Traditionally, bioactive glasses have been used to fill and restore bone defects. More recently, this category of biomaterials has become an emerging research field for bone tissue engineering applications. Here, we review and discuss current knowledge on porous bone tissue engineering scaffolds on the basis of melt-derived bioactive silicate glass compositions and relevant composite structures. Starting with an excerpt on the history of bioactive glasses, as well as on fundamental requirements for bone tissue engineering scaffolds, a detailed overview on recent developments of bioactive glass and glass-ceramic scaffolds will be given, including a summary of common fabrication methods and a discussion on the microstructural-mechanical properties of scaffolds in relation to human bone (structure-property and structure-function relationship). In addition, ion release effects of bioactive glasses concerning osteogenic and angiogenic responses are addressed. Finally, areas of future research are highlighted in this review.

https://pure.tue.nl/ws/files/3034662/Metis245608.pdf

Bioactive Glass and Glass-Ceramic Scaffolds for Bone Tissue Engineering

In the last half-century, the development of biodegradable polymeric materials for biomedical applications has advanced significantly. Biodegradable polymeric materials are favored in the development of therapeutic devices, including temporary implants and three-dimensional scaffolds for tissue engineering. Further advancements have occurred in the utilization of biodegradable polymeric materials for pharmacological applications such as delivery vehicles for controlled/sustained drug release. These applications require particular physicochemical, biological, and degradation properties of the materials to deliver effective therapy. As a result, a wide range of natural or synthetic polymers able to undergo hydrolytic or enzymatic degradation is being studied for biomedical applications. This review outlines the current development of biodegradable natural and synthetic polymeric materials for various biomedical applications, including tissue engineering, temporary implants, wound healing, and drug delivery.

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Current development of biodegradable polymeric materials for biomedical applications

Hydrogels from different materials can be used in biomedical field as an innovative approach in regenerative medicine. Depending on the origin source, hydrogels can be synthetized through chemical and physical methods. Hydrogel can be characterized through several physical parameters, such as size, elastic modulus, swelling and degradation rate. Lately, research is focused on hydrogels derived from biologic materials. These hydrogels can be derived from protein polymers, such as collage, elastin, and polysaccharide polymers like glycosaminoglycans or alginate among others. Introduction of decellularized tissues into hydrogels synthesis displays several advantages compared to natural or synthetic based hydrogels. Preservation of natural molecules such as growth factors, glycans, bioactive cryptic peptides and natural proteins can promote cell growth, function, differentiation, angiogenesis, anti-angiogenesis, antimicrobial effects, and chemotactic effects. Versatility of hydrogels make possible multiple applications and combinations with several molecules on order to obtain the adequate characteristic for each scope. In this context, a lot of molecules such as cross link agents, drugs, grow factors or cells can be used. This review focuses on the recent progress of hydrogels synthesis and applications in order to classify the most recent and relevant matters in biomedical field.

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Overview of natural hydrogels for regenerative medicine applications

Characterization of topographical effects on macrophage behavior in a foreign body response model

Tissue engineering is a newly emerging biomedical technology, which aids and increases the repair and regeneration of deficient and injured tissues. It employs the principles from the fields of materials science, cell biology, transplantation, and engineering in an effort to treat or replace damaged tissues. Tissue engineering and development of complex tissues or organs, such as heart, muscle, kidney, liver, and lung, are still a distant milestone in twenty-first century. Generally, there are four main challenges in tissue engineering which need optimization. These include biomaterials, cell sources, vascularization of engineered tissues, and design of drug delivery systems. Biomaterials and cell sources should be specific for the engineering of each tissue or organ. On the other hand, angiogenesis is required not only for the treatment of a variety of ischemic conditions, but it is also a critical component of virtually all tissue-engineering strategies. Therefore, controlling the dose, location, and duration of releasing angiogenic factors via polymeric delivery systems, in order to ultimately better mimic the stem cell niche through scaffolds, will dictate the utility of a variety of biomaterials in tissue regeneration. This review focuses on the use of polymeric vehicles that are made of synthetic and/or natural biomaterials as scaffolds for three-dimensional cell cultures and for locally delivering the inductive growth factors in various formats to provide a method of controlled, localized delivery for the desired time frame and for vascularized tissue-engineering therapies.

Review paper: critical issues in tissue engineering: biomaterials, cell sources, angiogenesis, and drug delivery systems.

A composite fibrin-based scaffold for controlled delivery of bioactive pro-angiogenetic growth factors

The aim of the present work is to evaluate the in vitro immunocompatibility of an elastomeric material with feasible applications in the cardiovascular field. In particular, since it is well known that surface chemistry and topography play a key role in the foreign body response, their influence on human monocytes was evaluated. The material, constituted by a poly(ether)urethane (PEtU) and a polydimethylsiloxane (PDMS), was synthesized to manufacture films and small-diameter vascular grafts with three different surface topographical features, smooth, rough and porous, and siloxane rates, 10, 30 and 40. Human THP-1 monocytes have been cultured for 72 h on the films and human blood has been circulating for 2 h into the grafts to assess leukocyte adhesion and cytokine releases. Materials extracts were utilized to evaluate monocyte apoptosis. Smooth films showed lower cell adhesion degrees than rough and porous ones. All the PEtU-PDMS (poly(ether)urethane-polydimethylsiloxane) films and vascular grafts induced a narrow inflammatory response, as demonstrated by slight cytokine secretion levels, in particular samples with the highest PDMS contents (30 and 40%) induced the lowest IL-1β secretion. Moreover, an absence of monocyte apoptosis advises that the negligible release values have not to be ascribed to material toxicity. In the end, surface topography showed to affect only monocyte adhesion while siloxane content the cytokine release. Therefore, the possibility to modify the above tested parameters during material synthesis and manufacture could allow to bound the inflammatory potency of the PEtU-PDMS devices and render them excellent candidates for cardiovascular reconstruction.

Chiara Mirtelli

Papers

A composite fibrin-based scaffold for controlled delivery of bioactive pro-angiogenetic growth factors

In vitro evaluation of the PEtU-PDMS material immunocompatibility: the influence of surface topography and PDMS content