From stem cells to organoids in thyroid: Useful tools or a step for cell therapy?

Organoids are three-dimensional tissue cultures derived from stem cells. They replicate the complexity of different cell types in an organ and can survive in specific media. They also have the capacity to proliferate and self-renew. Thyroid organoids have now been established using a variety of cell sources, including murine or human embryonic stem cells, pluripotent stem cells, adult thyroid-derived stem cells, and even fetal thyroids. Experimental designs to obtain thyroid organoids depend on the originating cell types and whether a forced (transient or permanent) overexpression of two important transcription factors in thyroid development, Nkx2-1 and Pax8, has been used by lentiviral transduction. All cells are harvested in an extracellular membrane to achieve a three-dimensional cell culture. The development of strategies to obtain organoids has revealed the signaling pathways and growth factors that are essential for this type of culture, and which are also essential for thyroid development. The development of thyroid organoids has facilitated a deeper understanding of the key factors and stages involved in the differentiation of stem cells into thyroid follicular cells. Furthermore, they have demonstrated utility as a model for pathology, such as Graves' disease. Insights regarding other thyroidal pathologies will likely emerge in the future. Furthermore, thyroid organoids have demonstrated their potential for regenerative medicine, a promising but not yet fully efficient technology for treating definitive hypothyroidism.