1,721,004 research outputs found
ROLE OF TOLL-LIKE RECEPTORS-3 AND -4 IN THE INTERACTIONS BETWEEN NEUTROPHILS AND MESENCHYMAL STROMAL CELLS
Full text linkLe cellule stromali mesenchimali di derivazione midollare (Bone marrow-derived mesenchymal stromal cells, BM-MSC) sono precursori stromali dotati di estese capacità immunomodulatorie. Nel presente studio, ci siamo posti l’obiettivo di verificare se le BM-MSC potessero influenzare le risposte biologiche di neutrofili umani in cocultura dopo stimolo dei loro Toll-like receptors (TLR) -3 e -4. Dimostreremo come l’attivazione del TLR3 da parte del suo ligando poly(I:C) determini un drammatico aumento dell’effetto antiapoptotico esercitato costitutivamente su neutrofili in cocultura dalle BM-MSC in condizioni basali, in modo più significativo dell’attivazione del TLR4 da parte del lipopolisaccaride (LPS). Inoltre, le BM-MSC stimolate da TLR3 e TLR4 aumentano il burst respiratorio e l’espressione del CD11b dei neutrofili. La cocultura in assenza di contatto cellulare e l’incubazione dei neutrofili nei supernatanti raccolti da BM-MSC attivate da TLR3 e TLR4 determinano effetti paragonabili in termini di aumento di sopravvivenza e di modifiche immunofenotipiche, fatto che suggerisce il coinvolgimento di fattori solubili endogeni. Esperimenti di blocco con anticorpi monoclonali rivelano come gli effetti biologici esercitati sui neutrofili dalle BM-MSC dopo stimolo del TLR3 siano mediati dall’azione combinata di IL-6, IFN-β e GM-CSF, mentre quelli esercitati dopo stimolo del TLR4 siano per lo più dipendenti dalla produzione di GM-CSF. Cellule stromali mesenchimali derivate dal timo, dalla milza e dal tessuto adiposo sottocutaneo hanno mostrato comportamento simile alle BM-MSC.
Complessivamente, i nostri risultati evidenziano un nuovo meccanismo biologico tramite cui le cellule stromali mesenchimali sostengono e amplificano le funzioni dei neutrofili in risposta all’attivazione di TLR3 e TLR4, e possono di conseguenza contribuire alla patogenesi di svariate malattie infiammatorie.Bone marrow-derived mesenchymal stromal cells (BM-MSC) are stromal precursors endowed with extensive immunomodulative properties. In this study, we aimed to assess whether Toll-like receptor(TLR)3- and TLR4-activated BM-MSC influence human neutrophil responses under coculture conditions. We show that TLR3 triggering by poly(I:C) dramatically amplifies, in a more significant manner than TLR4 triggering by LPS, the antiapoptotic effects that resting BM-MSC constitutively exert on neutrophils under coculture conditions. In addition, TLR3- and TLR4-activated BM-MSC enhance respiratory burst ability and CD11b expression by neutrophils. The coculture in the absence of cell contact and the incubation of neutrophils in supernatants harvested from TLR3- and TLR4-activated BM-MSC yield comparable results in terms of increased survival and immunophenotypic changes, thus suggesting the involvement of endogenous soluble factors. Neutralizing experiments reveal that the biological effects exerted on neutrophils by TLR3-activated BM-MSC are mediated by the combined action of IL-6, IFN-β and GM-CSF, while those exerted by TLR4-activated BM-MSC mostly depend on GM-CSF. MSC isolated from thymus, spleen and subcutaneous adipose tissue behave similarly.
Therefore, our data highlight a novel mechanism by which MSC sustain and amplify the functions of neutrophils in response to TLR3- and TLR4-activation and may consequently contribute to inflammatory disorders
Human Bone Marrow and Adipose Tissue Mesenchymal Stem Cells: A User's Guide
No full textMesenchymal stem cells (MSCs) are adult stem cells that hold great promise in the field of regenerative medicine. They can be isolated from almost any tissue of the body and display, after expansion, very similar properties and minor differences, probably due to their microenvironment of origin. Expansion in vitro can be obtained in cytokine-free, serum-enriched media, as well as in serum-free, basic fibroblast growth factor-enriched media. A detailed immunophenotypic analysis is required to test the purity of the preparation, but no unique distinguishing marker has been described as yet. Functional assays, that is, differentiation studies in vitro, are needed to prove multilineage differentiation of expanded cells, and demonstration of pluripotency is necessary to identify most immature precursors. MSCs show powerful immunomodulative properties toward most of the cells of the immune system: this strengthens the theoretical rationale for their use also in an allogeneic setting across the major histocompatibility complex (MHC) immunological barriers. Systemic intravenous injection and local use have been tried: after systemic injection, MSCs show a high degree of chemotaxis based on pro-inflammatory cytokines, and localize at inflamed and neoplastic tissues; local regeneration has been improved using synthetic, as well as organic scaffolds. On the other hand, inadequate heterotopic in vivo differentiation and neoplastic transformation are potential risks of this form of cell therapy, even if evidence of this sort has been collected only from studies in mice, and generally after prolonged in vitro expansion. This review tries to provide a detailed technical overview of the methods used for human bone-marrow (BM)-derived and adipose-tissue (AT)-derived MSC isolation, in vitro expansion, and characterization for tissue repair. We chose to use BM-MSCs as a model to describe techniques that have been used for MSC isolation and expansion from very different sources, and AT-MSCs as an example of a reliable and increasingly common alternative source
Stem cells and cardiac regeneration
No full textL’ultima decade ha visto il fiorire di una serie di
approcci sperimentali innovativi finalizzati al raggiungimento
di un’efficace rigenerazione cardiaca
dopo infarto miocardico acuto (IMA). Al
momento attuale, due di questi approcci hanno
già determinato studi clinici randomizzati di fase
III: l’uso di cellule mononucleate di midollo osseo
(BM-MNC) e di mioblasti scheletrici. Nel
primo caso la procedura si è rivelata fattibile su
vasta scala e sicura, ma i vantaggi associati, per
quanto comprovati da studi clinici randomizzati
e da follow-up prolungato, sono stati per molti
aspetti inferiori alle attese iniziali. Nel secondo
caso, i potenziali benefici derivati dall’impiego
di mioblasti scheletrici sono stati limitati dalla
mancata integrazione delle aree di rigenerazione
cardiaca con il miocardio residuo peri-infartuale,
con conseguente squilibrio della funzione di
pompa e aumento del rischio di insorgenza di gravi
aritmi
Cell Therapy for Cardiac Regeneration after Myocardial Infarct: Which Cell is the Best?
No full textIn the last decade several attempts have been made to achieve the goal of cardiac regeneration after myocardial infarction. To date, two cell types have completed phase-III clinical trials: Skeletal Myoblasts and Bone-Marrow Mononuclear Cells (BM-MNCs). In the first case, all benefits have been limited by an increased risk of arrhythmia. In the case of BM-cells, most studies showed a significant, although limited, advantage in the cell-treated group. This may be due to the choice of the wrong BM cell type: other candidates would be e.g. CD34(+) HSCs, or non-hematopoietic Mesenchymal Stem Cells. After positive results from the experimental studies, phase I/II clinical trials are currently on-going for both. Ideally, the best cell to use to regenerate the heart would be a precursor of all cardiac lineages; until the isolation and expansion of Cardiac Stem Cells (CSCs), such a cell was thought to exist only during embryogenesis. Using CSCs researchers managed to generate electrically-coupled contractile tissue within the infarct of animal models. Still, some doubts persist over the possibility to translate such results in real-life patients. Another approach, therefore, involves the use of induced Pluripotent Stem Cells (iPS) obtained from fibroblasts after genetic reprogramming. This new type of cell would combine the pluripotency of embryonal stem cells with the advantages of an autologous use. Nevertheless, iPS cells form teratomas, and their effective differentiation in vivo is largely unknown. This review will critically compare the data from the Literature concerning cell therapy after myocardial infarction. Can we name the best cell
Chapter 4: Mesenchymal stem cell isolation and expansion methodology. In: Stem Cells And Cancer Stem Cells: Therapeutic Applications in Disease and Injury
No full textMesenchymal stem cells (MSCs) are adult
non-hematopoietic stem cells originally isolated from
bone marrow (BM) (Prockop, 1997), but they are virtually
present and can be isolated from almost every
tissue of the body (Da Silva et al., 2006), including
peripheral blood (Roufosse et al., 2004). This
evidence suggests that MSCs could be part of a
mesenchymal-stromal cell system diffused throughout
the body. The real in vivo counterpart of cultureexpanded
MSCs is still unknown; however, different
Authors suggested that MSCs are a subgroup of
vessel-lining pericytes that may contribute to vessel
homeostasis by reacting to tissue damage with regenerative
processes, locally modulating the inflammatory
reaction, and entering systemic circulation to migrate
according to cytokine gradients (Crisan et al., 2008).
The International Society of Cellular Therapy (ISCT)
stated the following three criteria for the definition
of MSCs after in vitro expansion (Dominici et al.,
2006): (1) the adherence to plastic under standard tissue
culture conditions; (2) the expression of a specific
combination of cell surface markers; (3) the capability
of multilineage differentiation under appropriate
in vitro conditions. These criteria are necessary to
overcome the problems due to the absence of MSCspecific
cell surface markers, the high heterogeneity
in terms of differentiation potential, and the similarities
to fibroblasts displayed by isolated and expanded
MSCs. Consequently, ISTC suggested to define MSCs as “Multipotent Mesenchymal Stromal Cells” instead
of “Mesenchymal Stem Cells”. In this Chapter, MSC
isolation, expansion and functional characterization
will be discussed in details
Remission of severe antiphospholipid syndrome associated with non Hodgkin's B-cell lymphoma after combined treatment with Rituximab and chemotherapy
No full text
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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