevent the disruption of homeostasis and associated biochemical changes to a great extent. The mechanism of prevention seemed possibly to involve (a) curcumin and Keap-1 interaction, (b) consequent escalated de novo GSH biosynthesis, and (c) the resultant toxicant disposition. These observations are important with respect to the development of vulnerability to arsenicosis and other morbidities later in life after repeated in utero or postnatal exposure to iAs in drinking water that may occur speculatively through impairment of adult stem cell dependent innate tissue repair mechanism.

Chemotherapy promotes tumour cell hybridization in vivo.

Spontaneous cell-cell fusion has been recognized to be an important mechanism for tissue and organ development and repair. In cancer, cell fusion is critically involved in tumourigenesis, metastasis and drug resistance, as illustrated by in vitro experiments. However, there has been no direct detection of tumour cell fusion or hybridization in an in vivo tumour environment, and the features of hybridized cells under selective pressures, such as chemotherapy, are unknown. Here, we expressed two fluorescent marker proteins in the human breast cancer cell line SKBR3 to detect tumour cell hybridization in vivo and performed a xenograft chemotherapy experiment in mice to evaluate the chemotherapeutic response of the hybrids. The mice treated by epirubicin showed that chemotherapy promoted tumour cell hybridization in vivo, which elicited the production of more hybrids in the outer section of the tumour. These results provide the first in vivo evidence of tumour cell fusion and indicate that chemotherapy may contribute to a poor prognosis by enriching for fused cells, which are more malignant. It is therefore necessary to reassess chemotherapy strategies.Electronic supplementary materialThe online version of this article (doi:10.1007/s13277-015-4337-7) contains supplementary material, which is available to authorized users.

Paracrine regulation in mesenchymal stem cells: the role of Rap1.

Since the first report more than a decade ago that bone marrow (BM) stem cells transplantation could promote heart regeneration following myocardial infarction (MI),1 different types of stem cells have been examined. Among those investigated to date, mesenchymal stem cells (MSCs) have attracted huge interest owing to some of their unique properties that include easy isolation, high expandability and low immunogenicity. Nonetheless despite the promising results of animal studies and clinical trials, MSC-based therapy for MI still faces some fundamental hurdles.2 One of the major challenges is the poor cell engraftment and low cell-survival rate following transplantation caused by the hostile environment of the injured heart and change to the immunologic milieu of transplanted MSCs. In addition, the mechanisms of stem cell-mediated tissue repair are not fully understood. Low cell retention and poor myocardial differentiation cannot explain the remarkable recovery of heart function following MSCs treatment. Therefore, the paracrine effects of MSCs are currently thought to have a predominant role. Although many cytokines released from MSCs contribute to heart function recovery,3 some are useless and even harmful.4 Thus, there is an urgent need to optimize MSCs before their transplantation to improve cell survival and augment their paracrine effects. Recently, Rap1, a telomeric repeat binding factor 2 interacting protein 1, has been identified as an important modulator of the nuclear factor kappa-B (NF-κB) pathway.5, 6 This pathway has been reported to regulate MSCs secretion profiling and survival.7, 8 On the basis of these findings, modulation of the NF-κB pathway to mediate MSCs therapy is feasible and important. Nonetheless total deletion of NF-κB is lethal to cells.9 Identification of an important regulator that can mediate activity of the NF-κB pathway and subsequently regulate MSC therapeutic efficacy for MI is vital. The roles of Rap1 in regulation of MSCs and the underlying mechanisms have not been classified, thus to understand how Rap1 regulates the paracrine effects and cell survival of MSC-mediated heart repair following infarction by regulation of the NF-κB pathway, therefore, is important.10

Multi-target drugs to address multiple checkpoints in complex inflammatory pathologies: evolutionary cues for novel "first-in-class" anti-inflammatory drug candidates: a reviewer's perspective.

Inflammation is a complex, metabolically expensive process involving multiple signaling pathways and regulatory mechanisms which have evolved over evolutionary timescale. Addressing multiple targets of inflammation holistically, in moderation, is probably a more evolutionarily viable strategy, as compared to current therapy which addresses drug targets in isolation. Polypharmacology, addressing multiple targets, is commonly used in complex ailments, suggesting the superior safety and efficacy profile of multi-target (MT) drugs. Phenotypic drug discovery, which generated successful MT and first-in-class drugs in the past, is now re-emerging. A multi-pronged approach, which modulates the evolutionarily conserved, robust and pervasive cellular mechanisms of tissue repair, with AMPK at the helm, regulating the complex metabolic/immune/redox pathways underlying inflammation, is perhaps a more viable strategy than addressing single targets in isolation. Molecules that modulate multiple molecular mechanisms of inflammation in moderation (modulating TH cells toward the anti-inflammatory phenotype, activating AMPK, stimulating Nrf2 and inhibiting NFκB) might serve as a model for a novel Darwinian "first-in-class" therapeutic category that holistically addresses immune, redox and metabolic processes associated with inflammatory repair. Such a multimodal biological activity is supported by the fact that several non-calorific pleiotropic natural products with anti-inflammatory action have been incorporated into diet (chiefly guided by the adaptive development of olfacto-gustatory preferences over evolutionary timescales) rendering such molecules, endowed with evolutionarily privileged molecular scaffolds, naturally oriented toward multiple targets.

A1M Ameliorates Preeclampsia-Like Symptoms in Placenta and Kidney Induced by Cell-Free Fetal Hemoglobin in Rabbit.

Preeclampsia is one of the most serious pregnancy-related diseases and clinically manifests as hypertension and proteinuria after 20 gestational weeks. The worldwide prevalence is 3-8% of pregnancies, making it the most common cause of maternal and fetal morbidity and mortality. Preeclampsia lacks an effective therapy, and the only “cure” is delivery. We have previously shown that increased synthesis and accumulation of cell-free fetal hemoglobin (HbF) in the placenta is important in the pathophysiology of preeclampsia. Extracellular hemoglobin (Hb) and its metabolites induce oxidative stress, which may lead to acute renal failure and vascular dysfunction seen in preeclampsia. The human endogenous protein, α1-microglobulin (A1M), removes cell-free heme-groups and induces natural tissue repair mechanisms. Exogenously administered A1M has been shown to alleviate the effects of Hb-induced oxidative stress in rat kidneys. Here we attempted to establish an animal model mimicking the human symptoms at stage two of preeclampsia by administering species-specific cell-free HbF starting mid-gestation until term, and evaluated the therapeutic effect of A1M on the induced symptoms. Female pregnant rabbits received HbF infusions i.v. with or without A1M every second day from gestational day 20. The HbF-infused animals developed proteinuria and a significantly increased glomerular sieving coefficient in kidney that was ameliorated by co-administration of A1M. Transmission electron microscopy analysis of kidney and placenta showed both intracellular and extracellular tissue damages after HbF-treatment, while A1M co-administration resulted in a significant reduction of the structural and cellular changes. Neither of the HbF-treated animals displayed any changes in blood pressure during pregnancy. In conclusion, infusion of cell-free HbF in the pregnant rabbits induced tissue damage and organ failure similar to those seen in preeclampsia, and was restored by co-administration of A1M. This study provides preclinical evidence supporting further examination of A1M as a potential new therapy for preeclampsia.

Acupuncture-Related Techniques: What To Do When Acupuncture Is Not Enough

Acupuncture has been widely accepted as valuable treatment for many pain and sport injuries in the United States and abroad. Medical literature reports varying rates of success for acupuncture treatment that is often as good or better than recovery seen with conventional biomedical therapeutics. However, all acupuncturists recognize that not all of their patients' pain and sport injuries are resolved through acupuncture. Acupuncture-related techniques may often eliminate pain and restore health and function when acupuncture alone has not succeeded. Techniques that have been generally recognized include moxibustion, cupping, scraping (Gwa Sha), various acupuncture microsystems (auricular, hand, scalp, etc.) and neural therapy. In addition, the current author proposes that prolotherapy is an invaluable acupuncture-related technique that leads to tissue regeneration and functional restoration, and should often be considered as a viable therapeutic modality when acupuncture has failed. The physiologic basis of joint and tissue regeneration through prolotherapy is presented along with a review of literature to provide an integrative understanding of the nature of tissue injury and repair mechanisms and therapeutic options when acupuncture fails to resolve a patient's condition. Prolotherapy is an invaluable acupuncture-related technique that has sound historical and physiologic bases, and produces enhanced clinical outcomes for many patients who have not experienced healing or recovery through acupuncture.

Kidney Regeneration: Lessons from Development.

A number of genes involved in kidney development are reactivated in the adult after acute kidney injury (AKI). This has led to the belief that tissue repair mechanisms recapitulate pathways involved in embryonic development after AKI. We will discuss evidence to support this hypothesis by comparing the mechanisms of development with common pathways known to regulate post-AKI repair, or that we identified as cell-specific candidates based on public datasets from recent AKI translational profiling studies. We will argue that while many of these developmental pathways are reactivated after AKI, this is not associated with general cellular reprogramming to an embryonic state. We will show that reactivation of these developmental genes is often associated with expression in cells that are not normally involved in mediating parallel responses in the embryo, and that depending on the cellular context, these responses can have beneficial or detrimental effects on injury and repair after AKI.

Complement activation in the context of stem cells and tissue repair.

The complement pathway is best known for its role in immune surveillance and inflammation. However, its ability of opsonizing and removing not only pathogens, but also necrotic and apoptotic cells, is a phylogenetically ancient means of initiating tissue repair. The means and mechanisms of complement-mediated tissue repair are discussed in this review. There is increasing evidence that complement activation contributes to tissue repair at several levels. These range from the chemo-attraction of stem and progenitor cells to areas of complement activation, to increased survival of various cell types in the presence of split products of complement, and to the production of trophic factors by cells activated by the anaphylatoxins C3a and C5a. This repair aspect of complement biology has not found sufficient appreciation until recently. The following will examine this aspect of complement biology with an emphasis on the anaphylatoxins C3a and C5a.

Relationship between Prolactin Plasma Levels and White Matter Volume in Women with Multiple Sclerosis.

Background. The role of prolactin (PRL) on tissue injury and repair mechanisms in multiple sclerosis (MS) remains unclear. The aim of this work was to investigate the relationship between PRL plasma levels and brain damage as measured by magnetic resonance imaging (MRI). Methods. We employed a chemiluminescence immunoassay for measuring plasma levels of PRL. We used a 1.5 T scanner to acquire images and Jim 4.0 and SIENAX software to analyse them. Results. We included 106 women with relapsing remitting (RR) MS and stable disease in the last two months. There was no difference in PRL plasma levels between patients with and without gadolinium enhancement on MRI. PRL plasma levels correlated with white matter volume (WMV) (rho = 0.284, p = 0.014) but not with grey matter volume (GMV). Moreover, PRL levels predicted changes in WMV (Beta: 984, p = 0.034). Conclusions. Our data of a positive association between PRL serum levels and WMV support the role of PRL in promoting myelin repair as documented in animal models of demyelination. The lack of an increase of PRL in the presence of gadolinium enhancement, contrasts with the view considering this hormone as an immune-stimulating and detrimental factor in the inflammatory process associated with MS.

Effect of resveratrol on plasmatic molecular indicators of brain tissue response to the hypoperfusion/ reperfusion challenge

It is well-documented that endocannabinoids (eCBs) and congeners show a neuroprotective role in several experimental models of brain injury and that changes in eCB levels in peripheral blood cells may reflect the severity of neurological insult. We have previously shown that the preventive administration of dietary natural compounds may increase the plasmatic levels of palmytoylethanolamide (PEA) and oleoylethanolamide (OEA) following the transient bilateral common carotid artery occlusion (BCCAO)-induced brain tissue challenge (1). Resveratrol (RVT), (3,4’, 5-trihidroxystilbene) is a strong natural antioxidant of polyphenolic structure found in grapes and red wine, with many physiological effects, including the prevention of lipid peroxidation in human LDL, inhibition of arachidonic acid metabolism, and platelet activity. RVT has been further shown to protect cerebral tissue and cardiac muscle from tissue damage caused by oxidative stress triggered by reperfusion (2) and has been proposed as a potential neuroprotective agent in treating acute states in focal cerebral ischemia injury (3). In this line, we intend to evaluate whether exogenous administration of RVT prior to induction of BCCAO followed by reperfusion influences the molecular changes occurring in cerebral cortex and plasma, with particular focus on the eCB system. With this aim, cerebral hypoperfusion was produced by a 30 min BCCAO followed by 60 min reperfusion (BCCAO/R). Animals were starved for 12 hours before surgery and 6 hours prior to ischemia RVT (40 mg/kg/0.45 ml of sunflower oil as vehicle) was administered via gavage. Biological samples of plasma, cerebrospinal fluid (CSF), and brain tissue were examined by HPLC, gel zymography, western blot and immunohistochemistry. Data obtained indicate that RVT appears to influence the outcome of BCCAO/R cerebral injury by modulating changes in levels of lipid hydroperoxides, markers of oxidative stress, eCBs and eCB congeners, expression of CB1 and CB2 receptors, peroxisome proliferator-activated receptor- (PPAR) alpha, ciclooxygenase-2 (COX-2) protein levels and enzymatic activity of matrix-metalloproteinase- 9 (MMP-9). Interestingly, changes in brain of some of these parameters, like lipid hydroperoxides, were also found in plasma. Results obtained suggest that exogenous administration of RVT may modulate the brain tissue compensatory or repair mechanisms triggered by the hypoperfusion/reperfusion and support the possible use of this molecule as treatment to prevent the BCCAO/R-induced brain insult. In addition, the finding that changes in plasma mirrored those found in cerebral tissue, opens to the possibility to test whether RSV exerts its positive activities in humans.

Stem Cells in Tooth Development, Growth, Repair, and Regeneration.

Human teeth contain stem cells in all their mesenchymal-derived tissues, which include the pulp, periodontal ligament, and developing roots, in addition to the support tissues such as the alveolar bone. The precise roles of these cells remain poorly understood and most likely involve tissue repair mechanisms but their relative ease of harvesting makes teeth a valuable potential source of mesenchymal stem cells (MSCs) for therapeutic use. These dental MSC populations all appear to have the same developmental origins, being derived from cranial neural crest cells, a population of embryonic stem cells with multipotential properties. In rodents, the incisor teeth grow continuously throughout life, a feature that requires populations of continuously active mesenchymal and epithelial stem cells. The discrete locations of these stem cells in the incisor have rendered them amenable for study and much is being learnt about the general properties of these stem cells for the incisor as a model system. The incisor MSCs appear to be a heterogeneous population consisting of cells from different neural crest-derived tissues. The epithelial stem cells can be traced directly back in development to a Sox10(+) population present at the time of tooth initiation. In this review, we describe the basic biology of dental stem cells, their functions, and potential clinical uses.

Elucidating the cellular actions of demineralised dentine matrix extract on a clonal dental pulp stem cell population in orchestrating dental tissue repair

Bioactive growth factors identified within the extracellular matrix of dentine have been proposed roles in regulating the naturally inherent regenerative dentine formation seen in teeth in response to trauma and infection, which may also be harnessed for novel clinical treatments in augmenting mineralised tissue repair. This study examined the specific biological action of demineralised dentine matrix extract on a clonal population of dental pulp stem cells in stimulating the prerequisite stages of wound healing associated with mineralised tissue repair. A clonal dental pulp stem cell population with sustained proliferative capacity and multi-potentiality towards osteogenic, adipogenic and chondrogenic lineages was isolated from the pulp of human third molars. Dentine was collected from human healthy teeth, powdered and treated with ethylenediaminetetraacetic acid to obtain a solubilised DDM protein extract. The influence of DDM on the DPSC clonal population was assessed in vitro. Exposure of cells to proteolytically degraded DDM or unsupplemented media served as controls. Compared to controls, DDM stimulated cell expansion, reduced apoptotic marker caspase 3, increased cell survival marker Akt1 and enhanced mineralised matrix deposition as determined by mineral deposition and increased expression of bone-related markers, alkaline phosphatase and osteopontin. Dental pulp stem cells successfully migrated into collagen gels supplemented with demineralised dentine matrix, with cells remaining viable and expanding in numbers over a 3-day period. Collectively, the results provide evidence that soluble proteins extracted from dentine matrix are able to exert a direct biological effect on dental pulp stem cells in promoting mineralised tissue repair mechanisms.

The messenger between worlds: the regulation of innate and adaptive type-2 immunity by innate lymphoid cells.

Although type-2 immune responses evolved primarily to defend against extracellular helminths, in part through the co-opting of tissue repair and remodeling mechanisms, they are often inappropriately directed towards relatively innocuous allergens resulting in conditions including asthma, allergic rhinitis, food allergy, and atopic dermatitis. The recent discovery of group 2 innate lymphoid cells (ILC2) has increased our understanding of the initiation of these responses and the roles played by CD4(+) T helper (Th) 2 cells in their modulation. This review focuses on the important messenger role of ILC2 in translating epithelial-derived alarmins into downstream adaptive type-2 responses via dendritic cells and T cells, with special emphasis on their roles in allergic disease.

New TB treatments hiding in plain sight.

As tuberculosis (TB) toll is revised upward according to the WHO's last estimates, the lack of vaccine strategy and the lengthy antibiotic treatments that unfortunately promote the emergence of drug resistance are a major set back in the fight against this pathogen. In this issue of EMBO Molecular Medicine, Schiebler et al (Mtb) propose a novel and compelling new approach to target Mycobacterium tuberculosis (Mtb) by pharmacologically stimulating intracellular mycobacteria clearance through autophagy.

Adenomyosis and endometriosis. Re-visiting their association and further insights into the mechanisms of auto-traumatisation. An MRI study.

PurposeIn a series of publications, we had developed the concept that uterine adenomyosis and pelvic endometriosis as well as endometriotic lesions at distant sites of the body share a common pathophysiology with endometriosis constituting a secondary phenomenon. Uterine auto-traumatization and the initiation of the mechanism of tissue injury and repair (TIAR) were considered the primary events in the disease process. The present MRI study was undertaken (1) to corroborate this concept by re-visiting, in view of discrepant results in the literature, the association of adenomyosis with endometriosis and (2) to extend our views concerning the mechanisms of uterine auto-traumatization.Patients and methodsMRI was performed in 143 women attending our center, in whom, on the basis of transvaginal sonography (TVS) and historical data, such as documented endometriosis and dysmenorrhea of various degrees of severity, the presence of uterine adenomyosis was suspected. In addition to the measurement of the diameter of junctional zone (JZ) of the anterior and posterior walls in the mid-sagittal plane, the diagnosis of adenomyosis was based on visualization, in that all planes were analyzed with scrutiny. By this method of “visualization” all transient enlargement of the JZ, such as peristaltic waves of the archimyometrium and sporadic neometral contractions that might mimic adenomyotic lesions could be excluded. At the same time, this method allowed to lower the limit of detection in terms of thickness of the JZ for assured diagnosis of adenomyosis. Furthermore, the localizations of the individual lesions, their shapes and patterns were described.ResultsWith the method of ‘visualization’, the diagnosis of uterine adenomyosis could be verified in 127 of the 143 patients studied. The prevalence of endometriosis in adenomyosis was 80.6 % and the prevalence of adenomyosis in endometriosis was 91.1 %. As concluded from their localization within the uterine wall, the adenomyotic lesions predominantly developed in the median region of the upper two-thirds of the uterine wall. Cystic cornual angle adenomyosis was a distinct phenomenon that was only observed in patients suffering from extreme primary dysmenorrhea. Aside from this, the majority of the patients complained of primary dysmenorrhea (80 %). On the basis of these findings and the fact that particularly extreme primary dysmenorrhea is associated with high intrauterine pressure, menstrual ‘archimetral compression by neometral contraction’ has to be considered as an important cause of uterine auto-traumatization in addition to uterine peristalsis and hyperperistalsis. Both mechanical functions of the non-pregnant uterus exert their strongest power in the upper region of the uterus, which is compatible with the predominant localization of the adenomyotic lesions.ConclusionsThe data confirm our previous results of a high association of adenomyosis with endometriosis and vice versa. Our view of the mechanism of uterine auto-traumatization by mechanical functions of the non-pregnant uterus has to be extended, in that ‘archimetral compression by neometral contractions’ could be realized as the predominant cause of mechanical strain to the non-pregnant uterus. The data of this study confirm our concept of the etiology and pathophysiology of adenomyosis and endometriosis in that the process of chronic proliferation and inflammation is induced at the level of the archimetra by chronic uterine auto-traumatization. Furthermore, with respect to the diagnosis of uterine adenomyosis (and consequently endometriosis) this study shows a high degree of accordance between the findings in real-time TVS and MRI.

Using animal models for the study of uveitis

AbstractOur understanding of inflammatory responses and mechanisms of immune‐mediated tissue damage in man has been greatly facilitated by our animal models systems. The talk will discuss the utility of animal model in uveitis from two aspects. Firstly, permitting fundamental elucidation of immune pathogenic mechanisms that are at play in uveitis and secondly, delivering a platform for preclinical assessment of drug or biologic intervention. We have been fortunate to be able to further manipulate animal models to create spontaneous models of uveitis and also humanised models of uveitis to assess antigen repertoires and responsiveness. Further we now have persistent models of disease activity, which have illuminated mechanisms of tissue repair and also mechanisms of immune mediated angiogenesis. To this end. the models permit us to look at and translate through to man interventions that have benefitted uveitic patients, and such successes will be highlighted throughout the talk

Abstract 245: Plasminogen Augments Cxcl12/cxcr4-regulated Stem Cell Homing And Contributes To Cardiac Repair After Myocardial Infarction.

Myocardial infarction (MI) is a leading cause of morbidity and mortality worldwide. Bone marrow (BM)-derived stem cells promote tissue repair and regeneration after MI. Thrombolytic treatment with plasminogen (Plg) activators significantly improves the clinical outcome in MI by restoration of cardiac perfusion. In addition to its canonical function, Plg is critical for cardiac repair, wound healing and liver injury, however, the mechanism for Plg-regulated tissue repair remains unclear. Here, we show a novel role of Plg in stem cell-mediated neovascularization and cardiac repair after MI. Our data show that Granulocyte colony-stimulating factor (G-CSF), a stem cell mobilizer, significantly increased neovascularization and decreased infarct size in the infarct area, and improved ejection fraction and LV internal diameter by echocardiogram in wild-type mice. No improvement in tissue repair and heart function was observed in Plg deficient (Plg-/-) mice indicating that Plg is required for stem cell-regulated cardiac repair after MI. In vivo tracking of GFP-expressing BM cells after BM transplantation revealed that in Plg-/- mice, recruitment of BM-derived stem cells (GFP+c-kit+ cells) to the infarcted heart and stem cell-derived vessels and arteries are dramatically decreased (by 11 fold) suggesting that Plg may regulate stem cell homing to the lesion sites and subsequently contribute stem cell-mediated tissue regeneration. Mechanistic studies show that Plg up-regulated CXCR4 expression on stem cell in vivo and in vitro, suggesting Plg may promotes stem cell homing by induction of CXCR4 expression in stem cells. Stem cell migration was enhanced by endogenous Plg in vitro, however, AMD3100, a CXCR4 antagonist, significantly inhibited Plg-regulated stem cell migration. Furthermore, lentiviral reconstitution of CXCR4 expression in BM cells rescued stem cell homing to the infarcted heart in Plg-/- mice, indicating that Plg mediates stem cell homing through regulating CXCR4 expression. These findings identified a novel role of Plg in cardiac repair by promoting stem cell homing to the injured heart after MI. Thus, targeting Plg may offer a new therapeutic strategy for strengthening stem cell-mediated cardiac repair and regeneration after MI.

Epimorphin alters the inhibitory effects of SOX9 on Mmp13 in activated hepatic stellate cells.

Background and AimsLiver fibrosis is a major cause of morbidity and mortality. It is characterised by excessive extracellular matrix (ECM) deposition from activated hepatic stellate cells (HSCs). Although potentially reversible, treatment remains limited. Understanding how ECM influences the pathogenesis of the disease may provide insight into novel therapeutic targets for the disease. The extracellular protein Epimorphin (EPIM) has been implicated in tissue repair mechanisms in several tissues, partially, through its ability to manipulate proteases. In this study, we have identified that EPIM modulates the ECM environment produced by activated hepatic stellate cells (HSCs), in part, through down-regulation of pro-fibrotic Sex-determining region Y-box 9 (SOX9).MethodsInfluence of EPIM on ECM was investigated in cultured primary rat HSCs. Activated HSCs were treated with recombinant EPIM or SOX9 siRNA. Core fibrotic factors were evaluated by immunoblotting, qPCR and chromatin immunoprecipitation (ChIP).ResultsDuring HSC activation EPIM became significantly decreased in contrast to pro-fibrotic markers SOX9, Collagen type 1 (COL1), and α- Smooth muscle actin (α-SMA). Treatment of activated HSCs with recombinant EPIM caused a reduction in α-SMA, SOX9, COL1 and Osteopontin (OPN), while increasing expression of the collagenase matrix metalloproteinase 13 (MMP13). Sox9 abrogation in activated HSCs increased EPIM and MMP13 expression.ConclusionThese data provide evidence for EPIM and SOX9 functioning by mutual negative feedback to regulate attributes of the quiescent or activated state of HSCs. Further understanding of EPIM's role may lead to opportunities to modulate SOX9 as a therapeutic avenue for liver fibrosis.

A gut reaction to IL-9.

The pathogenesis of inflammatory bowel disease is orchestrated by specific subsets of cytokine-secreting T cells. The interleukin 9–producing subset of helper T cells contributes to the pathogenesis of inflammatory bowel disease in part by disrupting intestinal barrier function and impairing tissue-repair mechanisms.

Concise review: new frontiers in microRNA-based tissue regeneration.

In recent years, the role of miRNAs in post-transcriptional gene regulation has come to the fore with strong evidence to indicate an important role for microRNAs (miRNAs) in the regulation of a wide range of fundamental biological processes. Notably, this includes the regulation of both endogenous tissue repair mechanisms and the growth and differentiation of stem cells (both adult and pluripotent). As a result, manipulation of miRNA signaling holds great promise for regenerative medicine, which aims to harness either endogenous or implanted cells to promote tissue repair. However, to fully realize this potential, it will be necessary to combine advances in our biological understanding with new technologies that allow precise spatiotemporal modulation of specific miRNA candidates. In this review, we highlight the role of miRNAs in tissue regeneration, discuss key challenges in translating this knowledge to the clinic, and outline recent technological advances that aim to address these issues. By combining a comprehensive knowledge of miRNA biology with cutting-edge delivery technologies, it is clear that miRNAs hold significant promise for tissue regenerative therapies in the future.