Metallic Scaffolds for Bone Regeneration

Abstract

Bone tissue engineering is an emerging interdisciplinary field in Science, combining expertise in medicine, material science and biomechanics. Hard tissue engineering research is focused mainly in two areas, osteo and dental clinical applications. There is a lot of exciting research being performed worldwide in developing novel scaffolds for tissue engineering. Although, nowadays the majority of the research effort is in the development of scaffolds for non-load bearing applications, primarily using soft natural or synthetic polymers or natural scaffolds for soft tissue engineering; metallic scaffolds aimed for hard tissue engineering have been also the subject of in vitro and in vivo research and industrial development. In this article, descriptions of the different manufacturing technologies available to fabricate metallic scaffolds and a compilation of the reported biocompatibility of the currently developed metallic scaffolds have been performed. Finally, we highlight the positive aspects and the remaining problems that will drive future research in metallic constructs aimed for the reconstruction and repair of bone.

Porous magnesium-based scaffolds for tissue engineering

“…Although, porosity is necessary for scaffolds, it considerably reduces the scaffold's strength which is vital, in particular, for large bone defects [18,19]. The trade-off between the mechanical strength and the porosity is one of the main challenges in designing tissue engineered bone scaffolds [6]. At present, various types of biomaterials have been employed for this aim, which are synthetic or naturally-derived.…”

“…In the past, such stability was mostly achieved by means of pins, screws and bone cements [6]. However, in recent experiments, researchers are attempting to improve the fixation by tissue engineering techniques [7].…”

“…Porous polymeric scaffolds cannot resist the high mechanical stresses present in bone replacement operations [16]. This has led researchers to study porous metals, based on orthopaedic metallic implants, due to their greater compressive strength, fracture toughness, and fatigue resistance, which are needed for load-bearing applications [6,16]. Due to the excellent physical and mechanical properties of magnesium compared to other permanent (nondegradable) metals, porous magnesium and Mg alloys became a good candidate to serve as a biodegradable scaffold for bone treatments [23,24].…”

Composite scaffolds for osteochondral repair obtained by combination of additive manufacturing, leaching processes and hMSC-CM functionalization

“…Among the most promising approaches, towards stable and effective composite scaffolds, it is important to note the combination of: a) phase separation or leaching processes, normally for obtaining the soft chondral phase, with b) computer aided rapid prototyping technologies based on addi tive manufacturing, usually for manufacturing the rigid bony phase [34]. In spite of the very positive results shown by metallic rapid prototyped prostheses and scaffolds for bone repair [35], most successful composite scaffolds for osteochondral repair are based on polymer ceramic com posites [31,34,36], polymer polymer composites [37], ceramic ceramic composites [38], ceramic metal composites [39] and metal metal composites [40]. Interestingly, metal polymer composites, which could benefit from the stiffness of metals for the bony phase and from the elasticity of polymers for the chondral phase are not so common.…”

Surface modification of biodegradable porous Mg bone scaffold using polycaprolactone/bioactive glass composite

“…1 Historically, nondegradable metals, namely stainless steel, cobalt-chromium and titanium alloys, have been intensively used due to their good mechanical properties, biological performance, and degradation resistance. 2,3 Currently, with the growth of tissue engineering techniques, biodegradable materials have attracted attention and their application has increased 4 since they can be replaced by the host tissue as well as applied for delivery of bioactive ions to improve hard tissue healing. 5 Recently, magnesium (Mg) and its alloys have been presented as a new class of biodegradable metallic materials for orthopedic applications.…”