Isolation and characterization of human thyroid endothelial cells

Cell Growth Dynamics in Embryonic and Adult Mouse Thyroid Revealed by a Novel Approach to Detect Thyroid Gland Subpopulations

BACKGROUND

The thyroid is composed of endocrine epithelial cells, blood vessels, and mesenchyme. However, no data exist thus far on absolute cell numbers, relative distribution, and proliferation of the different cell populations in the developing and mature thyroid. The aim of this study was therefore to establish a flow cytometry protocol that allows detection and quantification of discrete cell populations in embryonic and adult murine thyroid tissues.

METHODS

Cell-type anti-mouse specific antibodies were used for erythroid cells (Ter119), hematopoietic cells (CD45), epithelial cells (EpCam/CD326, E-cadherin/CD324), thyroid follicular cells and C-cells (Nkx2-1), endothelial cells (Pecam/CD31, Icam-1/CD54), and fibroblasts (PDGFRa/CD140a). Proliferating cells were detected after labeling with 5-bromo-2'-deoxyuridine (BrdU). For flow cytometry analyses, micro-dissected embryonic (E) and adult thyroids were pooled (E13.5, n = 25; E15.5, n = 15; E17.5, n = 15; adult, n = 4) in one sample.

RESULTS

The absolute parenchymal cell numbers per mouse thyroid (M ± SD), excluding the large number of CD45(+) and Ter119(+) cells, increased from 7425 ± 1338 at E13.5 to 271,561 ± 22,325 in adult tissues. As expected, Nkx2-1(+) cells represented the largest cell population in adult tissues (61.2 ± 1.1%). Surprisingly, at all three embryonic stages analyzed, thyroid follicular cells and C-cells accounted only for a small percentage of the total thyroid cell mass (between 4.7 ± 0.4% and 9.4 ± 1.6%). In contrast, the largest cell population at all three embryonic stages was identified as PDGFRa/CD140a(+) fibroblasts (61.4 ± 0.4% to 77.3 ± 1.1%). However, these cells represented the smallest population in adult tissues (5.2 ± 0.8%). Pecam/CD31(+) endothelial cells increased from E13.5 to E15.5 from 3.7 ± 0.8% to 8.5 ± 3.0%, then remained stable at E17.5 and adult tissues. Proliferation rates were sizable during the entire organogenesis but differed between cell populations, with distinct proliferative peaks at E13.5 in epithelial cells (32.7 ± 0.6% BrdU(+) cells), and at E15.5 in endothelial cells (22.4 ± 2.4% BrdU(+) cells). Fibroblasts showed a constant proliferation rate in embryonic tissues. In adult tissues, BrdU(+) cells were between 0.1% and 0.4% in all cell types.

CONCLUSIONS

Using a novel flow cytometry-based method, a previously unobserved highly dynamic growth pattern of thyroid cell populations during embryogenesis was uncovered. This approach will provide a useful new tool for cell function analyses in murine thyroid disease models.

The pituitary tumor transforming gene in thyroid cancer

The pituitary tumor transforming gene (PTTG) is a multifunctional proto-oncogene that is over-expressed in various tumors including thyroid carcinomas, where it is a prognostic indicator of tumor recurrence. PTTG has potent transforming capabilities in vitro and in vivo, and many studies have investigated the potential mechanisms by which PTTG contributes to tumorigenesis. As the human securin, PTTG is involved in critical mechanisms of cell cycle regulation, whereby aberrant expression induces aneuploidy. PTTG may further contribute to tumorigenesis through its role in DNA damage response pathways and via complex interactions with hormones and growth factors. Furthermore, PTTG over-expression negatively impacts upon the efficacy of radioiodine therapy in thyroid cancer, through repression of expression and function of the sodium iodide symporter. Given its various roles at all disease stages, PTTG appears to be an important oncogene in thyroid cancer. This review discusses the current knowledge of PTTG with particular focus on its role in thyroid cancer.

Angiogenesis in Malignant Thyroid Tumors

It is well known that radiation significantly impacts the morbidity of thyroid cancer and that is why Belarus has the highest incidence of the malignancy. Author describes statistical data, classification of angiogenesis, and typical pathological features of malignant thyroid diseases with regard to the vascular network.

Isolation and Characterization of Human Bone-Derived Endothelial Cells

Historically, the etiology of local bone pathologies, such as avascular necrosis, has been related to intravascular occlusion. Recent reports have highlighted the occlusion of arteries, venules, and/or capillaries in bone tissue. Endothelium of bone presumably participates locally in the formation of the microvascular thrombosis. It is also known that endothelial cells (ECs) play a central role in angiogenesis, a process seen in osteosarcoma, amongst other bone diseases. Given the well-recognized heterogeneity of ECs throughout the body, investigations of local bone disease related to endothelium processes may be more appropriately targeted on bone ECs rather than other primary ECs or an immortalized EC line. In the current study, mechanical and enzymatic methods are described to isolate ECs from cancellous human bone tissue followed by immunomagnetic bead separation to purify the cell populations. The human bone-derived endothelial cells (hBDECs) were characterized based on endothelial cell antigen expression and functional assays. This study is the first report of isolation and expansion of ECs from human bone tissue. Isolation of hBDECs in human vascular bone diseases may facilitate the study of the molecular and/or genetic abnormalities in the vasculature system that contributes to the initiation and/or progression of the disease.

Quantitative characteristics of calcitonin-producing cells in the thyroid and lungs of uremic rats

Uremia leads to a number of metabolic and hormonal disorders induced by renal failure with definite biological and clinical sequels. For this reason and the absence of reports on influence of CRF on calcitonin (CT)-producing cells of the thyroid glands and airways, the author decided to investigate the behavior of neuroendocrine cells in experimental uremia, taking CT-producing cells as an example. The aim of the present study was to examine the number and distribution of CT-producing cells in the thyroid glands and lungs of uremic rats. Fragments of the thyroids and lungs were collected one week after nephrectomy. Paraffin-embedded sections were stained with H+E and by silver impregnation. To identify neuroendocrine cells, immunohistochemical reaction was performed with the use of a specific antibody against calcitonin. It was revealed that the number of CT-immunoreactive cells decrease in the thyroid and considerable increase in the lungs of rats, when compared to the value in the control animals. The results can be regarded as the morphological manifestation of calcitonin-producing endocrine cells in the rat thyroid and lungs to disorders in the internal environment of the body induced by the impairment of renal parenchyma functioning.

Hyperactivity of fibroblasts and functional regression of endothelial cells contribute to microvessel occlusion in hypertrophic scarring

Hypertrophic scars (HSc) have an excess of microvessels, most of which are partially or totally occluded. The mechanisms underlying microvessel endothelial cell accumulation and microvessel occlusion are poorly understood. In this study, we observed the microvessels with H&E staining and electron microscopy, and detected the cytokine expression with immunochemistry. In addition, we isolated fibroblasts and endothelial cells from both human HSc tissue and normal skin and studied their cytokine expression. Furthermore, we assayed the endothelial cell proliferation when co-cultured with normal endothelial cells and blocked with anti-VEGF and anti-bFGF neutralizing. The results revealed that more endothelial cells in HSc microvessels and the cells were swollen. The cultured HSc fibroblasts secreted significantly more while HSc endothelial cells secreted significantly less cytokines, and the same trend was found with cytokines and collagen mRNAs, which was also confirmed by immunochemistry finding. In addition, endothelial cells proliferated faster when co-cultured with HSc fibroblasts, and reduced by anti-VEGF and anti-bFGF neutralizing. This is the first report regarding the function of endothelial cells in hypertrophic scars. The hyperactivity in cytokine secretion and collagen production is largely responsible for over-proliferation and functional regression of endothelial cells, and the malfunctioning of both cell types contributes to microvessel occlusion.

Isolation and characterization of human gingival microvascular endothelial cells

BACKGROUND AND OBJECTIVE

Endothelial cells have a substantial role in maintaining vascular homeostasis, and their dysregulation can contribute to the development of pathology. The plasminogen activators and their inhibitors may, arguably, be the single most important proteolytic system of the endothelium for vascular maintenance by controlling plasminogen activation and other proteolytic cascades that impact on clotting, hemodynamics, angiogenesis and the character of the vascular wall. In chronic periodontal disease, significant changes to the microvasculature occur in association with the severity of the disease. Investigation of the role played by endothelial cells in periodontal health and disease has been limited to in situ immunolocalization or to the use of endothelial cells of nongingival origin, such as human umbilical vein endothelial cells. The objective of this research was to establish a replicable protocol for isolating microvascular endothelial cells from the gingiva.

MATERIAL AND METHODS

From inflamed gingiva, isolated cells were characterized by morphology, the expression of factor VIII-related antigen, the expression of UEA-1 ligand, the uptake of acetylated low-density lipoprotein, network formation on Matrigel, and by the expression levels of urokinase plasminogen activator, tissue plasminogen activator, plasminogen activator inhibitor-1 and collagen IV.

RESULTS AND CONCLUSION

Gingival endothelial cells were most readily obtained from inflamed gingival tissues, and these endothelial cells, when isolated by the protocol established herein, demonstrated endothelial characteristics and constitutively secreted plasminogen activators and plasminogen activator inhibitor-1 in culture.

The comparison of serum vascular endothelial growth factor levels between patients with metastatic and non-metastatic thyroid cancer, and patients with nontoxic multinodular goiter

BACKGROUND

One of the important proangiogenic factors involved in the growth of normal and neoplastic tissues is vascular endothelial growth factor (VEGF).

AIM

We hypothesized that serum VEGF concentration would differ between patients with metastatic and non-metastatic thyroid cancer, multinodular goiter, and healthy subjects. We also hypothesized that endogenous TSH stimulation would affect serum VEGF level.

SUBJECTS AND METHODS

The study group consisted of 71 patients (62 females and 9 males), aged 44.9 +/- 12.3 years, with differentiated thyroid cancer (50 papillary, 17 follicular, and 4 oxyphilic), treated in our department during the years 2003-2006. All patients had undergone total or near-total thyroidectomy and radioactive iodine treatment, that had resulted in remission in 59 patients and persistent/recurrent disease in 12 patients. The study included two control groups: 30 patients with nontoxic multinodular goiter and 30 healthy subjects.

RESULTS

Serum VEGF concentrations were significantly higher in patients with distant metastases than those in remission or healthy patients. (423.4 vs 217.6 vs 235.55 pg/ml respectively, P < 0.05). This was not observed in patients with locoregional metastases. During endogenous TSH stimulation, VEGF decreased significantly (215.3 vs 169.6 pg/ml, P < 0.05). Patients with multinodular goiter showed significantly lower VEGF concentrations than the remaining study groups.

CONCLUSIONS

Serum VEGF concentration might be used as an additional marker of thyroid cancer with distant metastases, but its interpretation should be undertaken very cautiously. Endogenous TSH stimulation decreases VEGF levels in patients either with or without thyroid tissue, suggesting that its regulatory effects are through receptors located outside the thyrocytes.

Regulation of plasminogen activators in human thyroid follicular cells and their relationship to differentiated function

Human thyroid cells in culture take up and organify (125)I when cultured in TSH (acting through cAMP) and insulin. They also secrete urokinase (uPA) and tissue-type (tPA) plasminogen activators (5-100 IU/10(6)cells/day). TSH and insulin both decreased secreted PA activity (PAA), uPA and tPA protein and their mRNAs. Autocrine fibroblast growth factor increased secreted PAA and inhibited thyroid cell (125)I uptake. Epidermal growth factor (EGF) and the protein kinase C (PKC) activator, TPA significantly increased PAA and inhibited thyroid differentiated function, (TPA > EGF). For TPA, effects were rapid, increased PAA secretion and decreased (125)I uptake being seen at 4 h whereas for EGF, a 24 h incubation was required. qRT-PCR showed significantly increased mRNA expression of uPA with lesser effects on tPA. Aprotinin, which inhibits PAA, increased (125)I uptake but did not abrogate the effects of TPA and EGF. The MEKK inhibitor, PD98059 partially reversed the effects of EGF and TPA on PAA, and largely reversed the effects of EGF but not TPA on differentiated function. PKC inhibitors bisindoylmaleimide 1, and the specific PKCbeta inhibitor, LY379196 completely reversed the effects of TPA on (125)I uptake and PAA whereas EGF effects were unaffected. TPA inhibited follicle formation and this effect was blocked by LY379196 but not PD98059. We conclude that in thyroid cells, MAPK activation inversely correlates with (125)I uptake and directly correlates with PA expression, in contrast to the effects of cAMP. TPA effects on iodide metabolism, dissolution of follicles and uPA synthesis are mediated predominantly through PKCbeta whereas EGF exerts its effects through MAPK but not PKCbeta.

Iodide inhibits vascular endothelial growth factor-A expression in cultured human thyroid follicles: a microarray search for effects of thyrotropin and iodide on angiogenesis factors

OBJECTIVE

Excess iodide has been administered to hyperthyroid patients before thyroid surgery to reduce intraoperative bleeding and oozing. The purpose of this study was to elucidate the mechanism by which iodide reduces blood flow in the hypervascular thyroid gland.

DESIGN

Human thyroid follicles were cultured in the presence or absence of thyrotropin (TSH), or in medium containing various concentrations of iodide, and TSH-or iodide-regulated gene expression was analyzed by cDNA microarray.

MAIN OUTCOME

TSH stimulated the expression of thyroglobulin, peroxidase, sodium iodide symporter, vascular endothelial growth factor (VEGF)-A, VEGF-B, and placental growth factor (PGF) but decreased that of VEGF-C by half. When thyroid follicles were cultured in high-iodide (10(5) M) medium, TSH-induced expression of VEGF-A, VEGF-B, and PGF was decreased, accompanied by a reduction of VEGF-A release into the medium. Furthermore, expression of putative angiogenesis inhibitors such as urokinase-type plasminogen activator (PLAU) was increased. These findings were confirmed by real-time polymerase chain reaction (PCR) and Northern blot hybridization.

CONCLUSIONS

We have demonstrated for the first time that iodide at high concentration decreases the expression of the angiogenic factors VEGF-A, VEGF-B, and PGF, accompanied by an increase in the expression of possible antiangiogenic factors such as PLAU. These proangiogenic and antiangiogenic factors may at least partly account for the iodide-induced decrease in thyroid blood flow.

Vascular endothelial growth factor in thyroid cancers

Vascular endothelial growth factor (VEGF) is an essential peptide in new vessel growth in physiology (endometrial growth, embryonic development); pathological conditions (diabetic retinopathy, rheumatoid arthritis); as well as in tumor cell growth, particularly distant metastases. This study focused on VEGF structure, receptors, and angiogensis in tumors, especially their roles in thyroid cancer. The VEGF mRNA undergoes alternative splicing events that generate four homodimeric isoforms, including VEGF121, VEGF165, VEGF189, or VEGF206. Using VEGF purified from a culture medium conditioned by A-431 human epidermoid carcinoma cells, VEGF-binding site complexes of 230, 170, and 125 kDa were detected on human umbilical vein endothelial cells. The VEGF specifically induced the tyrosine phosphorylation of a 190-kDa polypeptide, which had similar mass to the largest binding site detected through affinity cross-linking. A transmembrane receptor belongs to the tyrosine kinase family, fms-like tyrosine kinase (FLT). These receptor tyrosine kinases encoded by the FLT gene family have distinct functions in regulating blood vessel growth and differentiation. Regulation of VEGF is a complex, multistep mechanism in various kinds of cells and tissues. Hypoxia-dependent and -independent mechanisms are illustrated in different cancer tissues. Hypoxic tumor cells may switch to a proangiogenic phenotype, which increases VEGF transcription. Clinical applications of VEGF in cancer have included diagnosis, prediction of prognosis, and treatment in different solid tumors, including thyroid tumors. Studies involving thyroid cancer cell lines, serum level determination, immunohistocytochemical staining, molecular biological studies, and gene therapy to the in vivo clinical trials, have shown that antiangiogensis therapy can provide another treatment modality for thyroid cancer. Future studies focused on recombinant human anti-VEGF research involving patients with advanced thyroid cancer, and investigation of the protection of high-risk patients by using novel antiangiogenic vaccines, are warranted.

Isolation of thyroid cells obtained by fine-needle aspiration biopsy

Usually thyroid cells isolated from tissue obtained by surgery or thyroid cell lines are used to investigate the pathogenesis of autoimmune thyroid diseases. Isolation and cultivation of thyrocytes from fine-needle aspiration biopsy (FNAB) has not yet been published. The aim of this study was to isolate and cultivate thyrocytes from samples of FNAB. FNAB samples were obtained from nine adults and nine children with Hashimoto's thyroiditis (HT). The aspiration material was filtered resulting in small samples of tissue on the surface of the filter membrane. These tissue fragments were digested by collagenase I and dispase II. The yielding cells were cultivated for 3 weeks in Ham's F12 Kaighn's Modification medium in presence of 1 mU/mL bovine thyrotropin (TSH), 10 microg/mL human insulin, 6 microg/mL transferrin, and 10(-8) M hydrocortisone. Finally, isolated thyroid cells were characterized by determination of gene expression of thyrotropin receptor (TSHR), thyroperoxidase (TPO), and thyroglobulin (Tg) using a nested reverse transcriptase-polymerase chain reaction (RT-PCR). Thyroid cells obtained by FNAB can be maintained over a time period of approximately 3 weeks. Depending on the sample size a final number of 1000-14,000 cells was gained per FNAB. In addition, all cells isolated by the described method expressed TPO mRNA. TSHR mRNA was found in 4 samples, whereas 15 samples were Tg mRNA-positive. There were no differences with respect to the expression TSHR and TPO mRNA between samples from adults and children. The isolation and cultivation of thyroid cells obtained by FNAB has been established. In contrast to surgical specimen, this technique provides an easy access to thyrocytes derived from individual patients allowing repeated sampling to investigate the time progression of the chronic disease or the effect of treatment over time.

Angiogenesis in benign and malignant thyroid disease

CONTEXT

Angiogenesis has been recognized as an important process contributing to the pathophysiology of many benign and malignant diseases. It is not surprising, therefore, that this complex process is proving to be an important regulator of both benign and malignant disease processes in the thyroid gland. This paper will review the general principles of angiogenesis and lymphangiogenesis, as well as the importance of the balance between angiogenic stimulators and inhibitors in the normal thyroid gland. We will also review how this balance is disturbed in benign and malignant thyroid conditions. Finally, we will address the role manipulation of this process may play in the development of novel treatment strategies for diseases of the thyroid.

OBJECTIVE

To review the literature concerning the role of angiogenesis in the thyroid gland.

CONCLUSIONS

Angiogenesis is an important process which has been shown to be involved in the pathophysiology of benign and malignant diseases of the thyroid gland. Manipulation of this process holds great promise for the development of novel treatments for these disorders. As the mechanisms regulating angiogenesis in the thyroid become increasingly clear, researchers will come ever closer to turning this promise into clinical reality.

Review article--involvement of gastric APUD cells in chronic renal failure

Uremia leads to a number of metabolic and hormonal disorders induced by renal failure with definite biological and clinical sequels. Most frequently, alimentary disorders are the first to appear, followed by symptoms from other organs and systems. The gastrointestinal tract is a site of synthesis of many compounds that have hormonal or hormonal-like biological activity. These substances are produced by highly-specialised receptor-effector cells, that are dispersed in the gastrointestinal mucosa and classified as APUD cells. The present review is an attempt to make a synthesis of current opinions and views concerning the effect of homeostatic dysfunction of the kidneys on the morphology and action of APUD cells in the stomach.

Role and regulation of the fibroblast growth factor axis in human thyroid follicular cells

Thyroidal levels of fibroblast growth factor-2 (FGF-2) and fibroblast growth factor receptor 1 (FGFR1) are elevated in human thyroid hyperplasia. To understand the significance of this, effects of FGFR1 activation on normal human thyrocyte growth and function in vitro and the regulation of FGF-2 and FGFR1 expression have been examined. FGF-2 stimulated cell growth, as measured by cell counting, and inhibited thyroid function as measured by 125I uptake. Sensitivity to FGF-2 disappeared after 7 days, although FGFR1 expression was maintained. Thyroid-stimulating hormone (TSH, 300 mU/l) increased FGFR1 mRNA expression within 4 h and protein expression by 8 h. Exogenous FGF-2 decreased FGFR1 protein. Endogenous FGF-2 levels were low (approximately 1-2 pg/microg protein), and TSH treatment decreased these by 50%. Protein kinase C (PKC) activation increased FGF-2 mRNA and FGF-2 secretion within 2 h. This effect was enhanced (4.4-fold) when cells were cultured in TSH. We conclude that TSH stimulates FGFR1 but not FGF-2 expression. PKC activation stimulates FGF-2 synthesis and secretion, and TSH synergizes with PKC activators. Increases in FGFR1 or FGF-2 or in both may contribute to goitrogenesis.