Intervertebral disc (IVD) degeneration is highly associated with lower back pain. Current treatment methods can be invasive and are often ineffective, which has led to research focused on developing non-invasive regenerative cell and biological therapies. Current studies are often performed in culture systems that fail to model the in vivo nutrient microenvironment; IVD cell metabolism can vary widely under different nutrient conditions. Therefore, the goal of this project is to design a continuous feed 3D cell culture bioreactor, to maintain steady state concentrations of nutrients at realistic levels.
The main factors considered for the design of the bioreactor were: reusable, sterile materials; method of controlling overall volume; size of alginate beads; and cell density. We designed a system that uses a multichannel peristaltic pump at 1 mL/min into a 50 mL autoclavable glass container with a rubber stopper containing ports for the input and output of media. The glucose consumption, an indicator of cell metabolism, can be calculated as half the amount of lactic acid produced.
The overall design of the bioreactor can maintain steady state flow within the flask. Future design of this system would integrate continuous sampling. Use of a multichannel peristaltic pump will allow for multiple factors to be tested at the same time.
The cell viability throughout the 3D culturing process has significantly decreased after each step of the gel bead making process. The 3D culturing process contains several steps throughout the process where viability was significantly decreased. Future investigation will be required to maintain viability throughout and after the culturing process. Several factors, including pH, osmolarity, and shear stress were investigated as determinants of cell viability. It was found that pH has the largest impact on cell viability. An efficient design of this overall bioreactor will create a more accurate method to grow and test IVD cells in future studies.