Diverse regulations of albumin gene expression by hepatocyte growth factor in HepG2 human hepatoma cells and primary culture of rat hepatocytes

Molecular mechanisms underlying antiproliferative and differentiating responses of hepatocarcinoma cells to subthermal electric stimulation

Capacitive Resistive Electric Transfer (CRET) therapy applies currents of 0.4–0.6 MHz to treatment of inflammatory and musculoskeletal injuries. Previous studies have shown that intermittent exposure to CRET currents at subthermal doses exert cytotoxic or antiproliferative effects in human neuroblastoma or hepatocarcinoma cells, respectively. It has been proposed that such effects would be mediated by cell cycle arrest and by changes in the expression of cyclins and cyclin-dependent kinase inhibitors. The present work focuses on the study of the molecular mechanisms involved in CRET-induced cytostasis and investigates the possibility that the cellular response to the treatment extends to other phenomena, including induction of apoptosis and/or of changes in the differentiation stage of hepatocarcinoma cells. The obtained results show that the reported antiproliferative action of intermittent stimulation (5 m On/4 h Off) with 0.57 MHz, sine wave signal at a current density of 50 µA/mm², could be mediated by significant increase of the apoptotic rate as well as significant changes in the expression of proteins p53 and Bcl-2. The results also revealed a significantly decreased expression of alpha-fetoprotein in the treated samples, which, together with an increased concentration of albumin released into the medium by the stimulated cells, can be interpreted as evidence of a transient cytodifferentiating response elicited by the current. The fact that this type of electrical stimulation is capable of promoting both, differentiation and cell cycle arrest in human cancer cells, is of potential interest for a possible extension of the applications of CRET therapy towards the field of oncology.

Use of perfluorocarbons to enhance the performance of perfused three-dimensional hepatic cultures

Bioartificial liver devices (BALs) are extracorporeal systems designed to temporarily bridge patients until a suitable donated liver is available for transplantation and also have value for pharmaceutical testing applications. Yet critical issues exist that limit the functional performance of their current designs. One of these concerns scale up issues connected to oxygen (O2 ) delivery to the cells housed within their three-dimensional (3D) configurations, and its consequences to device performance. As primary blood substitute candidates with extraordinarily high O2 capacity, perfluorocarbons (PFCs) offer hope as one strategy for addressing the O2 delivery issue encountered when scaling up the tissue space of current BAL designs. This study utilizes a PFC-based second-generation O2 carrier OXYCYTE®, as an additive to regular nutrient medium, for augmenting O2 delivery in a customized 3D tissue assembly system. The results demonstrate that the addition of PFCs significantly increases the O2 capacity of regular medium and that net cytochrome P450 activity levels are considerably increased under flow in PFC-treated systems, as compared to controls. This work thus clarifies the benefits of using PFCs to enhance the functional performance of 3D liver systems.