Papers by Miguel Oliveira
Comprehensive Biomaterials II, 2017
Recent advances in tissue engineering and regenerative medicine have shown that combining biomate... more Recent advances in tissue engineering and regenerative medicine have shown that combining biomaterials, cells, and bioactive molecules are important to promote the regeneration of damaged tissues or as therapeutic systems. Natural origin polymers have been used as matrices in such applications due to their biocompatibility and biodegradability. This chapter provides an up-to-date review on the most promising natural biopolymers, focused on polysaccharides and proteins, their properties and applications. Membranes, micro/ nanoparticles, scaffolds, and hydrogels as biomimetic strategies for tissue engineering and processing are described, along with the use of bioactive molecules and growth factors to improve tissue regeneration potential. Finally, current biomedical applications are also presented.
Journal of tissue engineering and regenerative medicine, Jan 5, 2016
Hydrogels of spatially controlled physicochemical properties are appealing platforms for tissue e... more Hydrogels of spatially controlled physicochemical properties are appealing platforms for tissue engineering and drug delivery. In this study, core-shell silk fibroin (SF) hydrogels of spatially controlled conformation were developed. The core-shell structure in the hydrogels was formed by means of soaking the preformed (enzymatically crosslinked) random coil SF hydrogels in methanol. When increasing the methanol treatment time from 1 to 10 min, the thickness of the shell layer can be tuned from about 200 to about 850 μm as measured in wet status. After lyophilization of the rehydrated core-shell hydrogels, the shell layer displayed compact morphology and the core layer presented porous structure, when observed by scanning electron microscopy. The conformation of the hydrogels was evaluated by Fourier transform infrared spectroscopy in wet status. The results revealed that the shell layer possessed dominant β-sheet conformation and the core layer maintained mainly random coil conform...
Journal of Tissue Engineering and Regenerative Medicine, 2017
Damage of non-vascularised tissues such as cartilage and cornea can result in healing processes a... more Damage of non-vascularised tissues such as cartilage and cornea can result in healing processes accompanied by a non-physiological angiogenesis. Peptidic aptamers have recently been reported to block the vascular endothelial growth factor (VEGF). However, the therapeutic applications of these aptamers is limited due to their short half-life in vivo. In this work, an enhanced stability and bioavailability of a known VEGF blocker aptamer sequence (WHLPFKC) was pursued through its tethering of molecular scaffolds based on hyperbranched peptides, the poly(ɛ-lysine) dendrons, bearing three branching generations. The proposed design allowed simultaneous and orderly-spaced exposure of sixteen aptamers per dendrimer to the surrounding biological microenvironent, as well as a relatively hydrophobic core based on di-phenylalanine aiming to promote an hydrophobic interaction with the hydrophobic moieties of ionically-crosslinked metacrylated gellan gum (iGG-MA) hydrogels. The VEGF blocker dendrons were entrapped in iGG-MA hydrogels and their capacity to prevent endothelial cell sprouting was assessed qualitatively and quantitatively using 3D in vitro models and the in vivo chick chorioallantoic membrane (CAM) assay. The data demonstrate that at nanoscale concentrations, the dendronised structures were able to enhance control of the biological actvity of WHLPFKC at the material/tissue interface and hence the anti-angiogenic capacity of iGG-MA hydrogels not only preventing blood vessel invasion, but also inducing their regression at the tissue/iGG-MA interface. The in ovo study confirmed that iGG-MA functionalised with the dendron VEGF blockers do inhibit angiogenesis by controlling both size and ramifications of blood vessels in proximity of the implanted gel surface.
Translating Regenerative Medicine to the Clinic, 2016
The treatment/regeneration of bone and cartilage diseases or defects, whether induced by rheumati... more The treatment/regeneration of bone and cartilage diseases or defects, whether induced by rheumatism, joint dysplasia, trauma, or surgery presents great challenges that have not been fully solved by the current therapies. In the last few years, tissue engineering and regenerative medicine have been proposing advanced tools and technologies for bone and cartilage tissue regeneration, and some of which have successfully reached the market. Beyond the source of cells, the creation of superior structures for replacing defective bone and cartilage requires strong research in biomechanical signaling and synthesis of advanced biomaterials to mimic human tissues at the most varied levels. Natural and synthetic polymers, bioresorbable inorganic materials, and composites have been investigated for its potential as scaffolding materials with enhanced mechanical and biological properties. Porous scaffolds, hydrogels, and fibers are the most commonly biomimetic structures used for bone and cartilage tissue engineering. Herein, the concepts and current treatment strategies for bone and cartilage repair, as well as biomimetic strategies for bone and cartilage tissue engineering are overviewed. A global review of the ongoing clinical trials and of the scaffolds commercially available for the repair of osteochondral tissue is also presented.
Handbook of Bioceramics and Biocomposites, 2015
In the last few years, many reports have been describing promising biocompatible and biodegradabl... more In the last few years, many reports have been describing promising biocompatible and biodegradable materials that can mimic in a certain extent the multidimensional hierarchical structure of bone, while are also capable of releasing bioactive agents or drugs in a controlled manner. Despite these great advances, new developments in the design and fabrication technologies are required to address the need to engineer suitable biomimetic materials in order tune cells functions, i.e. enhance cell-biomaterial interactions, and promote cell adhesion, proliferation, and differentiation ability. Scaffolds, hydrogels, fibres and composite materials are the most commonly used as biomimetics for bone tissue engineering. Dynamic systems such as bioreactors have also been attracting great deal of attention as it allows developing a wide range of novel in vitro strategies for the homogeneous coating of scaffolds and prosthesis with ceramics, and production of biomimetic constructs, prior its implantation in the body. Herein, it is overviewed the biomimetic strategies for bone tissue engineering, recent developments and future trends. Conventional and more recent processing methodologies are also described. Nowadays, the development of new biomaterials for bone tissue engineering has made important contribution to modern health care. Each biomaterial has specific chemical, physical, mechanical and biological properties, important for the behaviour and outcome of the implant. Autografts and allografts have been used to repair bone fractures and other defects, however concerns include risk of disease transfer, infection, potential immunogenicity, and insufficient supply .
ACS Biomaterials Science & Engineering, 2015
In the last few years, great progress has been made to validate tissue engineering strategies in ... more In the last few years, great progress has been made to validate tissue engineering strategies in preclinical studies and clinical trials on the regeneration of osteochondral defects. In the preclinical studies, one of the dominant strategies comprises the development of biomimetic/bioactive scaffolds, which are used alone or incorporated with growth factors and/or stem cells. Many new trends are emerging for modulation of stem cell fate towards osteogenic and chondrogenic differentiations, but bone/cartilage interface regeneration and physical stimulus have been showing great promise. Besides the matrix-associated autologous chondrocyte implantation (MACI) procedure, the matrix-associated stem cells implantation (MASI) and layered scaffolds in acellular or cellular strategy are also applied in clinic. This review outlines the progresses at preclinical and clinical levels, and identifies the new challenges in osteochondral tissue engineering. Future perspectives are provided, e.g., the applications of extracellular matrix-like biomaterials, computer-aided design/manufacture of osteochondral implant and reprogrammed cells for osteochondral regeneration.
Advanced Materials, 2015
Tissue engineering and regenerative medicine has been providing exciting technologies for the dev... more Tissue engineering and regenerative medicine has been providing exciting technologies for the development of functional substitutes aimed to repair and regenerate damaged tissues and organs. Inspired by the hierarchical nature of bone, nanostructured biomaterials are gaining a singular attention for tissue engineering, owing their ability to promote cell adhesion and proliferation, and hence new bone growth, compared with conventional microsized materials. Of particular interest are nanocomposites involving biopolymeric matrices and bioactive nanosized fillers. Biodegradability, high mechanical strength, and osteointegration and formation of ligamentous tissue are properties required for such materials. Biopolymers are advantageous due to their similarities with extracellular matrices, specific degradation rates, and good biological performance. By its turn, calcium phosphates possess favorable osteoconductivity, resorbability, and biocompatibility. Herein, an overview on the availa...
Key Engineering Materials, 2013
It has been shown that hydrogel bilayered scaffolds combining cartilage- and bone-like layers are... more It has been shown that hydrogel bilayered scaffolds combining cartilage- and bone-like layers are most advantageous for treating osteochondral defects. In this study, it is proposed the use of low acyl gellan gum (LAGG) for developing bilayered hydrogel scaffolds for osteochondral tissue engineering. The cartilage-like layer of the GG-based bilayered hydrogel scaffolds is composed of LAGG (2 wt%). By adding a 2 wt% LAGG aqueous solution to different amounts of HAp (5-20 wt%) it was possible to produce the bone-like layer. In vitro bioactivity tests were performed by means of soaking the LAGG/LAGG-HAp hydrogel scaffolds in a simulated body fluid solution up to 14 days. Scanning electron microscopy, Fourier transform infra-red spectroscopy and X-ray diffraction analyses demonstrated that apatite formation is limited to the bone-like layer of the LAGG/LAGG-HAp bilayered hydrogel scaffolds.
Nanomedicine: Nanotechnology, Biology and Medicine, 2011
The control of stem cell differentiation to obtain osteoblasts in vivo is still regarded as a cha... more The control of stem cell differentiation to obtain osteoblasts in vivo is still regarded as a challenge in stem-cell-based and bone-tissue engineering strategies. Biodegradable dexamethasone-loaded dendron-like nanoparticles (NPs) of carboxymethylchitosan/poly(amidoamine) dendrimer have been proposed as intracellular drug-delivery systems of bioactive molecules. In this study, combination of nanotechnology, stem-cell engineering and tissue engineering is proposed in pre-programming the fate of rat bone marrow stromal cells (RBMSCs) towards osteoblasts cells and development of new bone tissue, in vivo. This work demonstrated that the developed NPs were able to be taken up by RBMSCs, and exhibited a noncytotoxic behavior in vitro. The performance of the developed dendronlike NP system for the intracellular delivery of dexamethasone was investigated by seeding the engineered RBMSCs onto starch-polycaprolactone scaffolds ex vivo, and implanting subcutaneously in the back of Fischer 344/N rats (Syngeneic), in the absence of the typical osteogenic supplements. Favorable results were observed in vivo, thus suggesting that stem cell "tune-up" strategy can open up a new regenerative strategy for bone-tissue engineering. From the Clinical Editor: In this study, a combination of nanotechnology, stem-cell engineering and tissue engineering is proposed in preprogramming the fate of rat bone marrow stromal cells (RBMSCs) towards osteoblasts cells and development of new bone tissue in vivo.
Journal of The Royal Society Interface, 2007
The fields of tissue engineering and regenerative medicine aim at promoting the regeneration of t... more The fields of tissue engineering and regenerative medicine aim at promoting the regeneration of tissues or replacing failing or malfunctioning organs, by means of combining a scaffold/support material, adequate cells and bioactive molecules. Different materials have been proposed to be used as both three-dimensional porous scaffolds and hydrogel matrices for distinct tissue engineering strategies. Among them, polymers of natural origin are one of the most attractive options, mainly due to their similarities with the extracellular matrix (ECM), chemical versatility as well as typically good biological performance. In this review, the most studied and promising and recently proposed naturally derived polymers that have been suggested for tissue engineering applications are described. Different classes of such type of polymers and their blends with synthetic polymers are analysed, with special focus on polysaccharides and proteins, the systems that are more inspired by the ECM. The ada...
Journal of Bioactive and Compatible Polymers, 2013
Macro/microporous silk/nano-sized calcium phosphate scaffolds (SC16) with bioactive and superior ... more Macro/microporous silk/nano-sized calcium phosphate scaffolds (SC16) with bioactive and superior physicochemical properties are currently being developed. In this study, we evaluated the new bone formation ability in rat femur of the SC16 scaffolds in vivo, using silk fibroin scaffolds (S16) as control. The CaP distribution profile in the scaffolds was characterized by micro-computed tomography and the CaP phase was found to be distributed homogeneously in the SC16 scaffolds. Mineralization was only observed in SC16 scaffolds, and both scaffolds gradually degraded with time. By staining the explants, new bone growth was observed directly on the SC16 surface and with higher density than that observed on the S16 scaffolds. These results demonstrated that the SC16 hybrid scaffolds are osteoconductive and can be good candidates for bone tissue engineering as they promote superior de novo bone formation.
International Materials Reviews, 2012
Marine organisms are constituted by materials with a vast range of properties and characteristics... more Marine organisms are constituted by materials with a vast range of properties and characteristics that may justify their potential application within the biomedical field. Moreover, assuring the sustainable exploitation of natural marine resources, the valorisation of residues from marine origin, like those obtained from food processing, constitutes a highly interesting platform for development of novel biomaterials, with both economic and environmental benefits. In this perspective, an increasing number of different types of compounds are being isolated from aquatic organisms and transformed into profitable products for health applications, including controlled drug delivery and tissue engineering devices. This report reviews the work that is being developed on the isolation and characterisation of some polysaccharides, proteins, glycosaminoglycans and ceramics from marine raw materials. Emphasis is given to agar, alginates, carrageenans, chitin and chitosan, among other polysaccharides, collagen, glycosaminoglycans such as chondroitin sulphate, heparin and hyaluronic acid, calcium phosphorous compounds and biosilica. Finally, this report ends by reviewing the application of the previously mentioned materials on specific biomedical applications, in particular their participation on the development of controlled drug delivery systems and tissue engineering scaffolds.
Bone, 2010
Dexamethasone-loaded carboxymethylchitosan/poly(amidoamine) dendrimer nanoparticles Hydroxyapatit... more Dexamethasone-loaded carboxymethylchitosan/poly(amidoamine) dendrimer nanoparticles Hydroxyapatite In vivo test Recently, our group has proposed a combinatorial strategy in tissue engineering principles employing carboxymethylchitosan/poly(amidoamine) dendrimer nanoparticles (CMCht/PAMAM) towards the intracellular release and regimented supply of dexamethasone (Dex) aimed at controlling stem cell osteogenic differentiation in the absence of typical osteogenic inducers, in vivo. In this work, we have investigated if the Dex-loaded CMCht/PAMAM dendrimer nanoparticles could play a crucial role in the regulation of osteogenesis, in vivo. Macroporous hydroxyapatite (HA) scaffolds were seeded with rat bone marrow stromal cells (RBMSCs), whose cells were expanded in MEM medium supplemented with 0.01 mg ml -1 Dexloaded CMCht/PAMAM dendrimer nanoparticles and implanted subcutaneously on the back of rats for 2 and 4 weeks. HA porous ceramics without RBMSCs and RBMSCs/HA scaffold constructs seeded with cells expanded in the presence and absence of 10 -8 M Dex were used as controls. The effect of initial cell number seeded in the HA scaffolds on the bone-forming ability of the constructs was also investigated. Qualitative and quantitative new bone formation was evaluated in a non-destructive manner using micro-computed tomography analyses of the explants. Haematoxylin and Eosin stained implant sections were also used for the histomorphometrical analysis. Toluidine blue staining was carried out to investigate the synthesis of proteoglycan extracellular matrix. In addition, alkaline phosphatase and osteocalcin levels in the explants were also quantified, since these markers denote osteogenic differentiation. At 4 weeks post-implantation results have shown that the novel Dex-loaded carboxymethylchitosan/poly(amidoamine) dendrimer nanoparticles may be beneficial as an intracellular nanocarrier, supplying Dex in a regimented manner and promoting superior ectopic de novo bone formation.
Biotechnology Advances, 2013
Low back pain (LBP) is one of the most common painful conditions that lead to work absenteeism, m... more Low back pain (LBP) is one of the most common painful conditions that lead to work absenteeism, medical visits, and hospitalization. The majority of cases showing signs of LBP are due to age-related degenerative changes in the intervertebral disk (IVD), which are, in fact, associated with multiple spine pathologies. Traditional and more conservative procedures/clinical approaches only treat the symptoms of disease and not the underlying pathology, thus limiting their long-term efficiency. In the last few years, research and development of new approaches aiming to substitute the nucleus pulposus and annulus fibrosus tissue and stimulate its regeneration has been conducted. Regeneration of the damaged IVD using tissue engineering strategies appears particularly promising in pre-clinical studies. Meanwhile, surgical techniques must be adapted to this new approach in order to be as minimally invasive as possible, reducing recovering time and side effects associated to traditional surgeries. In this review, the current knowledge on IVD, its associated pathologies and current surgical procedures are summarized. Furthermore, it also provides a succinct and up-to-date overview on regenerative medicine research, especially on the newest tissue engineering strategies for IVD regeneration.
Carbohydrate Polymers, 2013
Journal of Biomaterials Science, Polymer Edition, 2021
The bone is a complex and dynamic structure subjected to constant stress and remodeling. Due to t... more The bone is a complex and dynamic structure subjected to constant stress and remodeling. Due to the worldwide incidence of bone disorders, tissue scaffolds and engineered bone tissues have emerged as solutions for bone grafting, which require sophisticated scaffolding architectures while keeping high mechanical performance. However, the conjugation of a bone-like scaffold architecture with efficient mechanical properties is still a critical challenge for biomedical applications. In this sense, the present study focused on the modulating the architecture of silk fibroin (SF) scaffolds crosslinked with horseradish peroxidase and mixed with zinc (Zn) and strontium (Sr)-doped β-tricalcium phosphate (ZnSr.TCP) to mimic bone structures. The ZnSr.TCP-SF hydrogels were tuned by programmable ice-templating parameters, and further freeze-dried, in order to obtain 3D scaffolds with controlled pore orientation. The results showed interconnected channels in the ZnSr.TCP-SF scaffolds that mimic the porous network of the native subchondral bone matrix. The architecture of the scaffolds was characterized by microCT, showing tunable pore size according to freezing temperatures (-196 ºC: ~80.2 ± 20.5 µm;-80 ºC: ~73.1 ± 20.5 µm;-20 ºC: ~104.7 ± 33.7 µm). The swelling ratio, weight loss, and rheological properties were also assessed, revealing efficient scaffold integrity and morphology after aqueous immersion. Thus, the ZnSr.TCP-SF scaffolds made of aligned porous structure were developed as affordable candidates for future applications in clinical osteoregeneration and in vitro bone tissue modelling.
Injuries and Health Problems in Football, 2017
The knowledge related to meniscus biology, ultrastructure, and biomechanics has developed dramati... more The knowledge related to meniscus biology, ultrastructure, and biomechanics has developed dramatically in the last years. Moreover, clinical data related to several different options for treatment has also increased. Nowadays, the tendency when dealing with meniscus tears is “preservation whenever possible.” Nevertheless, meniscectomy is still one of the most frequent orthopedic surgical procedures today. The development of repair techniques is making this option more and more possible and has been connected with surgical and technological improvements. The success rate of meniscus repair depends on several factors and is influenced by the location and type of tear. Moreover, any treatment option must consider patient’s expectations. When dealing with high-level athletes (e.g., football), the player, the family, the manager, the club, and several other socioeconomic factors play a role, regardless of the surgeon’s opinion. Classification of meniscal injuries, preoperative planning, and surgical training (including cadaver courses) are very important. Meniscus allograft transplantation and partial replacement by acellular scaffolds have been indicated in selected cases. However, there is few data supporting their use when return to high-level sports activity is the goal. This work aims to provide a comprehensive approach to the most frequent techniques and indications for treatment of meniscal injuries.
Journal of biomedical semantics, Jan 8, 2018
Pathogenesis of inflammatory diseases can be tracked by studying the causality relationships amon... more Pathogenesis of inflammatory diseases can be tracked by studying the causality relationships among the factors contributing to its development. We could, for instance, hypothesize on the connections of the pathogenesis outcomes to the observed conditions. And to prove such causal hypotheses we would need to have the full understanding of the causal relationships, and we would have to provide all the necessary evidences to support our claims. In practice, however, we might not possess all the background knowledge on the causality relationships, and we might be unable to collect all the evidence to prove our hypotheses. In this work we propose a methodology for the translation of biological knowledge on causality relationships of biological processes and their effects on conditions to a computational framework for hypothesis testing. The methodology consists of two main points: hypothesis graph construction from the formalization of the background knowledge on causality relationships,...
A meniscectomia (total ou parcial) tem sido a abordagem clinica mais frequente no que respeita ao... more A meniscectomia (total ou parcial) tem sido a abordagem clinica mais frequente no que respeita ao tratamento da maioria das lesoes do menisco. A reparacao meniscal representa uma tendencia recente, uma vez que a importância funcional destas estruturas na articulacao do joelho e as consequencias a longo prazo da sua remocao sao agora melhor compreendidas. Contudo, as suas indicacoes sao ainda limitadas e, apesar de garantir melhores resultados funcionais e radiologicos a longo prazo, as tecnicas de reparacao apresentam ainda uma taxa muito elevada de falencia e reintervencao. As lesoes destas estruturas continuam a estar entre as mais frequentes patologias que motivam intervencao cirurgica em Ortopedia e tem um importante impacto socio-economico. Verifi camos um interesse crescente da comunidade medica nos aspetos da biologia do menisco humano mas continuam a existir poucos estudos relacionados com este tema. Um dos objetivos desde grupo de investigacao e acrescentar conhecimento relevante sobre este tecido com o objetivo de facilitar aplicacoes clinicas futuras, nomeadamente pelo conhecimento das propriedades biomecânicas do menisco a fresco (sem processo de congelamento) e da sua biologia celular. Da analise mecânica dinâmica (DMA) dos segmentos do menisco humano a fresco observamos a seguinte tendencia decrescente de rigidez: segmento anterior MI (0,25 MPa a 1Hz) <anterior ME< medio ME<posterior MI< posterior ME< medio MI (0,9 MPa a 1 Hz). As celulas isoladas das diferentes amostras incluem fi brocondrocitos e celulas estaminais mesenquimais (positivas para CD105, CD73 e CD90; negativas para CD34 e CD45). A densidade celular decresce da periferia para o centro. Existe assimetria na celularidade entre os diferentes segmentos avaliados. Efetuamos a primeira revisao sistematica da literatura sobre aplicacoes da Engenharia de Tecidos e Medicina Regenerativa Helder Pereira[1,2,3,4] Joana Silva-Correia[1,2] Ana Margarida Frias[1,2] Joaquim Miguel Oliveira[1,2] Jose Mesquita Montes[4] Rui Luis Reis[1,2] Joao Espregueira-Mendes[1,2,3]
Biotechnology progress, Jan 3, 2017
Tissue Engineering (TE) envisions the creation of functional substitutes for damaged tissues thro... more Tissue Engineering (TE) envisions the creation of functional substitutes for damaged tissues through integrated solutions, where medical, biological and engineering principles are combined. Bone regeneration is one of the areas in which designing a model that mimics all tissue properties is still a challenge. The hierarchical structure and high vascularization of bone hampers a TE approach, especially in large bone defects. Nanotechnology can open-up a new era for TE, allowing the creation of nanostructures that are comparable in size to those appearing in natural bone. Therefore, nanoengineered systems are now able to more closely mimic the structures observed in naturally occurring systems, and it is also possible to combine several approaches, such drug delivery and cell labeling, within a single system. This review aims to cover the most recent developments on the use of different nanoparticles for bone TE, with emphasis on their application for scaffolds improvement; drug and g...
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Papers by Miguel Oliveira