Nanofibrous Scaffolds Incorporating PDGF-BB Microspheres Induce Chemokine Expression and Tissue Neogenesis In Vivo

Platelet-derived growth factor (PDGF) exerts multiple cellular effects that stimulate wound repair in multiple tissues. However, a major obstacle for its successful clinical application is the delivery system, which ultimately controls the in vivo release rate of PDGF. Polylactic-co-glycolic acid (PLGA) microspheres (MS) in nanofibrous scaffolds (NFS) have been shown to control the release of rhPDGF-BB in vitro. In order to investigate the effects of rhPDGF-BB release from MS in NFS on gene expression and enhancement of soft tissue engineering, rhPDGF-BB was incorporated into differing molecular weight (MW) polymeric MS. By controlling the MW of the MS over a range of 6.5 KDa–64 KDa, release rates of PDGF can be regulated over periods of weeks to months in vitro. The NFS-MS scaffolds were divided into multiple groups based on MS release characteristics and PDGF concentration ranging from 2.5–25.0 µg and evaluated in vivo in a soft tissue wound repair model in the dorsa of rats. At 3, 7, 14 and 21 days post-implantation, the scaffold implants were harvested followed by assessments of cell penetration, vasculogenesis and tissue neogenesis. Gene expression profiles using cDNA microarrays were performed on the PDGF-releasing NFS. The percentage of tissue invasion into MS-containing NFS at 7 days was higher in the PDGF groups when compared to controls. Blood vessel number in the HMW groups containing either 2.5 or 25 µg PDGF was increased above those of other groups at 7d (p<0.01). Results from cDNA array showed that PDGF strongly enhanced in vivo gene expression of the CXC chemokine family members such as CXCL1, CXCL2 and CXCL5. Thus, sustained release of rhPDGF-BB, controlled by slow-releasing MS associated with the NFS delivery system, enhanced cell migration and angiogenesis in vivo, and may be related to an induced expression of chemokine-related genes. This approach offers a technology to accurately control growth factor release to promote soft tissue engineering in vivo

Governança e governamentalidade: relação e relevância de dois conceitos científico-sociais proeminentes na educação comparada

Contrapondo-se ao retrospecto da existência de uma relação volátil entre o Estado e "seu" sistema educacional, este trabalho enfoca dois conceitos que podem ser empregados como ferramentas de análise para estudar as transformações em curso. O termo "governança" está mais relacionado a aspectos técnicos: tratam-se de instrumentos e modos, procedimentos e atores, além de suas constelações e formas de cooperação. Ele concentra a pesquisa em questões como: quem oferece serviços educacionais, qual é a relação entre ensino público e privado etc. Ele também é extremamente útil na investigação da relação entre os diversos níveis de análise e provou-se particularmente importante para a compreensão teórica adequada do papel das organizações internacionais na formulação de políticas educacionais. A sociologia e a ciência política são duas disciplinas cuja associação se mostra mais notável na elaboração do conceito sob diversas perspectivas. "Governamentalidade", por sua vez, apesar de compartilhar muitas características com governança, é um termo foucautiano dedicado à geração de subjetividades distintas por meio de técnicas e modos de regulação e conduta em sentido lato. Assim, governamentalidade inclui investigações do nexo tipicamente foucautiano conhecimento/poder. Consideramos ambas as perspectivas em conjunto para discutir suas implicações para a educação comparada.Against the background of a changing relation between the state and "its" education system, the present contribution focuses on two concepts that can be used as analytical tools in order to analyze the current transformations. "Governance" is more concerned with technical issues: with instruments and modes, procedures and actors, with their constellations and forms of cooperation. It focuses research on questions such as: who provides educational services, what is the relation between public and private education etc. It is also very useful in investigating the relation between the various levels of analysis and has proven particularly useful for an adequate theoretical understanding of the role of international organizations in shaping educational policies. Sociology and political science are the two disciplines most prominently associated with elaborating the concept under various perspectives. Governmentality, on the other hand, although sharing many characteristics with governance, is a Foucauldian term concerned with the generation of different subjectivities through techniques and modes of ruling and guiding in an encompassing sense. Governmentality thus includes investigations of the typical Foucauldian knowledge/power nexus. Both perspectives are brought together to discuss the implications for comparative education