Talks and Poster Presentations (without Proceedings-Entry):
"Bioprinter (3D-Drucker für Gewebe und Organe) in der Medizin - aktueller Stand";
Talk: Symposium Intensivmedizin und Intensivpflege,
Additive manufacturing technologies (AMT) have great potential for shaping 3D-structures with high shape complexity and high resolution. With the development of easy-to-use sys-tems exhibiting sufficiently fast build-speeds and decreased system prizes, AMT has moved from the arena of niche-manufacturing processes into the spotlight of a much larger audi-ence.
Additive Manufacturing Technologies is the currently used standardized term for all process-es (ASTM F2792), where 3D-structures are fabricated by adding material in form of thin lay-ers to finally obtain the targeted geometry. In literature, the terms Rapid Prototyping, Layered Manufacturing, Solid Freeform Fabrication 3D-Fabbing and 3D-printing are used synony-mously. In this work, the terms AMT and 3D-printing will be used to describe the general manufacturing principle.
AMT is capable of shaping individual geometries on demand, without the requirement of ex-pensive tooling. This makes AMT the ideal manufacturing process for applications in medi-cine and biomedical engineering, where customized, patient specific geometries are of high benefit. Fields of applications with current clinical use include the fabrication of drill guides for implantology and maxillo-facial surgery  as well as models  for digital dentistry. It is estimated that around 50 000 patients are treated every year using 3D-printed surgical plan-ning instruments . For these applications, the required level regarding biocompatibility, bio-functional and structural (mechanical) properties of the used materials is achievable with currently available materials. The challenge is rather to provide structures with sufficient pre-cision and resolution at low cost.
From a commercial point of view, the probably most successful case of AMT in biomedical applications are invisible aligners  for orthodontics, where currently millions of parts are fabricated every year. In the case of invisible aligners, the 3D-printed geometry is moulded into a biocompatible thermoplastic material, which is then shipped to the patient. This means, again, that the requirements for this application are more on the side of geometrical and eco-nomic challenges.
A field of increasing clinical interest is the use of titanium implants made by selective laser sintering (SLS) or electron beam melting (EBM). SLS and EBM offer the possibility to use a clinically proven material (titanium) and provide implants with customized geometries . Due to the use of titanium, even load-bearing applications can be targeted. AMT of titanium also simplifies the preparation of surfaces with mechanical retentions which potentially im-proves the in-growth of bone. Since more than 30 000 patients have been treated with EBM-implants alone, it can be claimed that titanium-based AMT implants are becoming an estab-lished method in orthopaedic surgery.
An even more attractive (but also more challenging) idea is to use AMT to fabricate cellular, biodegradable scaffolds for tissue engineering . A significant number of research projects has been undertaken in this direction, with a focus on using material extrusion (e.g. fused deposition modelling, FDM) to fabricate cellular structures made of (degradable) thermo-plastic biopolymers like polylactic acid and polycaprolactone. An alternative route was to re-ly on binder jetting for manufacturing cellular scaffolds made of bioceramics (e.g. calcium phosphates). Both routes led to the development of commercial products, with a focus on hard-tissue regeneration. But the clinical impact of these developments did not meet the orig-inal very high expectations. A possible reason for this might be related to the limited defect size that can be treated with these initially rather simple scaffolds. Using classical, well estab-lished bone-replacement materials (e.g. bovine derived xenografts, bioceramic foams, colla-gen fleece, ...) very similar clinical outcome can be achieved. Therefore the motivation to es-tablish new, more complex repair systems based on AMT is rather low.
For the regeneration of larger defects or more complicated tissue constructs (e.g. osteochon-dral scaffolds for the treatment of osteoarthritis) it is obviously not sufficient, to just provide a 3D-printed cellular construct. Among other things, it will be necessary to incorporate 3D-functionalities to trigger sufficient vascularization. In order to better mimic the biological conditions in multi-tissue constructs (e.g. the zonal organization of cartilage-bone constructs)  it will also be necessary to have a closer look, how the micro- and nano-morphology of the scaffold material influences cell behaviour. AMT provides an excellent tool-set for de-veloping and systematically investigating these next-generation scaffold structures.
With the recently gained knowledge about the importance of the influence of the 3D-micro-environment  surrounding the cells, the relevance of manufacturing systems being capable of providing such a defined 3D-environment will certainly grow in the coming years.
An even more visionary strategy, compared to providing functional scaffolds for tissue re-generation, is the printing of whole organs. With the development of inkjet-based systems ca-pable of depositing living cells  a completely new route for engineering living tissue was opened. Initially systems based on household inkjetting devices  with a focus on increas-ing throughput were used. In recent years, a whole industry has emerged around the devel-opment of dedicated bio-inkjetting and bioplotting systems. Despite the fact that amazing re-sults have been achieved in this field, it has to be noted that alternative approaches (e.g. by utilizing decellularized biological matrices ) have also shown astonishing results, and are probably even closer to clinical applications compared to 3D-bioplotted constructs.
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Created from the Publication Database of the Vienna University of Technology.