1,720,993 research outputs found
Mesenchymal stromal cells on bioscaffold for liver bioengineering
Full text linkTissue bioengineering is the creation of functional tissues or whole organs by manufacturing body parts ex vivo, seeding cells on a supporting scaffold. The final goal of organ bioengineering is the use of the bioengineered organs as ‘replacement parts’ for the human body. The need for bioengineered livers is significant: currently, the only effective treatment for end-stage liver failure is orthotopic liver transplantation. However, the shortage of organ donors results every year in the death of many patients in the waiting list. Moreover, the advantage of this technology is the use of autologous cells that eliminates the need for post-transplant immunosuppression.
In the present study, we decellularized pig livers and then repopulated them with allogeneic porcine mesenchymal stromal cells (pMSCs) to study the interaction between pMSCs and liver specific ECM. The final aim was to understand if ECM can influence and/or promote pMSCs toward differentiation into hepatocytes or hepatocyte-like cells without specific growth factor in culture medium.
In our experimental project, porcine livers were obtained by a surgical technique similar to the one used for explant in a human cadaveric donor. Liver samples were cut and then decellularized through agitation with 0.15% SDS. The quality of the decellularization was evaluated both qualitatively and quantitatively, with histological staining and DNA quantification respectively. pMSCs were isolated from the porcine bone marrow (BM) and expanded in vitro. pMSC were characterized by assessment of morphology, proliferation capacity, immunophenotype and their differentiation ability. Then, pMSCs were used for seeding the scaffolds with static culture method. The repopulation of the recellularized scaffold was evaluated at 3, 7, 14 and 21 days after seeding with H&E stain, DAPI, MTT assay and SEM analysis, showing an increase in the cell number with increasing culture days. In order to determinate whether culture on liver ECM-scaffold could promote/address differentiation of pMSC towards hepatocyte, the transcriptional levels of some hepatic genes were tested. In particular, we evaluated six genes (ALB, AFP, HNF4a, Cyp1a1, Cyp7a1 and Krt18) associated to different phases of the hepatic development. A comparison with the expression profile was made with both porcine primary hepatocyte and pMSC.
The observations obtained so far allow us to state that: i) our decellularization protocol is effective in the removal of the cells from native liver, respecting the parameters for decellularization without damage the structure of ECM; ii) pMSCs obtained from porcine BM have characteristic phenotypically and functionally comparable to those of their human counterparts and therefore they can be used as a model for experimental studies such as for liver ECM recellularization; iii) the static seeding strategy of pMSCs on the scaffold resulted to be effective in terms of ECM cell attachment, cell proliferation and migration inside the specimen, iv) the genic profile of cells seeded on ECM scaffold without any growth factors is more similar to pMSC suggesting that the only contact with liver specific ECM is not strong enough to induce a complete differentiation in HLCs. Despite this, we observed that Cyp7a1 gene, expressed in hepatocyte but not in MSC, was present in pMSC seeded scaffolds at each time points.
In conclusion, we can observe that our results are in accordance with data reported in literature and sustain the possibility to use decellularizated organs as biological scaffold to create functional organs. We believe that our results may provide new insights toward a better understanding of early HLCs development on ECM-scaffolds. However, a more detailed decellularization process, a better cell differentiation capacity and a more detailed understanding of the interaction between cells and ECM could represent crucial steps in the progression of this research field
Commentary: Insulin-Producing Organoids Engineered From Islet and Amniotic Epithelial Cells to Treat Diabetes
No full textA Commentary on : "Insulin-Producing Organoids Engineered from Islet and Amniotic Epithelial Cells to Treat Diabetes" By Lebreton F, Lavallard V, Bellofatto K, Bonnet R, Wassmer CH, Perez L, Kalandadze V, Follenzi A, Boulvain M, Kerr-Conte J, Goodman DJ, Bosco D, Berney T, Berishvili E. Nat Commun. (2019). 10(1):4491. doi: 10.1038/s41467-019-12472-3
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
Bronchial hyperresponsiveness, airway inflammation, and reversibility in patients with chronic obstructive pulmonary disease
Full text linkBackground: Bronchial hyperresponsiveness (BHR), sputum eosinophilia, and bronchial reversibility are often thought to be a hallmark of asthma, yet it has been shown to occur in COPD as well. Objectives: To evaluate the relationship between BHR, lung function, and airway inflammation in COPD patients. Methods: Thirty-one, steroid-free patients with stable, mild and moderate COPD were studied. The following tests were carried out: baseline lung function, reversibility, provocative dose of methacholine causing a 20% fall in forced expiratory volume in 1 second, a COPD symptom score, and sputum induction. Results: Twenty-nine patients completed the procedures. About 41.4% had BHR, 31.0% had increased sputum eosinophils, and 37.9% had bronchial reversibility. Some of the patients had only one of these characteristics while others had two or the three of them. Patients with BHR had higher sputum eosinophils than patients without BHR (P=0.046) and those with sputum eosinophils ≥3% had more exacerbations in the previous year and a higher COPD symptom score than patients with sputum eosinophils <3% (P=0.019 and P=0.031, respectively). In patients with BHR, the cumulative dose of methacholine was negatively related to the symptom score and the number of exacerbations in the previous year. When patients with bronchial reversibility were considered, bronchodilation was positively related to sputum eosinophils. Conclusion: Our study showed that BHR, sputum eosinophilia, and bronchial reversibility were not clustered in one single phenotype of COPD but could be present alone or together. Of interest, BHR and airway eosinophilia were associated with clinical data in terms of exacerbations and symptoms. Further investigation is needed to clarify this topic
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
Freeze-dried and GMP-compliant pharmaceuticals containing mesenchymal exosomes for acellular MSC immunomodulant therapy
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