Neural Regenerative Potential of Stem Cells Derived from the Tooth Apical Papilla.

The regenerative effects of stem cells derived from dental tissues have been previously investigated. This study assessed the potential of human tooth stem cells from apical papilla (SCAP) on nerve regeneration. The SCAP collected from nine individuals were characterized and polarized by exposure to interferon-γ (IFN-γ). IFN-γ increased kynurenine and interleukin-6 (IL-6) production by SCAP, without affecting the cell viability. IFN-γ-primed SCAP exhibited a decrease of brain-derived neurotrophic factor (BDNF) mRNA levels, followed by an upregulation of glial cell-derived neurotrophic factor mRNA. Ex vivo, the co-culture of SCAP with neurons isolated from the rat dorsal root ganglion induced neurite outgrowth, accompanied by increased BDNF secretion, irrespective of IFN-γ priming. In vivo, the local application of SCAP reduced the mechanical and thermal hypersensitivity in Wistar rats that had been submitted to sciatic chronic constriction injury. The SCAP also reduced the pain scores, according to the evaluation of the Grimace scale, partially restoring the myelin damage and BDNF immunopositivity secondary to nerve lesion. Altogether, our results provide novel evidence about the regenerative effects of human SCAP, indicating their potential to handle nerve injury-related complications.

The role of kinin B1 and B2 receptors in the mouse model of oxazolone-induced atopic dermatitis.

This study evaluated the role of kinin B1 and B2 receptors in the pre-clinical mouse model of oxazolone-induced atopic dermatitis. The B1 R715 or B2 HOE140 receptor antagonists were dosed at different schemes of treatment. After assessment of clinical lesion scores and pruritus, lesional skin samples were collected for histopathological analysis. The plasma extravasation and the expression of the metalloproteinase ADAMTS5 were also assessed. The immunopositivity for kinin receptors was evaluated in the skin, dorsal root ganglion (DRG), thoracic spinal cord and brain cortex sections. Marked upregulation of B1 and B2 receptors was observed in the skin of oxazolone-treated mice. The induction of atopic dermatitis led to a downregulation of both receptors in the DRG, without any alteration in the spinal cord and brain cortex. The repeated administration of HOE140 (50 nmol/kg; i.p.) partially inhibited the oxazolone-related pruritus, associated with a reduction of ADAMTS5 immunolabelling in the skin. Alternatively, R715 (438 nmol/kg; i.p.) produced a mild inhibition of plasma extravasation in oxazolone-challenged mice. Noteworthy, the repeated i.d. injection of R715 (30 nmol/site) or HOE140 (3 nmol/site) significantly reduced the histiocyte numbers, according to the histopathological analysis. Either B1 or B2 kinin antagonists, irrespective of the protocol of treatment, did not alter any other evaluated clinical or histological parameters. Data brings novel evidence about the role of kinin receptors in allergy-related conditions, such as atopic dermatitis. Further studies to test different protocols of treatment with kinin antagonists on in-depth cellular alterations underlying oxazolone-induced atopic dermatitis remain to be performed.

Nociceptin/orphanin FQ receptor modulates painful and fatigue symptoms in a mouse model of fibromyalgia.

Generalized pain and fatigue are both hallmarks of fibromyalgia, a syndrome with an indefinite etiology. The treatment options for fibromyalgia are currently limited, probably because of its intricate pathophysiology. Thus, further basic and clinical research on this condition is currently needed. This study investigated the effects of nociceptin/orphanin FQ (N/OFQ) receptor (NOPr) ligands and the modulation of the NOP system in the preclinical mouse model of reserpine-induced fibromyalgia. The effects of administration of the natural agonist N/OFQ and the selective NOPr antagonists (UFP-101 and SB-612111) were evaluated in fibromyalgia-related symptoms in reserpine-treated mice. The expression of prepronociceptin/orphanin FQ and NOPr was assessed in central and peripheral sites at different time points after reserpine administration. Nociceptin/orphanin FQ displayed dual effects in the behavioral changes in the reserpine-elicited fibromyalgia model. The peptide NOPr antagonist UFP-101 produced analgesic and antifatigue effects, by preventing alterations in brain activity and skeletal muscle metabolism, secondary to fibromyalgia induction. The nonpeptide NOPr antagonist SB-612111 mirrored the favorable effects of UFP-101 in painful and fatigue alterations induced by reserpine. A time-related up- or downregulation of prepronociceptin/orphanin FQ and NOPr was observed in supraspinal, spinal, and peripheral sites of reserpine-treated mice. Our data shed new lights on the mechanisms underlying the fibromyalgia pathogenesis, supporting a role for N/OFQ-NOP receptor system in this syndrome.

Hypoxia upregulates the expression of the pluripotency markers in the stem cells from human deciduous teeth.

OBJECTIVES: Cultivation under hypoxia promotes different responses in the mesenchymal stem cells and it has been producing promising results for clinical applications. Pulp tissue from deciduous teeth is a source of stem cells which has a high proliferative potential but this is usually discarded. This study has evaluated the effects of hypoxia on proliferation, apoptosis, and the expression of the pluripotency-related genes of the stem cells from human exfoliated deciduous teeth (SHED). MATERIALS AND METHODS: The cells were isolated from dental pulp (n = 5) and characterized as mesenchymal stem cells, in accordance with the International Society for Cell Therapy. The cells were cultivated under hypoxia (3% oxygen) and compared to the normoxia cells (21% oxygen). The proliferation rate was evaluated by the Ki67 antibody for up to 7 days, while the metabolic activity was measured by the wst-8 assay for up to 14 days. The apoptotic cells were analyzed by Annexin V and propidium iodide staining at 24 h and 4 and 7 days. The expression of the pluripotent genes (OCT4, SOX2, and NANOG) was quantified by qPCR after 24 h, or 7 days, when cultivated under hypoxia or normoxia. RESULTS: No differences in the metabolic activity, the proliferation rate, and the apoptosis of SHED when cultivated under hypoxia or normoxia (p > 0.05) were observed. The expression of the pluripotent genes was significantly higher after 24 h and 7 days of the cells that were exposed to hypoxia (p < 0.01). CONCLUSION: These findings have indicated an increase of the pluripotency-related genes within 7 days as being the main advantage of SHED culture under hypoxia. CLINICAL RELEVANCE: Hypoxia culture may help maintain the quiescent state of the SHED, which could be advantageous for their future clinical applications.

Design and optimization of biocompatible polycaprolactone/poly (l-lactic-co-glycolic acid) scaffolds with and without microgrooves for tissue engineering applications.

This study investigated the effects of smooth and microgrooved membrane blends, with different polycaprolactone (PCL)/ poly(lactic-co-glycolic acid) (PLGA) ratios on the viability, proliferation, and adhesion of different mammalian cell types. The polymer matrices with and without microgrooves, obtained by solvent casting, were characterized by field-emission scanning electron microscopy, atomic force microscopy, contact angle and Young's modulus. Blend characterization showed an increase in roughness and stiffness of membranes with 30% PLGA, without any effect on the contact angle value. Pure PCL significantly decreased the viability of Vero, HaCaT, RAW 264.7, and human fetal lung and gingival fibroblast cells, whereas addition of increasing concentrations of PLGA led to a reduced cytotoxicity. Increased proliferation rates were observed for all cell lines. Fibroblasts adhered efficiently to smooth membranes of the PCL70/PLGA30 blend and pure PLGA, compared to pure PCL and silicone. Microgrooved membranes promoted similar cell adhesion for all groups. Microstructured membranes (15 and 20-µm wide grooves) promoted suitable orientation of fibroblasts in both PCL70/PLGA30 and pure PLGA, as compared to pure PCL. Neuronal cells of the dorsal root ganglion exhibited an oriented adhesion to all the tested microgrooved membranes. Data suggest a satisfactory safety profile for the microgrooved PCL70/PLGA30 blend, pointing out this polymer combination as a promising biomaterial for peripheral nerve regeneration when cell orientation is required. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 106A: 1522-1534, 2018.

In Vivo Immunogenic Response to Allogeneic Mesenchymal Stem Cells and the Role of Preactivated Mesenchymal Stem Cells Cotransplanted with Allogeneic Islets.

Mesenchymal stem cells (MSCs) are multipotent cells capable of differentiating into cells from the mesenchymal lineage. The hypoimmunogenic characteristic of MSCs has encouraged studies using allogeneic MSCs for the treatment of autoimmune diseases and inflammatory conditions. Promising preclinical results and the safety of allogeneic MSC transplantation have created the possibility of "off-the-shelf" clinical application of allogeneic cells. This study has aimed to evaluate the survival of untreated and IFN-γ- and TNF-α-treated (preactivated) allogeneic MSCs transplanted under the kidney capsule of immunocompetent mice together with the role of preactivated MSCs after cotransplantation with allogeneic islets. The preactivation of MSCs upregulated the gene expression of anti-inflammatory molecules and also enhanced their immunomodulatory capacity in vitro. In vivo, allogeneic MSCs provoked an immunogenic response, with the infiltration of inflammatory cells at the transplant site and full graft rejection in both the untreated and preactivated groups. Allogeneic islets cotransplanted with preactivated MSCs prolonged graft survival for about 6 days, compared with islet alone. The present results corroborate the hypothesis that allogeneic MSCs are not immune-privileged and that after playing their therapeutic role they are rejected. Strategies that reduce allogeneic MSC immunogenicity can potentially prolong their in vivo persistence and improve the therapeutic effects.

Effect of feeder free poly(lactide-co-glycolide) scaffolds on morphology, proliferation, and pluripotency of mouse embryonic stem cells.

The aim of the study has been to evaluate the morphology, proliferation, and pluripotency maintenance of mouse embryonic stem cells (mESCs) cultivated on poly(lactic-co-glycolic acid) scaffolds. The scaffolds were hydrolyzed with NaOH (treated) and nonhydrolyzed (untreated). Morphological and mechanical characterization of the scaffolds was performed. mESC were evaluated for cell viability, cytotoxicity, expression of pluripotency markers, colony morphology, and overall distribution. The treatment generated a reduction in the hydrophobic characteristics of the scaffolds, leading to a higher wettability compared to the untreated group. The viability, cytotoxicity, number of colonies, and the thickness of the cell layer presented similar results between the scaffold groups. The viability test showed that it was possible to cultivate the mESCs on the scaffolds. The cytotoxicity analysis showed that the PLGA scaffolds were not harmful for the cells. The cells maintained the expression of the pluripotency markers Oct4 and Sox2. The number of colonies and the thickness of the cell layer on the scaffold showed that they were not able to colonize the entire volume of the scaffolds. The area occupied by the mESCs was the same between the treated and untreated groups after 14 days in culture. It is possible to conclude that both conditions are equally suitable for maintaining mESC culture. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 105A: 424-432, 2017.

Role of the autologous mesenchymal stem cells compared with platelet rich plasma on cicatrization of cutaneous wounds in diabetic mice / Papel das células-tronco mesenquimais autólogas em comparação com plasma rico em plaquetas na cicatrização de feridas cutâneas em camundongos diabéticos

Chronic cutaneous lesions affect 15% of diabetic human patients and represent a risk 15 to 46 times larger of limb amputations compared to people with normal glycemia. It is assumed that half of these amputations could be prevented by early treatment of wounds, for example, with proper cell therapy. Objectives: In this study, the action of the autologous transplant of mesenchymal stem-cells (MSC) was evaluated compared to the treatment with autologous platelet rich plasma (PRP) in the cicatrization of cutaneous lesions induced in diabetic mice. These animals were previously treated with streptozootocin to induce diabetes mellitus and round wounds of 1.5cm in diameter were created in the posterior region. Diameters of the wounds and healing time were evaluated during 30 days and the results were submitted to variance analysis and Tukey's test average. It was noticed that the animals treated with MSC presented a more accelerated cicatrization of the cutaneous lesion than the animals treated with PRP. However, the treatment with PRP presented better results than just the daily asepsis of the lesions with saline or covering them with semi-permeable bandage. Besides, the use of semi-permeable bandage kept the cutaneous lesions of diabetic mice did not interfere negatively with cicatrization, proved to be harmless to use, but kept the cutaneous lesions more hydrated than the ones exposed to the environment.(AU)

Lesões cutâneas crônicas afetam 15% dos pacientes diabéticos e humanos representam um risco 15 a 46 vezes maior de amputações de membros em comparação com as pessoas com a glicemia normal. Supõe-se que a metade destas amputações poderia ser evitada por meio do tratamento precoce das feridas cutâneas com, por exemplo, uma adequada terapia celular. Objetivos: Neste estudo, a ação do transplante autólogo de células estaminais mesenquimais (MSC) foi avaliada em comparação com o tratamento com plasma rico em plaquetas autólogo (PRP) na cicatrização de lesões cutâneas induzidas em camundongos diabéticos. Estes animais foram previamente tratados com estreptozotocina para induzir diabetes mellitus e feridas redondas de 1,5 cm de diâmetro foram criadas na região posterior. Os diâmetros dos ferimentos e tempo de cicatrização foram avaliados durante 30 dias e os resultados foram submetidos à análise de variância e média pelo teste de Tukey. Verificou-se que os animais tratados com MSC apresentam uma cicatrização mais acelerada da lesão cutânea que do que os animais tratados com PRP. No entanto, o tratamento com PRP apresentou melhores resultados do que apenas a assepsia das lesões diariamente com solução salina ou cobrindo-os com atadura semi-permeável. Além disso, a utilização de atadura semi-permeável mantidas as lesões cutâneas de camundongos diabéticos não interfere negativamente com a cicatrização, provou ser inofensiva para usar, mas manteve as lesões cutâneas hidratadas mais do que os expostos ao meio ambiente.(AU)

The effects of hypoxia on in vitro culture of dental-derived stem cells.

The culture of cells under hypoxia is considered one of the hot topics of tissue engineering, especially when exploring the proliferation capacity, a critical step for cellular-based therapies. The use of in vitro hypoxic environment aims to simulate the oxygen concentrations found in stem cell niches. Dental tissues are attractive sources of stem cells, as they are obtained from discarded tissue, after third molar extraction and exfoliation deciduous teeth, respectively. However, small amounts of cells are obtained from these sources. Thus, optimizing the in vitro conditions for proliferation and differentiation of these cells is essential for future regenerative strategies. This review presents a summary of the results regarding the effect of hypoxia on dental-derived stem cells after an electronic search on PubMed databases. The studies show increased differentiation potential and paracrine action of dental-derived stem cells under hypoxic environment. There are controversies related to proliferation of dental-derived stem cells under induced hypoxia. The lack of standardization in cell culture techniques contributes to these biases and future studies should describe in more detail the protocols used. The knowledge regarding the effect of hypoxia on dental-derived stem cells needs further clarification for assisting the clinical application of these cells.

The current state of research with human pluripotent stem cells in Brazil.

This article provides a brief overview of research with human pluripotent stem cells in Brazil, the federal funding supporting this research, and the legislation that allows the isolation of human embryonic stem cells.

Pre-culturing islets with mesenchymal stromal cells using a direct contact configuration is beneficial for transplantation outcome in diabetic mice.

BACKGROUND AIMS: We recently showed that co-transplantation of mesenchymal stromal cells (MSCs) improves islet function and revascularization in vivo. Pre-transplant islet culture is associated with the loss of islet cells. MSCs may enhance islet cell survival or function by direct cell contact mechanisms and soluble mediators. We investigated the capacity of MSCs to improve islet cell survival or ß-cell function in vitro using direct and indirect contact islet-MSC configurations. We also investigated whether pre-culturing islets with MSCs improves islet transplantation outcome. METHODS: The effect of pre-culturing islets with MSCs on islet function in vitro was investigated by measuring glucose-stimulated insulin secretion. The endothelial cell density of fresh islets and islets cultured with or without MSCs was determined by immunohistochemistry. The efficacy of transplanted islets was tested in vivo using a syngeneic streptozotocin-diabetic minimal islet mass model. Graft function was investigated by monitoring blood glucose concentrations. RESULTS: Indirect islet-MSC co-culture configurations did not improve islet function in vitro. Pre-culturing islets using a direct contact MSC monolayer configuration improved glucose-stimulated insulin secretion in vitro, which correlated with superior islet graft function in vivo. MSC pre-culture had no effect on islet endothelial cell number in vitro or in vivo. CONCLUSIONS: Pre-culturing islets with MSCs using a direct contact configuration maintains functional ß-cell mass in vitro and the capacity of cultured islets to reverse hyperglycemia in diabetic mice.

Activin receptor-like kinase 5 inhibition reverses impairment of endothelial cell viability by endogenous islet mesenchymal stromal cells.

Following islet transplantation, islet graft revascularization is compromised due to loss of endothelial cells (ECs) during islet culture. TGF-ß signaling pathways are essential for vascular homeostasis but their importance for islet EC function is unclear. We have identified a population of multipotent mesenchymal stromal cells (MSCs) within islets and investigated how modulation of TGF-ß signaling by these cells influences islet EC viability. Cultured islets exhibited reduced expression of EC markers (VEGFR2, VE-cadherin and CD31), which was associated with diminished but sustained expression of endoglin a marker of both ECs and MSCs. Double fluorescent labeling of islets in situ with the EC marker CD31 disclosed a population of CD31-negative cells which were positive for endoglin. In vitro coculture of microvascular ECs with endoglin-positive, CD31-negative islet MSCs reduced VEGFR2 protein expression, disrupted EC angiogenic behavior, and increased EC detachment. Medium conditioned by islet MSCs significantly decreased EC viability and increased EC caspase 3/7 activity. EC:MSC cocultures showed enhanced Smad2 phosphorylation consistent with altered ALK5 signaling. Pharmacological inhibition of ALK5 activity with SB431542 (SB) improved EC survival upon contact with MSCs, and SB-treated cultured islets retained EC marker expression and sensitivity to exogenous VEGF164 . Thus, endoglin-expressing islet MSCs influence EC ALK5 signaling in vitro, which decreases EC viability, and changes in ALK5 activity in whole cultured islets contribute to islet EC loss. Modifying TGF-ß signaling may enable maintenance of islet ECs during islet isolation and thus improve islet graft revascularization post-transplantation.

Treatment of critical defects produced in calvaria of mice with mesenchymal stem cells.

Mesenchymal stem cells (MSC) are present in specialized niches in perivascular regions of adult tissues and are able to differentiate into various cell types, such as those committed to repairing. Bone marrow derived MSC from eight young mice C57BL/ 6 gfp(+) were expanded in culture for repairing critical defects in calvarial bone produced in twenty-four young isogenic adult C57BL/6 mice. The animals were subjected to a cranial defect of 6.0mm diameter and divided into two equal experimental groups. Control group did not receive any treatment and the treated group received a MSC pellet containing 1.0 x 10(7) cells/mL into the defects. The group treated with MSC showed increased angiogenesis and amount of new bone deposited on the defect limits than that observed in the control group. The results demonstrated that transplantation of bone marrow-derived MSC of C57BL/6 gfp(+) mice to bone critical defects produced in mice calvarial contributes positively to the bone repair process. MSC presets ability to influence the correct functioning of osteoblasts, increases the amount of mobilized cells for the repairing process, speeds up growth, and increases deposition of bone matrix.

Methodology, biology and clinical applications of human mesenchymal stem cells.

Stem cells are known by their capacity of self-renewal and differentiation into at least one specialized cell type. Mesenchymal stem cells (MSCs) were isolated initially from bone marrow but are now known to exist in any vascularized organ or tissue in adults. MSCs have a great therapeutic potential, due to their ability to migrate to sites of tissue injury and secrete trophic factors that hasten endogenous repair. They have also been shown to present immunosuppressive properties that may be used in the treatment of autoimmune or graft-versus-host diseases. Clinical trials employing MSCs show that the therapy is safe, but the efficiency needs to be in tested in phase III and IV studies. We describe here protocols for the isolation of human MSCs from human bone marrow and adipose tissue. The safe use of these cells demand a thorough in vitro characterization, as described in protocols of immunophenotyping by flow cytometry and analysis of their capacity to differentiate into adipogenic, osteogenic, and chondrogenic lineages.

Association of mesenchymal stem cells with platelet rich plasma on the repair of critical calvarial defects in mice.

PURPOSE: To evaluate the effects of mesenchymal stem cells (MSC) from eight mice C57BL/6 gfp(+) bone marrows expanded in cultures associated with platelets rich plasma (PRP) deriving from another eight mice, in the repair of critical defects in calvarial bone produced in twenty-four adult isogenic mice C57BL/6. METHODS: The animals were submitted to a cranial defect of 6.0mm in diameter and divided into two equal experimental groups. Control group did not receive treatment and the treated group received a MSC pellet containing 1.0 x 10(7) cells/mL associated with 50.0 µL of plasma gel containing 1.0 x 10(9) autologous platelets within the defect. RESULTS: In the treated group was observed process of angiogenesis and bone repair better than control group. CONCLUSION: Mesenchymal stem cells derived from bone marrow of C57BL/6 gfp(+) mice associated with PRP gel applied in bone critical defects produced in calvarial contributes positively to the process of bone repair.

Association of mesenchymal stem cells with platelet rich plasma on the repair of critical calvarial defects in mice / Associação de células-tronco mesenquimais com plasma rico em plaquetas na reparação de defeitos críticos em calvária de camundongos

PURPOSE: To evaluate the effects of mesenchymal stem cells (MSC) from eight mice C57BL/6 gfp+ bone marrows expanded in cultures associated with platelets rich plasma (PRP) deriving from another eight mice, in the repair of critical defects in calvarial bone produced in twenty-four adult isogenic mice C57BL/6. METHODS: The animals were submitted to a cranial defect of 6.0mm in diameter and divided into two equal experimental groups. Control group did not receive treatment and the treated group received a MSC pellet containing 1.0 x 10(7) cells/mL associated with 50.0µL of plasma gel containing 1.0 x 10(9) autologous platelets within the defect. RESULTS: In the treated group was observed process of angiogenesis and bone repair better than control group. CONCLUSION: Mesenchymal stem cells derived from bone marrow of C57BL/6 gfp+ mice associated with PRP gel applied in bone critical defects produced in calvarial contributes positively to the process of bone repair.

OBJETIVO: Avaliar os efeitos da associação das células-tronco mesenquimais (MSC) oriundas da medula óssea de oito camundongos jovens C57BL/6 gfp+ e expandidas em culturas, com Plasma Rico em Plaquetas (PRP) provenientes de outros oito camundongos, na reparação de defeitos críticos confeccionados em calvária de 24 camundongos adultos C57BL/6. MÉTODOS: Os animais foram submetidos a um defeito craniano de 6,0mm de diâmetro e separados em dois grupos experimentais iguais. O grupo controle não recebeu tratamento e no grupo tratado foi administrado, no interior do defeito, pellet de MSC contendo 1,0 x 10(7) células/mL associado com 50,0µL de plasma em gel autólogo contendo 1,0 x 10(9) plaquetas. RESULTADOS: No grupo tratado verificou-se processo de angiogênese e reparação óssea superior ao grupo controle. CONCLUSÃO: A associação das células-tronco mesenquimais (MSC) derivadas da medula óssea de camundongos C57BL/6 gfp+ com gel de PRP aplicadas em defeitos ósseos críticos confeccionadas em calvária de camundongos C57BL/6 jovens, contribuiu positivamente para o processo de reparação óssea.

Mesenchymal stem cell-conditioned medium triggers neuroinflammation and reactive species generation in organotypic cultures of rat hippocampus.

Cell therapy using bone marrow-derived mesenchymal stem cells (MSCs) seems to be a new alternative for the treatment of neurodegenerative diseases. Despite several promising results with their use, possible side effects are still unknown. In a previous work, we have shown that MSC-conditioned medium is toxic to hippocampal slice cultures and aggravates cell death induced by oxygen and glucose deprivation. In this work, we investigated whether the inflammatory response and/or reactive species formation could be involved in that toxicity. Rat organotypic hippocampal cultures were exposed for 24 h to conditioned medium from MSCs isolated from rat bone marrow. A marked glial activation was observed after exposure of cultures to MSC-conditioned medium, as evidenced by glial fibrillary acid protein (GFAP) and isolectin B(4) increase. Tumor necrosis factor-α and interleukin-6 levels were increased in the culture medium, and 2,7-dihydrodichlorofluorescein diacetate oxidation (indicating reactive species generation) and inducible nitric oxide synthase (iNOS) immunocontent were also higher after exposure of cultures to MSC-conditioned medium. Antioxidants (ascorbic acid and TROLOX(®)), N(ω)-nitro-l-arginine methyl ester hydrochloride, and anti-inflammatory drugs (indomethacin and dexamethasone) reduced cell death in hippocampal organotypic cultures after their exposure to MSC-conditioned medium. The results obtained here suggest that MSC-secreted factors trigger reactive species generation and neuroinflammation in organotypic cultures of hippocampus, introducing a note of caution in the use of these cells for neurological application.

Biology of stem cells: an overview.

Stem cells are defined as precursor cells that have the capacity to self-renew and to generate multiple mature cell types. Only after collecting and culturing tissues is it possible to classify cells according to this operational concept. This difficulty in identifying stem cells in situ, without any manipulation, limits the understanding of their true nature. This review aims at presenting, to health professionals interested in this area, an overview on the biology of embryonic and adult stem cells, and their therapeutic potential.

Biology and applications of mesenchymal stem cells.

Undifferentiated adult stem cells are responsible for cell replacement in adult organisms. Initially isolated from the bone marrow, they are now known to be distributed throughout the organism as a whole, with a perivascular location. They are defined by properties which include proliferation as adherent cells, a defined immunophenotype, and the capacity to differentiate in vitro into osteoblasts, adipocytes and chondroblasts. Mesenchymal stem cells (MSCs) are considered as one of the most promising cell types for therapeutic applications. Mechanisms responsible for this therapeutic role are not well understood, and may involve diferentiation or, as most evidences point out, paracrine activity. The ability to modulate the immune system opens a wide range of applications, mainly for autoimmune diseases and graft-versus-host disease. Preclinical and clinical studies show promising results, but controversial results are still reported, indicating the need for further basic and preclinical investigation on their therapeutic potential. This review will focus on recent advances in understanding MSC biology and applications in cell therapy.

Association of killer cell immunoglobulin-like receptors and human leukocyte antigen-C genotypes in South Brazilian with type 1 diabetes.

Type 1 diabetes mellitus (T1D) is a multifactorial and chronic autoimmune disease caused by the deficiency of insulin synthesis and or by its secretion or action defects. Genetic and environmental factors are known to be involved in its pathogenesis. The human leukocyte antigen complex (human leukocyte antigen (HLA)) constitutes the most relevant region contributing with 50% of the inherited risk for T1D. Natural killer cells (NK) are part of the innate immune system recognizing class I HLA molecules on target cells through their membrane receptors, called killer immunoglobulin-like receptors (KIR). The aim of our study is to evaluate the association between the KIR genes and HLA alleles in patients with T1D and healthy controls. Two hundred forty-eight T1D patients and 250 healthy controls were typed for HLA and KIR genes by PCR-SSP. Our results showed an increase of C2 in controls (p = 0.002). The genotype 2DL1/C2+ was also more common in controls (p = 0.001), as well as haplotype association KIR2DL2/DR3/DR4+ and the combination with only DR3+ (p < 0.001; p < 0.001). The maximum protection was seen when KIR2DL2/DR3-were absent when the combination of KIR2DL1/C2+ were present (p < 0.001) and the maximum risk was observed when KIR2DL2/DR3/DR4+ were present in the absence of KIR2DL1/C2- (p = 0.005). Our results confirmed the association of the KIR2DL2/DR3 increasing risk for T1D and suggest a protective role of KIR2DL1/C2.