Characterization of a Fetal Liver Cell Population Endowed with Long-Term Multiorgan Endothelial Reconstitution Potential.

Stable reconstitution of vascular endothelial beds upon transplantation of progenitor cells represents an important challenge due to the paucity and generally limited integration/expansion potential of most identified vascular related cell subsets. We previously showed that mouse fetal liver (FL) hemato/vascular cells from day 12 of gestation (E12), expressing the Stem Cell Leukaemia (SCL) gene enhancer transgene (SCL-PLAP+ cells), had robust endothelial engraftment potential when transferred to the blood stream of newborns or adult conditioned recipients, compared to the scarce vascular contribution of adult bone marrow cells. However, the specific SCL-PLAP+ hematopoietic or endothelial cell subset responsible for the long-term reconstituting endothelial cell (LTR-EC) activity and its confinement to FL developmental stages remained unknown. Using a busulfan-treated newborn transplantation model, we show that LTR-EC activity is restricted to the SCL-PLAP+ VE-cadherin+ CD45- cell population, devoid of hematopoietic reconstitution activity and largely composed by Lyve1+ endothelial-committed cells. SCL-PLAP+ Ve-cadherin+ CD45- cells contributed to the liver sinusoidal endothelium and also to the heart, kidney and lung microvasculature. LTR-EC activity was detected at different stages of FL development, yet marginal activity was identified in the adult liver, revealing unknown functional differences between fetal and adult liver endothelial/endothelial progenitors. Importantly, the observations that expanding donor-derived vascular grafts colocalize with proliferating hepatocyte-like cells and participate in the systemic circulation, support their functional integration into young livers. These findings offer new insights into the engraftment, phonotypical, and developmental characterization of a novel endothelial/endothelial progenitor cell subtype with multiorgan LTR-EC activity, potentially instrumental for the treatment/genetic correction of vascular diseases. Stem Cells 2017;35:507-521.Spanish Ministry of Economy and Competitiveness (Grant IDs: BFU2010- 15801, CSD-2007-00008), Junta de Andalucıa Regional Government (Grant ID: CVI-295), European Regional Development Funds, Wellcome Trust, Medical Research CouncilThis is the final version of the article. It first appeared from Wiley via http://dx.doi.org/10.1002/stem.249

Focused scores enable reliable discrimination of small differences in steatosis

Background: Automated image analysis enables quantitative measurement of steatosis in histological images. However, spatial heterogeneity of steatosis can make quantitative steatosis scores unreliable. To improve the reliability, we have developed novel scores that are “focused” on steatotic tissue areas. Methods: Focused scores use concepts of tile-based hotspot analysis in order to compute statistics about steatotic tissue areas in an objective way. We evaluated focused scores on three data sets of images of rodent liver sections exhibiting different amounts of dietary-induced steatosis. The same evaluation was conducted with the standard steatosis score computed by most image analysis methods. Results: The standard score reliably discriminated large differences in steatosis (intraclass correlation coefficient ICC = 0.86), but failed to discriminate small (ICC = 0.54) and very small (ICC = 0.14) differences. With an appropriate tile size, mean-based focused scores reliably discriminated large (ICC = 0.92), small (ICC = 0.86) and very small (ICC = 0.83) differences. Focused scores based on high percentiles showed promise in further improving the discrimination of very small differences (ICC = 0.93). Conclusions: Focused scores enable reliable discrimination of small differences in steatosis in histological images. They are conceptually simple and straightforward to use in research studies

Gene networks and transcription factor motifs defining the differentiation of stem cells into hepatocyte-like cells

Background & AimsThe differentiation of stem cells to hepatocyte-like cells (HLC) offers the perspective of unlimited supply of human hepatocytes. However, the degree of differentiation of HLC remains controversial. To obtain an unbiased characterization, we performed a transcriptomic study with HLC derived from human embryonic and induced stem cells (ESC, hiPSC) from three different laboratories.MethodsGenome-wide gene expression profiles of ESC and HLC were compared to freshly isolated and up to 14days cultivated primary human hepatocytes. Gene networks representing successful and failed hepatocyte differentiation, and the transcription factors involved in their regulation were identified.ResultsGene regulatory network analysis demonstrated that HLC represent a mixed cell type with features of liver, intestine, fibroblast and stem cells. The “unwanted” intestinal features were associated with KLF5 and CDX2 transcriptional networks. Cluster analysis identified highly correlated groups of genes associated with mature liver functions (n=1057) and downregulated proliferation associated genes (n=1562) that approach levels of primary hepatocytes. However, three further clusters containing 447, 101, and 505 genes failed to reach levels of hepatocytes. Key TF of two of these clusters include SOX11, FOXQ1, and YBX3. The third unsuccessful cluster, controlled by HNF1, CAR, FXR, and PXR, strongly overlaps with genes repressed in cultivated hepatocytes compared to freshly isolated hepatocytes, suggesting that current in vitro conditions lack stimuli required to maintain gene expression in hepatocytes, which consequently also explains a corresponding deficiency of HLC.ConclusionsThe present gene regulatory network approach identifies key transcription factors which require modulation to improve HLC differentiation

Cutting-Edge Topics in Research on Veterinary Sciences

We are pleased to announce the first edition of the SVU-International Journal of Veterinary Sciences (SVU-IJVS). We hope that this journal will advance the field of animal sciences and related biomedical disciplines. SVU-IJVS is particularly interested to publish any work –of a high quality-in the field of animal sciences. Beside conventional animal-related work, interdisciplinary articles i.e. medicine, biology, bioinformatics and mathematics which may not be published by the narrow windows journals, are highly appreciated in the SVU-IJVS. We hope that SVU-IJVS will play a positive role in this field of research

Perspectives Of Tissues In Silico

PubMe

Creation of Three-dimensional Liver Tissue Models from Experimental Images for Systems Medicine

PubMed-listedInternational audienceIn this chapter, we illustrate how three-dimensional liver tissue models can be created from experimental image modalities by utilizing a well-established processing chain of experiments, microscopic imaging, image processing, image analysis and model construction. We describe how key features of liver tissue architecture are quantified and translated into model parameterizations, and show how a systematic iteration of experiments and model simulations often leads to a better understanding of biological phenomena in systems biology and systems medicine

Detection of aflatoxin-producing fungi isolated from Nile Tilapia and fish feed

Contamination of fish by fungi and their mycotoxins poses major health concerns to human and animals. Therefore, our study was aimed to investigate Aspergillus flavus (A. flavus) infections and the levels of aflatoxins in Nile tilapia, Oreochromis niloticus (O. niloticus), and fish feed. Samples from O. niloticus and fish feed (n=25 for each) were randomly collected from private fish farms at Qena province, Egypt, during the winter season. Different Aspergillus spp. were detected in 60 % and 64 % of O. niloticus and fish feed, respectively. HPLC-based analysis revealed aflatoxin-producing activity in 75 % and 83 % of A. flavus isolates from fish and fish feed, respectively. While 96 % of O. niloticus muscles and fish feed samples were contaminated with aflatoxins, the detected levels were below the permissible limits, i.e. 20 μg/kg. Moreover, experimental infection with toxicogenic A. flavus isolates was conducted to evaluate their pathogenicity in O. niloticus. Expectedly, experimental infections of O. niloticus with A. flavus were associated with several clinical symptoms reported in naturally infected fish, e.g. yellow coloration with skin ulceration, hemorrhagic ulcerative patches on gills and skin, corneal opacity, fin rot and abdominal distention. Furthermore, aflatoxicogenic A. flavus isolates from fish were sensitive to herbal clove oil.Even though the measured levels of aflatoxin were below permissible limits, effort should be placed on furtherreduction of exposure to genotoxic and carcinogenic mycotoxins