@article{TomaschMaleinerHeheretal., author = {Tomasch, Janine and Maleiner, Babette and Heher, Philipp and Rufin, Manuel and Andriotis, Orestis G. and Thurner, Philipp J. and Redl, Heinz and Fuchs, Christiane and Teuschl-Woller, Andreas H.}, title = {Changes in Elastic Moduli of Fibrin Hydrogels Within the Myogenic Range Alter Behavior of Murine C2C12 and Human C25 Myoblasts Differently}, series = {Froniers in Bioengineering and Biotechnology}, volume = {10}, journal = {Froniers in Bioengineering and Biotechnology}, pages = {836520}, abstract = {Fibrin hydrogels have proven highly suitable scaffold materials for skeletal muscle tissue engineering in the past. Certain parameters of those types of scaffolds, however, greatly affect cellular mechanobiology and therefore the myogenic outcome. The aim of this study was to identify the influence of apparent elastic properties of fibrin scaffolds in 2D and 3D on myoblasts and evaluate if those effects differ between murine and human cells. Therefore, myoblasts were cultured on fibrin-coated multiwell plates ("2D") or embedded in fibrin hydrogels ("3D") with different elastic moduli. Firstly, we established an almost linear correlation between hydrogels' fibrinogen concentrations and apparent elastic moduli in the range of 7.5 mg/ml to 30 mg/ml fibrinogen (corresponds to a range of 7.7-30.9 kPa). The effects of fibrin hydrogel elastic modulus on myoblast proliferation changed depending on culture type (2D vs 3D) with an inhibitory effect at higher fibrinogen concentrations in 3D gels and vice versa in 2D. The opposite effect was evident in differentiating myoblasts as shown by gene expression analysis of myogenesis marker genes and altered myotube morphology. Furthermore, culture in a 3D environment slowed down proliferation compared to 2D, with a significantly more pronounced effect on human myoblasts. Differentiation potential was also substantially impaired upon incorporation into 3D gels in human, but not in murine, myoblasts. With this study, we gained further insight in the influence of apparent elastic modulus and culture type on cellular behavior and myogenic outcome of skeletal muscle tissue engineering approaches. Furthermore, the results highlight the need to adapt parameters of 3D culture setups established for murine cells when applied to human cells.}, subject = {Tissue Engineering}, language = {en} } @article{DeiningerWagnerHeimeletal., author = {Deininger, Christian and Wagner, Andrea and Heimel, Patrick and Salzer, Elias and Monforte Vila, Xavier and Weißenbacher, Nadja and Grillari, Johannes and Redl, Heinz and Wichlas, Florian and Freude, Thomas and Tempfer, Herbert and Teuschl-Woller, Andreas and Traweger, Andreas}, title = {Enhanced BMP-2-Mediated Bone Repair Using an Anisotropic Silk Fibroin Scaffold Coated with Bone-like Apatite}, series = {Int. J. Mol. Sci.}, volume = {23}, journal = {Int. J. Mol. Sci.}, number = {1 / 283}, abstract = {The repair of large bone defects remains challenging and often requires graft material due to limited availability of autologous bone. In clinical settings, collagen sponges loaded with excessive amounts of bone morphogenetic protein 2 (rhBMP-2) are occasionally used for the treatment of bone non-unions, increasing the risk of adverse events. Therefore, strategies to reduce rhBMP-2 dosage are desirable. Silk scaffolds show great promise due to their favorable biocompatibility and their utility for various biofabrication methods. For this study, we generated silk scaffolds with axially aligned pores, which were subsequently treated with 10× simulated body fluid (SBF) to generate an apatitic calcium phosphate coating. Using a rat femoral critical sized defect model (CSD) we evaluated if the resulting scaffold allows the reduction of BMP-2 dosage to promote efficient bone repair by providing appropriate guidance cues. Highly porous, anisotropic silk scaffolds were produced, demonstrating good cytocompatibility in vitro and treatment with 10× SBF resulted in efficient surface coating. In vivo, the coated silk scaffolds loaded with a low dose of rhBMP-2 demonstrated significantly improved bone regeneration when compared to the unmineralized scaffold. Overall, our findings show that this simple and cost-efficient technique yields scaffolds that enhance rhBMP-2 mediated bone healing.}, subject = {Tissue Engineering}, language = {en} } @article{FarokhiAleemardaniSolouketal., author = {Farokhi, Maryam and Aleemardani, Mina and Solouk, Atefeh and Mirzadeh, Hamid and Teuschl, Andreas Herbert and Redl, Heinz}, title = {Crosslinking strategies for silk fibroin hydrogels: promising biomedical materials}, series = {Biomedical Materials}, volume = {16}, journal = {Biomedical Materials}, number = {2}, pages = {022004}, abstract = {Due to their strong biomimetic potential, silk fibroin (SF) hydrogels are impressive candidates for tissue engineering, due to their tunable mechanical properties, biocompatibility, low immunotoxicity, controllable biodegradability, and a remarkable capacity for biomaterial modification and the realization of a specific molecular structure. The fundamental chemical and physical structure of SF allows its structure to be altered using various crosslinking strategies. The established crosslinking methods enable the formation of three-dimensional (3D) networks under physiological conditions. There are different chemical and physical crosslinking mechanisms available for the generation of SF hydrogels (SFHs). These methods, either chemical or physical, change the structure of SF and improve its mechanical stability, although each method has its advantages and disadvantages. While chemical crosslinking agents guarantee the mechanical strength of SFH through the generation of covalent bonds, they could cause some toxicity, and their usage is not compatible with a cell-friendly technology. On the other hand, physical crosslinking approaches have been implemented in the absence of chemical solvents by the induction of β-sheet conformation in the SF structure. Unfortunately, it is not easy to control the shape and properties of SFHs when using this method. The current review discusses the different crosslinking mechanisms of SFH in detail, in order to support the development of engineered SFHs for biomedical applications.}, subject = {Tissue Engineering}, language = {en} } @article{BachmannSpitzSchaedletal., author = {Bachmann, Barbara and Spitz, Sarah and Sch{\"a}dl, Barbara and Teuschl, Andreas and Redl, Heinz and N{\"u}rnberger, Sylvia and Ertl, Peter}, title = {Stiffness Matters: Fine-Tuned Hydrogel Elasticity Alters Chondrogenic Redifferentiation}, series = {Froniers in Bioengineering and Biotechnology}, volume = {2020}, journal = {Froniers in Bioengineering and Biotechnology}, number = {8}, pages = {373}, abstract = {Biomechanical cues such as shear stress, stretching, compression, and matrix elasticity are vital in the establishment of next generation physiological in vitro tissue models. Matrix elasticity, for instance, is known to guide stem cell differentiation, influence healing processes and modulate extracellular matrix (ECM) deposition needed for tissue development and maintenance. To better understand the biomechanical effect of matrix elasticity on the formation of articular cartilage analogs in vitro, this study aims at assessing the redifferentiation capacity of primary human chondrocytes in three different hydrogel matrices of predefined matrix elasticities. The hydrogel elasticities were chosen to represent a broad spectrum of tissue stiffness ranging from very soft tissues with a Young's modulus of 1 kPa up to elasticities of 30 kPa, representative of the perichondral-space. In addition, the interplay of matrix elasticity and transforming growth factor beta-3 (TGF-β3) on the redifferentiation of primary human articular chondrocytes was studied by analyzing both qualitative (viability, morphology, histology) and quantitative (RT-qPCR, sGAG, DNA) parameters, crucial to the chondrotypic phenotype. Results show that fibrin hydrogels of 30 kPa Young's modulus best guide chondrocyte redifferentiation resulting in a native-like morphology as well as induces the synthesis of physiologic ECM constituents such as glycosaminoglycans (sGAG) and collagen type II. This comprehensive study sheds light onto the mechanobiological impact of matrix elasticity on formation and maintenance of articular cartilage and thus represents a major step toward meeting the need for advanced in vitro tissue models to study both re- and degeneration of articular cartilage.}, subject = {Tissue Engineering}, language = {en} } @misc{TeuschlSchuhWeihsetal., author = {Teuschl, Andreas and Schuh, Christina and Weihs, Anna and Guillaume, Olivier and Monforte Vila, Xavier and Redl, Heinz and Kaplan, David and R{\"u}nzler, Dominik}, title = {Tailoring bioactivity of silk-based biomaterials via delivering and functionalization strategies with fibrinogen/thrombin, plant lectins or laminin}, subject = {Biomaterials}, language = {en} } @article{BerkovitchCohenPeledetal., author = {Berkovitch, Yulia and Cohen, Talia and Peled, Eli and Schmidhammer, Robert and Hildner, Florian and Teuschl, Andreas and Wolbank, Susanne and Yelin, Dvir and Redl, Heinz and Seliktar, Dror}, title = {Hydrogel composition and laser micropatterning to regulate sciatic nerve regeneration.}, series = {Journal of Tissue Engineering and Regenerative Medicine}, journal = {Journal of Tissue Engineering and Regenerative Medicine}, pages = {1049 -- 1061}, abstract = {Treatment of peripheral nerve injuries has evolved over the past several decades to include the use of sophisticated new materials endowed with trophic and topographical cues that are essential for in vivo nerve fibre regeneration. In this research, we explored the use of an advanced design strategy for peripheral nerve repair, using biological and semi-synthetic hydrogels that enable controlled environmental stimuli to regenerate neurons and glial cells in a rat sciatic nerve resection model. The provisional nerve growth conduits were composed of either natural fibrin or adducts of synthetic polyethylene glycol and fibrinogen or gelatin. A photo-patterning technique was further applied to these 3D hydrogel biomaterials, in the form of laser-ablated microchannels, to provide contact guidance for unidirectional growth following sciatic nerve injury. We tested the regeneration capacity of subcritical nerve gap injuries in rats treated with photo-patterned materials and compared these with injuries treated with unpatterned hydrogels, either stiff or compliant. Among the factors tested were shear modulus, biological composition, and micropatterning of the materials. The microchannel guidance patterns, combined with appropriately matched degradation and stiffness properties of the material, proved most essential for the uniform tissue propagation during the nerve regeneration process.}, subject = {Tissue Engineering}, language = {en} } @article{BernhardFergusonRiederetal., author = {Bernhard, Jonathan and Ferguson, James and Rieder, Bernhard and Heimel, Patrick and Nau, Thomas and Tangl, Stefan and Redl, Heinz and Vunjak-Novakovic, Gordana}, title = {Tissue-engineered hypertrophic chondrocyte grafts enhanced long bone repair biomaterials}, series = {Biomaterials}, journal = {Biomaterials}, number = {139}, pages = {202 -- 212}, subject = {Grafting}, language = {en} } @article{NuernbergerSchneiderKeibletal., author = {N{\"u}rnberger, S. and Schneider, C. and Keibl, C. and Sch{\"a}dl, Barbara and Heimel, P. and Monforte, X. and Teuschl, A. H. and Nalbach, M. and Thurner, P. J. and Grillari, J. and Redl, Heinz and Wolbank, S.}, title = {Repopulation of decellularised articular cartilage by laser-based matrix engraving}, series = {EBioMedicine.}, volume = {64}, journal = {EBioMedicine.}, number = {103196.}, abstract = {Background: In spite of advances in the treatment of cartilage defects using cell and scaffold-based therapeutic strategies, the long-term outcome is still not satisfying since clinical scores decline years after treatment. Scaffold materials currently used in clinical settings have shown limitations in providing suitable biomechanical properties and an authentic and protective environment for regenerative cells. To tackle this problem, we developed a scaffold material based on decellularised human articular cartilage. Methods: Human articular cartilage matrix was engraved using a CO2 laser and treated for decellularisation and glycosaminoglycan removal. Characterisation of the resulting scaffold was performed via mechanical testing, DNA and GAG quantification and in vitro cultivation with adipose-derived stromal cells (ASC). Cell vitality, adhesion and chondrogenic differentiation were assessed. An ectopic, unloaded mouse model was used for the assessment of the in vivo performance of the scaffold in combination with ASC and human as well as bovine chondrocytes. The novel scaffold was compared to a commercial collagen type I/III scaffold. Findings: Crossed line engravings of the matrix allowed for a most regular and ubiquitous distribution of cells and chemical as well as enzymatic matrix treatment was performed to increase cell adhesion. The biomechanical characteristics of this novel scaffold that we term CartiScaff were found to be superior to those of commercially available materials. Neo-tissue was integrated excellently into the scaffold matrix and new collagen fibres were guided by the laser incisions towards a vertical alignment, a typical feature of native cartilage important for nutrition and biomechanics. In an ectopic, unloaded in vivo model, chondrocytes and mesenchymal stromal cells differentiated within the incisions despite the lack of growth factors and load, indicating a strong chondrogenic microenvironment within the scaffold incisions. Cells, most noticeably bone marrow-derived cells, were able to repopulate the empty chondrocyte lacunae inside the scaffold matrix. Interpretation: Due to the better load-bearing, its chondrogenic effect and the ability to guide matrix-deposition, CartiScaff is a promising biomaterial to accelerate rehabilitation and to improve long term clinical success of cartilage defect treatment. Funding: Austrian Research Promotion Agency FFG ("CartiScaff" \#842455), Lorenz B{\"o}hler Fonds (16/13), City of Vienna Competence Team Project Signaltissue (MA23, \#18-08). Keywords: Cartilage regeneration; Decellularisation; Ectopic animal model; Laser engraving; Mechanical testing; Repopulation.}, subject = {Tissue Engineering}, language = {en} } @article{JohannesWeihsKarneretal., author = {Johannes, Hackethal and Weihs, Anna and Karner, Lisa and Metzger, Magdalena and Dungel, Peter and Hennerbichler, Simone and Redl, Heinz and Teuschl-Woller, Andreas Herbert}, title = {Novel Human Placenta-Based Extract for Vascularization Strategies in Tissue Engineering}, series = {Tissue Eng Part C Methods}, volume = {27}, journal = {Tissue Eng Part C Methods}, number = {11}, pages = {616 -- 632}, abstract = {There is critical unmet need for new vascularized tissues to support or replace injured tissues and organs. Various synthetic and natural materials were already established for use of two-dimensional (2D) and three-dimensional (3D) in vitro neovascularization assays, however, they still cannot mimic the complex functions of the sum of the extracellular matrix (ECM) in native intact tissue. Currently, this issue is only addressed by artificial products such as Matrigel™, which comprises a complex mixture of ECM proteins, extracted from animal tumor tissue. Despite its outstanding bioactivity, the isolation from tumor tissue hinders its translation into clinical applications. Since nonhuman ECM proteins may cause immune reactions, as are frequently observed in clinical trials, human ECM proteins represent the best option when aiming for clinical applications. Here, we describe an effective method of isolating a human placenta substrate (hpS) that induces the spontaneous formation of an interconnected network of green fluorescence-labeled human umbilical vein endothelial cells (gfpHUVECs) in vitro. The substrate was biochemically characterized by using a combination of bicinchoninic acid (BCA) assay, DNA, and glycosaminoglycan (GAG) content assays, sodium dodecyl sulfate/polyacrylamide gel electrophoresis (SDS-PAGE) analysis and Western blot, angiogenesis arrays, chromatographic thrombin detection, high performance liquid chromatography (HPLC)-based amino acid quantification analysis, and assessment of antimicrobial properties. 2D in vitro cell culture experiments have been performed to determine the vasculogenic potential of hpS, which demonstrated that cell networks developed on hpS show a significantly higher degree of complexity (number of tubules/junctions; total/mean tube length) when compared with Matrigel. As 3D cell culture techniques represent a more accurate representation of the in vivo condition, the substrate was 3D solidified using various natural polymers. 3D in vitro vasculogenesis assays have been performed by seeding gfpHUVECs in an hpS-fibrinogen clot. In conclusion, hpS provides a potent human/material-based alternative to xenogenic-material-based biomaterials for vascularization strategies in tissue engineering.}, subject = {Tissue Engineering}, language = {en} }