Endocrine Abstracts

Cell culture models are widely used to evaluate different facets of whole-organ biology, including mechanisms of organ function and consequences of genetic perturbation or pharmacological modulation. The thyroid is a complex organ, consisting of polarized thyrocytes organized into follicular structures with a clear distinction in membrane protein expression between the apical and basal aspect of the follicle. This cellular polarisation is essential for permitting uptake of Iodine and synthesis, storage and secretion of thyroid hormone. Under conditions of monolayer culture, primary thyrocytes may lose functional activity, and there is a lack of human thyrocyte cell lines that maintain sufficient differentiation for study of normal thyroid function. We have developed methodology for culturing three-dimensional, functionally active primary human thyroid follicles. Human thyrocytes are isolated from surgical thyroidectomy specimens by enzymatic digestion, these dissociated thyrocytes can then be suspended in a 3D-matrix. In this 3D culture system these cells spontaneously reorganise to form follicular structures, comparable to the organ niche, in contrast to a predominantly monolayer of cells in a 2D culture system. Direct comparison of the same cells cultured in 2D or 3D demonstrates increased mRNA expression of key indicators of thyroid function (SLC5A5, TG, TSHR) with appropriate response to TSH, preserved polarised expression of key thyroidal proteins and an increased cellular uptake of ¹²⁵I in the 3D cell culture system. Additionally, we have established that these structures are amenable to viral transduction and therefore future applications of this model can include genetic manipulation. Human thyrocytes also tolerate cryopreservation and recovery. Moreover, this methodology is equally applicable to culturing freshly isolated murine thyroid follicles. Thus, our paradigm represents an exciting tool for future evaluation of thyroid biology and function through manipulation of gene expression, pharmacological modulation and comparison of primary thyroid follicular cultures from relevant murine models and human primary cells.