Functional properties of human thyroid follicles cultured within collagen gel

Optimizing SH-SY5Y cell culture: exploring the beneficial effects of an alternative media supplement on cell proliferation and viability

In the quest to unravel the mysteries of neurological diseases, comprehending the underlying mechanisms is supreme. The SH-SY5Y human neuroblastoma cell line serves as a crucial tool in this endeavor; however, the cells are known for its sensitivity and slow proliferation rates. Typically, this cell line is cultured with 10% Fetal Bovine Serum (FBS) supplement. Nu-Serum (NuS), a low-protein alternative to FBS, is promising to advance cell culture practices. Herein, we evaluated the substitution of NuS for FBS to test the hypothesis that an alternative serum supplement can aid and promote SH-SY5Y cell proliferation and differentiation. Our findings revealed that the NuS-supplemented group exhibited a notable increase in adhered cells compared to both the FBS and serum-free (SF) groups. Importantly, cell viability remained high in both sera treated groups, with the NuS-supplemented cells displaying significantly larger cell sizes compared to the SF-treated group. Furthermore, cell proliferation rates were higher in the NuS-treated group, and neuroblast-like morphology was observed earlier than FBS group. Notably, both FBS and NuS supported the differentiation of these cells into mature neurons. Our data supports NuS as an alternative for SH-SY5Y cell culture, with the potential to elevate the quality of research in the neuroscience field.

Engineering a functional thyroid as a potential therapeutic substitute for hypothyroidism treatment: A systematic review

Background

Hypothyroidism is a common hormone deficiency disorder. Although hormone supplemental therapy can be easily performed by daily levothyroxine administration, a proportion of patients suffer from persisting complaints due to unbalanced hormone levels, leaving room for new therapeutic strategies, such as tissue engineering and regenerative medicine.

Methods

Electronic searches of databases for studies of thyroid regeneration or thyroid organoids were performed. A systematic review including both in vitro and in vivo models of thyroid regenerative medicine was conducted.

Results

Sixty-six independent studies published between 1959 and May 1st, 2022 were included in the current systematic review. Among these 66 studies, the most commonly involved species was human (19 studies), followed by mouse (18 studies), swine (14 studies), rat (13 studies), calf/bovine (4 studies), sheep/lamb (4 studies) and chick (1 study). In addition, in these experiments, the most frequently utilized tissue source was adult thyroid tissue (46 studies), followed by embryonic stem cells (ESCs)/pluripotent stem cells (iPSCs) (10 studies), rat thyroid cell lines (7 studies), embryonic thyroid tissue (2 studies) and newborn or fetal thyroid tissue (2 studies). Sixty-three studies reported relevant thyroid follicular regeneration experiments in vitro, while 21 studies showed an in vivo experiment section that included transplanting engineered thyroid tissue into recipients. Together, 12 studies were carried out using 2D structures, while 50 studies constructed 3D structures.

Conclusions

Each aspect of thyroid regenerative medicine was comprehensively described in this review. The recovery of optimal hormonal equilibrium by the transplantation of an engineered functional thyroid holds great therapeutic promise.

Thyroid Gland Organoids: Current models and insights for application in tissue engineering

The incidence of treatment of thyroid disease and consequential hypothyroidism has been increasing over the past few years. To maintain adequate thyroid hormone levels, these patients require daily supplementation with levothyroxine (L-T4) for the rest of their lives. However, a large part of these patients experiences difficulties due to the medication, which causes a decrease in their quality of life. Regenerative medicine through tissue engineering could provide a potential therapy by establishing tissue engineering models, such as those employing thyroid-derived organoids. The development of such treatment options may replace the need for additional hormonal replacement therapy. This review aims to highlight the current knowledge on thyroid regenerative medicine using organoids for tissue engineering, and to discuss insights into potential methods to optimize thyroid engineering culture systems. Finally, we will describe several challenges faced when utilising these models.

Stem Cells for Next Level Toxicity Testing in the 21st Century

The call for a paradigm change in toxicology from the United States National Research Council in 2007 initiates awareness for the invention and use of human-relevant alternative methods for toxicological hazard assessment. Simple 2D in vitro systems may serve as first screening tools, however, recent developments infer the need for more complex, multicellular organotypic models, which are superior in mimicking the complexity of human organs. In this review article most critical organs for toxicity assessment, i.e., skin, brain, thyroid system, lung, heart, liver, kidney, and intestine are discussed with regards to their functions in health and disease. Embracing the manifold modes-of-action how xenobiotic compounds can interfere with physiological organ functions and cause toxicity, the need for translation of such multifaceted organ features into the dish seems obvious. Currently used in vitro methods for toxicological applications and ongoing developments not yet arrived in toxicity testing are discussed, especially highlighting the potential of models based on embryonic stem cells and induced pluripotent stem cells of human origin. Finally, the application of innovative technologies like organs-on-a-chip and genome editing point toward a toxicological paradigm change moves into action.

Development of an In Vitro Human Thyroid Microtissue Model for Chemical Screening

Thyroid hormones (TH) are essential for regulating a number of diverse physiological processes required for normal growth, development, and metabolism. The US EPA Endocrine Disruptor Screening Program (EDSP) has identified several molecular thyroid targets relevant to hormone synthesis dynamics that have been adapted to high-throughput screening (HTS) assays to rapidly evaluate the ToxCast/Tox21 chemical inventories for potential thyroid disrupting chemicals (TDCs). The uncertainty surrounding the specificity of active chemicals identified in these screens and the relevance to phenotypic effects on in vivo human TH synthesis are notable data gaps for hazard identification of TDCs. The objective of this study was to develop a medium-throughput organotypic screening assay comprised of reconstructed human thyroid microtissues to quantitatively evaluate the disruptive effects of chemicals on TH production and secretion. Primary human thyroid cells procured from qualified euthyroid donors were analyzed for retention of NK2 homeobox 1 (NKX2-1), Keratin 7 (KRT7), and Thyroglobulin (TG) protein expression by high-content image analysis to verify enrichment of follicular epithelial cells. A direct comparison of 2-dimensional (2D) and 3-dimensional (3D) 96-well culture formats was employed to characterize the morphology, differential gene expression, TG production, and TH synthesis over the course of 20 days. The results indicate that modeling human thyroid cells in the 3D format was sufficient to restore TH synthesis not observed in the 2D culture format. Inhibition of TH synthesis in an optimized 3D culture format was demonstrated with reference chemicals for key molecular targets within the thyroid gland. Implementation of the assay may prove useful for interpreting phenotypic effects of candidate TDCs identified by HTS efforts currently underway in the EDSP.

Preparation and culture of a serum-free human thyroid follicle system and its application for measuring thyroid hormone secretion, iodide uptake and organification, cyclic adenosine monophosphate formation, gene expression, and cell growth

We describe a system of human thyroid follicles cultured in collagen suspended in serum-free medium. The method allows measurement of thyroid hormone secretion, iodide uptake and organification, cyclic adenosine monophosphate (cAMP) formation, gene expression, as well as cell growth. The system is superior to follicles freely suspended in cultured medium and also, as demonstrated by parallel experiments, to monolayer culture systems. A detailed description of the optimal conditions of the method is provided that, over a period of 8 years, has proven to be a powerful tool for measuring thyroid cell function, gene expression and cell proliferation.

Long-term culture of human pancreatic islets in an extracellular matrix: morphological and metabolic effects

In this experiment, various conditions for embedding cultures of human pancreatic islets in type I collagen gel were studied in an attempt to maintain the highly differentiated functions of islet cells and particularly insulin secretion over a long period of time. The islets isolated by a collagenase digestion technique were plated either on or within the collagen gel and refed with either Eagle's minimum essential medium (5.5 mM D-glucose) or RPMI 1640 medium (11 mM D-glucose) supplemented with 10% FCS and antibiotics. The comparison between the two culture media showed that embedded islets cultured in RPMI had a higher basal insulin secretion rate, survived longer than their MEM counterparts, but exhibited impaired response to an acute glucose test contrasting thus with islets cultured in MEM. The secretory behaviour of islets was also related to the different morphological modifications occurring during culture. Islets directly embedded within the collagen gel more or less maintained their spherical structure and highest secretory capacities. When overlaid with a second layer of collagen, well established monolayers of human islet cells grown on collagen underwent a gradual and complete reorganization into a three-dimensional islet-like structure with a striking reinforcement of their secretory activity. Both cultures were able to survive more than 8 weeks, thus proving the usefulness of such a new model for long-term culture. In contrast, standard cultures on culture treated plastic dishes on which islets cells rapidly established wide monolayers, exhibited a rapid and definitive decline in insulin secretion with a survival not exceeding 14 days. In the light of these different culture conditions, possible mechanisms responsible for disturbance of hormonal release and their implications for in-vitro study of isolated islets functions are discussed. In conclusion, this work is a new example of the permissive effects of collagen matrices on the establishment or maintenance of tissue-like structures in vitro, suggesting the definition of a new model for the study of human pancreatic islets in long-term culture.

ATP, bradykinin, TRH and TSH activate the Ca(2+)-phosphatidylinositol cascade of human thyrocytes in primary culture

We have recently shown that adenosine triphosphate (ATP), bradykinin and thyrotropin-releasing hormone (THR) increase the ([Ca2+]i) of human thyrocytes in primary culture. We show here that these agents also stimulate the generation of [3H]-inositol monophosphate (IP1), inositol bisphosphate (IP2) and inositol trisphosphate (IP3). The stimulation of IP3 generation followed two distinct kinetics: it was sustained when the cells were triggered with ATP and transient when the response was elicited by TRH or bradykinin. In addition, we have shown that under the appropriate experimental conditions, high thyroid-stimulating hormone (TSH) concentrations were also able to stimulate human thyrocyte IP1, IP2 and IP3 accumulation and to increase their [Ca2+]i. These data suggest that ATP, bradykinin, TRH and high TSH concentrations activate the Ca(2+)-phosphatidylinositol cascade of human thyrocytes. Since this cascade plays a crucial role in the control of protein iodination, ATP, TRH and bradykinin could be important regulators of thyroid hormone synthesis in human thyrocytes.

Correlated morphological and functional study of isolated rat thyroid follicles in suspension culture

Rat thyroid follicles were isolated by collagenase digestion and cultured in suspension on agarose for 1-12 days with 0-0.1-1 mU/ml thyrotropin (TSH). After a 4 h exposure to Na125I they were processed for light and electron microscopy, autoradiography and biochemical analysis. Follicular 125I accumulation (A) and organification (PBI) were measured. Thyroglobulin (Tg) content of follicles and 125I-labelled amino acids in Tg were analyzed by high-performance liquid chromatography (HPLC). Without TSH, follicular lumina and cell polarity persisted. From day 3, the rough endoplasmic reticulum (RER) and ribosomes disappeared while autophagic vacuoles appeared: 125I accumulation and PBI were significantly reduced. From day 6, ultrastructural cell dedifferentiation occurred. At day 12, autoradiographic labelling was found over very few lumina; half of the 125I accumulated was still organified. With 1 mU TSH, follicles formed aggregates with narrow densely labelled lumina lined by tall cells. The RER was well developed up to day 12. 125I accumulation, PBI and iodothyronine (T3, T4) formation in Tg remained significantly higher than in follicles cultured without TSH, showing a transient decrease at days 6 and 9. Monoiodotyrosine/diiodotyrosine (MIT/DIT) and T3/T4 ratios in Tg were not modified, suggesting the persistence in the follicles of a significant iodine pool available for iodination. With 0.1 mU TSH, alterations of cell morphology and reduction of functional properties occurred later than without TSH. In the presence of TSH, morphological signs of new follicle formation were seen. These data demonstrate that closed follicles keep their follicular structure up to 12 days of culture, even without TSH. However, TSH is necessary to maintain iodine accumulation and organification.

Adenosine triphosphate, bradykinin, and thyrotropin-releasing hormone regulate the intracellular Ca2+ concentration and the 45Ca2+ efflux of human thyrocytes in primary culture

The hormonal stimulation of phospholipase C and the consequent activation of the Ca2+-phosphatidylinositol cascade in eukaryotic cells is associated with modifications of the [Ca2+]i (intracellular Ca2+ concentration) which modulates cellular functions. In this study, these modifications were investigated in primary cultures of human thyroid cells. The mean apparent basal [Ca2+]i of human thyrocytes measured using the intracellularly trapped fluorescent indicator Quin-2 was found to be 89 +/- 16 nM (n = 49). ATP and, to a lesser extent, ADP, but not AMP or adenosine, elicited a concentration-dependent biphasic rise in human thyrocytes [Ca2+]i and increased their 45Ca2+ efflux. The first transient phase of the [Ca2+]i rise induced by ATP was resistant to extracellular Ca2+ depletion, whereas the second sustained phase was abolished in these conditions. This suggests that although the first phase of this response involves a release of Ca2+ from intracellular stores, the second phase requires extracellular Ca2+ influx. The response of human thyrocytes to analogs of ATP is compatible with a P2-purinergic effect of ATP on these cells. Bradykinin and TRH affected the human thyrocyte [Ca2+]i and 45Ca2+ efflux similarly to ATP. The human thyrocyte [Ca2+]i and the 45Ca2+ efflux were not modified by carbachol, a nonhydrolyzable analog of acetylcholine. The present results suggest the presence of P2-purinergic receptors to ATP and of receptors to TRH and bradykinin on human follicular thyroid cells. They also confirm that the Ca2+-phosphatidylinositol cascade is present in these cells and suggest that this cascade is modulated by ATP, TRH, and bradykinin. As this cascade is involved in the regulation of protein iodination, and therefore of thyroid hormones synthesis, these agents might have an important role in the regulation of the thyroid function.

Effect of amiodarone and propranolol on the functional properties of human thyroid follicles cultured in collagen gel

Amiodarone and propranolol have been known to inhibit the peripheral conversion of thyroxine (T4) to 3,5,3'-triiodothyronine (T3) but their direct effect on the thyroid gland is not understood. We therefore investigated the action of the two drugs on the functional properties of human thyroid follicles embedded in collagen gel. Amiodarone and propranolol induced a dose-dependent reduction or blocking of the follicular production of cyclic AMP (cAMP), thyroglobulin (Tg) and free triiodothyronine (FT3) under 200 microU/ml medium. Small drug doses and the drug solvents did not affect the follicular secretion. The inhibiting effect of amiodarone and propranolol on follicular production of cAMP, Tg and FT3 appears to result from several factors: (1) inhibition of thyroid 5'-deiodinase; (2) amiodarone high iodine content; (3) a quinidine-like effect of propranolol involving a membrane-stabilizing mechanism.