Therapeutic Potential of Amniotic Fluid Derived Mesenchymal Stem Cells Based on their Differentiation Capacity and Immunomodulatory Properties.

BACKGROUND: Amniotic Fluid Derived Mesenchymal Stem Cells (AF-MSCs) are adult, fibroblast- like, self-renewable, multipotent stem cells. During the last decade, the therapeutic potential of AF-MSCs, based on their huge differentiation capacity and immunomodulatory characteristics, has been extensively explored in animal models of degenerative and inflammatory diseases. OBJECTIVE: In order to describe molecular mechanisms responsible for the therapeutic effects of AFMSCs, we summarized current knowledge about phenotype, differentiation potential and immunosuppressive properties of AF-MSCs. METHODS: An extensive literature review was carried out in March 2018 across several databases (MEDLINE, EMBASE, Google Scholar), from 1990 to present. Keywords used in the selection were: "amniotic fluid derived mesenchymal stem cells", "cell-therapy", "degenerative diseases", "inflammatory diseases", "regeneration", "immunosuppression". Studies that emphasized molecular and cellular mechanisms responsible for AF-MSC-based therapy were analyzed in this review. RESULTS: AF-MSCs have huge differentiation and immunosuppressive potential. AF-MSCs are capable of generating cells of mesodermal origin (chondrocytes, osteocytes and adipocytes), neural cells, hepatocytes, alveolar epithelial cells, insulin-producing cells, cardiomyocytes and germ cells. AF-MSCs, in juxtacrine or paracrine manner, regulate proliferation, activation and effector function of immune cells. Due to their huge differentiation capacity and immunosuppressive characteristic, transplantation of AFMSCs showed beneficent effects in animal models of degenerative and inflammatory diseases of nervous, respiratory, urogenital, cardiovascular and gastrointestinal system. CONCLUSION: Considering the fact that amniotic fluid is obtained through routine prenatal diagnosis, with minimal invasive procedure and without ethical concerns, AF-MSCs represents a valuable source for cell-based therapy of organ-specific or systemic degenerative and inflammatory diseases.

Role of indoleamine 2,3-dioxygenase in pathology of the gastrointestinal tract.

Indoleamine 2,3-dioxygenase (IDO) has the most important role in modulation of tryptophan-dependent effects in the gastrointestinal tract, including modulation of intestinal immune response. An increased IDO activity maintains immune tolerance and attenuates ongoing inflammation but allows immune escape and uncontrolled growth of gastrointestinal tumors. Accordingly, IDO represents a novel therapeutic target for the treatment of inflammatory and malignant diseases of the gastrointestinal tract. In this review article, we summarize current knowledge about molecular and cellular mechanisms that are involved in IDO-dependent effects. We provide a brief outline of experimental and clinical studies that increased our understanding of how enhanced IDO activity: controls host-microbiota interactions in the gut; regulates detrimental immune response in inflammatory disorders of the gastrointestinal system; and allows immune escape and uncontrolled growth of gastrointestinal tumors. Additionally, we present future perspectives regarding modulation of IDO activity in the gut as possible new therapeutic approaches for the treatment of inflammatory and malignant diseases of the gastrointestinal system.

Indoleamine 2,3-dioxygenase-dependent expansion of T-regulatory cells maintains mucosal healing in ulcerative colitis.

BACKGROUND: Dendritic cell (DC)-derived indolamine 2,3-dioxygenase (IDO) degrades tryptophan to kynurenine, which promotes conversion of inflammatory T cells in immunosuppressive regulatory T cells (Tregs). We analyzed the significance of the IDO:Treg axis for inducing and maintaining mucosal healing in ulcerative colitis (UC). METHODS: Dextran sodium sulphate (DSS)-induced colitis in BALB/c mice (model for mucosal healing) and C57BL/6 mice (model for persistent disease) was used. Serum, fecal samples and colon-infiltrating immune cells of 65 patients with UC with mucosal healing or persistent colitis were analyzed. RESULTS: Significantly higher serum levels of kynurenine and downregulated inflammatory cytokines were noticed in DSS-treated BALB/c mice compared with C57BL/6 mice. Increased IDO activity and attenuated capacity for antigen presentation and production of inflammatory cytokines, observed in BALB/c DCs, was followed by a significantly lower number of inflammatory T helper 1 (Th1) and Th17 cells and a notably increased number of Tregs in the colons of DSS-treated BALB/c mice. DCs and Tregs were crucially important for the maintenance of mucosal healing since their depletion aggravated colitis. Mucosal healing, followed by an increase in kynurenine and intestinal Tregs, was re-established when BALB/c DCs were transferred into DC-depleted or Treg-depleted DSS-treated BALB/c mice. This phenomenon was completely abrogated by the IDO inhibitor. Significantly higher serum and fecal levels of kynurenine, accompanied by an increased presence of intestinal Tregs, were noticed in patients with UC with mucosal healing and negatively correlated with disease severity, fecal calprotectin, colon-infiltrating interferon γ and interleukin-17-producing cells, serum and fecal levels of inflammatory cytokines. CONCLUSION: IDO-dependent expansion of endogenous Tregs should be further explored as a new approach for the induction and maintenance of mucosal healing in patients with UC.

Stem Cells Therapy for Spinal Cord Injury.

Spinal cord injury (SCI), a serious public health issue, most likely occurs in previously healthy young adults. Current therapeutic strategies for SCI includes surgical decompression and pharmacotherapy, however, there is still no gold standard for the treatment of this devastating condition. Inefficiency and adverse effects of standard therapy indicate that novel therapeutic strategies are required. Because of their neuroregenerative and neuroprotective properties, stem cells are a promising tool for the treatment of SCI. Herein, we summarize and discuss the promising therapeutic potential of human embryonic stem cells (hESC), induced pluripotent stem cells (iPSC) and ependymal stem/progenitor cells (epSPC) for SCI.

Crosstalk between mesenchymal stem cells and T regulatory cells is crucially important for the attenuation of acute liver injury.

One of the therapeutic options for the treatment of fulminant hepatitis is repopulation of intrahepatic regulatory cells because their pool is significantly reduced during acute liver failure. Although it is known that mesenchymal stem cells (MSCs), which have beneficent effects in the therapy of fulminant hepatitis, may promote expansion of regulatory T cells (Tregs) and regulatory B cells (Bregs), the role of these regulatory cells in MSC-mediated attenuation of acute liver injury is unknown. Herewith, we described the molecular mechanisms involved in the crosstalk between MSCs and liver regulatory cells and analyzed the potential of MSC-based therapy for the expansion of intrahepatic regulatory cells in mouse model of acute liver failure. MSC-dependent attenuation of α-galactosylceramide (α-GalCer)-induced acute liver injury in mice was accompanied with an increased presence of interleukin (IL) 10-producing CD4+ CD25+ forkhead box P3+ Tregs and IL10- and transforming growth factor ß-producing marginal zone-like Bregs in the liver. Depletion of Bregs did not alter MSC-based alleviation of acute liver failure, whereas depletion of Tregs completely abrogated hepatoprotective effects of MSCs and inhibited their capacity to attenuate hepatotoxicity of liver natural killer T cells (NKTs), indicating that Tregs, and not Bregs, were critically involved in MSC-based modulation of acute liver inflammation. MSCs, in a paracrine, indoleamine 2,3-dioxygenase-dependent manner, significantly increased the capacity of Tregs to produce immunosuppressive IL10 and to suppress hepatotoxicity of liver NKTs. Accordingly, adoptive transfer of MSC-primed Tregs resulted in the complete attenuation of α-GalCer-induced acute liver failure. In conclusion, our findings highlighted the crucial importance of Tregs for MSC-based attenuation of acute liver failure and indicated the significance of MSC-mediated priming of Tregs as a new therapeutic approach in Treg-based therapy of acute liver injury. Liver Transplantation 24 687-702 2018 AASLD.

Intraperitoneal administration of mesenchymal stem cells ameliorates acute dextran sulfate sodium-induced colitis by suppressing dendritic cells.

Dendritic cells (DCs) have important pathogenic role in the induction and progression of ulcerative colitis (UC), but their role in mesenchymal stem cells (MSCs)-mediated suppression of colon injury and inflammation is not revealed. By using dextran sodium sulfate (DSS)-induced colitis, a well-established murine model of UC, we examined effects of MSCs on phenotype and function of colon infiltrating DCs. Clinical, histological, immunophenotypic analysis and passive transfer of MSCs-primed DCs were used to evaluate capacity of MSC to suppress inflammatory phenotype of DCs in vivo. Additionally, DCs:MSCs interplay was also investigated in vitro, to confirmed in vivo obtained findings. Intraperitoneally administered MSCs (2 × 106) significantly reduced progression of DSS-induced colitis and reduced serum levels of inflammatory cytokines (IL-1ß, IL-12, and IL-6). Passive transfer of in vivo MSCs-primed DCs reduced severity of colitis while passive transfer of MSCs-non-primed DCs aggravated DSS-induced colitis. Through the secretion of immunomodulatory Galectin 3, MSCs, in paracrine manner, down-regulated production of inflammatory cytokines in DCs and attenuated expression of co-stimulatory and major histocompatibility complex class II molecules on their membranes. Taken together, these results indicate that MSCs achieved their beneficial effects in DSS-induced colitis by suppressing inflammatory phenotype of DCs in Gal-3 dependent manner. Therapeutic targeting of DCs by MSCs should be explored in future studies as a useful approach for the treatment of UC.

Ethical and Safety Issues of Stem Cell-Based Therapy.

Results obtained from completed and on-going clinical studies indicate huge therapeutic potential of stem cell-based therapy in the treatment of degenerative, autoimmune and genetic disorders. However, clinical application of stem cells raises numerous ethical and safety concerns. In this review, we provide an overview of the most important ethical issues in stem cell therapy, as a contribution to the controversial debate about their clinical usage in regenerative and transplantation medicine. We describe ethical challenges regarding human embryonic stem cell (hESC) research, emphasizing that ethical dilemma involving the destruction of a human embryo is a major factor that may have limited the development of hESC-based clinical therapies. With previous derivation of induced pluripotent stem cells (iPSCs) this problem has been overcome, however current perspectives regarding clinical translation of iPSCs still remain. Unlimited differentiation potential of iPSCs which can be used in human reproductive cloning, as a risk for generation of genetically engineered human embryos and human-animal chimeras, is major ethical issue, while undesired differentiation and malignant transformation are major safety issues. Although clinical application of mesenchymal stem cells (MSCs) has shown beneficial effects in the therapy of autoimmune and chronic inflammatory diseases, the ability to promote tumor growth and metastasis and overestimated therapeutic potential of MSCs still provide concerns for the field of regenerative medicine. This review offers stem cell scientists, clinicians and patient's useful information and could be used as a starting point for more in-depth analysis of ethical and safety issues related to clinical application of stem cells.

Mesenchymal stem cells protect from acute liver injury by attenuating hepatotoxicity of liver natural killer T cells in an inducible nitric oxide synthase- and indoleamine 2,3-dioxygenase-dependent manner.

The effects of mesenchymal stem cells (MSCs) on the phenotype and function of natural killer T (NKT) cells is not understood. We used concanavalin A (Con A) and α-galactosylceramide (α-GalCer)-induced liver injury to evaluate the effects of MSCs on NKT-dependent hepatotoxicity. Mouse MSCs (mMSCs) significantly reduced Con A- and α-GalCer-mediated hepatitis in C57Bl/6 mice, as demonstrated by histopathological and biochemical analysis, attenuated the influx of inflammatory [T-bet+ , tumour necrosis factor-α (TNF-α), interferon-γ (IFN-γ)-producing and GATA3+ , interleukin-4 (IL-4)-producing] liver NKT cells and downregulated TNF-α, IFN-γ and IL-4 levels in the sera. The liver NKT cells cultured in vitro with mMSCs produced lower amounts of inflammatory cytokines (TNF-α, IFN-γ, IL-4) and higher amounts of immunosuppressive IL-10 upon α-GalCer stimulation. mMSC treatment attenuated expression of apoptosis-inducing ligands on liver NKT cells and suppressed the expression of pro-apoptotic genes in the livers of α-GalCer-treated mice. mMSCs reduced the cytotoxicity of liver NKT cells against hepatocytes in vitro. The presence of 1-methyl-dl-tryptophan, a specific inhibitor of indoleamine 2,3-dioxygenase (IDO), or l-NG -monomethyl arginine citrate, a specific inhibitor of inducible nitric oxide synthase (iNOS), in mMSC-conditioned medium injected into α-GalCer-treated mice, counteracted the hepatoprotective effect of mMSCs in vivo and restored pro-inflammatory cytokine production and cytotoxicity of NKT cells in vitro. Human MSCs attenuated the production of inflammatory cytokines in α-GalCer-stimulated human peripheral blood mononuclear cells in an iNOS- and IDO-dependent manner and reduced their cytotoxicity against HepG2 cells. In conclusion, MSCs protect from acute liver injury by attenuating the cytotoxicity and capacity of liver NKT cells to produce inflammatory cytokines in an iNOS- and IDO-dependent manner.

Molecular and Cellular Mechanisms Involved in Mesenchymal Stem Cell-Based Therapy of Inflammatory Bowel Diseases.

Mesenchymal stem cells (MSCs) are promising resource for the therapy of inflammatory bowel diseases (IBDs) on the grounds of their differentiation capabilities and immuno-modulatory characteristics. Results of clinical studies indicate that local application of MSCs is a secure and beneficial approach for the treatment of perianal fistulas while systemic application of MSCs leads to the attenuation or aggravation of IBDs. Herein, we emphasized molecular mechanisms and approaches that should improve efficacy of MSC-based therapy of IBDs.

Mesenchymal stem cells attenuate liver fibrosis by suppressing Th17 cells - an experimental study.

This study investigates molecular and cellular mechanisms involved in mesenchymal stem cell (MSC)-mediated modulation of IL-17 signaling during liver fibrosis. Mice received CCl4 (1 µl/g intraperitoneally) twice/week for 1 month. MSCs (1 × 106 ), or MSC-conditioned medium (MSC-CM), were intravenously injected 24 h after CCl4 and on every 7th day. Liver fibrosis was determined by macroscopic examination, histological analysis, Sirius red staining, and RT-PCR. Serum levels of cytokines, indoleamine 2,3-dioxygenase (IDO), and kynurenine were determined by ELISA. Flow cytometry was performed to identify liver-infiltrated cells. In vitro, CD4+ T cells were stimulated and cultured with MSCs. 1-methyltryptophan was used for inhibition of IDO. MSCs significantly attenuated CCl4 -induced liver fibrosis by decreasing serum levels of inflammatory IL-17, increasing immunosuppressive IL-10, IDO, and kynurenine, reducing number of IL-17 producing Th17 cells, and increasing percentage of CD4+ IL-10+ T cells. Injection of MSC-CM resulted with attenuated fibrosis accompanied with the reduced number of Th17 cells in the liver and decreased serum levels of IL-17. MSC-CM promoted expansion of CD4+ FoxP3+ IL-10+ T regulatory cells and suppressed proliferation of Th17 cells. This phenomenon was completely abrogated in the presence of IDO inhibitor. MSCs, in IDO-dependent manner, suppress liver Th17 cells which lead to the attenuation of liver fibrosis.

Mesenchymal Stem Cell-Dependent Modulation of Liver Diseases.

Acute liver failure and cirrhosis display sequential and overlapping severe pathogenic processes that include inflammation, hepatocyte necrosis, and fibrosis, carrying a high mortality rate. Mesenchymal stem cells (MSCs) are a heterogeneous subset of stromal stem cells with immunonodulatory characteristics. MSCs are considered to act through multiple mechanisms to coordinate a dynamic, integrated response to liver inflammation and fibrosis, which prevents the progressive distortion of hepatic architecture. Accordingly, MSCs as well as their products have been investigated as a novel therapeutic approach for the treatment of inflammatory and fibrotic liver diseases. In this review, we highlight the current findings on the MSC-based modulation of liver inflammation and fibrosis, and the possible use of MSCs in the therapy of immune-mediated liver pathology. We briefly describe the cellular and molecular mechanisms involved in MSC-dependent modulation of cytokine production, phenotype and function of liver infiltrated inflammatory cells and compare effects of engrafted MSCs versus MSC-generated conditioned medium (MSC-CM) in the therapy of acute liver injury. In order to elucidate therapeutic potential of MSCs and their products in modulation of chronic liver inflammation and fibrosis, we present the current findings regarding pathogenic role of immune cells in liver fibrosis and describe mechanisms involved in MSC-dependent modulation of chronic liver inflammation with the brief overview of on-going and already published clinical trials that used MSCs for the treatment of immune mediated chronic liver diseases. The accumulating evidence shows that MSCs had a significant beneficial effect in the treatment of immune-mediated liver diseases.

Mesenchymal Stem Cells Attenuate Cisplatin-Induced Nephrotoxicity in iNOS-Dependent Manner.

Mesenchymal stem cells (MSCs) are, due to their immunomodulatory characteristics, utilized in therapy of immune-mediated diseases. We used murine model of cisplatin nephrotoxicity to explore the effects of MSCs on immune cells involved in the pathogenesis of this disease. Intraperitoneal application of MSCs significantly attenuated cisplatin nephrotoxicity, decreased inflammatory cytokines TNF-α and IL-17, and increased anti-inflammatory IL-10, IL-6, nitric oxide (NO), and kynurenine in sera of cisplatin-treated mice. MSC treatment significantly attenuated influx of leukocytes, macrophages, dendritic cells (DCs), neutrophils, CD4+ T helper (Th), and CD8+ cytotoxic T lymphocytes (CTLs) in damaged kidneys and attenuated the capacity of renal-infiltrated DCs, CD4+ Th, and CD8+ CTLs to produce TNF-α and IL-17. Similar effects were observed after intraperitoneal injection of MSC-conditioned medium (MSC-CM) indicating that MSCs exert their beneficial effects in paracrine manner. Inhibition of inducible nitric oxide synthase (iNOS) in MSC-CM resulted with increased number of TNF-α-producing DCs and IL-17-producing CTLs, decreased number of IL-10-producing tolerogenic DCs and regulatory CD4+FoxP3+ T cells, and completely diminished renoprotective effects of MSC-CM. In conclusion, MSCs, in iNOS-dependent manner, attenuated inflammation in cisplatin nephrotoxicity by reducing the influx and capacity of immune cells, particularly DCs and T lymphocytes, to produce inflammatory cytokines.

Mesenchymal Stem Cells Promote Metastasis of Lung Cancer Cells by Downregulating Systemic Antitumor Immune Response.

Since majority of systemically administered mesenchymal stem cells (MSCs) become entrapped within the lungs, we used metastatic model of lung cancer, induced by intravenous injection of Lewis lung cancer 1 (LLC1) cells, to investigate the molecular mechanisms involved in MSC-mediated modulation of metastasis. MSCs significantly augmented lung cancer metastasis, attenuate concentrations of proinflammatory cytokines (TNF-α, IL-17), and increase levels of immunosuppressive IL-10, nitric oxide, and kynurenine in sera of LLC1-treated mice. MSCs profoundly reduced infiltration of macrophages, TNF-α-producing dendritic cells (DCs), TNF-α-, and IL-17-producing CD4+ T cells but increased IL-10-producing CD4+ T lymphocytes in the lungs of tumor-bearing animals. The total number of lung-infiltrated, cytotoxic FasL, perforin-expressing, TNF-α-, and IL-17-producing CD8+ T lymphocytes, and NKG2D-expressing natural killer (NK) cells was significantly reduced in LLC1 + MSC-treated mice. Cytotoxicity of NK cells was suppressed by MSC-conditioned medium. This phenomenon was abrogated by the inhibitors of inducible nitric oxide synthase (iNOS) and indoleamine 2,3-dioxygenase (IDO), suggesting the importance of iNOS and IDO for MSC-mediated suppression of antitumor cytotoxicity of NK cells. This study provides the evidence that MSCs promote lung cancer metastasis by suppressing antitumor immune response raising concerns regarding safety of MSC-based therapy in patients who have genetic susceptibility for malignant diseases.

Mesenchymal stem cell-derived factors: Immuno-modulatory effects and therapeutic potential.

Stem cell-based therapy is considered to be a new hope in transplantation medicine. Among stem cells, mesenchymal stem cells (MSCs) are, due to their differentiation and immuno-modulatory characteristics, the most commonly used as therapeutic agents in the treatment of immune-mediated diseases. MSCs migrate to the site of inflammation and modulate immune response. The capacity of MSC to alter phenotype and function of immune cells are largely due to the production of soluble factors which expression varies depending on the pathologic condition to which MSCs are exposed. Under inflammatory conditions, MSCs-derived factors suppress both innate and adaptive immunity by attenuating maturation and capacity for antigen presentation of dendritic cells, by inducing polarization of macrophages towards alternative phenotype, by inhibiting activation and proliferation of T and B lymphocytes and by reducing cytotoxicity of NK and NKT cells. In this review, we emphasized current findings regarding immuno-modulatory effects of MSC-derived factors and emphasize their potential in the therapy of immune-mediated diseases. © 2017 BioFactors, 43(5):633-644, 2017.

Mesenchymal stem cells attenuate acute liver injury by altering ratio between interleukin 17 producing and regulatory natural killer T cells.

Mesenchymal stem cells (MSCs) are, due to immunomodulatory characteristics, considered as novel agents in the treatment of immune-mediated acute liver failure. Although it is known that MSCs can regulate activation of T lymphocytes, their capacity to modulate function of neutrophils and natural killer T (NKT) cells, major interleukin (IL) 17-producing cells in acute liver injury, is still unknown. By using 2 well-established murine models of neutrophil and NKT cell-mediated acute liver failure (induced by carbon tetrachloride and α-galactoceramide), we investigated molecular and cellular mechanisms involved in MSC-mediated modulation of IL17 signaling during acute liver injury. Single intravenous injection of MSCs attenuate acute hepatitis and hepatotoxicity of NKT cells in a paracrine, indoleamine 2,3-dioxygenase (IDO)-dependent manner. Decreased levels of inflammatory IL17 and increased levels of immunosuppressive IL10 in serum, reduced number of interleukin 17-producing natural killer T (NKT17) cells, and increased presence of forkhead box P3 + IL10-producing natural killer T regulatory cells (NKTregs) were noticed in the injured livers of MSC-treated mice. MSCs did not significantly alter the total number of IL17-producing neutrophils, CD4+, and CD8 + T lymphocytes in the injured livers. Injection of mesenchymal stem cell-conditioned medium (MSC-CM) resulted with an increased NKTreg/NKT17 ratio in the liver and attenuated hepatitis in vivo and significantly reduced hepatotoxicity of NKT cells in vitro. This phenomenon was completely abrogated in the presence of IDO inhibitor, 1-methyltryptophan. In conclusion, the capacity of MSCs to alter NKT17/NKTreg ratio and suppress hepatotoxicity of NKT cells in an IDO-dependent manner may be used as a new therapeutic approach in IL17-driven liver inflammation. Liver Transplantation 23 1040-1050 2017 AASLD.

In vitro and in vivo anti-tumor effects of selected platinum(IV) and dinuclear platinum(II) complexes against lung cancer cells.

In the present study, cytotoxic effects of cisplatin, the most usually used chemotherapeutic agent, were compared with new designed platinum(IV) ([PtCl4(en)] (en = ethylenediamine) and [PtCl4(dach)]) (dach = (±)-trans-1,2-diaminocyclohexane) and platinum(II) complexes ([{trans-Pt(NH3)2Cl}2(µ-pyrazine)](ClO4)2 (Pt1), [{trans-Pt(NH3)2Cl}2(µ-4,4'-bipyridyl)](ClO4)2DMF(Pt2),[{trans-Pt(NH3)2Cl}2(µ-1,2-bis(4pyridyl)ethane)](ClO4)2 (Pt3)), in vitro and in vivo against human and murine lung cancer cells, to determine anti-tumor potential of newly synthesized platinum-based drugs in the therapy of lung cancer. Results obtained by MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide], Lactate dehydrogenase and Annexin V/Propidium Iodide assays showed that, among all tested complexes, [PtCl4(en)] had the highest cytotoxicity against human and murine lung carcinoma cells in vitro. [PtCl4(en)] showed significantly higher cytotoxicity then cisplatin in all tested concentrations, mainly by inducing apoptosis in lung cancer cells. [PtCl4(en)] was well tolerated in vivo. Clinical signs of [PtCl4(en)]-induced toxicity, such as changes in food, water consumption or body weight, nephrotoxicity or hepatotoxicity was not observed in [PtCl4(en)]-treated mice. [PtCl4(en)] managed to increase presence of CD45+ leukocytes, including F4/80+ macrophages, CD11c+ dendritic cells, CD4+ helper and CD8+ cytotoxic T cells (CTLs) in the lungs, cytotoxic NK, NKT and CTLs in the spleens of tumor bearing mice, resulting with reduction of metastatic lesions in the lungs, indicating its potential to stimulate anti-tumor immune response in vivo. Due to its anti-tumor cytotoxicity, biocompatibility, and potential for stimulation of anti-tumor immune response, [PtCl4(en)] may be a good candidate for further testing in the field of medicinal chemistry.

Stem Cells and Labeling for Spinal Cord Injury.

Spinal cord injury (SCI) is a devastating condition that usually results in sudden and long-lasting locomotor and sensory neuron degeneration below the lesion site. During the last two decades, the search for new therapies has been revolutionized with the improved knowledge of stem cell (SC) biology. SCs therapy offers several attractive strategies for spinal cord repair. The transplantation of SCs promotes remyelination, neurite outgrowth and axonal elongation, and activates resident or transplanted progenitor cells across the lesion cavity. However, optimized growth and differentiation protocols along with reliable safety assays should be established prior to the clinical application of SCs. Additionally, the ideal method of SCs labeling for efficient cell tracking after SCI remains a challenging issue that requires further investigation. This review summarizes the current findings on the SCs-based therapeutic strategies, and compares different SCs labeling approaches for SCI.

Pharmacological Inhibition of Gal-3 in Mesenchymal Stem Cells Enhances Their Capacity to Promote Alternative Activation of Macrophages in Dextran Sulphate Sodium-Induced Colitis.

Transplantation of mesenchymal stem cells (MSCs) reduces the severity of dextran sulphate sodium- (DSS-) induced colitis. MSCs are able to secrete Galectin-3 (Gal-3), a protein known to affect proliferation, adhesion, and migration of immune cells. We investigate whether newly synthetized inhibitor of Gal-3 (Davanat) will affect production of Gal-3 in MSCs and enhance their potential to attenuate DSS-induced colitis. Pharmacological inhibition of Gal-3 in MSCs enhances their capacity to promote alternative activation of peritoneal macrophages in vitro and in vivo. Injection of MSCs cultured in the presence of Davanat increased concentration of IL-10 in sera of DSS-treated animals and markedly enhanced presence of alternatively activated and IL-10 producing macrophages in the colons of DSS-treated mice. Pharmacological inhibition of Gal-3 in MSCs significantly attenuates concentration of Gal-3 in sera of DSS-treated animals, indicating that MSCs produce Gal-3 in this disease. In conclusion, our findings indicate that Davanat could be used for improvement of MSC-mediated polarization towards immunosuppressive M2 phenotype of macrophages.

Galectin-3 Plays an Important Pro-inflammatory Role in the Induction Phase of Acute Colitis by Promoting Activation of NLRP3 Inflammasome and Production of IL-1ß in Macrophages.

BACKGROUND AND AIMS: Galectin-3 [Gal-3] is an endogenous lectin with a broad spectrum of immunoregulatory effects: it plays an important role in autoimmune/inflammatory and malignant diseases, but the precise role of Gal-3 in pathogenesis of ulcerative colitis is still unknown. METHODS: We used a model of dextran sulphate sodium [DSS]-induced acute colitis. The role of Gal-3 in pathogenesis of this disease was tested by evaluating disease development in Gal-3 deficient mice and administration of Gal-3 inhibitor. Disease was monitored by clinical, histological, histochemical, and immunophenotypic investigations. Adoptive transfer was used to detect cellular events in pathogenesis. RESULTS: Genetic deletion or pharmacological inhibition of Gal-3 significantly attenuate DSS-induced colitis. Gal-3 deletion suppresses production of pro-inflammatory cytokines in colonic macrophages and favours their alternative activation, as well as significantly reducing activation of NOD-like receptor family, pyrin domain containing 3 [NLRP3] inflammasome in macrophages. Peritoneal macrophages isolated from untreated Gal-3(-/-) mice and treated in vitro with bacterial lipopolysaccharide or DSS produce lower amounts of tumour necrosis factor alpha [TNF-α] and interleukin beta [IL-1ß] when compared with wild type [WT] cells. Genetic deletion of Gal-3 did not directly affect total neutrophils, inflammatory dendritic cells [DCs] or natural killer [NK] T cells. However, the total number of CD11c+ CD80+ DCs which produce pro-inflammatory cytokines, as well as TNF-α and IL-1ß producing CD45+ CD11c- Ly6G+ neutrophils were significantly lower in colons of Gal-3(-/-) DSS-treated mice. Adoptive transfer of WT macrophages significantly enhanced the severity of disease in Gal-3(-/-) mice. CONCLUSIONS: Gal-3 expression promotes acute DSS-induced colitis and plays an important pro-inflammatory role in the induction phase of colitis by promoting the activation of NLRP3 inflammasome and production of IL-1ß in macrophages.

Mesenchymal stem cells: a friend or foe in immune-mediated diseases.

Mesenchymal stem cells (MSCs) are adult, self-renewable, multipotent cells that can be found in almost all postnatal tissues. Because of their capacity for self-renewal and differentiation into tissues of mesodermal origin and due to their immunomodulatory ability, MSCs are used in many preclinical and clinical studies as possible new therapeutic agents for the autoimmune or degenerative diseases treatment. In dependence of inflammatory environment to which they are exposed to, MSCs adopt immunosuppressive or pro-inflammatory phenotype. In the presence of high levels of pro-inflammatory cytokines or through activation of Toll-like receptor (TLR)-3, MSCs adopt an immune-suppressive phenotype and suppress the proliferation, activation and effector function of professional antigen presenting cells (dendritic cells, macrophages, B lymphocytes), T lymphocytes, NK cells, NKT cells, and neutrophils. During the early phase of inflammation, through TLR4 activation and in the presence of low levels of inflammatory cytokines, MSCs adopt a pro-inflammatory phenotype, promote neutrophil and T cell activation and enhance immune response. Here we review the current findings on the immunoregulatory plasticity of MSCs involved in regulation of immune response.