@article{EwaldFuchsBoegeleinetal.2023, author = {Ewald, Andrea and Fuchs, Andreas and Boegelein, Lasse and Grunz, Jan-Peter and Kneist, Karl and Gbureck, Uwe and Hoelscher-Doht, Stefanie}, title = {Degradation and bone-contact biocompatibility of two drillable magnesium phosphate bone cements in an in vivo rabbit bone defect model}, series = {Materials}, volume = {16}, journal = {Materials}, number = {13}, issn = {1996-1944}, doi = {10.3390/ma16134650}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-362824}, year = {2023}, abstract = {The use of bone-cement-enforced osteosynthesis is a growing topic in trauma surgery. In this context, drillability is a desirable feature for cements that can improve fracture stability, which most of the available cement systems lack. Therefore, in this study, we evaluated a resorbable and drillable magnesium-phosphate (MgP)-based cement paste considering degradation behavior and biocompatibility in vivo. Two different magnesium-phosphate-based cement (MPC) pastes with different amounts of phytic acid (IP 6) as setting retarder (MPC 22.5 and MPC 25) were implanted in an orthotopic defect model of the lateral femoral condyle of New Zealand white rabbits for 6 weeks. After explantation, their resorption behavior and material characteristics were evaluated by means of X-ray diffraction (XRD), porosimetry measurement, histological staining, peripheral quantitative computed tomography (pQCT), cone-beam computed tomography (CBCT) and biomechanical load-to-failure tests. Both cement pastes displayed comparable results in mechanical strength and resorption kinetics. Bone-contact biocompatibility was excellent without any signs of inflammation. Initial resorption and bone remodeling could be observed. MPC pastes with IP 6 as setting retardant have the potential to be a valuable alternative in distinct fracture patterns. Drillability, promising resorption potential and high mechanical strength confirm their suitability for use in clinical routine.}, language = {en} } @article{ElgheznawyOefteringEnglertetal.2023, author = {Elgheznawy, Amro and {\"O}ftering, Patricia and Englert, Maximilian and Mott, Kristina and Kaiser, Friederike and Kusch, Charly and Gbureck, Uwe and B{\"o}sl, Michael R. and Schulze, Harald and Nieswandt, Bernhard and V{\"o}gtle, Timo and Hermanns, Heike M.}, title = {Loss of zinc transporters ZIP1 and ZIP3 augments platelet reactivity in response to thrombin and accelerates thrombus formation in vivo}, series = {Frontiers in Immunology}, volume = {14}, journal = {Frontiers in Immunology}, doi = {10.3389/fimmu.2023.1197894}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-320154}, year = {2023}, abstract = {Zinc (Zn2+) is considered as important mediator of immune cell function, thrombosis and haemostasis. However, our understanding of the transport mechanisms that regulate Zn2+ homeostasis in platelets is limited. Zn2+ transporters, ZIPs and ZnTs, are widely expressed in eukaryotic cells. Using mice globally lacking ZIP1 and ZIP3 (ZIP1/3 DKO), our aim was to explore the potential role of these Zn2+ transporters in maintaining platelet Zn2+ homeostasis and in the regulation of platelet function. While ICP-MS measurements indicated unaltered overall Zn2+ concentrations in platelets of ZIP1/3 DKO mice, we observed a significantly increased content of FluoZin3-stainable free Zn2+, which, however, appears to be released less efficiently upon thrombin-stimulated platelet activation. On the functional level, ZIP1/3 DKO platelets exhibited a hyperactive response towards threshold concentrations of G protein-coupled receptor (GPCR) agonists, while immunoreceptor tyrosine-based activation motif (ITAM)-coupled receptor agonist signalling was unaffected. This resulted in enhanced platelet aggregation towards thrombin, bigger thrombus volume under flow ex vivo and faster in vivo thrombus formation in ZIP1/3 DKO mice. Molecularly, augmented GPCR responses were accompanied by enhanced Ca2+ and PKC, CamKII and ERK1/2 signalling. The current study thereby identifies ZIP1 and ZIP3 as important regulators for the maintenance of platelet Zn2+ homeostasis and function.}, language = {en} } @article{DiloksumpandeRuijterCastilhoetal.2020, author = {Diloksumpan, Paweena and de Ruijter, Myl{\`e}ne and Castilho, Miguel and Gbureck, Uwe and Vermonden, Tina and van Weeren, P Ren{\´e} and Malda, Jos and Levato, Riccardo}, title = {Combining multi-scale 3D printing technologies to engineer reinforced hydrogel-ceramic interfaces}, series = {Biofabrication}, volume = {12}, journal = {Biofabrication}, number = {2}, doi = {10.1088/1758-5090/ab69d9}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-254005}, year = {2020}, abstract = {Multi-material 3D printing technologies that resolve features at different lengths down to the microscale open new avenues for regenerative medicine, particularly in the engineering of tissue interfaces. Herein, extrusion printing of a bone-biomimetic ceramic ink and melt electrowriting (MEW) of spatially organized polymeric microfibres are integrated for the biofabrication of an osteochondral plug, with a mechanically reinforced bone-to-cartilage interface. A printable physiological temperature-setting bioceramic, based on α-tricalcium phosphate, nanohydroxyapatite and a custom-synthesized biodegradable and crosslinkable poloxamer, was developed as bone support. The mild setting reaction of the bone ink enabled us to print directly within melt electrowritten polycaprolactone meshes, preserving their micro-architecture. Ceramic-integrated MEW meshes protruded into the cartilage region of the composite plug, and were embedded with mechanically soft gelatin-based hydrogels, laden with articular cartilage chondroprogenitor cells. Such interlocking design enhanced the hydrogel-to-ceramic adhesion strength >6.5-fold, compared with non-interlocking fibre architectures, enabling structural stability during handling and surgical implantation in osteochondral defects ex vivo. Furthermore, the MEW meshes endowed the chondral compartment with compressive properties approaching those of native cartilage (20-fold reinforcement versus pristine hydrogel). The osteal and chondral compartment supported osteogenesis and cartilage matrix deposition in vitro, and the neo-synthesized cartilage matrix further contributed to the mechanical reinforcement at the ceramic-hydrogel interface. This multi-material, multi-scale 3D printing approach provides a promising strategy for engineering advanced composite constructs for the regeneration of musculoskeletal and connective tissue interfaces.}, language = {en} } @article{BruecknerMeiningerGrolletal.2019, author = {Br{\"u}ckner, Theresa and Meininger, Markus and Groll, J{\"u}rgen and K{\"u}bler, Alexander C. and Gbureck, Uwe}, title = {Magnesium Phosphate Cement as Mineral Bone Adhesive}, series = {Materials}, volume = {12}, journal = {Materials}, number = {23}, issn = {1996-1944}, doi = {10.3390/ma12233819}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-193052}, year = {2019}, abstract = {Mineral bone cements were actually not developed for their application as bone-bonding agents, but as bone void fillers. In particular, calcium phosphate cements (CPC) are considered to be unsuitable for that application, particularly under moist conditions. Here, we showed the ex vivo ability of different magnesium phosphate cements (MPC) to adhere on bovine cortical bone substrates. The cements were obtained from a mixture of farringtonite (Mg\(_3\)(PO\(_4\))\(_2\)) with different amounts of phytic acid (C\(_6\)H\(_{18}\)O\(_{24}\)P\(_6\), inositol hexaphosphate, IP6), whereas cement setting occurred by a chelation reaction between Mg\(^{2+}\) ions and IP6. We were able to show that cements with 25\% IP6 and a powder-to-liquid ratio (PLR) of 2.0 g/mL resulted in shear strengths of 0.81 ± 0.12 MPa on bone even after 7 d storage in aqueous conditions. The samples showed a mixed adhesive-cohesive failure with cement residues on the bone surface as indicated by scanning electron microscopy and energy-dispersive X-ray analysis. The presented material demonstrated appropriate bonding characteristics, which could enable a broadening of the mineral bone cements' application field to bone adhesives}, language = {en} } @article{BoehmMeiningerTeschetal.2018, author = {Boehm, Anne and Meininger, Susanne and Tesch, Annemarie and Gbureck, Uwe and M{\"u}ller, Frank A.}, title = {The mechanical properties of biocompatible apatite bone cement reinforced with chemically activated carbon fibers}, series = {Materials}, volume = {11}, journal = {Materials}, number = {2}, issn = {1996-1944}, doi = {10.3390/ma11020192}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-197808}, pages = {192}, year = {2018}, abstract = {Calcium phosphate cement (CPC) is a well-established bone replacement material in dentistry and orthopedics. CPC mimics the physicochemical properties of natural bone and therefore shows excellent in vivo behavior. However, due to their brittleness, the application of CPC implants is limited to non-load bearing areas. Generally, the fiber-reinforcement of ceramic materials enhances fracture resistance, but simultaneously reduces the strength of the composite. Combining strong C-fiber reinforcement with a hydroxyapatite to form a CPC with a chemical modification of the fiber surface allowed us to adjust the fiber-matrix interface and consequently the fracture behavior. Thus, we could demonstrate enhanced mechanical properties of CPC in terms of bending strength and work of fracture to a strain of 5\% (WOF5). Hereby, the strength increased by a factor of four from 9.2 ± 1.7 to 38.4 ± 1.7 MPa. Simultaneously, the WOF5 increased from 0.02 ± 0.004 to 2.0 ± 0.6 kJ∙m-2, when utilizing an aqua regia/CaCl2 pretreatment. The cell proliferation and activity of MG63 osteoblast-like cells as biocompatibility markers were not affected by fiber addition nor by fiber treatment. CPC reinforced with chemically activated C-fibers is a promising bone replacement material for load-bearing applications.}, language = {en} }