Luciana Cavalheiro Marti

Chemokines and immunity

Chemokines are a large family of small cytokines and generally have low molecular weight ranging from 7 to 15kDa. Chemokines and their receptors are able to control the migration and residence of all immune cells. Some chemokines are considered pro-inflammatory, and their release can be induced during an immune response at a site of infection, while others are considered homeostatic and are involved in controlling of cells migration during tissue development or maintenance. The physiologic importance of this family of mediators is resulting from their specificity − members of the chemokine family induce recruitment of well-defined leukocyte subsets. There are two major chemokine sub-families based upon cysteine residues position: CXC and CC. As a general rule, members of the CXC chemokines are chemotactic for neutrophils, and CC chemokines are chemotactic for monocytes and sub-set of lymphocytes, although there are some exceptions. This review discusses the potential role of chemokines in inflammation focusing on the two best-characterized chemokines: monocyte chemoattractant protein-1, a CC chemokine, and interleukin-8, a member of the CXC chemokine sub-family.

Umbilical cord mesenchymal stem cells labeled with multimodal iron oxide nanoparticles with fluorescent and magnetic properties: application for in vivo cell tracking

Here we describe multimodal iron oxide nanoparticles conjugated to Rhodamine-B (MION-Rh), their stability in culture medium, and subsequent validation of an in vitro protocol to label mesenchymal stem cells from umbilical cord blood (UC-MSC) with MION-Rh. These cells showed robust labeling in vitro without impairment of their functional properties, the viability of which were evaluated by proliferation kinetic and ultrastructural analyzes. Thus, labeled cells were infused into striatum of adult male rats of animal model that mimic late onset of Parkinson’s disease and, after 15 days, it was observed that cells migrated along the medial forebrain bundle to the substantia nigra as hypointense spots in T2 magnetic resonance imaging. These data were supported by short-term magnetic resonance imaging. Studies were performed in vivo, which showed that about 5 × 105 cells could be efficiently detected in the short term following infusion. Our results indicate that these labeled cells can be efficiently tracked in a neurodegenerative disease model.

Vascular endothelial growth factor-A enhances indoleamine 2,3-dioxygenase expression by dendritic cells and subsequently impacts lymphocyte proliferation

Dendritic cells (DCs) are antigen (Ag)-presenting cells that activate and stimulate effective immune responses by T cells, but can also act as negative regulators of these responses and thus play important roles in immune regulation. Pro-angiogenic vascular endothelial growth factor (VEGF) has been shown to cause defective DC differentiation and maturation. Previous studies have demonstrated that the addition of VEGF to DC cultures renders these cells weak stimulators of Ag-specific T cells due to the inhibitory effects mediated by VEGF receptor 1 (VEGFR1) and/or VEGFR2 signalling. As the enzyme indoleamine 2,3-dioxygenase (IDO) is recognised as an important negative regulator of immune responses, this study aimed to investigate whether VEGF affects the expression of IDO by DCs and whether VEGF-matured DCs acquire a suppressor phenotype. Our results are the first to demonstrate that VEGF increases the expression and activity of IDO in DCs, which has a suppressive effect on Ag-specific and mitogen-stimulated lymphocyte proliferation. These mechanisms have broad implications for the study of immunological responses and tolerance under conditions as diverse as cancer, graft rejection and autoimmunity.

In vitro analysis of neurospheres derived from glioblastoma primary culture: a novel methodology paradigm

Glioblastomas are the most lethal primary brain tumor that frequently relapse or progress as focal masses after radiation, suggesting that a fraction of tumor cells are responsible for the tumor regrowth. The identification of a brain tumor cell subpopulation with potent tumorigenic activity supports the cancer stem cell hypothesis in solid tumors. The goal of this study is to determine a methodology for the establishment of primary human glioblastoma cell lines. Our aim is achieved by taking the following approaches: (i) the establishment of primary glioblastoma cell culture; (ii) isolation of neurospheres derived from glioblastoma primary cultures; (iii) selection of CD133 cells from neurospheres, (iv) formation of subspheres in the CD133-positive population, (v) study of the expression level of GFAP, CD133, Nestin, Nanog, CD34, Sox2, CD44, and CD90 markers on tumor subspheres. Hence, we described a successful method for isolation of CD133-positive cell population and establishment of glioblastoma neurospheres from this primary culture, which are more robust than the ones derived straight from the tumor. Pointed out that the neurospheres derived from glioblastoma primary culture showed 29% more cells expressing CD133 then the ones straight tumor-derived, denoting a higher concentration of CD133-positive cells in the neurospheres derived from glioblastoma primary culture. These CD133-positive fractions were able to further generate subspheres. The subspheres derived from glioblastoma primary culture presented a well-defined morphology while the ones derived from the fresh tumor were sparce and less robust. And the negative fraction of CD133 cells was unable to generate subspheres. The tumor subspheres expressed GFAP, CD133, Nestin, Nanog, CD44, and CD90. Also, the present study describes an optimization of neurospheres/subspheres isolation from glioblastoma primary culture by selection of CD133-positive adherent stem cell.

A reduction in CD90 (THY-1) expression results in increased differentiation of mesenchymal stromal cells

BackgroundMesenchymal stromal cells (MSCs) are multipotent progenitor cells used in several cell therapies. MSCs are characterized by the expression of CD73, CD90, and CD105 cell markers, and the absence of CD34, CD45, CD11a, CD19, and HLA-DR cell markers. CD90 is a glycoprotein present in the MSC membranes and also in adult cells and cancer stem cells. The role of CD90 in MSCs remains unknown. Here, we sought to analyse the role that CD90 plays in the characteristic properties of in vitro expanded human MSCs.MethodsWe investigated the function of CD90 with regard to morphology, proliferation rate, suppression of T-cell proliferation, and osteogenic/adipogenic differentiation of MSCs by reducing the expression of this marker using CD90-target small hairpin RNA lentiviral vectors.ResultsThe present study shows that a reduction in CD90 expression enhances the osteogenic and adipogenic differentiation of MSCs in vitro and, unexpectedly, causes a decrease in CD44 and CD166 expression.ConclusionOur study suggests that CD90 controls the differentiation of MSCs by acting as an obstacle in the pathway of differentiation commitment. This may be overcome in the presence of the correct differentiation stimuli, supporting the idea that CD90 level manipulation may lead to more efficient differentiation rates in vitro.

The Ultrastructural Study of Tumorigenic Cells Using Nanobiomarkers

Despite recent advances, patients with malignant brain tumors still have a poor prognosis. Glioblastoma (WHO grade 4 astrocytoma), the most malignant brain tumor, represents 50% of all astrocytomas, with a median survival rate of <1 year. It is, therefore, extremely important to search for new diagnostic and therapeutic approaches for patients with glioblastoma. This study describes the application of superparamagnetic nanoparticles of iron oxide, as well as monoclonal antibodies, of immunophenotypic significance, conjoined to quantum dots for the ultrastructural assessment of glioblastoma cells. For this proposal, an immunophenotypic study by flow cytometry was carried out, followed by transmission electron microscopy analysis. The process of tumor cell labeling using nanoparticles can successfully contribute to the identification of tumorigenic cells and consequently for better understanding of glioblastoma genesis and recurrence. In addition, this method may help further studies in tumor imaging, diagnosis, and prognostic markers detection.

Increasing Doses of Simvastatin Versus Combined Ezetimibe/Simvastatin Effect on Circulating Endothelial Progenitor Cells

Background: Patients with coronary artery disease (CAD) should be treated with statins to attain very low cholesterol levels, in order to reduce cardiovascular adverse events. More than 70% of these patients do not reach the appropriate cholesterol goal despite moderate statin doses. However, it is not known whether therapeutic uptitration with different lipid-lowering strategies has a similar “pleiotropic” effect on atherosclerotic endothelial dysfunction evaluated by measurement of endothelial progenitor cells (EPCs). Objective: We sought to compare, in patients with stable CAD and with a low-density lipoprotein cholesterol (LDL-C) >70 mg/dL on treatment with simvastatin 20 mg, the effects on EPCs by increasing simvastatin to 80 mg versus adding ezetimibe 10 mg. Methods: Patients (n = 68, 63 ± 9 years, 39% men) were randomly allocated to receive ezetimibe 10/simvastatin 20 mg or simvastatin 80 mg for 6 weeks. Circulating EPCs were measured by flow cytometry before and after the treatment. Results: Both strategies presented similar effects on metabolic parameters. The LDLs were equally reduced by ezetimibe 10/simvastatin 20 mg and simvastatin 80 mg (28.9% ± 13% vs 21.1% ± 33%; P = .46, respectively). The levels of EPCs were unaffected by ezetimibe 10/simvastatin 20 mg (median [25th, 75th]: pre- vs posttreatment, 7.0 [2.3; 13.3] vs 3.1 [0.1; 13.2] EPCs/104 mononuclear cells; P = .43) or simvastatin 80 mg (pre- vs posttreatment, 6.1 [2.9; 15.2] vs 4.0 [1.4; 10.7] EPCs/104 mononuclear cells; P = .5) ,and there were no differences between the groups on treatment effects (P = .9). Conclusions: Among stable patients with CAD and with an LDL-C >70 mg/dL on simvastatin 20 mg, increasing simvastatin dose to 80 mg or adding ezetimibe 10 mg promoted similar further cholesterol reduction but did not have incremental effects on circulating EPCs. These data suggest that the effects of simvastatin moderate doses on EPCs are not increased by intensive lipid-lowering strategies (clinicaltrials.gov: NCT00474123).

Ultrastructural characterization of CD133(+) stem cells bound to superparamagnetic nanoparticles: possible biotechnological applications

CD133 antigen is an integral membrane glycoprotein that can bind with different cells. Originally, however, this cellular surface antigen was expressed in human stem cells and in various cellular progenitors of the haematopoietic system. Human cord blood has been described as an excellent source of CD133+ haematopoietic progenitor cells with a large application potential. One of the main objectives of the present study is to describe for the first time the ultrastructural characteristics of CD133+ stem cells using transmission electronic microscopy. Another objective of the manuscript is to demonstrate through transmission electronic microscopy the molecular image of magnetic nanoparticles connected to the stem cells of great biotechnological importance, as well as demonstrating the value of this finding for electronic paramagnetic resonance and its related nanobioscientific value. Ultrastructural results showed the monoclonal antibody anti‐CD133 bound to the superparamagnetic nanoparticles by the presence of electrondense granules in cell membrane, as well as in the cytoplasm, revealing the ultrastructural characteristics of CD133+ cells, exhibiting a round morphology with discrete cytoplasmic projections, having an active nucleus that follows this morphology. The cellular cytoplasm was filled up with mitochondrias, as well as microtubules and vesicles pinocitic, characterizing the process as being related to internalization of the magnetic nanoparticles that were endocyted by the cells in question. Electronic paramagnetic resonance analysis of the CD133+ stem cells detected that the signal (spectrum) generated by the labelled cells comes from the superparamagnetic nanoparticles that are bound to them. These results strongly suggest that these CD133+ cells can be used in nanobiotechnology applications, with benefits in different biomedical areas.

Predictors of high-quality cord blood units

Analysis of umbilical cord blood (UCB) transplants shows a correlation between engraftment and total number of infused cells. Thus, it is worth evaluating what maternal and neonatal characteristics and collection techniques may affect the quality of UCB units.

Interleukin 7 plays a role in T lymphocyte apoptosis inhibition driven by mesenchymal stem cell without favoring proliferation and cytokines secretion.

Since 2004, when a case report describing the use of human mesenchymal stem cells (hMSCs) infusion as a therapy for GVHD after bone marrow transplantation, a new perspective in MSC function emerged. Since then hMSCs immunomodulatory potential became the target of several studies. Although great progress has been made in our understanding of hMSCs, their effect on T cell remains obscure. Our study has confirmed the already described effect of hMSCs on lymphocytes proliferation and survival. We also show that the impairment of lymphocyte proliferation and apoptosis is contact-independent and occurs in a prostaglandin-independent manner. A potential correlation between IL-7 and hMSCs effect is suggested, as we observed an increase in IL-7 receptors (CD127) on lymphocyte membrane in MSC presence. Additionally, blocking IL-7 in hMSCs-lymphocytes co-cultures increased lymphocytes apoptosis and we also have demonstrated that hMSCs are able to produce this interleukin. Moreover, we found that during Th1/Th17 differentiation in vitro, hMSCs presence leads to Th1/Th17 cells with reduced capacity of INF-y and IL-17 secretion respectively, regardless of having several pro-inflammatory cytokines in culture. We did not confirm an increment of Treg in these cultures, but a reduced percentage of INF-y/IL-17 secreting cells was observed, suggesting that the ratio between anti and pro-inflammatory cells changed. This changed ratio is very important to GvHD therapy and links hMSCs to an anti-inflammatory role. Taken together, our findings provide important preliminary results on the lymphocyte pathway modulated by MSCs and may contribute for developing novel treatments and therapeutic targets for GvHD and others autoimmune diseases.