Pituitary organoids : tools to characterize pituitary development, plasticity and pathologies ?

Abstract

The pituitary gland, the master gland of the body, occupies a central place in the endocrine system. Composed of an anterior lobe responsible for hormone synthesis (adenohypophysis) and a posterior lobe with a nervous structure (neurohypophysis), it receives hormonal information from the hypothalamus, peripheral organs and its own cells, allowing it to regulate the major physiological functions such as growth, metabolism, reproduction or stress. Consisting of several cell types, each dedicated to a main function, the anterior pituitary must adapt its hormonal secretions according to the physiological demand or changes in its microenvironment related to contextual or pathological causes. For that, it shows a great plasticity involving changes in the number or the identity of the secreting cells. Stem/progenitor cells present in the adult tissue could be involved. The mechanisms underlying this plasticity are poorly understood. In order to clarify them, in vitro systems such as organoids capable of mimicking tissue architectural structure and function offer an interesting opportunity. They also allow to understand pituitary dysfunctions and to consider therapeutic approaches in humans and farm animals. In addition, their use contributes to the 3Rs principle for experimental approaches: replace, reduce and refine. Although current pituitary models are mainly developed in humans and rodents, their implementation in species of agronomic interest represents an important issue. The objective of this review is to provide an update on the studies aimed at developing pituitary organoid models by assessing their advantages and disadvantages. First, anterior pituitary histology and embryonic development as well pituitary plasticity to adapt to variations in its environment will be described.