Diana Gaspar

The nano-fibrous architecture of electro-spun meshes favours their use in biomedicine, but their low mechanical properties prohibit their wide use in clinical practice. Introduction of porosity, essential of tissue integration, decreases further mechanical integrity. Herein, we hypothesised that macro-porous electro-spun meshes with adequate mechanical properties can be fabricated through layering and subsequent compression. Two and three layers electro-spun poly- ε -caprolactone scaffolds were fabricated, compressed and subsequently 30% circular porosity was introduced through laser cutting. Three-layered porous electro-spun meshes exhibited mechanical properties similar to commercially available scaffolds without any structural or cytotoxic effect. This study brings electro-spun materials closer to clinical translation and commercialisation.

The purpose of this review is to provide a brief overview of bioreactor-based culture systems as alternatives to conventional two- and three- dimensional counterparts. The role, challenges and future aspirations of bioreactors in the musculoskeletal field (e.g. cartilage, intervertebral disc, tendon and bone) are discussed. Bioreactors, by recapitulating physiological processes, can be used effectively as part of the initial in vitro screening, reducing that way the number of animal required for preclinical assessment, complying with the 3R principles and, in most cases, allowing working with human tissues. The clinical significance of bioreactors is that, by providing more physiologically-relevant conditions to customarily used two- and three- dimensional cultures, they hold the potential to provide a testing platform that is more predictable of a whole tissue response, thereby facilitating the screening of treatments before the initiation of clinical trials. This article is protected by copyright. All rights reserved

Modular tissue engineering is based on the cells’ innate ability to create bottom-up supramolecular assemblies with efficiency and efficacy still unmatched by man-made devices. Although the regenerative potential of such tissue substitutes has been documented in preclinical and clinical setting, the prolonged culture time required to develop an implantable device is associated with phenotypic drift and/or cell senescence. Herein, we demonstrate that macromolecular crowding significantly enhances extracellular matrix deposition in human bone marrow mesenchymal stem cell culture at both 20% and 2% oxygen tension. Although hypoxia inducible factor - 1α was activated at 2% oxygen tension, increased extracellular matrix synthesis was not observed. The expression of surface markers and transcription factors was not affected as a function of oxygen tension and macromolecular crowding. The multilineage potential was also maintained, albeit adipogenic differentiation was significantly reduced in low oxygen tension cultures, chondrogenic differentiation was significantly increased in macromolecularly crowded cultures and osteogenic differentiation was not affected as a function of oxygen tension and macromolecular crowding. Collectively, these data pave the way for the development of bottom-up tissue equivalents based on physiologically relevant developmental processes.

Background: Electro-spun scaffolds are utilized in a diverse spectrum of clinical targets, with an ever-increasing quantity of work progressing to clinical studies and commercialization. The limited number of conformations in which the scaffolds can be fabricated hampers their wide acceptance in clinical practice. Materials & methods: Herein, we assessed a single-strep fabrication process for predesigned electro-spun scaffold preparation and the ramifications of the introduction of porosity (0, 30, 50, 70%) and pore shape (circle, rhomboid, square) on structural, mechanical (tensile and ball burst) and biological (dermal fibroblast and THP-1) properties. Results: The collector design did not affect the fibrous nature of the scaffold. Modulation of the porosity and pore shape offered control over the mechanical properties of the scaffolds. Neither the porosity nor the pore shape affected cellular (dermal fibroblast and THP-1) response. Conclusion: Overall, herein we provide evidence that electro-spun scaff...

Self‐assembly in tissue engineering refers to the spontaneous chemical or biological association of components to form a distinct functional construct, reminiscent of native tissue. Such self‐assembled systems have been widely used to develop platforms for the delivery of therapeutic and/or bioactive molecules and various cell populations. Tissue morphology and functional characteristics have been recapitulated in several self‐assembled constructs, designed to incorporate stimuli responsiveness and controlled architecture through spatial confinement or field manipulation. In parallel, owing to substantial functional properties, scaffold‐free cell‐assembled devices have aided in the development of functional neotissues for various clinical targets. Herein, we discuss recent advancements and future aspirations in scaffold and scaffold‐free self‐assembled devices for regenerative medicine purposes. Biotechnol. Bioeng. 2016;113: 1155–1163.

Tissue engineering has emerged as a possible alternative to current treatments for bone injuries and defects. However, the common tissue engineering approach presents some obstacles to the development of functional tissues, such as insufficient nutrient and metabolite transport and non-homogenous cell distribution. Culture of bone cells in three-dimensional constructs in bioreactor systems is a solution for those problems as it improves mass transport in the culture system. For bone tissue engineering spinner flasks, rotating wall vessels and perfusion systems have been investigated, and based on these, variations that support cell seeding and mechanical stimulation have also been researched. This review aims at providing an overview of the concepts, advantages and future applications of bioreactor systems for bone tissue engineering with emphasis on the design of different perfusion systems and parameters that can be „optimized.