Design of a 3D printer head for additive manufacturing of sugar glass for tissue engineering applications

Additive manufacturing is now considered as a new paradigm that is foreseen to improve progress in many fields. The field of tissue engineering has been facing the need for tissue vascularization when producing thick tissues. The use of sugar glass as a fugitive ink to produce vascular networks through rapid casting may offer the key to vascularization of thick tissues produced by tissue engineering. Here, a 3D printer head capable of producing complex structures out of sugar glass is presented. This printer head uses a motorized heated syringe fitted with a custom made nozzle. The printer head was adapted to be mounted on a commercially available 3D printer. A mathematical model was derived to predict the diameter of the filaments based on the printer head feed rate and extrusion rate. Using a 1 mm diameter nozzle, the printer accurately produced filaments ranging from 0.3 mm to 3.2 mm in diameter. One of the main advantages of this manufacturing method is the self-supporting behaviour of sugar glass that allows the production of long, horizontal, curved, as well as overhanging filaments needed to produce complex vascular networks. Finally, to establish a proof of concept, polydimethylsiloxane was used as the gel matrix during the rapid casting to produce various “vascularized” constructs that were successfully perfused, which suggests that this new fabrication method can be used in a number of tissue engineering applications, including the vascularization of thick tissues

Insights on post-breeding movements from a northeastern population of Canada Warblers (Cardellina canadensis)

ABSTRACT : The study of migratory songbird transition periods, such as the post-breeding period, is complex because birds undertake different types of movements that vary in space and time. Nonetheless, it is important to understand the extent and duration of the territory and specific sites use to identify human activities likely to affect the species’ survival. Individuals from different regional populations may exhibit specific movements during the various phases of their annual cycle, and therefore conservation actions must be adapted. We studied a population of Canada Warblers (Cardellina canadensis) from the Saguenay region of Quebec, Canada, in the northeastern part of the species’ breeding range. We used a coordinated radio-telemetry network (Motus) to determine the residence time within the breeding territory, dates and times of departure, and early fall migration routes of 18 adult birds. We expected individuals to leave by mid-August and to migrate through the eastern flyway, along the Atlantic Coast. Six tracked individuals remained on their breeding territory until early September, corresponding to a residence time of approximately 90 days. These individuals left just after sunset on their day of departure. Twelve individuals departed earlier, and in the daytime, before the end of August; their earlier departure was likely for a purpose other than migration. Nine individuals were detected outside their breeding territory along the Atlantic migratory flyway: four migrated through the Great Lakes region, one in the Great Appalachian Valley, three along the Atlantic Coast or coastal plain, and one with an undetermined route. Our results suggest that adult Canada Warblers remain in the Saguenay region longer than expected, and that, although some individuals remain close to their breeding territory during the post-breeding period, others may use surrounding territories prior to initiating their fall migration. Our results will allow regional conservation managers to recommend that regional industry postpone the timing of certain activities that could negatively affect the species’ survival. Our study highlights the importance of fine-scale studies focused on specific periods of migratory songbird annual cycles to fill important knowledge gaps for understanding of the ecology of their species. RÉSUMÉ : L'étude des périodes de transition de passereaux migrateurs, comme la période post-nuptiale, est complexe car les oiseaux entreprennent différents types de déplacements qui varient dans l'espace et le temps. Néanmoins, il est important de comprendre l'étendue et la durée de l'utilisation du territoire et de sites spécifiques pour qu'on puisse déterminer quelles activités humaines sont susceptibles d'affecter la survie de l'espèce. Les individus de différentes populations régionales peuvent présenter des déplacements spécifiques au cours des diverses étapes de leur cycle annuel, et les activités de conservation doivent donc être adaptées. Nous avons étudié une population de Parulines du Canada (Cardellina canadensis) de la région du Saguenay au Québec, Canada, située dans la partie nord-est de l'aire de nidification de l'espèce. Nous avons utilisé un réseau coordonné de radiotélémétrie (Motus) pour déterminer le temps de résidence dans le territoire de nidification, les dates et les heures de départ, et les routes de migration au début de l'automne de 18 oiseaux adultes. Nous nous attendions à ce que les individus quittent à la mi-août et migrent par la voie de migration de l'est, le long de la côte atlantique. Six individus sont restés sur leur territoire de nidification jusqu'à début septembre, soit un temps de résidence d'environ 90 jours. Ces individus ont quitté juste après le coucher du soleil le jour de leur départ. Douze individus sont partis plus tôt, et de jour, avant la fin du mois d'août; leur départ précoce avait sans doute un but autre que la migration. Neuf individus ont été détectés en dehors de leur territoire de nidification le long de la voie de migration de l'Atlantique : quatre ont migré par la région des Grands Lacs, un dans la vallée des Appalaches, trois le long de la côte atlantique ou de la plaine côtière, et un dont nous n'avons pu déterminer l'itinéraire. Nos résultats indiquent que les Parulines du Canada adultes restent dans la région du Saguenay plus longtemps que prévu et que, bien que certains individus restent à proximité de leur territoire de nidification pendant la période postnuptiale, d'autres peuvent utiliser des territoires environnants avant d'entreprendre leur migration automnale. Nos résultats vont permettre aux gestionnaires de la conservation de recommander à l'industrie régionale de reporter le moment d'activités qui pourraient nuire à la survie de l'espèce. Nous soulignons l'importance de mener des études à l'échelle fine visant des périodes spécifiques du cycle annuel des passereaux migrateurs afin de combler les lacunes importantes dans la compréhension de l'écologie de ceux-ci

A Nanoparticle Ink Allowing the High Precision Visualization of Tissue Engineered Scaffolds by MRI

peer reviewe

Vascularization in Oral and Maxillofacial Tissue Engineering

This book provides a thorough, up-to-date description of the scientific basis and concepts of tissue engineering in the oral and maxillofacial region. The opening chapters present an introduction to tissue engineering, describe the roles of biomaterials and stem cells, discuss the use of growth factors, and examine potential adverse reactions. The challenges of soft and hard tissue engineering for oral and maxillofacial reconstruction are then considered in detail. It is explained what has been achieved to date, and potential future perspectives are explored. The importance and the verification of adequate vascularization are discussed, and a further focus is the use of 3D printing, both in the planning and production of scaffolds and in the bioprinting of cells and biomaterials. Information is also included on safety, efficacy, and regulatory aspects. Tissue Engineering in Oral and Maxillofacial Surgery will be of interest to all researchers and practitioners who wish to learn more about the potential of tissue engineering to revolutionize practice in oral and maxillofacial surgery