A Mathematical Model of Liver Cell Aggregation In Vitro

The behavior of mammalian cells within three-dimensional structures is an area of intense biological research and underpins the efforts of tissue engineers to regenerate human tissues for clinical applications. In the particular case of hepatocytes (liver cells), the formation of spheroidal multicellular aggregates has been shown to improve cell viability and functionality compared to traditional monolayer culture techniques. We propose a simple mathematical model for the early stages of this aggregation process, when cell clusters form on the surface of the extracellular matrix (ECM) layer on which they are seeded. We focus on interactions between the cells and the viscoelastic ECM substrate. Governing equations for the cells, culture medium, and ECM are derived using the principles of mass and momentum balance. The model is then reduced to a system of four partial differential equations, which are investigated analytically and numerically. The model predicts that provided cells are seeded at a suitable density, aggregates with clearly defined boundaries and a spatially uniform cell density on the interior will form. While the mechanical properties of the ECM do not appear to have a significant effect, strong cell-ECM interactions can inhibit, or possibly prevent, the formation of aggregates. The paper concludes with a discussion of our key findings and suggestions for future work

The severity of Puumala hantavirus induced nephropathia epidemica can be better evaluated using plasma interleukin-6 than C-reactive protein determinations

<p>Abstract</p> <p>Background</p> <p>Nephropathia epidemica (NE) is a Scandinavian type of hemorrhagic fever with renal syndrome caused by Puumala hantavirus. The clinical course of the disease varies greatly in severity. The aim of the present study was to evaluate whether plasma C-reactive protein (CRP) and interleukin (IL)-6 levels associate with the severity of NE.</p> <p>Methods</p> <p>A prospectively collected cohort of 118 consecutive hospital-treated patients with acute serologically confirmed NE was examined. Plasma IL-6, CRP, and creatinine, as well as blood cell count and daily urinary protein excretion were measured on three consecutive days after admission. Plasma IL-6 and CRP levels higher than the median were considered high.</p> <p>Results</p> <p>We found that high IL-6 associated with most variables reflecting the severity of the disease. When compared to patients with low IL-6, patients with high IL-6 had higher maximum blood leukocyte count (11.9 <it>vs </it>9.0 × 10⁹/l, <it>P </it>= 0.001) and urinary protein excretion (2.51 <it>vs </it>1.68 g/day, <it>P </it>= 0.017), as well as a lower minimum blood platelet count (55 <it>vs </it>80 × 10⁹/l, <it>P </it>< 0.001), hematocrit (0.34 <it>vs </it>0.38, <it>P </it>= 0.001), and urinary output (1040 <it>vs </it>2180 ml/day, <it>P </it>< 0.001). They also stayed longer in hospital than patients with low IL-6 (8 <it>vs </it>6 days, <it>P </it>< 0.001). In contrast, high CRP did not associate with severe disease.</p> <p>Conclusions</p> <p>High plasma IL-6 concentrations associate with a clinically severe acute Puumala hantavirus infection, whereas high plasma CRP as such does not reflect the severity of the disease.</p

Frequent loss of endothelin-3 (EDN3) expression due to epigenetic inactivation in human breast cancer

Introduction: Endothelin (EDN) signalling plays a crucial role in cell differentiation, proliferation and migration processes. There is compelling evidence that altered EDN signalling is involved in carcinogenesis by modulating cell survival and promoting invasiveness. To date, most reports have focused on the oncogenic potential of EDN1 and EDN2, both of which are overexpressed in various tumour entities. Here, we aimed at a first comprehensive analysis on EDN3 expression and its implication in human breast cancer. Methods: EDN3 mRNA expression was assessed by Northern blotting in normal human tissues (n = 9) as well as in matched pairs of normal and tumourous tissues from breast specimens (n = 50). EDN3 mRNA expression in breast cancer was further validated by real-time polymerase chain reaction (PCR) (n = 77). A tissue microarray was used to study EDN3 protein expression in breast carcinoma (n = 150) and normal breast epithelium (n = 44). EDN3 promoter methylation was analysed by methylation-specific PCR in breast cell lines (n = 6) before and after demethylating treatment, normal breast tissues (n = 17) and primary breast carcinomas (n = 128). EDN3 expression and methylation data were statistically correlated with clinical patient characteristics and patient outcome. Results: Loss of EDN3 mRNA expression in breast cancer, as initially detected by array-based expression profiling, could be confirmed by Northern blot analysis (> 2-fold loss in 96%) and real-time PCR (> 2-fold loss in 78%). Attenuated EDN3 expression in breast carcinoma was also evident at the protein level (45%) in association with adverse patient outcome in univariate (P = 0.022) and multivariate (hazard ratio 2.0; P = 0.025) analyses. Hypermethylation of the EDN3 promoter could be identified as the predominant mechanism leading to gene silencing. Reversion of the epigenetic lock by 5-aza-2'-deoxycytidine and trichostatin A resulted in EDN3 mRNA reexpression in vitro. Furthermore, EDN3 promoter hypermethylation was detected in 70% of primary breast carcinomas with significant association to loss of EDN3 mRNA expression (P = 0.005), whilst normal matched breast tissues revealed no EDN3 promoter methylation. Conclusions EDN3 is a frequent target of epigenetic inactivation in human breast cancer, potentially contributing to imbalanced EDN signalling commonly found in this disease. The clinical implication supports the view that EDN3, in contrast to EDN1 and EDN2, may act as natural tumour suppressor in the human mammary gland

Erratum to: 36th International Symposium on Intensive Care and Emergency Medicine

[This corrects the article DOI: 10.1186/s13054-016-1208-6.]

Profiling the Impact of Medium Formulation on Morphology and Functionality of Primary Hepatocytes in vitro

The characterization of fully-defined in vitro hepatic culture systems requires testing of functional and morphological variables to obtain the optimal trophic support, particularly for cell therapeutics including bioartificial liver systems (BALs). Using serum-free fully-defined culture medium formulations, we measured synthetic, detoxification and metabolic variables of primary porcine hepatocytes (PPHs) - integrated these datasets using a defined scoring system and correlated this hepatocyte biological activity index (HBAI) with morphological parameters. Hepatic-specific functions exceeded those of both primary human hepatocytes (PHHs) and HepaRG cells, whilst retaining biotransformation potential and in vivo-like ultrastructural morphology, suggesting PPHs as a potential surrogate for PHHs in various biotech applications. The HBAI permits assessment of global functional capacity allowing the rational choice of optimal trophic support for a defined operational task (including BALs, hepatocellular transplantation, and cytochrome P450 (CYP450) drug metabolism studies), mitigates risk associated with sub-optimal culture systems, and reduces time and cost of research and therapeutic applications