34 research outputs found
ES cells-derived ectomesenchymal cells for tooth engineering.
Recent progresses in stem cell biology and tissue engineering allow considering the possible development of new therapies for compensating the dental tissue losses associated with traumas, pathologies or ageing. The possibility of generating a tooth by mimicking development through reassociations between dental epithelial cells and ectomesenchymal cells derived from the neural crest (NC) has been demonstrated in the mouse. In the search of cell sources to be used for a human transfer, pluripotent stem cells could represent a good alternative. Our study thus focuses on obtaining, ectomesenchymal cells from pluripotent ES cells, capable of promoting tooth histomorphogenesis, when reassociated with a competent dental epithelium. To this end, two ES differentiation protocols, using cyclopamine or a combination of FGF2 and BMP4, have been developed and tested for their capacity to generate such cells. The differentiated ES cells were characterized by quantitative RT-PCR. Both protocols led the cells to acquire in 10 days a mesenchymal-like cell morphology. Rapidly after induction, the cells loose their expression of pluripotent genes while sequentially activating typical NC specifiers. However, the kinetics of gene activation differed between the 2 protocols. Interestingly, Twist, a gene whose expression in the NC is associated with a commitment towards an ectomesenchymal fate, is only activated under the influence of FGF2 and BMP4. Reassociation experiments with a competent epithelium will allow testing the odontogenic potential of the differentiated ES cells. These experiments performed in the mouse system should allow defining a strategy for obtaining odontogenic competent human cells. Les progrĂšs en matiĂšre de biologie de cellules souches et dâingĂ©nierie tissulaire permettent dâenvisager le dĂ©veloppement de nouvelles thĂ©rapies pour pallier les pertes de tissus dentaires consĂ©cutives Ă des traumatismes, des situations pathologiques ou au vieillissement. La possibilitĂ© de gĂ©nĂ©rer une dent en mimant le dĂ©veloppement, par rĂ©associations entre cellules dentaires Ă©pithĂ©liales et mĂ©senchymateuses dĂ©rivĂ©es des crĂȘtes neurales (CN), a Ă©tĂ© dĂ©montrĂ©e chez la souris. Dans la recherche de ressources cellulaires utilisables pour un transfert chez lâhomme, les cellules souches pluripotentes pourraient constituer une alternative. Notre but est dâobtenir Ă partir de ces derniĂšres, des cellules ectomĂ©senchymateuses capables dâinteragir avec un Ă©pithĂ©lium dentaire pour promouvoir lâhistomorphogenĂšse dâune dent. Pour cela, deux protocoles de diffĂ©renciation de cellules ES, utilisant la cyclopamine ou une combinaison de FGF2/BMP4, ont Ă©tĂ© mis au point. Les cellules induites ont Ă©tĂ© caractĂ©risĂ©es par PCR quantitative. Les deux protocoles de diffĂ©renciation amĂšnent les cellules Ă acquĂ©rir en 10 jours, une morphologie de type mĂ©senchymateux. AprĂšs induction, lâexpression des gĂšnes de pluripotence chute de façon drastique alors que celle des gĂšnes spĂ©cificateurs de CN est activĂ©e. Toutefois, la cinĂ©tique varie selon le protocole. Le gĂšne Twist, dont lâexpression dans les CN est associĂ©e Ă un engagement vers lâectomĂ©senchyme, nâest activĂ© significativement que sous lâaction de FGF2/BMP4. Des expĂ©riences de rĂ©associations avec un Ă©pithĂ©lium dentaire sont en cours pour Ă©valuer le potentiel odontogĂšne des cellules ES diffĂ©renciĂ©es. A terme, ces approches menĂ©es chez la souris devraient permettre de dĂ©finir une stratĂ©gie pour lâobtention de cellules compĂ©tentes humaines.Recent progresses in stem cell biology and tissue engineering allow considering the possible development of new therapies for compensating the dental tissue losses associated with traumas, pathologies or ageing. The possibility of generating a tooth by mimicking development through reassociations between dental epithelial cells and ectomesenchymal cells derived from the neural crest (NC) has been demonstrated in the mouse. In the search of cell sources to be used for a human transfer, pluripotent stem cells could represent a good alternative. Our study thus focuses on obtaining, ectomesenchymal cells from pluripotent ES cells, capable of promoting tooth histomorphogenesis, when reassociated with a competent dental epithelium. To this end, two ES differentiation protocols, using cyclopamine or a combination of FGF2 and BMP4, have been developed and tested for their capacity to generate such cells. The differentiated ES cells were characterized by quantitative RT-PCR. Both protocols led the cells to acquire in 10 days a mesenchymal-like cell morphology. Rapidly after induction, the cells loose their expression of pluripotent genes while sequentially activating typical NC specifiers. However, the kinetics of gene activation differed between the 2 protocols. Interestingly, Twist, a gene whose expression in the NC is associated with a commitment towards an ectomesenchymal fate, is only activated under the influence of FGF2 and BMP4. Reassociation experiments with a competent epithelium will allow testing the odontogenic potential of the differentiated ES cells. These experiments performed in the mouse system should allow defining a strategy for obtaining odontogenic competent human cells. Les progrĂšs en matiĂšre de biologie de cellules souches et dâingĂ©nierie tissulaire permettent dâenvisager le dĂ©veloppement de nouvelles thĂ©rapies pour pallier les pertes de tissus dentaires consĂ©cutives Ă des traumatismes, des situations pathologiques ou au vieillissement. La possibilitĂ© de gĂ©nĂ©rer une dent en mimant le dĂ©veloppement, par rĂ©associations entre cellules dentaires Ă©pithĂ©liales et mĂ©senchymateuses dĂ©rivĂ©es des crĂȘtes neurales (CN), a Ă©tĂ© dĂ©montrĂ©e chez la souris. Dans la recherche de ressources cellulaires utilisables pour un transfert chez lâhomme, les cellules souches pluripotentes pourraient constituer une alternative. Notre but est dâobtenir Ă partir de ces derniĂšres, des cellules ectomĂ©senchymateuses capables dâinteragir avec un Ă©pithĂ©lium dentaire pour promouvoir lâhistomorphogenĂšse dâune dent. Pour cela, deux protocoles de diffĂ©renciation de cellules ES, utilisant la cyclopamine ou une combinaison de FGF2/BMP4, ont Ă©tĂ© mis au point. Les cellules induites ont Ă©tĂ© caractĂ©risĂ©es par PCR quantitative. Les deux protocoles de diffĂ©renciation amĂšnent les cellules Ă acquĂ©rir en 10 jours, une morphologie de type mĂ©senchymateux. AprĂšs induction, lâexpression des gĂšnes de pluripotence chute de façon drastique alors que celle des gĂšnes spĂ©cificateurs de CN est activĂ©e. Toutefois, la cinĂ©tique varie selon le protocole. Le gĂšne Twist, dont lâexpression dans les CN est associĂ©e Ă un engagement vers lâectomĂ©senchyme, nâest activĂ© significativement que sous lâaction de FGF2/BMP4. Des expĂ©riences de rĂ©associations avec un Ă©pithĂ©lium dentaire sont en cours pour Ă©valuer le potentiel odontogĂšne des cellules ES diffĂ©renciĂ©es. A terme, ces approches menĂ©es chez la souris devraient permettre de dĂ©finir une stratĂ©gie pour lâobtention de cellules compĂ©tentes humaines
Short-term effects of amelogenin gene splice products A+4 and A-4 implanted in the exposed rat molar pulp
In order to study the short-time effects of two bioactive low-molecular amelogenins A+4 and A-4, half-moon cavities were prepared in the mesial aspect of the first maxillary molars, and after pulp exposure, agarose beads alone (controls) or beads soaked in A+4 or A-4 (experimental) were implanted into the pulp. After 1, 3 or 7 days, the rats were killed and the teeth studied by immunohistochemistry. Cell proliferation was studied by PCNA labeling, positive at 3 days, but decreasing at day 7 for A+4, whilst constantly high between 3 and 7 days for A-4. The differentiation toward the osteo/odontoblast lineage shown by RP59 labeling was more apparent for A-4 compared with A+4. Osteopontin-positive cells were alike at days 3 and 7 for A-4. In contrast, for A+4, the weak labeling detected at day 3 became stronger at day 7. Dentin sialoprotein (DSP), an in vivo odontoblast marker, was not detectable until day 7 where a few cells became DSP positive after A-4 stimulation, but not for A+4. These results suggest that A +/- 4 promote the proliferation of some pulp cells. Some of them further differentiate into osteoblast-like progenitors, the effects being more precocious for A-4 (day 3) compared with A+4 (day 7). The present data suggest that A +/- 4 promote early recruitment of osteogenic progenitors, and evidence functional differences between A+4 and A-4
Differences in the pattern and regulation of mineral deposition in human cell lines of osteogenic and non-osteogenic origin
Bone marrow-derived mesenchymal stem cells (MSCs) are widely used as a cellular model of bone formation, and can mineralize in vitro in response to osteogenic medium (OM). It is unclear, however, whether this property is specific to cells of mesenchymal origin. We analysed the OM response in 3 non-osteogenic lines, HEK293, HeLa and NTera, compared to MSCs. Whereas HEK293 cells failed to respond to OM conditions, the 2 carcinoma-derived lines NTera and HeLa deposited a calcium phosphate mineral comparable to that present in MSC cultures. However, unlike MSCs, HeLa and NTera cultures did so in the absence of dexamethasone. This discrepancy was confirmed, as bone morphogenetic protein inhibition obliterated the OM response in MSCs but not in HeLa or NTera, indicating that these 2 models can deposit mineral through a mechanism independent of established dexamethasone or bone morphogenetic protein signalling
The phenotype of triparental hepatoma cell hybrids depends on the fusion sequence used to generate them.
Journal ArticleResearch Support, Non-U.S. Gov'tinfo:eu-repo/semantics/publishe
DES TRANSCRITS DE L'ALBUMINE ET DE L'ALPHA-FOETOPROTEINE SONT PRESENTS DANS DES POPULATIONS CELLULAIRES DISTINCTES DU REIN ET DU CERVEAU AU COURS DU DEVELOPPEMENT CHEZ LE RAT
International audienc
Coexistence of expressed and non-expressed alpha-fetoprotein genes in somatic cell hybrids.
Hybrids have been generated between mouse hepatoma cells, which actively synthesize alpha-fetoprotein (AFP), and adult hepatocytes, where AFP production is shut off. These hybrids maintain an active synthesis of mouse AFP. Using a specific radioimmunoassay, we found that rat AFP production is not activated. Southern blot analysis showed that mouse and rat AFP DNA sequences can be distinguished and that hybrid clones possessing something close to the complete chromosome sets of both parents have retained both parental AFP DNA sequences. Thus expressed and non-expressed AFP genes coexist in these hybrid cells as if their expression were dependent on a cis-acting event.Journal ArticleResearch Support, Non-U.S. Gov'tinfo:eu-repo/semantics/publishe
Expression of Fas, FasL, caspase-8 and other factors of the extrinsic apoptotic pathway during the onset of interdigital tissue elimination
Elimination of the interdigital web is considered to be the classical model for assessing apoptosis. So far, most of the molecules described in the process have been connected to the intrinsic (mitochondrial) pathway. The extrinsic (receptor mediated) apoptotic pathway has been rather neglected, although it is important in development, immunomodulation and cancer therapy. This work aimed to investigate factors of the extrinsic apoptotic machinery during interdigital regression with a focus on three crucial initiators: Fas, Fas ligand and caspase-8. Immunofluorescent analysis of mouse forelimb histological sections revealed abundant expression of these molecules prior to digit separation. Subsequent PCR Array analyses indicated the expression of several markers engaged in the extrinsic pathway. Between embryonic days 11 and 13, statistically significant increases in the expression of Fas and caspase-8 were observed, along with other molecules involved in the extrinsic apoptotic pathway such as Dapk1, Traf3, Tnsf12, Tnfrsf1A and Ripk1. These results demonstrate for the first time the presence of extrinsic apoptotic components in mouse limb development and indicate novel candidates in the molecular network accompanying the regression of interdigital tissue during digitalisation
Dentin Extracellular Matrix Molecules Implanted into Exposed Pulps Generate Reparative Dentin: a Novel Strategy in Regenerative Dentistry
U ovom je radu opisana proizvodnja prediva Predionice Klanjec. Prikazano je stanje predionice kroz povijest. Prikazan je i napredak proizvodnje kroz vremenska razdoblja, te postepeno poveÄanje proizvodnje. Tvornica je specijalizirana za proizvodnju preÄe pamuÄnog tipa. PredloĆŸeno je automatsko skidanje namotaka sa istezalice te automatski prijevoz do predilica. TakoÄer je predloĆŸena ugradnja dvije nove predilice te moguÄa automatizacija.This work describes the manufacturing of thread in Klanjec Spinning-Mill. It presents the conditions and situation of the spinning-mill during the course of history. It also shows the progress and the gradual increase of manufacturing through the history periods. The factory is specialized in the manufacturing of coton thread. Automatic removal of spools from the drawing machine and automatic transport to the spinning wheels are suggested. Mounting and automation of two spinning wheels are also proposed