Chondrogenesis and mineralization during in vitro culture of human mesenchymal stem cells on three-dimensional woven scaffolds.

Human mesenchymal stem cells (hMSCs) and three-dimensional (3D) woven poly(ɛ-caprolactone) (PCL) scaffolds are promising tools for skeletal tissue engineering. We hypothesized that in vitro culture duration and medium additives can individually and interactively influence the structure, composition, mechanical, and molecular properties of engineered tissues based on hMSCs and 3D poly(ɛ-caprolactone). Bone marrow hMSCs were suspended in collagen gel, seeded on scaffolds, and cultured for 1, 21, or 45 days under chondrogenic and/or osteogenic conditions. Structure, composition, biomechanics, and gene expression were analyzed. In chondrogenic medium, cartilaginous tissue formed by day 21, and hypertrophic mineralization was observed in the newly formed extracellular matrix at the interface with underlying scaffold by day 45. Glycosaminoglycan, hydroxyproline, and calcium contents, and alkaline phosphatase activity depended on culture duration and medium additives, with significant interactive effects (all p < 0.0001). The 45-day constructs exhibited mechanical properties on the order of magnitude of native articular cartilage (aggregate, Young's, and shear moduli of 0.15, 0.12, and 0.033 MPa, respectively). Gene expression was characteristic of chondrogenesis and endochondral bone formation, with sequential regulation of Sox-9, collagen type II, aggrecan, core binding factor alpha 1 (Cbfα1)/Runx2, bone sialoprotein, bone morphogenetic protein-2, and osteocalcin. In contrast, osteogenic medium produced limited osteogenesis. Long-term culture of hMSC on 3D scaffolds resulted in chondrogenesis and regional mineralization at the interface between soft, newly formed engineered cartilage, and stiffer underlying scaffold. These findings merit consideration when developing grafts for osteochondral defect repair.

The use of mineral trioxide aggregate in endodontics - status report

Mineral trioxide aggregate (MTA) is a clinical product comprising a mixture of Portland cement and bismuth oxide which is currently used as a root−filling material in dentistry. It has good biological compatibility, is capable of promoting both osteogenesis and cementogensis, and is finding increasing use in endodontic therapy. It is dimensionally stable, and provides an acceptable and durable seal for endodontically treated teeth. This article reviews the chemistry and applications of MTA, and highlights the fact that very little is currently known about the hydration chemistry, phase evolution and stability of this cement in physiological environments. However, biological effects of MTA have been well documented and are considered in detail. The article concludes that this material is a useful addition to the range of materials available for clinical application in endodontics.

Bioreactor Expansion of Human Adult Bone Marrow-Derived Mesenchymal Stem Cells

Supplementation of mesenchymal stem cells (MSCs) during hematopoietic stem cell transplantation (HSCT) alleviates complications such as graft-versus-host disease, leading to a speedy recovery of hematopoiesis. To meet such clinical demand, a fast MSCs expansion method is required. In the present study, we examined the feasibility of expanding MSCs from the isolated bone marrow mononuclear cells using a rotary bioreactor system. The cells were cultured in a rotary bioreactor with Myelocult� medium containing a combination of supplementary factors, including stem cell factor (SCF), interleukin 3 and 6 (IL-3, IL-6). After 8 days of culture, total cell numbers, Stro-1+CD44+CD34- MSCs and CD34+CD44+Stro-1- HSCs were increased 9, 29, and 8 folds respectively. Colony forming efficiency-fibroblast per day (CFE-F/day) of the bioreactor-treated cells was 1.44-fold higher than that of the cells without bioreactor treatment. The bioreactor-expanded MSCs showed expression of primitive MSCs markers endoglin (SH2) and vimentin, whereas markers associated with lineage differentiation including osteocalcin (osteogenesis), Type II collagen (chondrogenesis) and C/EBPα (adipogenesis) were not detected. Upon induction, the bioreactor-expanded MSCs were able to differentiate into osteoblasts, chondrocytes and adipocytes. Taken together, we conclude that the rotary bioreactor with the modified Myelocult� medium reported in this study may be used to rapidly expand MSCs.

Osteoclastogenesis induced by sRANKL and M-CSF from the non-adherent cell population of human bone marrow is inhibited by rhBMP-2 alone or together with rhVEGF

During bone development and repair, angiogenesis, osteogenesis and bone remodelling are closely associated processes that share some common mediators. In the present study non-adherent human bone marrow mononuclear cells under the induction of sRANKL and M-CSF, differentiated into osteoclasts with TRAP positive staining, VNR expression, and Ca-P resorptive activity. The effects of various combinations of rhBMP-2 (0, 3, 30, 300 ng/ml) and rhVEGF (0, 25 ng/ml) on osteoclastogenesis potentials were examined in this experimental system. The percentages of TRAP-positive multiple nucleated cells represent osteoclast differentiation potential and the percentages of resorptive areas in the Ca-P coated plates resemble osteoclast resorption capability. The presence of rhBMP-2 at 30 and 300 ng/ml showed inhibitory effects on osteoclast differentiation and their resorptive capability in the human osteoclast culture system. rhVEGF (25 ng/ml) enhanced the resorptive function of osteoclast whenever it was used alone or combined with 3 ng/ml rhBMP-2. However, rhVEGF induced resorptive function was inhibited by 30 ng/ml and 300 ng/ml rhBMP-2 at a dose-dependent manner. Statistical analysis demonstrated that an interactive effect exists between rhBMP-2 and rhVEGF on human osteoclastogenesis. These findings suggested that an interactive regulation may exist between BMPs and VEGF signaling pathways during osteoclastogenesis, exact mechanisms are yet to be elucidated.

The molecular signature of the stroma response in prostate cancer-induced osteoblastic bone metastasis highlights expansion of hematopoietic and prostate epithelial stem cell niches

The reciprocal interaction between cancer cells and the tissue-specific stroma is critical for primary and metastatic tumor growth progression. Prostate cancer cells colonize preferentially bone (osteotropism), where they alter the physiological balance between osteoblast-mediated bone formation and osteoclast-mediated bone resorption, and elicit prevalently an osteoblastic response (osteoinduction). The molecular cues provided by osteoblasts for the survival and growth of bone metastatic prostate cancer cells are largely unknown. We exploited the sufficient divergence between human and mouse RNA sequences together with redefinition of highly species-specific gene arrays by computer-aided and experimental exclusion of cross-hybridizing oligonucleotide probes. This strategy allowed the dissection of the stroma (mouse) from the cancer cell (human) transcriptome in bone metastasis xenograft models of human osteoinductive prostate cancer cells (VCaP and C4-2B). As a result, we generated the osteoblastic bone metastasis-associated stroma transcriptome (OB-BMST). Subtraction of genes shared by inflammation, wound healing and desmoplastic responses, and by the tissue type-independent stroma responses to a variety of non-osteotropic and osteotropic primary cancers generated a curated gene signature ("Core" OB-BMST) putatively representing the bone marrow/bone-specific stroma response to prostate cancer-induced, osteoblastic bone metastasis. The expression pattern of three representative Core OB-BMST genes (PTN, EPHA3 and FSCN1) seems to confirm the bone specificity of this response. A robust induction of genes involved in osteogenesis and angiogenesis dominates both the OB-BMST and Core OB-BMST. This translates in an amplification of hematopoietic and, remarkably, prostate epithelial stem cell niche components that may function as a self-reinforcing bone metastatic niche providing a growth support specific for osteoinductive prostate cancer cells. The induction of this combinatorial stem cell niche is a novel mechanism that may also explain cancer cell osteotropism and local interference with hematopoiesis (myelophthisis). Accordingly, these stem cell niche components may represent innovative therapeutic targets and/or serum biomarkers in osteoblastic bone metastasis.

Les sources de motivation au regard de la carrière des jeunes inscrits aux programmes Sport-études à l'ordre d'enseignement secondaire

Lorsqu'il est question de l'impact du sport sur le développement de jeunes adolescents' c'est généralement en fonction de leurs comportements. Toutefois, lorsqu'il s'agit d'évaluer l'influence de la pratique sportive sur le développement scolaire et professionnel des élèves-athlètes, nombreux sont les gens qui voient le sport comme une distraction notable à l'engagement et à la poursuite de leurs études. Pourtant nous remarquons, depuis quelques années, l'apparition et la multiplication de programmes d'études voulant favoriser à la fois la réussite scolaire ainsi que la réussite sportive de jeunes athlètes. Conformément aux propos de Boute, Lepert, Syndiqué et Taupin (1981), nous croyons que les programmes Sport-études concrétisent deux idées (et deux désirs) qui mûrissaient depuis longtemps: l'idée qu'il n'est pas nécessaire d'abandonner ses études pour se consacrer à un sport, et plus important, l'idée qu'il n'est pas nécessaire d'abandonner le sport pour mener à bien ses études secondaires. Selon cette perspective, il serait logique de penser que les programmes scolaires misant sur la combinaison des études et de la pratique du sport de haut niveau s'associent à des caractéristiques particulières notamment, en ce qui à trait à leur motivation au regard de leur projet professionnel. Notre étude vise donc à identifier les sources spécifiques de motivation des élèves inscrits aux programmes Sport-études et régulier à l'ordre d'enseignement secondaire et de vérifier l'existence possible de différences entre ces deux groupes de sujets. Ce mémoire se divise en trois parties. La première partie vise à exposer la problématique de notre recherche. Nous identifions d'abord notre problème de recherche en dressant un portrait général de la situation actuelle des jeunes à l'ordre d'enseignement secondaire puis nous traitons du rôle qu'occupe l'orientation quant à la motivation des élèves au regard de leurs études. À cela s'ajoute l'examen d'une littérature appropriée aux élèves-athlètes et aux sources de motivation particulières qui leur sont attribuées. Nous présentons ensuite le cadre théorique de notre recherche en analysant les concepts de motivation et de développement de carrière. Nous complétons cette partie par l'étude de certaines recherches et expériences en lien avec notre problématique et nous démontrons la pertinence de notre recherche avant d'identifier les objectifs poursuivis. En ce qui à trait à la deuxième partie de notre étude, elle concerne la méthodologie. Nous présentons dans cette section les principales démarches utilisées afin de rencontrer nos objectifs de recherche. Il s'agit entre autres de l'instrument de mesure retenu, les sujets sélectionnés, du déroulement de l'expérience, de la présentation des programmes Sport-études, des limites de notre recherche et des techniques statistiques employées pour analyser et interpréter les résultats obtenus. Quant à la troisième partie, elle contient essentiellement les données obtenues au cours de notre recherche. Dans un premier temps, nous dégageons un portrait général des sources de motivation au regard de la carrière des élèves inscrits aux programmes réguliers et Sport-études. Puis, dans un deuxième temps, nous essayons de dégager les particularités du profil motivationnel de ces élèves en fonction du programme d'études auquel ils sont inscrits. Enfin, quelques implications possibles de nos résultats pour la pratique de l'orientation professionnelle font l'objet de la conclusion de ce mémoire.

Identification and molecular characterization of bone-related micrornas: functional implications

Tese de doutoramento, Ciências Biomédicas, Departamento de Ciências Biomédicas e Medicina, Universidade do Algarve, 2014

Avaliação online das aprendizagens com propósitos formativos : nota positiva?

Trabalho de projeto de mestrado, Tecnologias e Metodologias em E-Learning, Universidade de Lisboa, Instituto de Educação, Faculdade de Ciências, 2013

O impacto (custo) das LMELT decorrente de acidentes de trabalho numa organização de saúde

RESUMO - A morbilidade associada às lesões músculoesqueléticas ligadas ao trabalho (LMELT) origina uma elevada perda de produtividade (absentismo e presentismo) em organizações de saúde, o que induz um substantivo impacto (custo) económico. Nesse contexto, os profissionais de saúde, como grupo vulnerável à ocorrência de LMELT, nomeadamente aqueles que mobilizam os doentes diariamente, apresentam elevadas taxas de acidentes de trabalho com absentismo. Considerando a importância do capital humano em saúde e tendo em conta o contexto actual de contenção da despesa no sector da saúde português, o despiste de situações de perda de produtividade e seu impacto económico em instituições de saúde, assume um papel fundamental na gestão dessas organizações. O presente estudo teve como objetivo avaliar o impacto (custo) das LMELT por acidente de trabalho em enfermeiros e assistentes operacionais do CMRA durante o período de 2009 a 2013. Partindo da identificação dos acidentes de trabalho (AT) ocorridos nestes grupos profissionais entre 2009 e 2013, da lesão musculoesquelética resultante e do absentismo registado os participantes no estudo responderam aos itens da escala WQL-8 e SPS-6, para se determinar também os níveis de presentismo. Este estudo adotou a metodologia do capital humano para estimar os custos indiretos ou perda de produtividade das LMELT. Constatou-se que são as transferências a maior causa das LMELT, com uma sintomatologia mais prevalente na região lombar. Existe perda de produtividade nesta instituição entre 2009 e 2013 com um custo total estimado em 222.015,98€, absentismo e presentismo, sendo a Distração Evitada a dimensão que apresenta maiores valores.

Product quality judgments in a two-sequence cue environment

Previous research demonstrated that the sequence of informational cues and the level of distraction have an impact on the judgment of a product’s quality. This study investigates the influence of the force behind the processing of these cues, working memory (WM). The results indicate that without distraction, consumers with low and high WM capacity (WMC) equally base their product evaluation on the first sequential cue. In the presence of a distractor, however, low WM individuals are no longer able to recall the initial cue, and thus derive their product judgment from the final cue. Moreover, evidence of intercultural differences in the perception of product related cues, and their aptitude for signaling a favorable product quality is provided.

Translation of biomechanical concepts in bone tissue engineering: from animal study to revision knee arthroplasty.

Bone defects in revision knee arthroplasty are often located in load-bearing regions. The goal of this study was to determine whether a physiologic load could be used as an in situ osteogenic signal to the scaffolds filling the bone defects. In order to answer this question, we proposed a novel translation procedure having four steps: (1) determining the mechanical stimulus using finite element method, (2) designing an animal study to measure bone formation spatially and temporally using micro-CT imaging in the scaffold subjected to the estimated mechanical stimulus, (3) identifying bone formation parameters for the loaded and non-loaded cases appearing in a recently developed mathematical model for bone formation in the scaffold and (4) estimating the stiffness and the bone formation in the bone-scaffold construct. With this procedure, we estimated that after 3 years mechanical stimulation increases the bone volume fraction and the stiffness of scaffold by 1.5- and 2.7-fold, respectively, compared to a non-loaded situation.

The G0/G1 switch gene 2 is a novel PPAR target gene.

PPARs (peroxisome-proliferator-activated receptors) alpha, beta/delta and gamma are a group of transcription factors that are involved in numerous processes, including lipid metabolism and adipogenesis. By comparing liver mRNAs of wild-type and PPARalpha-null mice using microarrays, a novel putative target gene of PPARalpha, G0S2 (G0/G1 switch gene 2), was identified. Hepatic expression of G0S2 was up-regulated by fasting and by the PPARalpha agonist Wy14643 in a PPARalpha-dependent manner. Surprisingly, the G0S2 mRNA level was highest in brown and white adipose tissue and was greatly up-regulated during mouse 3T3-L1 and human SGBS (Simpson-Golabi-Behmel syndrome) adipogenesis. Transactivation, gel shift and chromatin immunoprecipitation assays indicated that G0S2 is a direct PPARgamma and probable PPARalpha target gene with a functional PPRE (PPAR-responsive element) in its promoter. Up-regulation of G0S2 mRNA seemed to be specific for adipogenesis, and was not observed during osteogenesis or myogenesis. In 3T3-L1 fibroblasts, expression of G0S2 was associated with growth arrest, which is required for 3T3-L1 adipogenesis. Together, these data indicate that G0S2 is a novel target gene of PPARs that may be involved in adipocyte differentiation.

Predictors of academic achievement and social competence in adolescence : facilitation, inhibition and general cognitive processing /

The relevance of attentional measures to cognitive and social adaptive behaviour was examined in an adolescent sample. Unlike previous research, the influence of both inhibitory and facilitory aspects of attention were studied. In addition, contributions made by these attentional processes were compared with traditional psychometric measures of cognitive functioning. Data were gathered from 36 grade 10 and 1 1 high school students (20 male and 16 female students) with a variety of learning and attentional difficulties. Data collection was conducted in the course of two testing sessions. In the first session, students completed questionnaires regarding their medical history, and everyday behaviours (the Brock Adaptive Functioning Questionnaire), along with non-verbal problem solving tasks and motor speed tasks. In the second session, students performed working memory measures and computer-administered tasks assessing inhibitory and facilitory aspects of attention. Grades and teacher-rated measures of cognitive and social impulsivity were also gathered. Results indicate that attentional control has both cognitive and social/emotional implications. Performance on negative priming and facilitation trials from the Flanker task predicted grades in core courses, social functioning measures, and cognitive and social impulsivity ratings. However, beneficial effects for academic and social functioning associated with inhibition were less prevalent in those demonstrating a greater ability to respond to facilitory cues. There was also some evidence that high levels of facilitation were less beneficial to academic performance, and female students were more likely to exceed optimal levels of facilitory processing. Furthermore, lower negative priming was ''S'K 'i\':y-: -'*' - r " j«v ; ''*.' iij^y Inhibition, Facilitation and Social Competence 3 associated with classroom-rated distraction and hyperactivity, but the relationship between inhibition and social aspects of impulsivity was stronger for adolescents with learning or reading problems, and the relationship between inhibition and cognitive impulsivity was stronger for male students. In most cases, attentional measures were predictive of performance outcomes independent of traditional psychometric measures of cognitive functioning. >,, These findings provide support for neuropsychological models linking inhibition to control of interference and arousal, and emphasize the fundamental role of attention in everyday adolescent activities. The findings also warrant further investigation into the ways which inhibitory and facilitory attentional processes interact, and the contextdependent nature of attentional control.associated with classroom-rated distraction and hyperactivity, but the relationship between inhibition and social aspects of impulsivity was stronger for adolescents with learning or reading problems, and the relationship between inhibition and cognitive impulsivity was stronger for male students. In most cases, attentional measures were predictive of performance outcomes independent of traditional psychometric measures of cognitive functioning. >,, These findings provide support for neuropsychological models linking inhibition to control of interference and arousal, and emphasize the fundamental role of attention in everyday adolescent activities. The findings also warrant further investigation into the ways which inhibitory and facilitory attentional processes interact, and the contextdependent nature of attentional control.

L’effet des différents facteurs de croissance sur la viabilité et la prolifération des ostéoblastes scoliotiques

Résumé: La Scoliose Idiopathique de l’Adolescent (SIA) est une condition débilitante qui peut avoir comme résultat une douleur importante, une altération du fonctionnement quotidien et une détérioration de la qualité de vie. Pour les patients qui ne répondent pas au traitement conservateur, la fusion vertébrale, en utilisant des greffes osseuses, est devenue un traitement de choix pour stabiliser la colonne. Des connaissances plus pointues à propos des facteurs impliqués dans l’ostéogénèse et la formation de l’os peuvent raccourcir le processus de guérison et permettre aux patients de réintégrer leurs activités dans un laps de temps plus court. Les plaquettes peuvent jouer un rôle important dans la première étape de la guérison des fractures car elles sont une source autologue de plusieurs facteurs de croissance qui soutiennent la prolifération et la différenciation des ostéoblastes in vivo et in vitro. Au cours des dernières années, plusieurs tentatives ont été réalisées afin de trouver des traitements additionnels pour : 1) Raccourcir le temps de guérison des fractures relativement long ; 2) Obtenir une plus courte période de convalescence pour les patients qui ont besoin de prothèses ; 3) Corriger plus facilement plusieurs maladies congénitales; 4) Améliorer le processus de fusion vertébrale et 5) Développer de nouvelles approches thérapeutiques, notamment au niveau des processus régularisant le remodelage osseux et la régénération des tissus osseux. Dans le cadre de la présente étude, j’ai étudié la contribution possible du facteur de croissance de l’insuline (IGF) et du facteur vasculaire endothélial de croissance (VEGF) sur la maturation de l’ostéoblaste scoliotique dans des cultures cellulaires in vitro et j’ai comparé les résultats avec celles obtenues dans les mêmes conditions mais en stimulant les ostéoblastes avec de la mélatonine. Cette étude préliminaire a été réalisée sur des échantillons d’os récoltés de quatre patients atteints par la Scoliose Idiopathique de l‘Adolescent (SIA), ainsi que sur des échantillons d’os issus de quatre sujets témoins (cas traumatiques). Les résultats montrent que l’IGFs et le VEGFs possèdent une action d’inhibition sur la prolifération d’ostéoblastes scoliotiques et non scoliotiques, et que cette action est proportionnelle à la concentration de ces facteurs. Les ostéoblastes scoliotiques tendent à avoir une prolifération cellulaire plus rapide et plus élevée que les témoins non scoliotiques. De façon générale les ostéoblastes provenant de patients scoliotiques ont une ostéogénèse in vitro plus accélérée que le sujet non scoliotique. De plus, il semble que la mélatonine joue un rôle physiologique dans la différenciation de l’ostéoblaste scoliotique et elle semble aider à avoir une différenciation plus précoce que chez les non traités. Les ostéoblastes scoliotiques expriment un défaut d’expression de l’IGF 1 et d’IGF 1R en présence de la mélatonine. En conclusion, le VEGF A et l’IGF 1 peuvent également promouvoir la différenciation et la prolifération des ostéoblastes humains scoliotiques en culture primaire.

L’influence d’activités en arts plastiques sur l’expérience d’appréciation musicale d’élèves de sixième année du primaire

Depuis 2001, le Programme de formation de l’école québécoise impose l’enseignement de la compétence « apprécier » dans les quatre disciplines artistiques. Ce mémoire s’intéresse à l’influence que peuvent avoir des activités intégrant les arts plastiques à la musique sur l’expérience d’appréciation musicale d’élèves de sixième année du primaire. Plus spécifiquement, elle vise à rendre compte des différentes dimensions présentes dans la description que font les élèves de leur expérience d’appréciation ainsi qu’à comprendre de quelle façon les activités d’appréciation intégrant les arts plastiques à la musique affectent la verbalisation que font les élèves de cette expérience. La recherche prend la forme d’études de cas réalisées auprès de cinq élèves de sixième année du primaire. Ces élèves, ainsi que tous les élèves de leur classe, ont participé à une activité d’appréciation musicale intradisciplinaire ainsi qu’à deux activités d’appréciation interdisciplinaires. Après chacune des activités, ces cinq élèves ont été rencontrés individuellement. Au cours d’entrevues semi-dirigées, il leur était demandé de rendre compte de leur expérience d’appréciation. Quatre grandes tendances ont émergé de l’analyse des propos des élèves, soit le sentiment de mieux s’approprier l’œuvre entendue, une verbalisation plus précise des éléments perçus, une verbalisation plus précise des sentiments ressentis et enfin, une forme de distraction par rapport à l’œuvre entendue. Au terme de cette étude, il semble que l’utilisation d’activité d’appréciation intégrant les arts plastiques à la musique, sans faire l’objet d’un usage systématique, pourrait constituer une forme de différenciation pédagogique qui serait utile à certains types d’apprenants.