1,720,973 research outputs found
A first approach to evaluate the cell dose in highly porous scaffolds by using a nondestructive metabolic method
Full text linkBackground: In cell-based therapies, in vitro studies on biomimetic cell–scaffold
constructs can facilitate the determination of the cell dose, a key factor in
guaranteeing the effectiveness of the treatment. However, highly porous scaffolds
do not allow a nondestructive evaluation of the cell number. Our objective was to
develop a nondestructive method for human mesenchymal stem cells dose evaluation
in a highly porous scaffold for bone regeneration. Materials & measurement
method: Proliferation trend of human mesenchymal stem cells on Biocoral® scaffolds
was measured by a resazurin-based assay here optimized for 3D cultures. The method
allows to noninvasively follow the cell proliferation on biocorals over 3 weeks with
very high reproducibility. Conclusion: This reliable method could be a powerful tool
in cell-based therapies for cell dose determination.
Stem cells regenerate damaged tissues when transplanted into the patient within
matrices mimicking the tissues architecture and mechanical properties. Cell number
needs to be appropriate to allow the cell survival in the new environment and to
stimulate the cell differentiation into the new tissue. In vitro experiments give
important hints to determine the appropriate number to transplant in the patient: in
this study cells are grown on highly porous matrices for bone regeneration and their
number is monitored over time by a method which does not perturb the system and
which was here optimized and evaluated as highly reliable.Background: In cell-based therapies, in vitro studies on biomimetic cell-scaffold constructs can facilitate the determination of the cell dose, a key factor in guaranteeing the effectiveness of the treatment. However, highly porous scaffolds do not allow a nondestructive evaluation of the cell number. Our objective was to develop a nondestructive method for human mesenchymal stem cells dose evaluation in a highly porous scaffold for bone regeneration. Materials & measurement method: Proliferation trend of human mesenchymal stem cells on Biocoral (R) scaffolds was measured by a resazurin-based assay here optimized for 3D cultures. The method allows to noninvasively follow the cell proliferation on biocorals over 3 weeks with very high reproducibility. Conclusion: This reliable method could be a powerful tool in cell-based therapies for cell dose determination.Stem cells regenerate damaged tissues when transplanted into the patient within matrices mimicking the tissues architecture and mechanical properties. Cell number needs to be appropriate to allow the cell survival in the new environment and to stimulate the cell differentiation into the new tissue. In vitro experiments give important hints to determine the appropriate number to transplant in the patient: in this study cells are grown on highly porous matrices for bone regeneration and their number is monitored over time by a method which does not perturb the system and which was here optimized and evaluated as highly reliable
Diagnostic uncertainty in Alzheimer's disease : A bio-metrology perspective addressed to microRNA-based biomarkers
No full textUncertainties affecting diagnostic tests for Alzheimer's disease (AD) are discussed from a bio-metrological point of view. The estimated sensitivity and specificity of a test are analyzed in a numerical example as predictors of its performance in real cases application. Current trends in molecular diagnostic research are outlined in view of reducing the effects of uncertainty factors involved in AD diagnosis
MicroRNA-Mediated Direct Reprogramming of Human Adult Fibroblasts Toward Cardiac Phenotype
Full text linkModulation of microRNA expression holds the promise to achieve direct reprogramming of fibroblasts into cardiomyocyte-like cells as a new strategy for myocardial regeneration after ischemic heart disease. Previous reports have shown that murine fibroblasts can be directly reprogrammed into induced cardiomyocytes (iCMs) by transient transfection with four microRNA mimics (miR-1, 133, 208, and 499, termed “miRcombo”). Hence, study on the effect of miRcombo transfection on adult human cardiac fibroblasts (AHCFs) deserves attention in the perspective of a future clinical translation of the approach. In this brief report, we studied for the first time whether miRcombo transient transfection of AHCFs by non-viral vectors might trigger direct reprogramming of AHCFs into cardiomyocyte-like cells. Initially, efficient miRNA delivery to cells was demonstrated through the use of a commercially available transfection agent (DharmaFECT1). Transient transfection of AHCFs with miRcombo was found to upregulate early cardiac transcription factors after 7 days post-transfection and cardiomyocyte specific marker cTnT after 15 days post-transfection, and to downregulate the expression of fibroblast markers at 15 days post-transfection. The percentage of cTnT-positive cells after 15 days from miRcombo transfection was ∼11%, as evaluated by flow cytometry. Furthermore, a relevant percentage of miRcombo-transfected AHCFs (∼38%) displayed spontaneous calcium transients at 30 days post-transfection. Results evidenced the role of miRcombo transfection on triggering the trans differentiation of AHCFs into iCMs. Although further investigations are needed to achieve iCM maturation, early findings from this study pave the way toward new advanced therapies for human cardiac regeneration
Cardiac Tissue-like 3D Microenvironment Enhances Route towards Human Fibroblast Direct Reprogramming into Induced Cardiomyocytes by microRNAs
No full textThe restoration of cardiac functionality after myocardial infarction represents a major clinical challenge. Recently, we found that transient transfection with microRNA combination (miRcombo: miR-1, miR-133, miR-208 and 499) is able to trigger direct reprogramming of adult human cardiac fibroblasts (AHCFs) into induced cardiomyocytes (iCMs) in vitro. However, achieving efficient direct reprogramming still remains a challenge. The aim of this study was to investigate the influence of cardiac tissue-like biochemical and biophysical stimuli on direct reprogramming efficiency. Biomatrix (BM), a cardiac-like extracellular matrix (ECM), was produced by in vitro culture of AHCFs for 21 days, followed by decellularization. In a set of experiments, AHCFs were transfected with miRcombo and then cultured for 2 weeks on the surface of uncoated and BM-coated polystyrene (PS) dishes and fibrin hydrogels (2D hydrogel) or embedded into 3D fibrin hydrogels (3D hydrogel). Cell culturing on BM-coated PS dishes and in 3D hydrogels significantly improved direct reprogramming outcomes. Biochemical and biophysical cues were then combined in 3D fibrin hydrogels containing BM (3D BM hydrogel), resulting in a synergistic effect, triggering increased CM gene and cardiac troponin T expression in miRcombo-transfected AHCFs. Hence, biomimetic 3D culture environments may improve direct reprogramming of miRcombo-transfected AHCFs into iCMs, deserving further study
Cell elasticity change as a biomarker for cancer detection: An AFM metrological approach
No full textThe cancer diagnosis relies on morphological examination of human cells or tissue samples: This is considered the 'gold standard' for the diagnosis of malignancy in any organ system. However, diagnosis based on morphological examination can be difficult, recent studies recognized the cell elasticity changes as a marker for cancer detection. A metrological characterized AFM can be used to make reproducible elasticity measurements on biological samples. In this paper a method to accurately measure a cell elasticity change based on measurement of a stable and homogeneous material is proposed. Nanoindenter characteristics (nanoindenter with pyramidal tip and triangular shape) and indentation parameters (0.1 V as approaching point, 5 um/s as indentation speed and indentation load of 0.4 V) were found feasible for all tested samples. A modal cell elastic modulus of 0.5 kPa for lung tumor cell and a limit AFM measurement reproducibility of 4% was obtained
Solid silica nanoparticles as carriers of fluorescent squaraine dyes in aqueous media: Toward a molecular engineering approach
Full text linkHybrid squaraine-SiO 2 nanoparticles extremely homogeneous in size (50 ± 2 nm), and with photoluminescent emission in the optical tissue window, were prepare by using the reverse microemulsion technique. Three different high quantum-yield squaraine dyes were used and the photophysical behavior of the prepared samples were qualitatively and quantitatively studied, by steady state and time-resolved photoluminescence, in order to establish structure-property relationships useful for the optimization of the preparation method. These squaraine dyes are insoluble in water and suffer a severe decrease of quantum yield if derivatized with polar groups. The role of the hydrophilicity of the dye-APTS adduct in ruling its dispersion in the nascent silica matrix was confirmed, and the possibility to improve the tuning of the process by properly administration of the adduct with the co-surfactant was demonstrated
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
CARDIAC TISSUE-LIKE 3D MICROENVIRONMENT ENHANCES THE DIRECT REPROGRAMMING PATH OF HUMAN FIBROBLASTS INTO INDUCED CARDIOMYOCYTES BY MICRORNAS
No full textVariations 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
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