Generation of functional thyroid from embryonic stem cells

Abstract

The primary function of thyroid gland is to metabolize iodide by synthesizing thyroid hormones that are critical regulators of growth, development and metabolism in virtually all tissues. To date, research on thyroid morphogenesis was missing an efficient stem-cell model system which allows to recapitulate in vitro the molecular and morphogenic events regulating thyroid follicular cells differentiation and subsequent assembly into functional thyroid follicles. Here we report that a transient overexpression of the transcription factors NKX2.1 and PAX8 is sufficient to direct mouse embryonic stem-cells (mESC) differentiation into thyroid follicular cells which organized into three-dimensional follicular structures when treated with thyrotropin. Those in vitro derived follicles showed significant iodide organification activity. Importantly, when grafted in vivo into athyreoid mice, these follicles rescued thyroid hormone plasma levels and promoted subsequent symptomatic recovery. Thus, mESC can be induced to differentiate into thyroid follicular cells in vitro and generate functional thyroid tissue.

Differential Expression of Extracellular Matrix and Growth Factors by Embryoid Bodies in Hydrodynamic and Static Cultures

“…4,19,20 A number of different methods for EB formation and differentiation exist, with recent improvements in controlled EB formation and maintenance of uniform sizes achieved by microtechnologies alone or in combination with hydrodynamic culture systems. 13,21,22 Regardless of the specific methods used, EBs generally exhibit a similar loss of pluripotent markers before progressive expression of differentiated phenotypes is observed.…”

The transcriptional regulation of pluripotency

“…Most remarkably, it was recently demonstrated that pluripotent stem cells retain a self-organising ability to differentiate into 3D organoids, which resemble optic cups [142,143] and adenohypophysis tissues [144]. Similarly, intestinal organoids have been reported to develop from hESC-derived posterior endoderm monolayers upon exposure to the appropriate signalling factors [145], and functional thyroid gland tissue has been generated from mESCs [146]. Therefore, if one were to harness this powerful self-developing property of pluripotent stem cells for the generation of novel complex organ types for research or medical purposes, it would be important to first determine the mechanisms underlying these processes.…”

Normal vs cancer thyroid stem cells: the road to transformation

“…After treatment with TSH, these cells showed molecular, morphological and functional characteristics of thyroid follicles and were able to fulfil thyroid hormone deficits when transplanted orthotopically into an immunodeficient mouse. 33 Pax-8 and TTF-1 co-expression is therefore required for assembling the follicular cells into becoming a follicle-like structure, as recently confirmed. 38 Longmire et al demonstrated that the presence of activin A led ESCs to differentiate into definitive endoderm, expressing forkhead box protein A2 (Foxa2 + ).…”

“…31,32 As discussed below, the co-expression of TTF-1 and Pax-8, is an essential event for cell commitment towards follicular cell fate. 33 While, FGF and bone morphogenetic protein (BMP) signalling pathways act in the early stages of thyroid development 34 before TSH/TSH-R and IGF/insulin signalling that promote the full differentiation of follicular cells ( Figure 4 and Table 1). 35 In order to identify early and late markers of thyroid development, several studies are being carried out using mouse ESCs as a source of in vitro differentiating thyrocytes.…”

“…33 In particular, the simultaneous ectopic expression of TTF-1 and Pax-8 induced the in vitro differentiation of mouse ESCs into follicular cells. After treatment with TSH, these cells showed molecular, morphological and functional characteristics of thyroid follicles and were able to fulfil thyroid hormone deficits when transplanted orthotopically into an immunodeficient mouse.…”