Dawn of the organoid era

Novel and updated approaches of culturing cells in 3D are rapidly advancing our understanding of development, health, and disease. As tissues have been found to behave more realistically in 3D than in 2D cultures, organoid technology in combination with recent advances in the isolation and generation of stem cells, has rapidly become a promising concept in developmental and regenerative research. The development of all kinds of tissues can now be studied “in a dish,” allowing more detailed observations of stem cell maintenance, morphogens, and differentiation. This review explores how organoids have revolutionized academic research over the last 4 decades, and how they may continue to do so. It also addresses remaining hurdles in 3D cell culturing, and how they may be overcome. Allowing stem cells to grow and divide free from the constraints of flat surfaces (so‐called 3D cultures) often results in the activation of self‐organizing principles and the formation of so‐called organoids. These serve as model systems to study morphogenesis, neoplasia, and congenital diseases, for drug testing and as a source for transplantation and regeneration.