Advanced silk-based biotextiles for bone regeneration applications

Increasing efforts have been made in tissue engineering (TE) research for novel biomaterials and scaffolds that can efficiently support bone tissue regeneration and repair. Textile-based technologies are predefined manufacturing processes of particular interest since they allow for producing finely tuned fiber-based structures with controlled three-dimensional architecture and improved mechanical properties. Highly reproducible scaffolds can be achieved with interconnected macro- and micro-porosity suitable for controlling cell functions and guiding bone tissue regeneration and repair. Herein, the recent studies dealing with the processing methodologies, physical properties, and biocompatibility of fiber-based scaffolds for bone TE applications are overviewed. The fundamentals and application of silk fibroin (SF) protein as biomaterial for scaffolds production, made up of micro- and nano-fibers are also considered. The promising outcomes of such investigations are summarized and discussed in depth.The authors thank to the project FROnTHERA (NORTE-01-0145-FEDER-000023), supported by Norte Portugal Regional Operational Programme (NORTE 2020), under the PORTUGAL 2020 Partnership Agreement, through the European Regional Development Fund (ERDF). The financial support from the Portuguese Foundation for Science and Technology to Fun4TE project (PTDC/EMD-EMD/31367/2017), for the Junior Researcher contract (POCI-01-0145-FEDER 031367), and for the FCT distinction attributed to J. M. Oliveira under the Investigador FCT program (IF/01285/2015) are also greatly acknowledged

Advances on gradient scaffolds for osteochondral tissue engineering

The osteochondral (OC) tissue is one of the most hierarchical and complex structures known and it is composed by two main compartments of hyaline articular cartilage and subchondral bone. It exhibits unique cellular and molecular transitions from the cartilage to the bone layers. OC diseases such as osteoarthritis and traumatic lesions may affect the articular cartilage, calcified cartilage (interface region) and subchondral bone, thus posing great regenerative challenges. Tissue engineering (TE) principles can offer novel technologies and combinatorial approaches that can better recapitulate the biological OC challenges and complexity in terms of biochemical, mechanical, structural and metabolic gradients, and ultimately can provide biofunctional 3D scaffolds with high reproducibility, versatility and adaptability to each patientâ s needs, as it occurs in OC tissue defects. The recent reports and future directions dealing with gradient scaffolds for OCTE strategies are overviewed herein. A special focus on clinical translation/regulatory approval is given.The authors thank the financial support provided by the EU-EC through the BAMOS project (H2020-MSCA-RISE-2016-734156). Viviana P Ribeiro acknowledge for the Junior Researcher contract (POCI-01-0145-FEDER-031367) attributed by the Portuguese Foundation for Science and Technology to Fun4TE project (PTDC/EMD-EMD/31367/2017)

Special issue: Biopolymer-based materials for biomedical engineering

In the field of tissue engineering and regenerative medicine (TERM), the use of traditional biomaterials capable of integrating the host tissue to promote the healing and regenerative process while it degrades has become less and less a focus of inspiration. The current trend is to increase the complexity of the host materials in order to better emulate the extracellular microenvironment of heathy and disease tissues. Thus, the combination of materials engineering with other emerging fields, such as nanotechnology, cell and molecular therapy, and precision medicine, can allow for the development of innovative biopolymer-based scaffolds for specific biomedical approaches

Combinatory approach for developing silk fibroin-based scaffolds with hierarchical porosity and enhanced performance for cartilage tissue engineering applications

Introduction: The combination of several processing technologies can open the possibility for producing scaffolds with superior performance for tissue engineering (TE) applications. Hydrogels are structurally similar to the natural extracellular matrix microenvironment presenting high elasticity and resistance to compression forces. They have been extensively used in biomedical devices fabrication and for TE applications, including for cartilage defects repair[1]. Recently, it was found that proteins like silk fibroin (SF), presenting tyrosine groups can be used to prepare fast formed hydrogels with controlled gelation properties, via an enzyme-mediated cross-linking reaction using horseradish peroxidase (HRP) and hydrogen peroxide (H2O2)[2],[3]. Moreover, the high versatility, processability and tailored mechanical properties of SF, make this natural polymer attractive for the development of innovative scaffolding strategies for cartilage TE applications[4],[5]. Materials and Methods: The present work proposes a novel route for developing SF-based scaffolds derived from high- concentrated SF (16wt%) enzymatically cross-linked by a HRP/H2O2 complex. The combination of salt-leaching and freeze-drying methodologies was used to prepare macro/microporous SF scaffolds with an interconnected structure and specific features regarding biodegradation and mechanical properties (Fig. 1a). The scaffolds morphology and porosity were analyzed by SEM and micro-CT. The mechanical properties (Instron) and protein conformation (FTIR, XRD) were also assessed. In order to evaluate the scaffolds structural integrity, swelling ratio and degradation profile studies were performed for a period of 30 day. This work also aims to evaluate the in vitro chondrogenic differentiation response by culturing human adipose derived stem cells (hASCs) over 21 days in basal and chondrogenic conditions. Cell behaviour in the presence of the macro/microporous structures will be evaluated through different quantitative (Live/Dead, DNA, GAGs, RT PCR) and qualitative (SEM, histology, immunocytochemistry) assays. Results and Discussion: The macro/microporous SF scaffolds showed high porosity and interconnectivity with the trabecular structures evenly distributed (Fig. 1b,c). A dramatic decrease of compressive modulus was observed for samples in hydrated state. Chemical analysis revealed that SF scaffolds displayed the characteristic peaks for β-sheet conformation. Swelling ratio data demonstrated a large swelling capacity, maintaining their structural integrity for 30 days. As expected, when immersed in protease XIV the degradation rate of SF scaffolds increased. Based on the promising morphology and physicochemical properties of the developed SF scaffolds, in vitro chondrogenic differentiation studies with hASCs are envisioned in order to validate their performance for cartilage regeneration applications. Conclusion: This study proposes an innovative approach to produce fast-formed porous SF scaffolds using enzymatically cross- linked SF hydrogels structured by the combination of salt-leaching and freeze-drying methodologies. The obtained results can provide a valuable reference of SF as a tunable and versatile biomaterial with great potential for applications in cartilage TE scaffolding. Portuguese Foundation for Science and Technology (FCT) project PEst-C/SAU/LA0026/201; ERDP funding through POCTEP Project 0687_NOVOMAR_1_P; Investigator FCT program IF/00423/2012 and IF/00411/2013 References: [1] Xia, L.-W., R. Xie, X.-J. Ju, W. Wang, Q. Chen, and L.-Y. Chu, Nano-structured smart hydrogels with rapid response and high elasticity. Nature communications, 2013. 4. [2] Sofia, S.J., A. Singh, and D.L. Kaplan, Peroxidase-catalyzed crosslinking of functionalized polyaspartic acid polymers. Journal of Macromolecular Science, Part A, 2002. 39(10): p. 1151-1181. [3] Reis, R.L., L.-P. Yan, A.L. Oliveira, J.M. Oliveira, D.R. Pereira, C. Correia, and R.A. Sousa, Hydrogels derived from silk fibroin: Methods and uses thereof. 2014. 107426. [4] Chen, C.-H., J.M.-J. Liu, C.-K. Chua, S.-M. Chou, V.B.-H. Shyu, and J.-P. Chen, Cartilage tissue engineering with silk fibroin scaffolds fabricated by indirect additive manufacturing technology. Materials, 2014. 7(3): p. 2104-2119. [5] Yan, L.-P., J.M. Oliveira, A.L. Oliveira, S.G. Caridade, J.F. Mano, and R.L. Reis, Macro/microporous silk fibroin scaffolds with potential for articular cartilage and meniscus tissue engineering applications. Acta biomaterialia, 2012. 8(1): p. 289-301.Â

Hierarchical HRP-crosslinked silk fibroin/ZnSr-TCP scaffolds for osteochondral tissue regeneration: assessment of the mechanical and antibacterial properties

"Article 49"The biomaterials requirements for osteochondral (OC) defects restoration simultaneously include adequate mechanical behavior, and the prevention of bacterial adherence and biofilm formation, without impairing local tissue integration. Bilayered and hierarchical scaffolds combining a cartilage-like layer interconnected to an underlying subchondral bone-like layer appeared as innovative technological solutions able to mimic the native OC tissue hierarchical architecture. This study is focused on the assessment of the combined compression-shear stresses and possible bacterial biofilm formation of hierarchical scaffolds prepared from a horseradish peroxidase-crosslinking reaction of silk fibroin (SF) combined with zinc (Zn) and strontium (Sr)-doped β-tricalcium phosphate (β-TCP) for OC tissue regeneration. Scaffolds with undoped-β-TCP incorporation were used as control. Results showed that the bilayered scaffolds presented suitable aptitude to support compression and shear loading for OC tissue, with better mechanical properties for the ZnSr-containing structures. Young and shear moduli presented values close to 0.01 MPa in the region 10â 20% strain. The investigation of biomaterials surface ability to prevent biofilm formation showed reduced bacterial adhesion of Escherichia coli (E. coli, gram-negative) and Staphylococcus aureus (S. aureus, gram-positive) on both scaffolds, thus suggesting that the proposed hierarchical scaffolds have a positive effect in preventing gram-positive and gram-negative bacteria proliferation.This research was funded by the Portuguese Foundation for Science and Technology for the Hierarchitech project (M-era-Net/0001/2014), and by the Research and Innovation Staff Exchanges (RISE) action (H2020 Marie Skłodowska-Curie actions) for the BAMOS project (H2020-MSCA-RISE-2016- 734156). The authors also thank the funds provided under the distinctions attributed to JO (IF/01285/2015) and SP (CEECIND/03673/2017)

Scaffolding strategies for tissue engineering and regenerative medicine applications

During the past two decades, tissue engineering and the regenerative medicine field have invested in the regeneration and reconstruction of pathologically altered tissues, such as cartilage, bone, skin, heart valves, nerves and tendons, and many others. The 3D structured scaffolds and hydrogels alone or combined with bioactive molecules or genes and cells are able to guide the development of functional engineered tissues, and provide mechanical support during in vivo implantation. Naturally derived and synthetic polymers, bioresorbable inorganic materials, and respective hybrids, and decellularized tissue have been considered as scaffolding biomaterials, owing to their boosted structural, mechanical, and biological properties. A diversity of biomaterials, current treatment strategies, and emergent technologies used for 3D scaffolds and hydrogel processing, and the tissue-specific considerations for scaffolding for Tissue engineering (TE) purposes are herein highlighted and discussed in depth. The newest procedures focusing on the 3D behavior and multi-cellular interactions of native tissues for further use for in vitro model processing are also outlined. Completed and ongoing preclinical research trials for TE applications using scaffolds and hydrogels, challenges, and future prospects of research in the regenerative medicine field are also presented.This research was funded by Norte Portugal Regional Operational Programme (NORTE 2020), under the PORTUGAL 2020 Partnership Agreement, through the European Regional Development Fund (ERDF) (NORTE-01-0145-FEDER-000023) and by the Portuguese Foundation for Science and Technology ((M-ERA-NET/0022/2016), Transitional Rule DL 57/2016 (CTTI-57/18-I3BS(5)), and (IF/01285/2015))

Morphogenetic variability, cultural characteristics, aggressiveness, and transmission of Bipolaris oryzae isolates in Rio Grande do sul: Variabilidade morfogenética, características culturais, agressividade e transmissão de Bipolaris oryzae isolados no Rio Grande do Sul

Brown spot disease, caused by Bipolaris oryzae, is one of the most important rice diseases. This pathogen causes reductions in rice crop yield and quality, and its variability has been a problem for the management of brown spot disease due to its morphological and cultural similarity with other species that cause leaf spots and grain blight. The aim of this study was to determine the variability of B. oryzae isolates using different approaches and report information on patterns in aggressiveness and transmission of this pathogen from rice seed to seedlings. Fifteen isolates from different geographic rice crop regions of Rio Grande do Sul were used. The isolates were analyzed for genetic diversity, morphological and cultural characteristics, aggressiveness, and transmission ability from rice seeds to seedlings. Isolates fell into five morphological groups, based on cultural characteristics. Range values of the spore dimensions, color and mycelial growth showed high variation among the isolates. The most aggressive and transmissible isolates were those that form black colonies and had suppressed growth. The results show that isolates from Rio Grande do Sul are morphologically and genetically diverse and distributed throughout the state. This is the first study in which isolates representing the main rice growing areas in Rio Grande do Sul were taken into consideration for the study of variability, aggressiveness, and transmission

Adaptações no Serviço de Cirurgia Vascular do CHULN durante a pandemia de COVID-19 e impacto na atividade global

© SPACVWith the onset of the SARS-CoV-2 pandemic in early 2020, health services and personnel adapted their resources to mitigate and control the outbreak. These needs inevitably led to adaptations in most medical and surgical departments, including in our Vascular Surgery department. As we are facing a second outbreak of this pandemic, with unpredictable outcomes and repercussions in health services, it is crucial to learn from previous experiences and share strategies to perform the best care to our patients, despite the restrictions that have been imposed. Through this paper, we review the adaptations in Centro Hospitalar Universitário Lisboa Norte and particularly in our department to overcome the pandemic. We also assess the impact of these changes in our activity and compare with the experience of other fellow surgeons. With an upcoming second outbreak, it is crucial to learn from this and other departments’ experiences to overcome a potential health crisis.info:eu-repo/semantics/publishedVersio

Finely tuned fiber-based porous structures for bone tissue engineering applications

[Excerpt] Scaffolds developed for bone tissue engineering (TE) must possess specific structural properties to allow neo-tissue formation and integration within the material[1]. Several polymeric systems and processing methodologies have been proposed to develop bone TE scaffolds. Nevertheless, the so far proposed strategies do not fulfil all the requirements for effective bone regeneration. Textile technologies have recently emerged as an industrial route for producing more complex fibre-based porous scaffolds[2]. Silk fibroin (SF) from Bombyx mori has already proved to be a good biomaterial for bone TE[3]. SF-based structures are known for the impressive mechanical properties and biocompatibility, which meet the basic requirements for developing bone TE scaffolds[4],[5]. [...]Portuguese Foundation for Science and Technology (FCT) for the project TISSUE2TISSUE (PTDC/CTM/105703/2008); Investigator FCT program IF/00423/2012 and IF/00411/2013