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- Design of tissue engineering scaffolds based on hyperbolic surfaces: Structural numerical evaluationPublication . Almeida, Henrique A.; Bártolo, Paulo J.Tissue engineering represents a new field aiming at developing biological substitutes to restore, maintain, or improve tissue functions. In this approach, scaffolds provide a temporary mechanical and vascular support for tissue regeneration while tissue in-growth is being formed. These scaffolds must be biocompatible, biodegradable, with appropriate porosity, pore structure and distribution, and optimal vascularization with both surface and structural compatibility. The challenge is to establish a proper balance between porosity and mechanical performance of scaffolds.This work investigates the use of two different types of triple periodic minimal surfaces, Schwarz and Schoen, in order to design better biomimetic scaffolds with high surface-to-volume ratio, high porosity and good mechanical properties. The mechanical behaviour of these structures is assessed through the finite element method software Abaqus. The effect of two parametric parameters (thickness and surface radius) is also evaluated regarding its porosity and mechanical behaviour.
- Promoting Nerve Regeneration in a Neurotmesis Rat Model Using Poly(DL-lactide-ε-caprolactone) Membranes and Mesenchymal Stem Cells from the Wharton’s Jelly: In Vitro and In Vivo AnalysisPublication . Pereira, T.; Gärtner, A.; Amorim, I.; Almeida, A.; Caseiro, A.R.; Armada-da-Silva, Paulo A. S.; Amado, Sandra; Fregnan, Federica; Varejão, A. S. P.; Santos, J. D.; Bártolo, P. J.; Geuna, S.; Luís, A. L.; Maurício, A. C.In peripheral nerves MSCs can modulate Wallerian degeneration and the overall regenerative response by acting through paracrine mechanisms directly on regenerating axons or upon the nerve-supporting Schwann cells. In the present study, the effect of human MSCs from Wharton’s jelly (HMSCs), differentiated into neuroglial-like cells associated to poly (DL-lactide-ε-caprolactone) membrane, on nerve regeneration, was evaluated in the neurotmesis injury rat sciatic nerve model. Resultsin vitroshowed successful differentiation of HMSCs into neuroglial-like cells, characterized by expression of specific neuroglial markers confirmed by immunocytochemistry and by RT-PCR and qPCR targeting specific genes expressed.In vivotesting evaluated during the healing period of 20 weeks, showed no evident positive effect of HMSCs or neuroglial-like cell enrichment at the sciatic nerve repair site on most of the functional and nerve morphometric predictors of nerve regeneration although the nociception function was almost normal. EPT on the other hand, recovered significantly better after HMSCs enriched membrane employment, to values of residual functional impairment compared to other treated groups. When the neurotmesis injury can be surgically reconstructed with an end-to-end suture or by grafting, the addition of a PLC membrane associated with HMSCs seems to bring significant advantage, especially concerning the motor function recovery.
- Turbomachinery component manufacture by application of electrochemical, electro-physical and photonic processesPublication . Klocke, Fritz; Klink, Andreas; Veselovac, Drazen; Aspinwall, David Keith; Soo, Sein Leung; Schmidt, Michael; Schilp, Johannes; Levy, Gideon; Kruth, Jean-PierreThis paper presents an overview of the current technological and economical capabilities of electrochemical (ECM-based), electro-physical (EDM-based) and photonic (Laser-/EBM-based) additive and removal processes for turbomachinery component manufacture. Starting with the industrial demands and challenges of today, the technologies are reviewed in detail regarding achievable geometrical precision and surface integrity as well as material removal and deposition rates for conventionally difficult-to-cut Ti- and Ni-based alloys and dedicated steels. Past, existing and future areas of technology application of these advanced non-mechanical manufacturing processes are discussed. The paper focusses on the description of shaping processes therefore excludes pure welding or coating applications.
- Effects of Human Mesenchymal Stem Cells Isolated from Wharton’s Jelly of the Umbilical Cord and Conditioned Media on Skeletal Muscle Regeneration Using a Myectomy ModelPublication . Pereira, T.; Armada-da Silva, P.A.S.; Amorim, I.; Rêma, A.; Caseiro, A.R.; Gärtner, A.; Rodrigues, M.; Lopes, M. A.; Bartolo, P.J.; Santos, J.D.; Luís, A.L.; Maurício, A.C.keletal muscle has good regenerative capacity, but the extent of muscle injury and the developed fibrosis might prevent complete regeneration. Thein vivoapplication of human mesenchymal stem cells (HMSCs) of the umbilical cord and the conditioned media (CM) where the HMSCs were cultured and expanded, associated with different vehicles to induce muscle regeneration, was evaluated in a rat myectomy model. Two commercially available vehicles and a spherical hydrogel developed by our research group were used. The treated groups obtained interesting results in terms of muscle regeneration, both in the histological and in the functional assessments. A less evident scar tissue, demonstrated by collagen type I quantification, was present in the muscles treated with HMSCs or their CM. In terms of the histological evaluation performed by ISO 10993-6 scoring, it was observed that HMSCs apparently have a long-term negative effect, since the groups treated with CM presented better scores. CM could be considered an alternative to thein vivotransplantation of these cells, as it can benefit from the local tissue response to secreted molecules with similar results in terms of muscular regeneration. Searching for an optimal vehicle might be the key point in the future of skeletal muscle tissue engineering.
- 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.