Modeling and Real-Time Simulation of a Vascularized Liver Tissue

International audienceIn Europe only, about 100,000 deaths per year are related to cirrhosis or liver cancer. While surgery remains the option that offers the foremost success rate against such pathologies, several limitations still hinder its widespread development. Among the limiting factors is the lack of accurate planning systems, which has been a motivation for several recent works, aiming at better resection planning and training systems, relying on pre-operative imaging, anatomical and biomechanical modelling. While the vascular network in the liver plays a key role in defining the operative strategy, its influence at a biomechanical level has not been taken into account. In the paper we propose a real-time model of vascularized organs such as the liver. The model takes into account separate constitutive laws for the parenchyma and vessels, and defines a coupling mechanism between these two entities. In the evaluation section, we present results of in vitro porcine liver experiments that indicate a significant influence of vascular structures on the mechanical behaviour of tissue. We confirm the val- ues obtained in the experiments by computer simulation using standard FEM. Finally, we show that the conventional modelling approach can be efficiently approximated with the proposed composite model capable of real-time calculations

Persistent left superior vena cava: Review of the literature, clinical implications, and relevance of alterations in thoracic central venous anatomy as pertaining to the general principles of central venous access device placement and venography in cancer patients

Persistent left superior vena cava (PLSVC) represents the most common congenital venous anomaly of the thoracic systemic venous return, occurring in 0.3% to 0.5% of individuals in the general population, and in up to 12% of individuals with other documented congential heart abnormalities. In this regard, there is very little in the literature that specifically addresses the potential importance of the incidental finding of PLSVC to surgeons, interventional radiologists, and other physicians actively involved in central venous access device placement in cancer patients. In the current review, we have attempted to comprehensively evaluate the available literature regarding PLSVC. Additionally, we have discussed the clinical implications and relevance of such congenital aberrancies, as well as of treatment-induced or disease-induced alterations in the anatomy of the thoracic central venous system, as they pertain to the general principles of successful placement of central venous access devices in cancer patients. Specifically regarding PLSVC, it is critical to recognize its presence during attempted central venous access device placement and to fully characterize the pattern of cardiac venous return (i.e., to the right atrium or to the left atrium) in any patient suspected of PLSVC prior to initiation of use of their central venous access device

Designing an Algal Co-culture System for Increased Sustainability in Cellular Agriculture

The global demand for meat is expected to double in the next half-century, but current meat production practices pose significant hazards to the environment and human health. The emerging field of cellular agriculture has the potential to solve problems associated with traditional animal agriculture by culturing animal products in vitro. Cellular agriculture is potentially more environmentally sustainable, but there are hurdles to overcome in large-scale production. Cell culture media is the nutrient solution in which the cells are grown and is a limiting factor in the cost and environmental impact of large-scale cellular agriculture. There is a need to extend the lifetime of the media by removing metabolic waste products and replenishing the media with nutrients. This would reduce media-associated costs, water usage, and energy usage of the system. This project aimed to create a co-culture system of primary bovine satellite cells (PBSCs) and the microalga, Chlamydomonas reinhardtii, to extend the media lifetime and improve the sustainability of large-scale cellular agriculture. The success of this system was assessed by collecting data on dissolved oxygen concentrations, culture pH, and cell proliferation and viability. The data suggest that PBSCs can remain viable in co-culture with C. reinhardtii and that the system increases dissolved oxygen and buffers the pH drop normally observed in animal cell culture. In a 200:1 ratio of C. reinhardtii to PBSCs grown in hypoxic conditions, the PBSCs were able to undergo one doubling in three days. Based on the pH data, the media lifetime was extended by 85%. This system should be further explored to optimize the media recycling potential of C. reinhardtii co-cultures