2D and 3D cell cultures: what’s the difference?
2D cell culture remains the most common method of growing cells. Cells are seeded on flat surfaces (typically Petri dishes, flasks or plates), where supporting media encourages proliferation and cells grow in a monolayer (Figure 1). For many years, 2D cell culture has offered scientists a simple and low-cost method to maintain cells and perform experiments; such as testing cellular responses to drug candidates. However, in recent years, 3D cell culture techniques have caused quite a stir in the scientific community.
In contrast to 2D cell culture, cells in 3D cell culture can interact with their surroundings in all three dimensions. In 3D culture, cells often grow to form spheroids - cells that arrange themselves during proliferation into sphere-like formations (Figure 1). 3D cell cultures can be prepared using a support known as a scaffold which allows growth in all directions. Examples of scaffolds include hydrogels, polymeric hard materials, and hydrophilic glass fibre1. In scaffold-based 3D cultures using an extracellular matrix (ECM), cells are embedded into the matrix whereas hard polymer scaffolds can provide the physical support of a specialized tissue such as skin, tendons, or bones (Figure 1).
Scaffold-free approaches also exist and these rely on the self-aggregation of cells. One of the most well-known scaffold-free approaches is the hanging drop method; a technique that can be used both with and without specialist plates1,2. In this method, cells are encouraged to naturally form cellular aggregates, facilitated by gravitational and surface tension forces. In addition, bioreactors are increasingly used for large-scale cell culture. Examples of these include general bioreactors that are independent of a CO2 incubator, to alternative bioreactors, such as orbital shakers, spinner flasks, and rotating wall vessels3. All of which employ motion to prevent cells from adhering to surfaces, keeping cells and spheroids in solution (Figure 1).
2D and 3D cell cultures offer scientists a model platform for a wide range of applications. But, how do we know which one to choose?