HEMETβ: improvement of hepatocyte metabolism mathematical model

Cytotoxic and genotoxic properties of silver nanoparticles synthesized by ethanolic extract of Salacia chinensis

In this study, in vitro and in vivo methods were used to evaluate the cytotoxicity and genotoxicity properties of silver nanoparticles (Ag-NPs) made from a crude ethanolic extract of Salacia chinensis. The test Ag-NPs had no cytotoxicity on the fibroblast cell line at a concentration of 100 μg/mL, according to the MTT assay results. The Chinese hamster ovary (CHO) cell line treated with varied concentrations of test Ag-NPs, with a maximum concentration of 200 μg/mL, did not exhibit any appreciable genotoxic activity, either by comparing the results with positive controls of genotoxicity caused by Methyl methane sulfonate and Benzo (a) pyrene at the concentration of 20 μg/mL, the lack of genotoxicity was established. An in vivo study in Swiss albino mice using various concentrations (250, 500, and 1000 mg/kg) of test Ag-NPs, which were compared with positive controls, further confirmed this in vitro result pattern. Contrary to the genotoxicity caused by the positive control, mouse bone marrow micronucleus testing findings revealed the absence of genotoxicity. These findings imply that at the measured doses, the Ag-NPs produced from the crude ethanolic extract of Salacia chinensis do not exhibit any cytotoxicity or genotoxicity.

Succinate aggravates NAFLD progression to liver cancer on the onset of obesity: An in silico model

The incidence and prevalence of nonalcoholic fatty liver disease (NAFLD) have been increasing to epidemic proportions around the world. NAFLD, a chronic liver disease that affects the nondrinkers, is mainly associated with steatohepatitis and cirrhosis. The progression of NAFLD associated with obesity increases the risk of liver cancer, a disease with poor outcomes and limited therapeutic options. In order to investigate the underlying cellular dynamics leading to NAFLD progression towards cancer on the onset of obesity, we have integrated human hepatocyte pathway with hypoxia-inducible factor1- <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mi>α</mml:mi></mml:math> (HIF1- <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mi>α</mml:mi></mml:math> ) signaling pathway using state space model based on classical control theory. Modified Michaelis-Menten equation and mass action law have been used to define flux vectors of the proposed model. We have incorporated feedback inhibition/activation and allosteric effects into the simulink-based model. The values of kinetic constants have been taken from the literature. It is found that on the onset of obesity, HIF1- <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mi>α</mml:mi></mml:math> -induced proteins stabilize approximately 62 times that in the case of a normal cell. Consequently, the HIF1- <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mi>α</mml:mi></mml:math> -induced proteins enhance the enzymatic activities of hexokinase (HK), phosphofructo kinase (PFK), lactate dehydrogenase (LDH), and pyruvate dehydrogenase (PDH), which induce Warburg effect promoting an environment suitable for cancer cells.

In vitro lifespan and senescent behaviour of human periosteal derived stem cells

Periosteum derived progenitor cells (PDPCs) represent promising mesenchymal stem cells (MSCs) for skeletal regeneration and to test bone cell based tissue engineering strategies. Most of regenerative medicine approaches based on MSCs require a noteworthy amount of cells that must be expanded in vitro prior to their use. As culture expansion method may impact on cell behaviour, we assessed the replicative and metabolic capacity (nitric oxide production and glucose consumption), senescence hallmarks of PDPCs serially passaged as well as the expression of selected genes specifically related to early osteoblastic differentiation, bone remodelling and stemness during PDPC sequential passaging. We also scouted a Systems Biology approach to examine and elucidate the experimental results through mathematical modelling and in silico simulations. PDPC subculture led to a progressive proliferative decline but, despite this, PDPCs maintained almost constant their metabolic activity. In vitro, senescent PDPCs displayed the typical "replicative senescence" features, involving p16 and not p53 in the regulation of this phenomenon. Gene expression analysis evidenced the tendency of sub-cultured PDPCs to increase the expression of genes involved in bone resorption. The mathematical analysis of the experimental results showed a strict similarity between replicative senescence and age-related changes, enabling the definition of an in silico model mimicking PDPC behaviour in terms of nitric oxide (NO) production. The relationship between NO production and subculture passages could represent a cutting edge "replicative senescence index". Overall, our findings suggest the possibility to use early-passage PDPCs for bone regenerative approaches based on the local recruitment of stem cells, whilst the later cell passages could be a suitable in vitro tool to validate scaffolds intended for bone regeneration in elderly subjects.

In silico models for dynamic connected cell cultures mimicking hepatocyte-endothelial cell-adipocyte interaction circle

The biochemistry of a system made up of three kinds of cell is virtually impossible to work out without the use of in silico models. Here, we deal with homeostatic balance phenomena from a metabolic point of view and we present a new computational model merging three single-cell models, already available from our research group: the first model reproduced the metabolic behaviour of a hepatocyte, the second one represented an endothelial cell, and the third one described an adipocyte. Multiple interconnections were created among these three models in order to mimic the main physiological interactions that are known for the examined cell phenotypes. The ultimate aim was to recreate the accomplishment of the homeostatic balance as it was observed for an in vitro connected three-culture system concerning glucose and lipid metabolism in the presence of the medium flow. The whole model was based on a modular approach and on a set of nonlinear differential equations implemented in Simulink, applying Michaelis-Menten kinetic laws and some energy balance considerations to the studied metabolic pathways. Our in silico model was then validated against experimental datasets coming from literature about the cited in vitro model. The agreement between simulated and experimental results was good and the behaviour of the connected culture system was reproduced through an adequate parameter evaluation. The developed model may help other researchers to investigate further about integrated metabolism and the regulation mechanisms underlying the physiological homeostasis.

CREPE: mathematical model for crosstalking of endothelial cells and hepatocyte metabolism

The liver shows a close coexistence between endothelial cells and hepatocytes (HepG2). Endothelial cells' main purpose is to protect (HepG2) from blood vessel shear stress, acting as a barrier, but experimental evidence suggests that they could also play a role in regulating (HepG2) glucose metabolism. A well-known singular effect in hepatocyte-endothelial co-cultures is the reduction of glucose consumption respect to (HepG2) in single culture. (HepG2) were shown to reduce their glucose consumption supporting energy needs of endothelial cells. Monti have studied the effects of endothelin-1 (Et-1) on Glucokinase activity in adult rat (HepG2). They observed a reduction in hepatocytes Glucokinase catalytic rate, which is dependent on Et-1 concentration. We developed crosstalking of endothelial cells and hepatocyte metabolism (CREPE) that is a mathematical model of the endothelin-1 mediated crosstalk between HepG2 and endothelial cells (human umbilical vein endothelial cells) in a traditional static co-culture system. CREPE was validated against experimental data, showing good agreement with them. CREPE can be a starting point to develop predictive tools on complex and highly interconnected environments.