Histology and histopathology Vol.24,nº12 (2009)

Ir a Estadísticas

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    Signaling pathways governing osteoblast proliferation, differentiation and function
    (Murcia : F. Hernández, 2009) Fung Ling Chau, Jenny; Fook Leong, Wai; Li, Baojie
    Osteoblasts are bone forming cells that are responsible for bone growth and remodeling. They are derived from bone marrow mesenchymal stem cells through a series of processes including commitment, osteoprogenitor expansion, terminal differentiation and cell death. Osteoblastogenesis and bone formation are regulated by hormones, growth factors, cytokines, mechanical loading and aging. Osteoblasts can sense these external cues, transduce the signals through various signaling pathways and regulate the expression of specific genes, to determine the cell fate. In this review, we aim to update our current understanding of the signaling pathways that control different steps of osteoblast homeostasis, with special focus on how signaling events control cell fate through regulating gene expression.
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    Comparison of the effect of cryopreservation protocols on the histology of bioengineered tissues
    (Murcia : F. Hernández, 2009) Serrato, Deyanira; Nieto Aguilar, Renato; Garzon, Ingrid; Roda, Olga; Campos, Antonio; Alaminos, Miguel
    The purpose of this study was to compare the effects of five different cryopreservation protocols on the histology of bioengineered tissues. Although several artificial tissues have been developed to the date by tissue engineering, classical histological analysis methods and techniques must be optimized for these new tissues with special properties. The results of this study showed that the use of volatile solutions (formaldehyde, glutaraldehyde, glacial acetic acid and acetone) was not able to prevent the formation of large ice crystals that, in turn, can alter the structure of the artificial tissues. However, preincubation of the tissues in different concentrations of a carbon hydrate (glucose, maltose or trehalose) resulted in a better preservation of the tissue structure. We conclude that the best protocol that allows for an efficient analysis of the bioengineered tissues with very few artifacts is preincubation of the tissues in 0.300M or 0.400M trehalose for 30 or 120 min prior to OCT (optimal cutting temperature) embedding and cryosectioning. For all those reasons, we recommend the use of a cryoprotective agent before OCT embedding of human artificial tissues.
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    Immunohistochemical analysis of CDX2 expression in normal choroid plexus epithelium and choroid plexus tumors
    (Murcia : F. Hernández, 2009) Beschorner, R.; Mittelbronn, M.; Mugler, M.; Meyermann, R.; Schittenhelm, J.
    Background: The Wnt and BMP signaling pathways are involved in the morphogenesis of both gastrointestinal and choroid plexus epithelium. In the intestine, Wnt signaling represses the expression of the tumor suppressor gene CDX2 via SOX9, a transcription factor, which is also expressed in the choroid plexus. Recently, an inverse correlation between CDX2 expression and tumor grade, tumor stage and lymph node metastasis in colorectal adenocarcinomas has been reported. Besides intestinal tissues, expression of CDX2 has also been reported in various other epithelial tissues and carcinomas. To date, no data exist on expression of CDX2 in normal and neoplastic choroid plexus epithelium. Aim: To investigate CDX2 expression in normal and neoplastic choroid plexus. Materials and Methods: Paraffin-embedded samples from 60 normal choroid plexus, including 23 fetal tissue samples and from 65 choroid plexus tumors (47 choroid plexus papillomas WHO grade I, 16 atypical choroid plexus papillomas and 2 choroid plexus carcinomas WHO grade III) were examined by immunohistochemistry. Samples from normal choroid plexus were collected from 45 autopsy cases and from 15 neurosurgical specimens. Results: Normal and neoplastic choroid plexus lacked CDX2 expression. Conclusion: In our series, immunohistochemistry shows no evidence for a role of CDX2 in development or differentiation of normal choroid plexus from the 9th gestational week until adulthood. Since choroid plexus tumors reliably lack CDX2 immunoreactivity, this marker may be helpful in distinguishing cerebral metastases from CDX2-positive adenocarcinomas and choroid plexus neoplasms.
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    Regulation of hepatocyte glutathione content by hepatic sinusoidal cells activated with LPS: anatomical restrictions
    (Murcia : F. Hernández, 2009) Catalá, Myrian; Pagani, Raffaella; Portolés, M.Teresa
    The liver is the main organ for the elimination of bacterial endotoxin involving Kupffer and parenchymal cells. This process is accompanied by the release of free radicals. Parenchymal cells possess especially high levels of glutathione, which make them a key point in the response to free radicals. Sinusoidal cells regulate hepatic function in a very important fashion through the release of cytokines and/or adhesion molecules. These facts suggest the importance of finding new in vitro experimental models representing an intermediate step towards in vivo models. The treatment with LPS of sinusoidal and parenchymal cell co-cultures on porous membranes provokes an intense reduction of parenchymal cell intracellular glutathione, which does not correspond to in vivo results. However, the addition of supernatants of LPS-treated sinusoidal cells to parenchymal cells renders increases in glutathione which agree better with in vivo results. We conclude that the regulation of liver hepatocyte glutathione content and NO release in the presence of LPS is strongly modulated by liver non parenchymal cells. The study of this phenomenon requires new in vitro models taking into account liver histophysiology and histopathology and anatomical restrictions in cell communication.
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    Claudins as diagnostic and prognostic markers in gynecological cancer
    (Murcia : F. Hernández, 2009) Szabó, István; Kiss, András; Schaff, Zsuzsa; Sobel, Gábor
    Claudins are the main protein components of tight junctions (TJs) which function as selective barriers by controlling paracellular diffusion, maintain cellular polarity and play a role in signal transduction. The expression pattern of the 24 known members of the claudin family proved to be organ and tissue specific. The up- or downregulation of individual claudins has been described, especially during carcinogenesis. A significant increase of claudins-1 and -7 was detected in premalignant cervical lesions and invasive cancer compared with normal cervical epithelia. Claudins-3 and -4 were elevated in endometrial cancer. Claudin-1 overexpression characterized type II (seropapillary) endometrial carcinoma, while claudin-2 was elevated in type I (endometrioid) carcinoma. Claudins-3 and -4 were highly expressed in serous ovarian carcinoma. The expression data on claudins in different premalignant and malignant alterations suggest that these proteins might serve as diagnostic and prognostic markers and might be targets for future therapy.