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- Advanced Biofabrication Strategies for Skin Regeneration and RepairPublication . Pereira, Rúben F.; Barrias, Cristina C; Granja, Pedro L; Bártolo, Paulo J.Skin is the largest organ of human body, acting as a barrier with protective, immunologic and sensorial functions. Its permanent exposure to the external environment can result in different kinds of damage with loss of variable volumes of extracellular matrix. For the treatment of skin lesions, several strategies are currently available, such as the application of autografts, allografts, wound dressings and tissue-engineered substitutes. Although proven clinically effective, these strategies are still characterized by key limitations such as patient morbidity, inadequate vascularization, low adherence to the wound bed, the inability to reproduce skin appendages and high manufacturing costs. Advanced strategies based on both bottom-up and top-down approaches offer an effective, permanent and viable alternative to solve the abovementioned drawbacks by combining biomaterials, cells, growth factors and advanced biomanufacturing techniques. This review details recent advances in skin regeneration and repair strategies, and describes their major advantages and limitations. Future prospects for skin regeneration are also outlined.
- PrefacePublication . Bartolo, Paulo; Fernandes, PauloThis issue contains the papers presented at ICTE2013, the Third ECCOMAS Thematic Conference on Tissue Engineering, held in Leiria, Portugal from 6 to 8 June 2013, sponsored by ECCOMAS, the European Community Association on Computational Methods in Applied Sciences.
- EditorialPublication . Bártolo, Paulo; Chua, C.K.This is the first issue of Virtual and Physical Prototyping in 2013. The first three papers of this issue were selected from 2012 International Additive Manufacturing Forum held in Wuhan, China, from 13 to 16 December. The primary purpose of this conference was to review the latest state and trend of Additive Manufacturing technologies. This conference was dedicated to AM research. Through this conference, new findings on the AM processes and potential technical applications in major industries were shared and made available to participants. It was intended that this valuable information be made available to the AM research community to encourage further technological advancements in this field through this special issue.
- EditorialPublication . Bártolo, Paulo; C.K. ChuaWe are receiving paper submissions on increasingly wider topics. In the second issue of 2013, six quality papers were selected due to interesting discussions ranging from aerospace and marine to medicine, logistics, research, reverse engineering, as well as sports. We thank the authors for publishing their innovative research solutions to address industrial problems. Hollow turbine blades are critical components of next generation aircraft engines and marine propellers. The capability of manufacturing hollow turbine blades is therefore of a great industrial relevance and significance. In this issue, Zhong Liang Lu from Xi’an Jiao Tong University, China, reviewed and compared conventional and advanced technologies used for industrial manufacturing of hollow turbine blades to give readers an overview of current status in this field.
- BiomanufacturingPublication . Mitsuishi, Mamoru; Cao, Jian; Bártolo, Paulo; Friedrich, Dirk; Shih, Albert J.; Rajurkar, Kamlakar; Sugita, Naohiko; Harada, KanakoBiomedical markets are large and rapidly growing owing to increasing demand for better healthcare services. The development of innovative biomedical systems can produce major breakthroughs in the healthcare industry, and advanced manufacturing technologies can propel such innovations. This paper summarises the field of biomanufacturing: namely, biospecific design constraints, biomechatronics, biofabrication, biodesign, and assembly. This paper presents state-of-the-art research, current problems, and future goals while providing fundamental knowledge required for entry into the biomedical industry. Biomanufacturing provides excellent opportunities for multi-disciplinary collaborations, both in academia and industry, and can lead to further advances in many engineering fields.
- The first systematic analysis of 3D rapid prototyped poly(ε-caprolactone) scaffolds manufactured through BioCell printing: the effect of pore size and geometry on compressive mechanical behaviour andin vitrohMSC viabilityPublication . Domingos, M.; Intranuovo, F.; Russo, T.; De Santis, R.; Gloria, A.; Ambrosio, L.; Ciurana, J.; Bártolo, P.Novel additive manufacturing processes are increasingly recognized as ideal techniques to produce 3D biodegradable structures with optimal pore size and spatial distribution, providing an adequate mechanical support for tissue regeneration while shaping in-growing tissues. With regard to the mechanical and biological performances of 3D scaffolds, pore size and geometry play a crucial role. In this study, a novel integrated automated system for the production and in vitro culture of 3D constructs, known as BioCell Printing, was used only to manufacture poly(ε-caprolactone) scaffolds for tissue engineering; the influence of pore size and shape on their mechanical and biological performances was investigated. Imposing a single lay-down pattern of 0°/90° and varying the filament distance, it was possible to produce scaffolds with square interconnected pores with channel sizes falling in the range of 245–433 µm, porosity 49–57% and a constant road width. Three different lay-down patterns were also adopted (0°/90°, 0°/60/120° and 0°/45°/90°/135°), thus resulting in scaffolds with quadrangular, triangular and complex internal geometries, respectively. Mechanical compression tests revealed a decrease of scaffold stiffness with the increasing porosity and number of deposition angles (from 0°/90° to 0°/45°/90°/135°). Results from biological analysis, carried out using human mesenchymal stem cells, suggest a strong influence of pore size and geometry on cell viability. On the other hand, after 21 days of in vitro static culture, it was not possible to detect any significant variation in terms of cell morphology promoted by scaffold topology. As a first systematic analysis, the obtained results clearly demonstrate the potential of the BioCell Printing process to produce 3D scaffolds with reproducible well organized architectures and tailored mechanical properties.
- Improved osteoblast cell affinity on plasma-modified 3-D extruded PCL scaffoldsPublication . Domingos, M.; Intranuovo, F.; Gloria, A.; Gristina, R.; Ambrosio, L.; Bártolo, P. J.; Favia, P.Cellular adhesion and proliferation inside three-dimensional synthetic scaffolds represent a major challenge in tissue engineering. Besides the surface chemistry of the polymers, it is well recognized that scaffold internal architecture, namely pore size/shape and interconnectivity, has a strong effect on the biological response of cells. This study reports for the first time how polycaprolactone (PCL) scaffolds with controlled micro-architecture can be effectively produced via bioextrusion and used to enhance the penetration of plasma deposited species. Low-pressure nitrogen-based coatings were employed to augment cell adhesion and proliferation without altering the mechanical properties of the structures. X-ray photoelectron spectroscopy carried out on different sections of the scaffolds indicates a uniform distribution of nitrogen-containing groups throughout the entire porous structure. In vitro biological assays confirm that plasma deposition sensitively promotes the activity of Saos-2 osteoblast cells, leading to a homogeneous colonization of the PCL scaffolds.
- Influence of Aloe vera on water absorption and enzymatic in vitro degradation of alginate hydrogel filmsPublication . Pereira, Rúben F.; Carvalho, Anabela; Gil, M.H.; Mendes, Ausenda; Bártolo, Paulo J.This study investigates the influence of Aloe vera on water absorption and the in vitro degradation rate of Aloe vera-Ca-alginate hydrogel films, for wound healing and drug delivery applications. The influence of A. vera content (5%, 15% and 25%, v/v) on water absorption was evaluated by the incubation of the films into a 0.1 M HCl solution (pH 1.0), acetate buffer (pH 5.5) and simulated body fluid solution (pH 7.4) during 24 h. Results show that the water absorption is significantly higher for films containing high A. vera contents (15% and 25%), while no significant differences are observed between the alginate neat film and the film with 5% of A. vera. The in vitro enzymatic degradation tests indicate that an increase in the A. vera content significantly enhances the degradation rate of the films. Control films, incubated in a simulated body fluid solution without enzymes, are resistant to the hydrolytic degradation, exhibiting reduced weight loss and maintaining its structural integrity. Results also show that the water absorption and the in vitro degradation rate of the films can be tailored by changing the A. vera content.
- Body composition, strength static and isokinetic, and bone health: comparative study between active adults and amateur soccer playersPublication . Óscar M. Tavares; João P. Duarte; André O. Werneck; Daniela C. Costa; Paulo Sousa-e-Silva; Diogo Martinho; Leonardo G. O. Luz; Morouço, Pedro; João Valente-dos-Santos; Rui Soles-Gonçalves; Jorge Conde; José M. Casanova; Manuel J. Coelho-e-SilvaObjective: To compare tissue composition, total and regional bone mineral content and bone mineral density, static hand grip and knee joint isokinetic strength between amateur soccer players and Control Group. Methods: Cross-sectional study. Air displacement plethysmography was used to estimate body volume and, in turn, density. Body composition, bone mineral content and bone mineral density were assessed for the whole body and at standardized regions using dual energy X-ray absorptiometry. Static grip strength was assessed with an adjustable dynamometer, and peak torque derived from isokinetic strength dynamometer (concentric muscular knee actions at 60°/s). Magnitude of the differences between groups was examined using d-Cohen. Results: Compared to healthy active adults, soccer players showed larger values of whole body bone mineral content (+651g; d=1.60; p<0.01). In addition, differences between groups were large for whole body bone mineral density (d=1.20 to 1.90; p<0.01): lumbar spine, i.e. L1-L4 (+19.4%), upper limbs (+8.6%) and lower limbs (+16.8%). Soccer players attained larger mean values in strength test given by static hand grip protocol (+5.6kg, d=0.99; p<0.01). Conclusion: Soccer adequately regulates body composition and is associated better bone health parameters (bone mineral content and density at whole-body and at particular sites exposed to mechanical loadings).
- Semidirect products and crossed modules in monoids with operationsPublication . Martins-Ferreira, Nelson; Montoli, Andrea; Sobral, ManuelaWe describe actions, semidirect products and crossed modules in categories of monoids with operations. Moreover we characterize, in this context, the internal categories corresponding to crossed modules. Concrete examples in the cases of monoids, semirings and distributive lattices are given.