Neural and Neural Crest-Derived Stem Cell Distribution in the Adult Human Dental Pulp / Distribución de Células Madre Neurales y Derivadas de la Cresta Neural en la Pulpa Dental Humana Adulta

SUMMARY: Despite comprehensive studies and reports about the properties of dental pulp stem cells (DPSCs) in vitro, we still need to confirm whether these in vitro characteristics coincide with the nature of DPSCs in situ. The anatomical location of DPSCs populations in the dental pulp has yet to be investigated. Moreover, the mesenchymal DPSCs have been much more studied than the neural crest-derived DPSCs. In this study, well-recognized neural/neural crest stem cell markers NCAM1, Nestin, SNAIL/SLUG, SOX9, and S100 are being investigated by immunohistochemistry to localize the precise location of these populations of DPSCs within the human adult dental pulp.All previously mentioned markers were expressed in the dental pulp, and their intensity and location of expression were reported.

A pesar de estudios e informes exhaustivos sobre las propiedades de las células madre de la pulpa dental (DPSC) in vitro, todavía necesitamos confirmar si estas características in vitro coinciden con la naturaleza de las DPSC in situ. La ubicación anatómica de las poblaciones de DPSC en la pulpa dental aún no se ha investigado. Además, las DPSC mesenquimales han sido mucho más estudiadas que las DPSC derivadas de la cresta neural. En este estudio, se están investigando mediante inmunohisto química marcadores de células madre de la cresta neural/ neural NCAM1, Nestin, SNAIL/SLUG, SOX9 y S100 para localizar la ubicación precisa de estas poblaciones de DPSC dentro de la pulpa dental humana adulta. Todos los marcadores mencionados anteriormente se expresaron en la pulpa dental y se informó su intensidad y ubicación de expresión.

Immunohistochemical characterization of stem cell, vascular, neural, and differentiation markers in the apical papilla and dental pulp of human teeth at various stages of root development.

This study aimed to evaluate the expression of several differentiation markers in the apical papilla (AP) and dental pulp (DP) of human permanent teeth. Twenty young human teeth were extracted and classified according to three Moorrees tooth development stages: initial root formation (Ri), root length ½ (R1/2), and root length complete (Rc). Immunohistochemical assays were performed using STRO-1, VEGF Receptor-2, Neurofilament heavy (NFH), and Nestin antibodies and analyzed under light microscopy. Decalcified, formalin fixed paraffin embedded tooth sections stained with hematoxylin and eosin showed an apical cell rich zone between the DP and AP. The AP revealed fewer vascular and cellular components than the DP. STRO-1 was expressed on vascular and neuronal elements beneath the odontoblast (OB) and in the sub-odontoblastic (SOB) zone, and VEGFR-2 positive cells were observed in the endothelium, arterioles, and blood vessels. Neuroepithelial stem cell protein (Nestin) was highly expressed in differentiated odontoblasts in the predentin odontotoblast and odontoblast cell processes. Neurofilament heavy (NFH) was expressed in mature axons throughout the DP. STRO-1 and VEGFR-2 microvascular expression was higher at the stages Ri and R1/2 while STRO-1 and NFH expression showed strong spatial distribution of Rc neuronal elements as compared to Ri and R1/2. Differentiated OB and SOB cells showed Nestin expression, indicating a reservoir of newly differentiated odontoblast-like cells.

Analysis of a cell niche with proliferative potential at the roof of the aqueduct of Sylvius.

The aqueduct of Sylvius connects the third with the fourth ventricle and is surrounded by the Periaqueductal Grey. Here, we report a novel niche of cells in the dorsal section of the aqueduct, hereby named dorsal aqueduct niche or DAN, by applying a battery of selective markers and transgenic mouse lines. The somata of DAN cells are located toward the lumen of the ventricle forming multiple layers in close association with the cerebrospinal fluid (CSF). A single process emerges from the soma and run with the blood vessels. Cells of the DAN express radial glia/stem cell markers such as GFAP, vimentin and nestin, and the glutamate transporter GLAST or the oligodendrocyte precursor/pericyte marker NG2, thereby suggesting their potential for the generation of new cells. Morphologically, DAN cells resemble tanycytes of the third ventricle, which transfer biochemical signals from the CSF to the central nervous system and display proliferative capacity. The aqueduct ependymal lining can proliferate as observed by the integration of BrdU and expression of Ki67. Thus, the dorsal section of the aqueduct of Sylvius possesses cells that may act a niche of new glial cells in the adult mouse brain.

Nestin-Expressing Cells in the Lung: The Bad and the Good Parts.

Nestin is a member of the intermediate filament family, which is expressed in a variety of stem or progenitor cells as well as in several types of malignancies. Nestin might be involved in tissue homeostasis or repair, but its expression has also been associated with processes that lead to a poor prognosis in various types of cancer. In this article, we review the literature related to the effect of nestin expression in the lung. According to most of the reports in the literature, nestin expression in lung cancer leads to an aggressive phenotype and resistance to chemotherapy as well as radiation treatments due to the upregulation of phenomena such as cell proliferation, angiogenesis, and metastasis. Furthermore, nestin may be involved in the pathogenesis of some non-cancer-related lung diseases. On the other hand, evidence also indicates that nestin-positive cells may have a role in lung homeostasis and be capable of generating various types of lung tissues. More research is necessary to establish the true value of nestin expression as a prognostic factor and therapeutic target in lung cancer in addition to its usefulness in therapeutic approaches for pulmonary diseases.

Circulating Nestin-GFP+ Cells Participate in the Pathogenesis of Paracoccidioides brasiliensis in the Lungs.

Multiple infectious diseases lead to impaired lung function. Revealing the cellular mechanisms involved in this impairment is crucial for the understanding of how the lungs shift from a physiologic to a pathologic state in each specific condition. In this context, we explored the pathogenesis of Paracoccidioidomycosis, which affects pulmonary functioning. The presence of cells expressing Nestin-GFP has been reported in different tissues, and their roles as tissue-specific progenitors have been stablished in particular organs. Here, we explored how Nestin-GFP+ cells are affected after lung infection by Paracoccidioides brasiliensis, a model of lung granulomatous inflammation with fibrotic outcome. We used Nestin-GFP transgenic mice, parabiosis surgery, confocal microscopy and flow cytometry to investigate the participation of Nestin-GFP+ cells in Paracoccidioides brasiliensis pathogenesis. We revealed that these cells increase in the lungs post-Paracoccidioides brasiliensis infection, accumulating around granulomas. This increase was due mainly to Nestin-GPF+ cells derived from the blood circulation, not associated to blood vessels, that co-express markers suggestive of hematopoietic cells (Sca-1, CD45 and CXCR4). Therefore, our findings suggest that circulating Nestin-GFP+ cells participate in the Paracoccidioides brasiliensis pathogenesis in the lungs.

Characterization of Gastrospheres Using 3D Coculture System.

To understand the molecular mechanisms involved in gastric disorders and regeneration, we need an in vitro tridimensional (3D) culture model, which can mimic the in vivo gastric microenvironment. A 3D coculture system named gastrosphere is proposed herein, composed of primary human gastric epithelial and stromal cells. The primary cultures were obtained from endoscopic gastric biopsies, and after mechanical and enzymatic dispersion, epithelial (HGE3) and stromal (HGS12) cells were expanded. After extensive immunocytochemical characterization, cells were seeded onto 96-well round bottom plates previously covered with 1% agarose. Cells were cultured in KM-F12 culture medium with 10% fetal bovine serum (FBS), antibiotics, and antimycotics, in humidified air at 37 °C and atmosphere containing 5% CO2 for 72 h or until spheres formation. Then gastrospheres were carefully transferred to a rotary cell culture system (RCCS-4), and maintained for 07, 14, 21, and 28 days. Gastrospheres were morphologically characterized by immunocytochemistry [cytokeratins (CK), vimentin, α-smooth muscle actin (α-SMA), laminin (LN), fibronectin (FN), and type IV collagen (CIV), proliferating cell nuclear antigen (PCNA)], and electron microscopy. In gastrospheres, the cytokeratin-positive epithelial cells were found in the outer layer, while vimentin-positive stromal cells were localized in the center of the gastrospheres. PCNA+ cells were mainly seen at the peripheral and in the intermediary region while nestin+ cells were also depicted in the latter zone. Scanning electron microscopy revealed groups of cohesive gastric cells at the periphery, while transmission electron microscopy demonstrated some differentiated mucous-like or zymogenic-like cells in the periphery and stromal structures located at the center of the 3D structures. Extracellular matrix was deposed between cells. Our data suggest that in vitro gastrospheres recapitulate the in vivo gastric microenvironment.

Expression of nestin, transcription factor SOX3 and homeobox protein DLX-4 in the facial tissue of children with cleft lip and palate / Expresión de nestina, factor de transcripción SOX3 y proteína homeobox DLX-4 en el tejido facial de niños con fisura labiopalatina

The failure of fusion of nasal and maxillary processes results in cleft lip and palate (CLP), which is one of the most common birth defects. The morphopathogenesis of this pathology is multifactorial and still largely unclear. The aim of this study was to evaluate the presence of nestin, transcriptor factor SOX3 (Sox3) and homeobox protein DLX-4 (Dlx-4) in complete unilateral (CU) and complete bilateral (CB) CLP affected facial tissue. Oral mucosa tissue samples were obtained from 17 CUCLP and 13 CBCLP patients during surgical cleft correction and 6 unaffected control subjects. Obtained tissue sections were stained with hematoxylin and eosin and by immunohistochemistry for nestin, Sox3 and Dlx-4. The intensity of staining was graded semiquantitatively. Nestin-positive structures were detected in all CUCLP and CBCLP patients' tissue samples, varying from moderate number of nestin-positive structures to numerous. Sox3 immunoreactivity was more prominent in epithelial cells in both patient groups with frequently patchy distribution. Mainly moderate number of Dlx-4-positive cells was observed in most of tissue samples. Statistically significant moderate positive correlation was found between nestin and Sox3 factors in CUCLP patient group (Spearman's rank correlation coefficient = .517, P = .034). Increase of nestinpositive structures suggests its role in the regulation of the remodeling of tissue in both CUCLP and CBCLP affected tissue. Dominance of Sox3 positivity in cleft affected epithelium indicates its possible role in (compensatory) formation of defective oral epithelium of CUCLP and CBCLP patients. The reduced expression of Dlx-4 implicates its limited regulatory role on the craniofacial development in CUCLP and CBCLP affected tissue.

La falla en la fusión de los procesos nasal y maxilar son causante de la fisura labiopalatina (FLP), que es uno de los defectos congénitos más comunes. La morfopatogenia de esta patología es multifactorial y aún poco clara. El objetivo de este estudio fue evaluar la presencia de nestina, el factor transcriptor SOX3 (Sox3) y la proteína homeobox DLX-4 (Dlx-4) en todo el tejido facial afectado por FLP bilateral unilateral (FU) y bilateral completa (FB). Se obtuvieron muestras de tejido de mucosa oral de 17 pacientes FUFLP y 13 FBFLP durante la corrección quirúrgica de la fisura y de 6 sujetos de control no afectados. Las secciones de tejido obtenidas se tiñeron con hematoxilina y eosina y mediante inmunohistoquímica para nestina, Sox3 y Dlx-4. La intensidad de la tinción fue graduada semicuantitativamente. Se detectaron estructuras positivas para nestina en todas las muestras de tejido de pacientes FUFLP y FBFLP, variando desde un número moderado a numerosas estructuras positivas para nestina. La inmunorreactividad de Sox3 fue más prominente en las células epiteliales en ambos grupos de pacientes con distribución frecuentemente irregular. Se observó un número principalmente moderado de células Dlx-4-positivas en la mayoría de las muestras de tejido. Se encontró una correlación positiva moderada estadísticamente significativa entre los factores de nestina y Sox3 en el grupo de pacientes FUFLP (coeficiente de correlación de rangos de Spearman = 0,517, P = 0,034). El aumento de estructuras positivas para nestina sugiere su papel en la regulación de la remodelación de tejido, tanto en tejido afectado por FUFLP como FBFLP. La dominancia de la positividad de Sox3 en el epitelio afectado de la fisura, indica su posible papel en la formación (compensatoria) del epitelio oral defectuoso de pacientes FUFLP y FBFLP. La expresión reducida de Dlx-4 implica su función reguladora limitada en el desarrollo craneofacial en tejido afectado por FUFLP y FBFLP.

Expression of stem cell markers Nanog and Nestin in lip squamous cell carcinoma and actinic cheilitis.

Cancer stem cell (CSC) proteins have been observed in several lesions and are associated with tumor beginning, evolution, and resistance to treatment. OBJECTIVES: To investigate the presence of NANOG, NESTIN, and ß-tubulin in lip squamous cell carcinoma (LSCC), actinic cheilitis (AC), and normal epithelium (NE). MATERIALS AND METHODS: Thirty cases of LSCC, thirty cases of AC (both analyzed according to the WHO classification and AC according to the binary classification), and twenty cases of NE were submitted to an immunohistochemical study. RESULTS: NANOG was more expressed in the nuclei of AC compared to NE (p = 0.007), as well as in high-risk AC cases (p = 0.017) and well-differentiated LSCCs (no significance). There was an accumulation of nuclear NANOG from mild to moderate and severe ACs. NESTIN was significantly less present in NE compared to AC (p = 0.001) and LSCC (p = 0.003). There was a higher expression in severe dysplasia or high-risk AC and well-differentiated LSCC. These results indicate an upregulation of NANOG and NESTIN in the early stages of carcinogenesis. ß-tubulin was intensely present in all lesions. CONCLUSION: The results suggest an upregulation of NANOG and NESTIN in the biological behavior these diseases, mainly in the transformation from AC to LSCC.

Neurogenesis in the postnatal cerebellum after injury.

The cerebellum plays major role in motor coordination and learning. It contains half of the neurons in the brain. Thus, deciphering the mechanisms by which cerebellar neurons are generated is essential to understand the cerebellar functions and the pathologies associated with it. In a recent study, Wojcinski et al. (2017) by using in vivo Cre/loxP technologies reveal that Nestin-expressing progenitors repopulated the external granular cell layer after injury. Depletion of postnatal external granular cell layer is not sufficient to induce motor behavior defects in adults, as the cerebellum recovers these neurons. Strikingly, Nestin-expressing progenitors differentiate into granule cell precursors and mature granule neurons after ablation of perinatal external granular layer, either by irradiation or by genetic ablation. This work identified a novel role of Nestin-expressing progenitors in the cerebellar microenvironment during development, and revealed that extracellular signals can convert specified progenitors into multipotent stem cells. Here, we discuss the findings from this study, and evaluate recent advances in our understanding of the cerebellar neurogenesis.

Fast transdifferentiation of human Wharton's jelly mesenchymal stem cells into neurospheres and nerve-like cells.

BACKGROUND: The human mesenchymal stem cells derived from Wharton's jelly tissue (hWJ-MSCs) represent a tool for cell-based therapies and regenerative medicine. hWJ-MSCs form neurospheres (NSs) within 3-7 days. No data is available to establish the neuro-phenotypic markers and time of formation of nerve-like (NLCs) and glial cells from NSs derived from hWJ-MSCs. NEW METHOD: hWJ-MSCs were incubated with Fast-N-Spheres medium for 24 and 72h. The new formed NSs were in turn incubated with forskolin in neurogenic NeuroForsk medium for 1-7days. RESULTS: hWJ-MSCs cultured with Fast-N-Spheres medium trans-differentiated into NSs in just 24h compared to 72h for hWJ-MSCs cultured with classic growth factor medium. The NSs generated from the Fast-N-Spheres medium expressed reduced levels SOX2, OCT4 and NANOG, as markers of pluripotency compared to undifferentiated hWJ-MSCs. The formed NSs exposed to NeuroForsk medium differentiated into NLCs in 4days as evidenced by high levels of protein expression of the neuronal markers, and no expression of the glial marker GFAP. COMPARISON WITH EXISTING METHOD(S): Currently, the formation and harvest of NSs is expensive and time consuming. Published protocols require 3-7days to form NSs from whole human umbilical cord MSCs. We report for the first time, to our knowledge, the differentiation of NSs-derived from hWJ-MSCs into NLCs. CONCLUSIONS: The fastest method to obtain NSs and NLCs from hWJ-MSCs takes only five days using the two-step incubation media Fast-N-Spheres and NeuroForsk.

Migration of bone marrow progenitor cells in the adult brain of rats and rabbits.

Neurogenesis takes place in the adult mammalian brain in three areas: Subgranular zone of the dentate gyrus (DG); subventricular zone of the lateral ventricle; olfactory bulb. Different molecular markers can be used to characterize the cells involved in adult neurogenesis. It has been recently suggested that a population of bone marrow (BM) progenitor cells may migrate to the brain and differentiate into neuronal lineage. To explore this hypothesis, we injected recombinant SV40-derived vectors into the BM and followed the potential migration of the transduced cells. Long-term BM-directed gene transfer using recombinant SV40-derived vectors leads to expression of the genes delivered to the BM firstly in circulating cells, then after several months in mature neurons and microglial cells, and thus without central nervous system (CNS) lesion. Most of transgene-expressing cells expressed NeuN, a marker of mature neurons. Thus, BM-derived cells may function as progenitors of CNS cells in adult animals. The mechanism by which the cells from the BM come to be neurons remains to be determined. Although the observed gradual increase in transgene-expressing neurons over 16 mo suggests that the pathway involved differentiation of BM-resident cells into neurons, cell fusion as the principal route cannot be totally ruled out. Additional studies using similar viral vectors showed that BM-derived progenitor cells migrating in the CNS express markers of neuronal precursors or immature neurons. Transgene-positive cells were found in the subgranular zone of the DG of the hippocampus 16 mo after intramarrow injection of the vector. In addition to cells expressing markers of mature neurons, transgene-positive cells were also positive for nestin and doublecortin, molecules expressed by developing neuronal cells. These cells were actively proliferating, as shown by short term BrdU incorporation studies. Inducing seizures by using kainic acid increased the number of BM progenitor cells transduced by SV40 vectors migrating to the hippocampus, and these cells were seen at earlier time points in the DG. We show that the cell membrane chemokine receptor, CCR5, and its ligands, enhance CNS inflammation and seizure activity in a model of neuronal excitotoxicity. SV40-based gene delivery of RNAi targeting CCR5 to the BM results in downregulating CCR5 in circulating cells, suggesting that CCR5 plays an important role in regulating traffic of BM-derived cells into the CNS, both in the basal state and in response to injury. Furthermore, reduction in CCR5 expression in circulating cells provides profound neuroprotection from excitotoxic neuronal injury, reduces neuroinflammation, and increases neuronal regeneration following this type of insult. These results suggest that BM-derived, transgene-expressing, cells can migrate to the brain and that they become neurons, at least in part, by differentiating into neuron precursors and subsequently developing into mature neurons.

Temporal and Regional Expression of Glucose-Dependent Insulinotropic Peptide and Its Receptor in Spinal Cord Injured Rats.

Spinal cord injury (SCI) results in loss of movement, sensibility, and autonomic control at the level of the lesion and at lower parts of the body. Several experimental strategies have been used in attempts to increase endogenous mechanisms of neuroprotection, neuroplasticity, and repair, but with limited success. It is known that glucose-dependent insulinotropic peptide (GIP) and its receptor (GIPR) can enhance synaptic plasticity, neurogenesis, and axonal outgrowth. However, their role in the injury has never been studied. The aim of this study was to evaluate the changes in expression levels of both GIP and GIPR in acute and chronic phases of SCI in rats. Following SCI (2 to 24 h after damage), the rat spinal cord showed a lesion in which the epicenter had a cavity with hemorrhage and necrosis. Furthermore, the lesion cavity also showed ballooned cells 14 and 28 days after injury. We found that SCI induced increases in GIPR expression in areas neighboring the site of injury at 6 h and 28 days after the injury. Moreover, higher GIP expression was observed in these regions on day 28. Neuronal projections from the injury epicenter showed an increase in GIP immunoreactivity 24 h and 14 and 28 days after SCI. Interestingly, GIP was also found in progenitor cells at the spinal cord canal 24 h after injury, whereas both GIP and GIPR were present in progenitor cells at the injury epicenter 14 days after in SCI animals. These results suggest that GIP and its receptor might be implicated with neurogenesis and the repair process after SCI.

Detection of a novel stem cell probably involved in normal turnover of the lung airway epithelium.

Regeneration of the lung airway epithelium after injury has been extensively studied. In contrast, analysis of its turnover in healthy adulthood has received little attention. In the classical view, this epithelium is maintained in the steady-state by the infrequent proliferation of basal or Clara cells. The intermediate filament protein nestin was initially identified as a marker for neural stem cells, but its expression has also been detected in other stem cells. Lungs from CD1 mice at the age of 2, 6, 12, 18 or 24 months were fixed in neutral-buffered formalin and paraffin-embedded. Nestin expression was examined by an immunohistochemical peroxidase-based method. Nestin-positive cells were detected in perivascular areas and in connective tissue that were in close proximity of the airway epithelium. Also, nestin-positive cells were found among the cells lining the airway epithelium. These findings suggest that nestin-positive stem cells circulate in the bloodstream, transmigrate through blood vessels and localize in the lung airway epithelium to participate in its turnover. We previously reported the existence of similar cells able to differentiate into lung chondrocytes. Thus, the stem cell reported here might be a bone marrow-derived mesenchymal stem cell (BMDMSC) able to generate several types of lung tissues. In conclusion, our findings indicate that there exist a BMDMSC in healthy adulthood that participates in the turnover of the lung airway epithelium. These findings may improve our knowledge about the lung stem cell biology and also provide novel approaches to therapy for devastating pulmonary diseases.

Nestin-positive stem cells participate in chondrocyte renewal in healthy adult lung cartilage / Células troncales nestin-positivas participan en la renovación de condrocitos en el cartílago pulmonar del adulto sano

It is considered that healthy adult cartilage has little or no capacity for renewal, and that chondrocytes maintain a stable resting phenotype and resist proliferation and differentiation throughout life. Recently we found that cell turnover in lung cartilage is possible and that nestin-positive cells may have a role in it. In this paper, we report additional findings about chondrocyte renewal in lung cartilage. Lung specimens from CD1 mice at the age of 2, 6, 12, 18 or 24 months were fixed in 10% neutral-buffered formalin and paraffin-embedded. Nestin expression was examined by an immunohistochemical peroxidase-based method. We found nestin-positive cells inside of cartilage islets and cells in division very close from them. Our findings indicate that there exist nestin-positive mesenchymal stem cells in the adult that are able to differentiate into lung chondrocytes, perhaps to maintain homeostasis or repair damaged tissue. These findings may improve our knowledge about the cartilage biology and could provide new cell candidates for cartilage tissue engineering.

Se considera que el cartílago adulto sano tiene poca o ninguna capacidad para renovarse, y que sus condrocitos permanecen en un estado de reposo estable, careciendo de las propiedades de proliferación y diferenciación. Recientemente encontramos que el recambio celular en el cartílago pulmonar es posible y que células troncales positivas para nestin pudieran tener algún papel en el mismo. En este artículo, reportamos nuevos hallazgos acerca de la renovación de condrocitos en el cartílago pulmonar. Pulmones de ratones CD1 de 2, 6, 12, 18 o 24 meses de edad se fijaron en formalina amortiguada al 10% y se incluyeron en parafina. Se analizó la expresión de nestin utilizando un método inmunohistoquímico basado en un sistema de detección con peroxidasa. Encontramos células positivas para nestin en el interior de los islotes de cartílago y células en división muy cercanas a ellas. Estos hallazgos indican que existen células madre mesenquimales positivas para nestin en el adulto con capacidad para diferenciarse en condrocitos pulmonares, probablemente para mantener la homeostasis tisular o reparar daños en el tejido. Asimismo, estos hallazgos pueden aumentar nuestra comprensión acerca de las propiedades biológicas del cartílago y podrían proporcionar nuevos candidatos para la ingeniería celular en la terapia regenerativa en enfermedades de las articulaciones.

Nestin down-regulation of cortical radial glia is delayed in rats submitted to recurrent status epilepticus during early postnatal life / Atraso no desaparecimento da nestina na glia radial cortical de ratos submetidos a recorrentes status epilepticus durante o desenvolvimento pós-natal precoce

OBJECTIVE: Nestin is temporarily expressed in several tissues during development and it is replaced by other protein types during cell differentiation process. This unique property allows distinguishing between undifferentiated and differentiated cells. This study was delineated to analyze the temporal pattern of nestin expression in cortical radial glial cells of rats during normal development and of rats submitted to recurrent status epilepticus (SE) in early postnatal life (P). METHOD: Experimental rats were submitted to pilocarpine-induced SE on P7-9. The cortical temporal profile of nestin was studied by immunohistochemistry at multiple time points (P9, P10, P12, P16, P30 and P90). RESULTS: We observed delayed nestin down-regulation in experimental rats of P9, P10, P12 and P16 groups. In addition, few radial glial cells were still present only in P21 experimental rats. CONCLUSION: Our results suggested that SE during early postnatal life alters normal maturation during a critical period of brain development.

OBJETIVO: A nestina, temporariamente expressa em diversos tecidos durante o desenvolvimento, é substituída no processo de diferenciação celular, o que permite a distinção entre células diferenciadas e indiferenciadas. O objetivo deste estudo foi verificar o padrão temporal da expressão da nestina nas células da glia radial cortical de ratos durante o desenvolvimento normal e nos ratos submetidos a sucessivos status epilepticus (SE) no periodo pós-natal precoce (P). MÉTODO: Os animais foram submetidos ao SE induzido pela pilocarpina em P7-9. O perfil temporal da nestina foi estudado por imuno-histoquímica em P9, P10, P12, P16, P30 e P90. RESULTADOS: Nos ratos experimentais, observamos atraso no desaparecimento da nestina nos grupos P9, P10, P12 e P16. Ainda, encontramos algumas glias radiais corticais apenas em P21 experimental. CONCLUSÃO: Nossos resultados sugerem que o SE durante o desenvolvimento pós-natal precoce altera o processo de maturação durante um periodo crítico do desenvolvimento encefálico.

Páncreas y células beta: mecanismos de diferenciación, morfogénesis y especificación celular endocrina. ¿Regeneración? / Pancreas and β cells: Differentiation mechanisms, morphogenesis and endocrine cellular specification. Regeneration?

La diabetes mellitus tipo 1 es una enfermedad metabólica multifactorial en la que los mecanismos inmunológicos juegan un papel fundamental. Una vez desarrollada la enfermedad, los pacientes son dependientes de la administración exógena de insulina. Actualmente, el campo de la investigación experimental ha identificado una población pancreática con características de células madre. Esta población de células positivas a nestina, se expresa bajo ciertas condiciones especiales y abre la posibilidad de desarrollar técnicas para la obtención de nuevas células β que pudieran regenerar el tejido dañado. Este trabajo es una revisión acerca del desarrollo embrionario del páncreas, las células madre pancreáticas embrionarias, los modelos actuales de lesión para la inducción de la expresión de células madre en páncreas adultos, el papel de los radicales libres sobre la expresión de nuevas células madre y las terapias experimentales actuales para mejorar la expresión de estas células.

Diabetes mellitus type 1 is a multifactorial metabolic disease in which immunological mechanisms play an essential role. Once the disease is fully established, affected individuals are dependent upon exogenous insulin administration. Current research has identified a pancreatic population resembling stem cells features. This population of nestin-positive cells is activated under specific circumstances and opens the possibility of developing procedures for obtaining new β cells for the regeneration of the pancreatic islets. In this work we review the embryonic development of pancreas, pancreatic stem cells, the current models for the induction of stem cells in adult pancreas, the role of free radicals on the induction of new stem cells, and the current therapeutic procedures to improve the expression of these cells.