This research provides evidence that human periodontal ligament, in addition to its mesodermal derivatives, produces neural crest-like cells. Such features suggest a recapitulation of their embryonic state. The human periodontal ligament revealed itself as a viable alternative source for possible primitive precursors to be used in stem-cell therapies.

The combinatorial expression of Hox genes is an evolutionarily ancient program underlying body axis patterning in all Bilateria. In the head, the neural crest (NC)--a vertebrate innovation that contributes to evolutionarily novel skeletal and neural features--develops as a structure free of Hox-gene expression. The activation of Hoxa2 in the Hox-free facial NC (FNC) leads to severe craniofacial and brain defects. Here, we show that this condition unveils the requirement of three Six genes, Six1, Six2, and Six4, for brain development and morphogenesis of the maxillo-mandibular and nasofrontal skeleton. Inactivation of each of these Six genes in FNC generates diverse brain defects, ranging from plexus agenesis to mild or severe holoprosencephaly, and entails facial hypoplasia or truncation of the craniofacial skeleton. The triple silencing of these genes reveals their complementary role in face and brain morphogenesis. Furthermore, we show that the perturbation of the intrinsic genetic FNC program, by either Hoxa2 expression or Six gene inactivation, affects Bmp signaling through the downregulation of Bmp antagonists in the FNC cells. When upregulated in the FNC, Bmp antagonists suppress the adverse skeletal and cerebral effects of Hoxa2 expression. These results demonstrate that the combinatorial expression of Six1, Six2, and Six4 is required for the molecular programs governing craniofacial and cerebral development. These genes are crucial for the signaling system of FNC origin, which regulates normal growth and patterning of the cephalic neuroepithelium. Our results strongly suggest that several congenital craniofacial and cerebral malformations could be attributed to Six genes' misregulation.

Proliferation of neural crest (NC) stem cells and their subsequent differentiation into different neural cell types are key early events in the development of the peripheral nervous system. Soluble growth factors present at the sites where NC cells migrate are critical to the development of NC derivatives in each part of the body. In the present study, we further investigate the effect of microenvironmental factors on quail trunk NC development. We show for the first time that EGF induces differentiation of NC to the neuronal and melanocytic phenotypes, while fibroblast growth factor 2 (FGF2) promotes NC differentiation to Schwann cells. In the presence of both EGF and FGF2, the neuronal differentiation predominates. Our results suggest that FGF2 stimulates gliogenesis, while EGF promotes melanogenesis and neurogenesis. The combination of both growth factors stimulates neurogenesis. These findings suggest that these two growth factors may play an important role in the fate decision of NC progenitors and in the development of the peripheral nervous system.

Proteoglycans are considered to be important molecule in cell-microenvironment interactions. They are overexpressed in neoplastic cells modifying their growth and migration in hosts. In this work we verified that undersulfation of proteoglycans and other sulfated molecules, induced by sodium chlorate treatment, inhibited C6 glioma cells proliferation in a dose-dependent way. This effect was restored by the addition of exogenous heparin. We could not detect significant cell mortality in our culture condition. The treatment also impaired in a dose-dependent manner, C6 cell adhesion to extracellular matrix (ECM) proteins (collagen IV, laminin and fibronectin). In addition, sodium chlorate treatment altered C6 glioma cell morphology, from the fibroblast-like to a more rounded one. This effect was accompanied by increased synthesis of fibronectin and alterations in its extracellular network organization. However, we could not observe modifications on laminin organization and synthesis. The results suggest an important connection between sulfation degree with important tumor functions, such as proliferation and adhesion. We suggest that proteoglycans may modulate the glioma microenvironment network during tumor cell progression and invasion.

Pb(II) is a neurotoxic pollutant that produces permanent cognitive deficits in children. Pb(II) can modulate cell signaling pathways and cell viability in a variety of cell types. However, these actions are not well demonstrated on glial cells, which represent an important target for metals into the central nervous system. The present work was undertaken to determine the ability of Pb(II) in modulating the activity of mitogen activated protein kinases (MAPKs) in cultures of C6 rat glioma cells, a useful functional model for the study of astrocytes. Additionally, cell viability was analyzed by measurement of MTT reduction. Cells were exposed to lead acetate 0.1, 1, 10 microM for 24 and 48 h. MAPKs activation - in particular ERK1/2, p38(MAPK) and JNK1/2 - were analyzed by western blotting. Results showed that 10 microM Pb(II) treatment for 24 h caused a discrete stimulation of p38(MAPK) phosphorylation. However, 1 and 10 microM Pb(II) treatment for 48 h provoked a significant stimulation in the phosphorylation state of p38(MAPK) and JNK1/2. The phosphorylation state of ERK1/2 was not modified by any Pb(II) treatment. Moreover, data indicate that at 48 h treatment even 1 microM Pb(II) can be cytotoxic, causing impairment on cell viability. Therefore, depending on a long incubation period, a significant concomitant activation of p38(MAPK) and JNK1/2 by Pb(II) took place in parallel with the impairment of C6 glioma cells viability.

Background/Aim: Glioblastomas (GBMs) are the most malignant primary brain tumor. New treatment strategies against the disease are urgently needed, as therapies are not completely efficient. In this study, we evaluated the antitumorigenic activity of the carotenoid fucoxanthin (Fx) on human GBM cells in vitro. Materials and Methods: GBM1 cell viability and proliferation was assessed by MTT reduction, Ki67 and single cell cloning assays. GBM1 migration and invasion were analyzed by wound healing and Transwell assays. Apoptosis and necrosis were analyzed by flow cytometry, and the mitochondrial membrane potential (ΔΨm) by the selective fluorescent dye tetramethylrhodamine ethyl ester. Cell morphology was analyzed through scanning electron microscopy and transmission electron microscopy. Fx anti-angiogenic effect was assessed by the CAM ex ovo assay. Results: Fx decreased cell viability in a concentration-dependent manner (40-100 μ M) in GBM1, A172 and C6 cell lines and was not cytotoxic to murine astrocytes. In addition, Fx inhibited the proliferation and clonogenic potential, and decreased migration and invasion of GBM1 cells. Furthermore, Fx induced apoptosis, loss of ΔΨm and ultrastructural alterations in GBM1. Fx-treated GBM1 cells-conditioned medium reduced the quail yolk membrane vascularity. Conclusion: Fx induces cytotoxicity, anti-proliferative, antiinvasive and anti-angiogenic effects on GBM1 cells.Gliomas are primary tumors that affect the central nervous system (CNS). The origin of glioma cells is not completely elucidated, and may derive from dedifferentiation of a mature cell type, glial progenitor cells or primitive neural stem cells (1). The primary malignant brain neoplasms global-gender incidence rate is approximately 2.6 per 100,000 for females and 3.7 per 100,000 for males, per year (2). Gliomas compose only 27% of all CNS primary neoplasms, however, it represents almost 80% of all malignant primary tumors that affect this system (3,4).Gliomas are histopathologically categorized by the World Health Organization (WHO) into different subtypes and grades (I to IV), as oligodendroglioma, oligoastrocytoma and astrocytoma. Grade IV is reserved for a subtype of astrocytoma, the glioblastoma (GBM) (5). GBM is the most malignant glioma and the most frequent primary cerebral tumor, with an incidence of 3.2 cases per 100,000 person/year 6799

The effects of thyroid hormone (T(3)) on extracellular matrix (ECM) expression and organization in cerebellar astrocytes were studied. Control astrocytes exhibit laminin immunostaining distributed in a punctate configuration and fibronectin concentrated in focal points at the cell surface. These cells attach to the substratum by membrane points, as shown by scanning microscopy, possibly by focal points stained to fibronectin. In contrast, after T(3) treatment, laminin assumes a fibrillary pattern and fibronectin becomes organized in filaments homogeneously distributed on the cell surface; the cells acquire a very flat and spread morphology. T(3) treatment also modulates astrocyte adhesion. In addition, increased expression of both laminin and fibronectin was detected by Western blot. These alterations in fibronectin and/or laminin production and organization may be involved in the flat and spread morphology and in altered adhesion. We observed that fibroblast growth factor-2 (FGF(2)) added to cultures had similar effects to those described to T(3). Neutralizing antibodies against FGF(2) reversed T(3) effects on fibronectin and laminin distribution. We also observed that cerebellar neurons co-cultured on T(3)-treated astrocytes had an increase in the number of cells and presented longer neurites. Thus, we propose a novel mechanism of the effect of thyroid hormone on cerebellar development mediated by astrocytes: T(3) may induce astrocyte secretion of growth factors, mainly FGF(2), that autocrinally stimulate astrocyte proliferation, reorganization in ECM proteins, and alterations in cell spreading and adhesion. These effects may indirectly influence neuronal development.

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