Progress Toward and Challenges Remaining for Thyroid Tissue Regeneration.

Thyroid hormones play a pivotal role in diverse physiological processes, and insufficient synthesis of these hormones results in hypothyroidism, a prevalent disorder with a significant global impact. Research has shown that the residual thyroid tissue following surgery fails to fully regenerate the gland and restore normal function. The slow turnover rate of the thyroid gland and the presence of resident stem cells, which may contribute to regeneration within adult thyroid tissue, are topics of ongoing debate. This comprehensive review summarizes current research findings concerning the regeneration of the adult thyroid. Investigations have identified potential cellular mechanisms implicated in thyroid regeneration following partial tissue damage, including cells within microfollicles and a cluster of potential thyroid progenitors cells. Nevertheless, the exact mechanisms remain elusive. In cases of complete removal of the thyroid gland, regeneration does not occur, underscoring the necessity for an external source of thyroid tissue. The transplantation of thyroid organoids has emerged as a promising approach to restore thyroid function. Researchers have successfully derived thyroid organoids from various sources and demonstrated their functionality in both in vitro and in vivo animal models. Despite the challenges that still need to be addressed in achieving full maturation and functionality of human thyroid organoids, significant strides have been made in this regard. This review explores the potential of thyroid organoid transplantation and its implications for the field of regenerative medicine.