Tissue Engineering - the gateway to regenerative medicine

Tissue Engineering as an emerging biotechnology sector aims at the in vitro regeneration of diseased tissues and promises to profoundly change medical practice, offering the possibility of regenerating tissues and organs instead of just repairing them (regenerative medicine). Improved healing processes and a higher quality of life are the expected results. This article gives an overview of different technologies for regenerative medicine and presents results of our own current applied research and development. A recent project was successfully closed with the development of a natural biomaterial for soft tissue oral defects. The establishment of an in vitro bioreactor system enabled us to simulate the mechanical and biological environment in a healing wound and to investigate the suitability of different implant materials for the oral tissue regeneration. Moreover, focusing the attention on an alternative method for the intervertebral disc (IVD) regeneration, we established a new tissue engineered approach, based on the three-dimensional (3D) culture of autologous human IVD cells into a polyurethane (PU)-fibrin composite. IVD cells were able to proliferate and, thanks to the 3D conditions, to differentiate expressing the typical native tissue markers. The development of an automated platform was the goal of an additional project, to standardize the cell culture technology, increase the bio-safety and reduce the production costs, moving tissue engineering nearer to clinical application

Standardized 3D bioprinting of soft tissue models with human primary cells

Cells grown in 3D are more physiologically relevant than cells cultured in 2D. To use 3D models in substance testing and regenerative medicine, reproducibility and standardization are important. Bioprinting offers not only automated standardizable processes but also the production of complex tissue-like structures in an additive manner. We developed an all-in-one bioprinting solution to produce soft tissue models. The holistic approach included (1) a bioprinter in a sterile environment, (2) a light-induced bioink polymerization unit, (3) a user-friendly software, (4) the capability to print in standard labware for high-throughput screening, (5) cell-compatible inkjet-based printheads, (6) a cell-compatible ready-to-use BioInk, and (7) standard operating procedures. In a proof-of-concept study, skin as a reference soft tissue model was printed. To produce dermal equivalents, primary human dermal fibroblasts were printed in alternating layers with BioInk and cultured for up to 7 weeks. During long-term cultures, the models were remodeled and fully populated with viable and spreaded fibroblasts. Primary human dermal keratinocytes were seeded on top of dermal equivalents, and epidermis-like structures were formed as verified with hematoxylin and eosin staining and immunostaining. However, a fully stratified epidermis was not achieved. Nevertheless, this is one of the first reports of an integrative bioprinting strategy for industrial routine application

In vitro characterization of a new composite material for biomedical applications and 3D (bio)printing

Study goal: The present project aims at evaluating the cytocompatibility and printability of a new composite material, based on a mixture of a new methacrylate-based monomer developed within a CTI project (18514.1 PFLS-LS) and glass-ceramic powder supplemented with co- and photo-initiators (patent in preparation). This study is the basis to demonstrate the suitability of the biomaterial, for biomedical applications, such as stent, orthopedic implants and hearing aid components, as well as for 3D (bio)printing Key findings: - Cultivation, proliferation and differentiation of three different human cell types were successfully established on composite material discs (1cm diameter, 1mm height). Biological activity was shown - The material is suitable for 3D (bio)printing, printing protocols were established - The new composite material is suitable for cell and tissue interaction in biomedical application

A novel microplate 3D bioprinting platform for the engineering of muscle and tendon tissues

Two-dimensional (2D) cell cultures do not reflect the in vivo situation, and thus it is important to develop predictive three-dimensional (3D) in vitro models with enhanced reliability and robustness for drug screening applications. Treatments against muscle-related diseases are becoming more prominent due to the growth of the aging population worldwide. In this study, we describe a novel drug screening platform with automated production of 3D musculoskeletal-tendon-like tissues. With 3D bioprinting, alternating layers of photo-polymerized gelatin-methacryloyl-based bioink and cell suspension tissue models were produced in a dumbbell shape onto novel postholder cell culture inserts in 24-well plates. Monocultures of human primary skeletal muscle cells and rat tenocytes were printed around and between the posts. The cells showed high viability in culture and good tissue differentiation, based on marker gene and protein expressions. Different printing patterns of bioink and cells were explored and calcium signaling with Fluo4-loaded cells while electrically stimulated was shown. Finally, controlled co-printing of tenocytes and myoblasts around and between the posts, respectively, was demonstrated followed by co-culture and co-differentiation. This screening platform combining 3D bioprinting with a novel microplate represents a promising tool to address musculoskeletal diseases

Cell-seeded thermoreversible hydrogel-polyurethane composites for nucleus pulposus augmentation

Tissue engineering represents an alternative approach to the current invasive surgical procedures for the intervertebral disc (IVD) repair. The combination of injectable hydrogels and elastic biomaterials allow three-dimensional cell cultures and provide mechanical stability. In the present study a thermoreversible hyaluronan (HA) hydrogel as well as fibrin glue were mixed with polyurethane (PU) and their effect was investigated on the proliferation and differentiation of human IVD (hIVD cells) and mesenchymal stem cells (hMSCs) by in vitro and ex-vivo experiments

Aktuelle Trends bei der in vitro-Substanztestung in Deutschland und in der Schweiz

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Properties of additive-manufactured open porous titanium structures for patient-specific load-bearing implants

Additive manufacturing has been well established in many sectors, including the medical industry. For load-bearing bone implants, titanium and its alloys, such as Ti6Al4V, are widely used due to their high strength to weight ratio and osseointegrative properties. However, bone resorption and loosening of implants is related to the significantly higher stiffness of dense Ti6Al4V, leading to stress shielding. With the aging of population, there is an increasing need for orthopedic implants with a high success rate and a long implant life span. Besides that the treatment of non-healing segmental bone defects, where the self repairing properties of bone tissue are not sufficient, is still a challenge. In both fields of application, patient-specific titanium implants combined with functionally graded porosity designed according to locally expected loads unlock new possibilities. Many studies underline the huge potential of the new design freedom to generate open porous structures and more personalized implants with enhanced mechanical properties that also integrate well with surrounding tissues. Integration of functionally graded open porosity into implants allows for the implant to more closely mimic the mechanical properties of human bone and its internal architecture. The results of this work represent the basis for developing complex porous titanium structures with various pore sizes and shapes to tailor structural mechanical properties and biological responses. Therefore, 3D porous structures with various pore sizes and shapes were designed and manufactured in Ti6Al4V using laser powder bed fusion (PBF-LB/M). Based on these structures, the correlation of pore size and shape with cell ingrowth, morphology, metabolic activity, and early markers for bone formation (ALP activity) was investigated in static cell cultures using the osteosarcoma cell line Saos-2. Mechanical properties, such as stiffness and compression strength, were investigated with compression testing. The present study concludes that cell morphology, metabolic activity, and ALP activity are widely independent of pore shape and size within the tested range of 400–700 µm pore size. Furthermore, the mechanical properties of the evaluated structures were in the range of cortical and trabecular bone. This opens the possibility to design mechanical properties with gradient porosity without decisively affecting biological responses

Disease Cell models – Their Use in Industry TEDD Workshop in Sion on 27 March 2014: biotechnet Switzerland

On 27 March 2014, experts met at the first TEDD Workshop 2014, held at the HES-SO Valais/Wallis in Sion, to present innovative cell models for industrial applications. This was the first time that a TEDD event had been organized in French-speaking Switzerland and it offered local network partners an opportunity to showcase their research activities