Formation of Spheroids via Spinner Flask Culture 

This rendering depicts stem cell aggregates (spheroids) forming within a spinner flask for scale-up processes. We typically make spheroids by aggregating cells into micro-sized bins; however, this process is limited in scalability and require larger, more regulated strategies. Spinner flask cultures enable the user to easily inoculate cells that can divide and multiple rapidly due to the dynamic mixing of nutrients compared to a static condition. With time, these cells will eventually find each other and collide. If lucky, they stick together and this process continues until a spheroid is formed. This is a scalable method for spheroid culture that is currently used in industry and some academic labs. Sartorius is a very commonly used "spinner flask" company but at these scales that are typically called bioreactors.