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Preservation of functioning human thyroid organoids in the scid mouse: 1. System characterization.

We have characterized a system for preserving reconstituted human thyroid follicles in vivo by transplanting human thyrocytes into mice with severe combined immunodeficiency (scid mice). Human thyroid organoids were constructed from thyroid monolayer cells derived from both normal and abnormal thyroid tissue, and embedded within a basement membrane preparation which was then transferred sc to scid mice. As early as 4 weeks, and as late as 3 months post transplantation, histological examination of human thyroid organoids demonstrated widespread neofollicle formation and colloid accumulation which stained positive for human thyroglobulin (hTg). Although there were no changes in murine serum T4 levels; the transplanted thyroid epithelial cells secreted hTg into the scid mouse circulation (with an average level of 29 micrograms/L). In addition, hTg release was stimulated in vivo by ip administration of recombinant human TSH (0.1-1.0 IU/mouse) achieving greater than 20-fold increases in scid mouse serum hTg levels. In situ immunohistochemistry showed that thyroid organoids derived from patients with Graves' disease retained scattered lymphocytes in peripolesis with the thyroid epithelial cells; those lymphocytes were identified as human T cells of the memory (CD45RO +), rather than naive, type. These data demonstrate that functioning human thyroid organoids establish in scid mice and remain responsive to TSH stimulation. The system offers a unique opportunity to examine human thyroid-lymphocyte interaction within the confines of a predictable animal model.

Animals↗

Preservation of functioning human thyroid "organoids" in the severe combined immunodeficient mouse. III. Thyrotropin independence of thyroid follicle formation.

The severe combined immunodeficient (scid) mouse allows the in vivo reconstitution of thyroid follicles from thyroid monolayer cells when transplanted sc within an extracellular basement membrane matrix. After 2-3 weeks, these human thyroid organoids show an active microfollicular histology and secrete human thyroglobulin into the murine serum in response to the administration of recombinant human TSH. Furthermore, such organoids survive for more than 3 months in this functional state. To assess whether thyroid follicular reconstitution was TSH dependent, we examined organoid follicular reconstruction in T3-induced hyperthyroid scid mice, in which endogenous murine TSH was presumed to be totally suppressed. By providing water with 12 micrograms/ml T3, we increased the murine serum T3 levels from a mean of 1.9 nmol/liter in controls to greater than 12.0 nmol/liter. After 3 weeks, thyroid cells derived from normal human thyroid monolayers were suspended in an extracellular basement membrane matrix, and the suspension was transplanted sc into scid mice (with or without T3-induced hyperthyroidism) and allowed to reconstitute. Histological examination 4 weeks later showed a similar degree of thyroid follicle formation in mice treated with or without T3, indicating that the hyperthyroid state had caused no interference with thyroid follicle reconstitution. This was further confirmed by transmission electron microscopy, which demonstrated normal human thyroid follicle cell polarity in the organoids of both euthyroid and hyperthyroid mice. In addition, using an extracellular basement membrane preparation with reduced growth factor (epidermal growth factor, insulin-like growth factor-I, and platelet-derived growth factor) levels also allowed normal thyroid follicle formation in T3-fed mice. These data demonstrate that in vivo thyroid follicle formation is TSH independent and that extrathyroidal epidermal growth factor, insulin-like growth factor-I, and platelet-derived growth factor may be relatively unimportant. The factors and molecular mechanisms leading to follicular reorganization of adult human thyroid cells remain to be determined, but are likely to depend largely on intrathyroidal growth factor secretion and cell-cell interaction.

Animals↗

Preservation of functioning human thyroid organoids in the scid mouse: II. Biased use of intrathyroidal T cell receptor V genes.

The severe combined immunodeficiency (scid) mouse, which lacks functional B cells and T cells, has proven a useful model for exploring the survival of transplanted human lymphocytes and thyrocytes. In order to further characterize T cell infiltrates in reconstituted sc human thyroid organoids, we examined for the presence of 18 human T cell receptor (hTcR) V alpha and 21 hTcR V beta gene families using polymerase chain reaction (PCR) analysis. Human TcR V gene activity was confirmed by Southern blot analysis of the PCR fragments from all but one of the thyroid organoids, confirming the continued survival of human T cells within the thyroid organoids. However, only 3.5 out of 18 V alpha and 5.9 out of 21 V beta gene families were detected in these human thyroid organoids indicating a marked bias in T cell survival. Sequencing of the V-D-J regions of the amplified TcR fragments showed that approximately 60% of the sequences were representative of clonally expanded T cells. Hence, these passenger T cells exhibited highly biased use of particular TcR V gene families similar to that observed previously in thyroid tissue and intrathyroidal T cell cultures. Furthermore, variations in the V-D-J regions of sequences from similar V gene families indicated that the V gene region was important in T cell selection rather than the CD3 region.

Animals↗

Divergent PTEN-p53 interaction upon DNA damage in a human thyroid organoid model with germline PTEN mutations.

Germline mutations in the tumor suppressor phosphatase and tensin homolog (PTEN) cause PTEN hamartoma tumor syndrome (PHTS). PHTS is characterized by an elevated lifetime risk of differentiated thyroid cancer (DTC), 30 times higher than the general population. However, only 1 in 3 PHTS patients develop DTC, and it remains unknown whether specific PTEN variants are associated with an increased risk of DTC. PTEN antagonizes the phosphatidylinositol 3-kinase (PI3K)-AKT signaling pathway, a frequently affected pathway in sporadic DTC. PTEN also acts as a guardian of the genome by interacting with other tumor suppressors. Here, we report how ionizing radiation, an environmental tumorigenic contributor, modifies the DNA damage response based on the type of germline PTEN variants. We hypothesized that certain PTEN variants associated with DTC create a pro-oncogenic molecular signature upon radiation-induced DNA damage. DTC-associated (PTEN M134R ) or DTC-non-associated (PTEN G132D ) germline PTEN mutant alleles were introduced into a human induced pluripotent cell (hiPSC) line derived from a healthy donor utilizing CRISPR-Cas9 gene editing technology. We determined radiation-induced transcriptomic changes in functional thyroid organoids induced from wild-type and both heterozygous PTEN mutant hiPSCs. Both bulk and single-cell RNA sequencing data indicated that radiation upregulated the p53 network more potently in the thyroid organoids with PTEN WT/G132D than those with PTEN WT/M134R , which could be mediated by AKT-dependent MDM2 inactivation and PTEN-p53 physical interaction. Our data suggest that the lack of p53 pathway activation through PTEN-p53 network interactions explains why PTEN M134R is a DTC-susceptible variant.

Humans↗

Thyroid organoid formation in simulated microgravity: influence of keratinocyte growth factor.

The generation of artificial human thyroid tissues in suspension (low-shear environment, present in simulated microgravity [MG] and generated by a rotary cell culture system [RCCS]), was enhanced by increasing medium kinematic viscosity with a (3% v/v) suspension of extracellular matrix (basement membrane extract [BME]) in serum-free medium to generate artificial human thyroid organoids. Recombinant human keratinocyte growth factor (KGF, 7 ng/mL) facilitated human thyrocyte aggregation and three-dimensional (3-D) differentiation. There was an MG-associated decrease in extractable DNA that was reversed after addition of keratinocyte growth factor (KGF). In simulated MG, the increase in extractable DNA after KGF addition was up to 170% over non-KGF control cultures. In contrast, monolayer cultures in unit gravity showed a maximum DNA increase of 39% after KGF addition. Morphologically, differentiated thyroid neofollicles displayed polarization and were located in close proximity after 2 weeks of culture. Immunogold labeling with antibody to human thyroglobulin (Tg) revealed staining of follicular lumina and secretory vesicles, and a time-dependent increase in human Tg was detected in the culture media. Culture under simulated MG thus allowed direct visualization of KGF-facilitated thyrocyte/extracellular matrix interaction. Such artificial human thyroid organoids-generated in MG and in the presence of KGF-structurally resembled natural thyroid tissue. The above findings may have implications for autoimmune thyroid disease where KGF (if, for example, secreted locally by intraepithelial gammadelta T cells among other cells) may contribute to thyroid cell growth.

Cell Adhesion Molecules↗

Preservation of functioning human thyroid "organoids" in the scid mouse. IV. In vivo selection of an intrathyroidal T cell receptor repertoire.

To study the in vivo influence of thyroid cells on the T cell receptor repertoire in human autoimmune thyroid disease, we mixed lymphocyte-free thyrocytes (approximately 1.2 x 10[6]) from patients with Graves' disease with autologous peripheral blood mononuclear cells (PBMC; approximately 1.5 x 10[6]) and transplanted this mixture sc into scid mice while suspended in a basement membrane gel (approximately 0.4 ml). Controls included mice that received either thyrocytes only or PBMC only. The resulting artificial mixed cell thyroid organoids were explanted after 5 weeks, and their T cell receptor repertoire was examined. Of a total of 63 organoids constructed, 60 were recovered (95.2%). Total RNA was extracted and then analyzed by reverse transcription-PCR primarily for human T cell receptor (hTcR) Vbeta gene expression using 21 hTcR Vbeta amplimers. A restricted pattern of hTcR Vbeta gene expression was found, with 6 Vbeta genes (Vbeta5, 6, 7, 8, 13.1, and 18) predominantly expressed [P < 0.05, by ANOVA on ranks and Student-Newman-Keul's (SNK) test]. PBMC and control organoids showed no preferential selection of particular hTcR V gene-expressing T cells. This reductionist, mixed cell, thyroid model reflected earlier observations in human and murine autoimmune thyroid diseases in which a bias in hTcR V gene family expression had been observed. The model permitted in vivo T cell selection and/or enrichment of potentially disease relevant human T cells.

Animals↗

Cytoskeletal and functional changes in bioreactor assembled thyroid tissue organoids exposed to gamma radiation.

Fischer rat thyroid cells were grown under low-shear stress in a bioreactor to a stage of organization composed of integrated follicles resembling small thyroid glands prior to exposure to 3 Gray-gamma radiation. Bioreactor tissues and controls (both irradiated and non-irradiated) were harvested at 24, 48, 96 and 144 hours post-exposure. Tissue samples were fixed and fluorescently labeled for actin and microtubules. Tissues were assessed for changes in cytoskeletal components induced by radiation and quantified by laser scanning cytometry. ELISA's were used to quantify transforming growth factor-beta and thyroxin released from cells to the culture supernatant. Tissue architecture was disrupted by exposure to radiation with the structural organization of actin and loss of follicular content the most obviously affected. With time post-irradiation the actin appeared disordered and the levels of fluorescence associated with filamentous-actin and microtubules cycled in the tissue analogs, but not in the flask-grown cultures. Active transforming growth factor-beta was higher in supernatants from the irradiated bioreactor tissue. Thyroxin release paralleled cell survival in the bioreactors and control cultures. Thus, the engineered tissue responses to radiation differed from those of conventional tissue culture making it a potentially better mimic of the in vivo situation.

Animals↗

Nerve growth factor in medullary carcinoma of the thyroid.

In a case of medullary carcinoma of the thyroid gland assay was performed for nerve growth factor bioactivity. The tumor extract showed significant amounts of nerve growth factor bioactivity, but extracts of normal thyroid and other types of thyroid neoplasms showed no such bioactivity. Nerve growth factor may be useful as a tumor marker in the diagnosis and management of medullary carcinoma of the thyroid. It may play a role in the development of associated tumors of neural crest origin and may contribute to the development of cachexia in patients with medullary carcinoma of the thyroid.

Adult↗

Intracardiac ectopic thyroid.

The case of a patient with an intracardiac ectopic thyroid is reported. A lesion was found in a 25-year-old man and was diagnosed by two-dimensional echocardiography as a right intraventricular tumor. An operation was performed. Histologic and ultrastructural studies showed that the tumor was a thyroid mass. The origin of intracardiac ectopic thyroids is probably to be found in disturbances occurring early in embryogenesis.

Adult↗

Follicular adenoma of the thyroid with intranuclear vacuoles and clear nuclei. A case report.

Although the presence of intranuclear vacuoles in fine needle aspiration biopsy specimens and clear nuclei in histologic specimens is considered characteristic of papillary carcinoma of the thyroid, these findings are not pathognomonic of this disease. This paper reports a case of follicular adenoma of the thyroid with such features and emphasizes the importance of not relying solely on these criteria for the diagnosis of papillary carcinoma.

Adenoma↗