1,721,164 research outputs found
NEW HORIZONS ON STEM CELL CRYOPRESERVATION THROUGH THE ARTIFICIAL EYES OF CD 34+, USING MODERN FLOW CYTOMETRY TOOLS
No full textHematopoietic stem cell (HSC) cryopreservation is a critical step in autologous and cord blood transplantation (CBT). In most circumstances, cryopreservation is performed in a mixture containing dimethyl sulfoxide (DMSO), since DMSO is necessary to secure cell viability. Most centers use a controlled rate (slow) freezing before the long-term storage at vapor phase liquid nitrogen (LN2) temperatures (≤ −160 °C). The primary objectives for laboratories supporting HSCT programs are to provide secure storage for leukapheresis and cord blood products, and to adequately characterize the functional properties of the grafts before their infusion. In the autologous setting, the large majority of the published results dealt with the assessment of the graft before cryopreservation. On the contrary, in CBT, before a CB unit is released, a sample obtained from a contiguous segment of that CB unit needs to be tested to verify HLA type and cell viability. The effects of graft handling, cryopreservation, storage and thawing on the recovery of CD34+ cells needs to be carefully analyzed and standardized on a global level. Some technical unresolved issues still limit the application of the ISHAGE derived single platform flow cytometry protocol for the assessment of the thawed material; based on these considerations, an adaptation of both the acquisition setting and the gating strategyis necessary for reliable measurement of CD34-expressing HSC in cryopreserved grafts. Artificial intelligence applied to “big data” may provide a new tool for improving advanced processing procedures and quality management guidelines in this area of investigation
Stem cells transplantation supports the repair of injured olfactory neuroepithelium after permanent lesion.
No full textWe investigated whether human cord blood-selected CD133+ stem cells (HSC) may engraft the olfactory mucosa and contribute to restoration of neurolfactory epithelium (NE) in nod-scid mice damaged by dichlobenil. The herbicide dichlobenil selectively causes necrosis of the dorsomedial part of the NE and underlying mucosa, while the lateral part of the olfactory region remains undamaged. The aim of this research was to demonstrate that HSC stimulate self-renewal of neuronal stem cells and promote their differentiation into bipolar olfactory neurons to replace the injured NE. By PCR, we tested the presence of 3 human specific microsatellites (CODIS), used as DNA markers for traceability of the engrafted cells, demonstrating their presence in various tissues of the host, including the olfactory mucosa, after one month from transplantation. By immunohistochemistry and lectin staining, we demonstated that, in injured mice, HSC contributed to stimulating residual endogenous olfactory neurons, promoting recovery of the original phenotype of the NE, in contrast to the lack of spontaneous regeneration in similar injured areas always seen in the non-transplanted control mice. Multiple color-FISH (M-FISH) analysis detecting 7 human genomic sequences present in different chromosomes provided further evidence of positive prolonged engraftment of chimeric cells in the olfactory mucosa. This study provides the first evidence that transplanted HSC migrating to the neurolfactory mucosa may contribute to NE structure restoration with resumption of the sensorineural olfactory loss
Inner ear rehabilitation in the deafened cochlea of nod-scid mice following transplantation of human pluripotent mesenchymal stem cells
No full textObjectives. Mesenchymal stem cells (MSC) are currently being investigated in numerous pre-clinical and clinical settings of regenerative medicine. We had previously reported (Revoltella et al., Cell Transplant. 2008; 17, 665-678) that human umbilical cord blood CD133+ stem cells transplanted IV into pre-irradiated nod-scid mice made permanently deaf by ototoxic treatment with kanamycin or intense sound, were able to engraft the cochlea and contribute to inner ear restoration, in vivo. We further investigated here whether human adult MSC derived from either bone marrow or fat (lipid suction), if injected IV to deafened nod-scid mice pre-treated with kanamycin , were able to engraft the damaged cochlea regaining hearing.
Materials, Methods & Results. We tested HLA-DQa1 DNA and three human microsatellites (CODIS) as indicators of engrafted cells, finding polymerase chain reaction evidence of chimaerism in various tissues of the host, including the Organ of Corti in the damaged cochlea, at 7, 31 and 60 days following MSC transplant. After 31 days, histology, immunohistochemistry, and lectin staining confirmed the repair process and stimulation ex novo of morphological recovery in the inner ear, contrasting with the lack of morphological repair in control similarly injured but non-transplanted mice. FISH analysis, to detect human genomic sequences from different chromosomes, confirmed persistent engraftment of the regenerating inner ear with a very limited number of chimaeric cells. Dual color FISH analysis provided evidence of a limited positive engraftment in the inner ear and in other mouse tissues, also revealing small numbers of possible heterokaryons, probably resulting from unstable clones derived from fusion of donor with endogenous cells, up to 2 months following transplantation. Stem cells and differentiation pathways focused PCR arrays favoured to select MSC inducing the best response.
Conclusions. These findings support the concept that transplanted MSC migrating to the damaged inner ear area may provide conditions for the resumption of a damaged cochlea , emerging as a potential strategy for hearing rehabilitation
Riabitazione degli innesti spongiosi e tecniche di stimolazione [Bone allograft rehabilitation and growth factors]
No full textBone regeneration is based upon the three components of osteoconduction, osteoinduction and osteogenesis. During last years several bone substitutes have been developed to obtain a graft with ideal osteoconductive capabilities. Osteogenesis too has been emphasized with the progress of tissue engineering. Osteoinduction and the intrinsic osteoinductive properties of native bone have been already stressed by the historical works of Marshall Urist in 1965 about demineralised bone matrix (DBM). Only 20 years later the genetic sequences of the bone morphogenetic proteins (BMP) were identified and classified with the identification of a number of different BMPs whose precise role in the osteoinduction process is still extensively studied and not well defined. But experimental and preclinical studies have shown also that the BMPs are not playing alone on this stage. A lot of proteins secreted by the cells are implied in the process of healing and new bone formation; to these factors has been generically assigned the term of growth factor and an increasing number of these have been identified and used in experimental studies. The more debated are the transforming growth factor beta (TGF-β), the fibroblast growth factor (FGF), the insuline-like growth factor (IGF) and the platelets derived growth factors (PDGF). Obviously these are only some of the variety of factors that participate together with BMPs in a normal healing process
NEDA status in highly active MS can be more easily obtained with autologous hematopoietic stem cell transplantation than other drugs
No full textThe no evidence of disease activity (NEDA) composite measure has emerged as one attractive new target of therapies in relapsing-remitting multiple sclerosis (RRMS), consisting of the following features: (1) no relapses, (2) no disability progression, and (3) no magnetic resonance imaging (MRI) activity (new or enlarging T2 lesions or Gd-enhancing lesions). Achievement of NEDA status in patients receiving a disease-modifying therapy (DMT) seems to be an ambitious but ideal goal for therapies in RRMS. Recently, published post hoc analyses of clinical trials reported percentages of RRMS patients maintaining the NEDA status after 2 years of therapy ranging between 13% and 46%. Long-term assessment of NEDA patients in real-life settings showed very low probability to be NEDA in the long run. Against this scenario, immunoablative therapy followed by autologous hematopoietic stem cell transplantation (aHSCT) demonstrated the potential to maintain a much higher proportion of NEDA patients at 2 years (ranging from 78% to 83%) and also at 5 years (ranging from 60% to 68%). This is even more relevant when considering that MS patients who underwent aHSCT are much more active than patients usually enrolled in clinical trials. The emerging evidence of the efficacy of this therapeutic approach in early aggressive and treatment-resistant RRMS calls for the organization of a randomized comparative trial to fully evaluate the risk-benefit profile of aHSCT in patients with highly active MS not responding to DMTs
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
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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