(11b) Modeling Flow Patterns and Nutrient Consumption in Three-Dimensional Bioreactors for Tissue Engineering

The objective of this research is to explore the flow regimes in 3D simulations representative of the human bladder for future considerations in applications of tissue engineered materials. At present there are only two approaches to investigate the viability of biomaterials for applications: animal testing and ?external to body' laboratory experiments. While each method has merits, they also have disadvantages. Animal testing for example is expensive, requires long periods of dead time before results are obtained, and typical results vary widely, even in ideal experiments. External to body laboratory experiments often fail to capture complexity of biological systems, and are often limited to testing of material properties. This work explores the potential of modeling and simulating biological and tissue engineering systems, as a method to begin understanding and designing potential applications in the field of tissue engineering. At this time, there are two primary applications of modeling as a design tool in the field. First, a biological system can be modeled to determine the chemical and physical conditions a graft will experience, and the properties that tissue engineered materials must exhibit in order to function properly. Second, simulations can be used to determine the effectiveness of proposed materials under known body conditions. The benefits of simulation are that it is relatively inexpensive and fast, meaning that a multitude of simulations under multiple conditions can be performed in a short time at a low cost. If it can be shown that models agree with the behavior observed in an animal or experimental system, then much time and money can be saved by using simulations to quickly and easily test the potential of various biocompatible materials. The specific goal of the project was to characterize and better understand the flow system in the human bladder. First, data and information collected from previous research allowed representative 3D simulation models to be constructed. The geometry of the bladder must be accurately represented; with appropriate physical and chemical compositions and properties for the bladder as well as the fluid flowing within the vessel. With these models we simulated flow profiles; obtaining information about velocity, pressure, and shear stress, particularly at solid/fluid interfaces. These flow simulation results were then moved forward additional steps to characterize two types of flow systems. First, in a representation of a functioning human bladder and second a similar system which might be physically suitable as a medium for growing a tissue scaffold for an artificial bladder. Simulations of biologically active systems can be accurately modeled and provide an additional tool for tissue engineering as supplements to experimental laboratory work and animal testing in identifying the potentials and suitability of bio-materials for biological applications.