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This article is the fourth in a series that was published in the eBook “3D Model Systems: Spheroids, Organoids and Tissue Models”. You can download all the articles in the series, by downloading the eBook.   Introduction and Overview Debbie King Researchers have used 2D cell culture since the early 1900s, but we know that growing cells on planar surfaces have some drawbacks. Cells grown in vitro in 2D space don’t behave like cells found in vivo. They lack critical cell-cell and cell-matrix interactions that drive their form, function and response to external stimuli. This limits their prognostic capabilities. More recently, 3D cell culture techniques have become popular because the cell morphology, interactions and tissue-specific architecture more closely resembles that of in vivo tissues. Spheroids, organoids and more complex 3D tissue systems, such as ‘organ-on-a-chip’ are examples of 3D cultures used by researchers to model native tissues. Spheroids are simple, widely used 3D models that form based on the tendency of adherent cells to aggregate and can be generated from many different cell types. The multicellular tumor spheroid model is widely used in cancer research. Organoids are more complex 3D aggregates, more like miniaturized and simplified versions of an organ. They can be tissue or stem cell-derived with the ability to self-organize spatially and demonstrate organ-specific functionality. More complex yet, are technologies like organ-on-a-chip, which is a multi-channel 3D microfluidic cell culture system that mimics whole organ function with artificial vasculature. Cells are cultured in continuously perfused micrometer-sized chambers that recreate physiologically relevant levels of fluidic sheer force to allow for gas, nutrient and waste transport to the cell just as is observed in vivo vascularized tissues. How are spheroids impacting cancer research and what do you see as future applications for the technology? Audrey Bergeron Spheroids can be an improved model for cancer in the lab compared to standard 2D cell culture. When cancer cells are cultured as spheroids, they are able to maintain the shape, polarity, genotype, and heterogeneity observed in vivo (1). This allows researchers to create models that are much more reflective of what’s going on in the body. For a simple example, if you think about drug penetration into a 2D monolayer of cells it’s completely different from drug penetration into a solid tumor. In a 2D monolayer each cell is exposed to the same concentration of drug whereas in a spheroid, like a solid tumor, there are gradients of drug exposure. More and more we’re seeing researchers move away from cancer cell lines and move more toward specialized cancer models such as patient derived models. The hope here is to find the appropriate therapies for each individual patient. (1) Antoni, D., Burckel, H., Josset, E., & Noel, G. (2015). Three-dimensional cell culture: a breakthrough in vivo. International journal of molecular sciences, 16(3), 5517–5527. doi:10.3390/ijms16035517. What tools and technologies are needed to fully realize the potential of spheroid culture models? Debbie King One of the key parameters for success with spheroid culture is controlling the size of the spheroids. It can be very difficult to get consistent, reproducible results if the starting spheroid culture is not uniform in size and shape. Cell culture tools available on the market now, such as ultra-low attachment plates, facilitate the formation of uniformly sized spheroids for many research applications from low to high throughput modalities. Hilary Sherman There always needs to be a little bit of a balance between throughput and complexity in terms of creating models for research. That’s why there are so many options available for 3D research. Low attachment products such as Corning® spheroid microplate and Eplasia® plates are great for creating high throughput 3D models,