Swelling and mechanical properties of alginate hydrogels with respect to promotion of neural growth

Soft alginate hydrogels support robust neurite outgrowth, but their rapid disintegration in solutions of high ionic strength restricts them from long-term in vivo applications. Aiming to enhance the mechanical stability of soft alginate hydrogels, we investigated how changes in pH and ionic strength during gelation influence the swelling, stiffness, and disintegration of a three-dimensional (3D) alginate matrix and its ability to support neurite outgrowth. Hydrogels were generated from dry alginate layers through ionic crosslinks with Ca(2+) (<=10 mM) in solutions of low or high ionic strength and at pH 5.5 or 7.4. High- and low-viscosity alginates with different molecular compositions demonstrated pH and ionic strength-independent increases in hydrogel volume with decreases in Ca(2+) concentrations from 10 to 2 mM. Only soft hydrogels that were synthesized in the presence of 150 mM of NaCl (Ca-alginateNaCl) displayed long-term volume stability in buffered physiological saline, whereas analogous hydrogels generated in NaCl-free conditions (Ca-alginate) collapsed. The stiffnesses of Ca-alginateNaCl hydrogels elevated from 0.01 to 19 kPa as the Ca(2+)-concentration was raised from 2 to 10 mM; however, only Ca-alginateNaCl hydrogels with an elastic modulus <=1.5 kPa that were generated with <=4 mM of Ca(2+) supported robust neurite outgrowth in primary neuronal cultures. In conclusion, soft Ca-alginateNaCl hydrogels combine mechanical stability in solutions of high ionic strength with the ability to support neural growth and could be useful as 3D implants for neural regeneration in vivo

Hollow fibres integrated in a microfluidic cell culture system

Dieser Beitrag ist mit Zustimmung des Rechteinhabers aufgrund einer (DFG geförderten) Allianz- bzw. Nationallizenz frei zugänglich.This publication is with permission of the rights owner freely accessible due to an Alliance licence and a national licence (funded by the DFG, German Research Foundation) respectively.For in vitro drug screening a modified perfusion micro-bioreactor system with integrated hollow fibres will be demonstrated. This biocompatible system consists of an integrated closed flow circuit that includes reservoirs and pneumatic micro pumps. Additional optical online-monitoring devices allow the observation during the cell cultivation. The embedded hollow fibre system which acts as cell carrier consists of a biodegradable biopolymer. One option to fabricate such 3D structures is the technology of Organ Printing which is realised by an adapted rapid prototyping system entitled 3D Scaffold Printer. With this device specimens consisting of tubes with a diameter smaller than 2 mm can be prepared. It should be possible to cultivate the hollow fibres inside and outside with different kinds of cells and therefore generate models of complex tissues

Electrochemical method for isolation of chitinous 3D scaffolds from cultivated Aplysina aerophoba marine demosponge and its biomimetic application

Three-dimensional (3D) biopolymer-based scaffolds including chitinous matrices have been widely used for tissue engineering, regenerative medicine and other modern interdisciplinary fields including extreme biomimetics. In this study, we introduce a novel, electrochemically assisted method for 3D chitin scaffolds isolation from the cultivated marine demosponge Aplysina aerophoba which consists of three main steps: (1) decellularization, (2) decalcification and (3) main deproteinization along with desilicification and depigmentation. For the first time, the obtained electrochemically isolated 3D chitinous scaffolds have been further biomineralized ex vivo using hemolymph of Cornu aspersum edible snail aimed to generate calcium carbonates-based layered biomimetic scaffolds. The analysis of prior to, during and post-electrochemical isolation samples as well as samples treated with molluscan hemolymph was conducted employing analytical techniques such as SEM, XRD, ATR–FTIR and Raman spectroscopy. Finally, the use of described method for chitin isolation combined with biomineralization ex vivo resulted in the formation of crystalline (calcite) calcium carbonate-based deposits on the surface of chitinous scaffolds, which could serve as promising biomaterials for the wide range of biomedical, environmental and biomimetic applications. © 2020, The Author(s).Politechnika PoznaÅ ska, PUT: 0911/SBAD/0380/2019Deutsche Forschungsgemeinschaft, DFG: HE 394/3Deutscher Akademischer Austauschdienst, DAADRussian Science Foundation, RSF: 18-13-00220PPN/BEK/2018/1/0007103/32/SBAD/0906Sächsisches Staatsministerium für Wissenschaft und Kunst, SMWK: 02010311This work was performed with the financial support of Poznan University of Technology, Poland (Grant No. 0911/SBAD/0380/2019), as well as by the Ministry of Science and Higher Education (Poland) as financial subsidy to PUT No. 03/32/SBAD/0906. Krzysztof Nowacki was supported by the Erasmus Plus program (2019). Also, this study was partially supported by the DFG Project HE 394/3 and SMWK Project No. 02010311 (Germany). Marcin Wysokowski is financially supported by the Polish National Agency for Academic Exchange (PPN/BEK/2018/1/00071). Tomasz Machałowski is supported by DAAD (Personal Ref. No. 91734605). Yuliya Khrunyk is supported by the Russian Science Foundation (Grant No. 18-13-00220)

Advanced polymeric membranes as biomaterials based on marine sources envisaging the regeneration of human tissues

The self-repair capacity of human tissue is limited, motivating the arising of tissue engineering (TE) in building temporary scaffolds that envisage the regeneration of human tissues, including articular cartilage. However, despite the large number of preclinical data available, current therapies are not yet capable of fully restoring the entire healthy structure and function on this tissue when significantly damaged. For this reason, new biomaterial approaches are needed, and the present work proposes the development and characterization of innovative polymeric membranes formed by blending marine origin polymers, in a chemical free cross-linking approach, as biomaterials for tissue regeneration. The results confirmed the production of polyelectrolyte complexes molded as membranes, with structural stability resulting from natural intermolecular interactions between the marine biopolymers collagen, chitosan and fucoidan. Furthermore, the polymeric membranes presented adequate swelling ability without compromising cohesiveness (between 300 and 600%), appropriate surface properties, revealing mechanical properties similar to native articular cartilage. From the different formulations studied, the ones performing better were the ones produced with 3 % shark collagen, 3% chitosan and 10% fucoidan, as well as with 5% jellyfish collagen, 3% shark collagen, 3% chitosan and 10% fucoidan. Overall, the novel marine polymeric membranes demonstrated to have promising chemical, and physical properties for tissue engineering approaches, namely as thin biomaterial that can be applied over the damaged articular cartilage aiming its regeneration.The authors would like to acknowledge the Portuguese Foundation of Science and Technology (FCT) for Ph.D. fellowship (D. N. Carvalho, under the scope of doctoral program TERM&SC, ref. PD/BD/143044/2018), post-doctoral fellowship (L.C. Rodrigues, ref. SFRH/BPD/93697/2013) and research project with ref. PTDC/CTM-CTM/29813/2017-(POCI-01-0145-FEDER-029813). The authors also thank Jellagen Ltd. (UK) for the provision of purified jellyfish collagen and Julio Maroto (Fundación CETMAR, Vigo, Spain) for the kind offer of the squid pens for chitosan production.This work has been partially funded by ERDF under the scope of the Atlantic Area Program through project EAPA_151/2016 (BLUEHUMAN)

On the reproducibility of extrusion-based bioprinting: round robin study on standardization in the field

The outcome of three-dimensional (3D) bioprinting heavily depends, amongst others, on the interaction between the developed bioink, the printing process, and the printing equipment. However, if this interplay is ensured, bioprinting promises unmatched possibilities in the health care area. To pave the way for comparing newly developed biomaterials, clinical studies, and medical applications (i.e. printed organs, patient-specific tissues), there is a great need for standardization of manufacturing methods in order to enable technology transfers. Despite the importance of such standardization, there is currently a tremendous lack of empirical data that examines the reproducibility and robustness of production in more than one location at a time. In this work, we present data derived from a round robin test for extrusion-based 3D printing performance comprising 12 different academic laboratories throughout Germany and analyze the respective prints using automated image analysis (IA) in three independent academic groups. The fabrication of objects from polymer solutions was standardized as much as currently possible to allow studying the comparability of results from different laboratories. This study has led to the conclusion that current standardization conditions still leave room for the intervention of operators due to missing automation of the equipment. This affects significantly the reproducibility and comparability of bioprinting experiments in multiple laboratories. Nevertheless, automated IA proved to be a suitable methodology for quality assurance as three independently developed workflows achieved similar results. Moreover, the extracted data describing geometric features showed how the function of printers affects the quality of the printed object. A significant step toward standardization of the process was made as an infrastructure for distribution of material and methods, as well as for data transfer and storage was successfully established

On the reproducibility of extrusion-based bioprinting: round robin study on standardization in the field

The outcome of three-dimensional (3D) bioprinting heavily depends, amongst others, on the interaction between the developed bioink, the printing process, and the printing equipment. However, if this interplay is ensured, bioprinting promises unmatched possibilities in the health care area. To pave the way for comparing newly developed biomaterials, clinical studies, and medical applications (i.e. printed organs, patient-specific tissues), there is a great need for standardization of manufacturing methods in order to enable technology transfers. Despite the importance of such standardization, there is currently a tremendous lack of empirical data that examines the reproducibility and robustness of production in more than one location at a time. In this work, we present data derived from a round robin test for extrusion-based 3D printing performance comprising 12 different academic laboratories throughout Germany and analyze the respective prints using automated image analysis (IA) in three independent academic groups. The fabrication of objects from polymer solutions was standardized as much as currently possible to allow studying the comparability of results from different laboratories. This study has led to the conclusion that current standardization conditions still leave room for the intervention of operators due to missing automation of the equipment. This affects significantly the reproducibility and comparability of bioprinting experiments in multiple laboratories. Nevertheless, automated IA proved to be a suitable methodology for quality assurance as three independently developed workflows achieved similar results. Moreover, the extracted data describing geometric features showed how the function of printers affects the quality of the printed object. A significant step toward standardization of the process was made as an infrastructure for distribution of material and methods, as well as for data transfer and storage was successfully established