Biofabrication of SDF-1 functionalized 3D-printed cell-free scaffolds for bone tissue regeneration
(2020)
Large segmental bone defects occurring after trauma, bone tumors, infections or revision surgeries are a challenge for surgeons. The aim of our study was to develop a new biomaterial utilizing simple and cheap 3D-printing techniques. A porous polylactide (PLA) cylinder was printed and functionalized with stromal-derived factor 1 (SDF-1) or bone morphogenetic protein 7 (BMP-7) immobilized in collagen type I. Biomechanical testing proved biomechanical stability and the scaffolds were implanted into a 6 mm critical size defect in rat femur. Bone growth was observed via x-ray and after 8 weeks, bone regeneration was analyzed with µCT and histological staining methods. Development of non-unions was detected in the control group with no implant. Implantation of PLA cylinder alone resulted in a slight but not significant osteoconductive effect, which was more pronounced in the group where the PLA cylinder was loaded with collagen type I. Addition of SDF-1 resulted in an osteoinductive effect, with stronger new bone formation. BMP-7 treatment showed the most distinct effect on bone regeneration. However, histological analyses revealed that newly formed bone in the BMP-7 group displayed a holey structure. Our results confirm the osteoinductive character of this 3D-biofabricated cell-free new biomaterial and raise new options for its application in bone tissue regeneration.
In Bone Tissue Engineering (BTE), autologous bone-regenerative cells are combined with a scaffold for large bone defect treatment (LBDT). Microporous, polylactic acid (PLA) scaffolds showed good healing results in small animals. However, transfer to large animal models is not easily achieved simply by upscaling the design. Increasing diffusion distances have a negative impact on cell survival and nutrition supply, leading to cell death and ultimately implant failure. Here, a novel scaffold architecture was designed to meet all requirements for an advanced bone substitute. Biofunctional, porous subunits in a load-bearing, compression-resistant frame structure characterize this approach. An open, macro- and microporous internal architecture (100 µm–2 mm pores) optimizes conditions for oxygen and nutrient supply to the implant’s inner areas by diffusion. A prototype was 3D-printed applying Fused Filament Fabrication using PLA. After incubation with Saos-2 (Sarcoma osteogenic) cells for 14 days, cell morphology, cell distribution, cell survival (fluorescence microscopy and LDH-based cytotoxicity assay), metabolic activity (MTT test), and osteogenic gene expression were determined. The adherent cells showed colonization properties, proliferation potential, and osteogenic differentiation. The innovative design, with its porous structure, is a promising matrix for cell settlement and proliferation. The modular design allows easy upscaling and offers a solution for LBDT.
Unermüdliche Pflanzer sind die meisten Mosi, die - gemeinsam mit den Bisa - in Tenkodogo, Verwaltungshauptstadt der Provinz Boulgou im Südosten Burkina Fasos, die Bevölkerungsmehrheit stellen. Im Zentrum ihrer agrarisch geprägten Vorstellungswelt stehen die Kulturpflanzen, vor allem die Hirsearten Sorghum bicolor und Pennisetum americanum, von deren gutem Gedeihen das Überleben in jenem Gebiet weitgehend abhängt. Diese in der täglichen Ernährung unentbehrlichen Pflanzen spielen allerdings in unseren Ausführungen keine Rolle. Wir wollen vielmehr zeigen, wonach selten oder nicht genutze Wildpflanzen, vor allem Kräuter und Gräser, ihren Namen erhielten. Ihre Taxonomie stützt sich wesentlich auf Ordnungssysteme des Alltags, basierend auf der "natürlich-sozialen" Organisation und Opposition von Drinnen und Draußen, welche durch die Gegensätze Kulturland und Busch, Nutzpflanze und Unkraut, Haustier und Wildtier, Gruppenoberhäupter und gesellschaftliche Außenseiter, Menschen und Geister repräsentiert werden.
Nos travaux dans les villages mosi de la région de Tenkodogo, au centreest du Burkina Faso, portent directement sur le thème central du Projet de Recherche de l'Université de Francfort: Les relations mutuelles entre la culture d'une population et son milieu naturel. Sur la base d'une étude approfondie de l'environnement naturel, on devrait répondre à la question suivante: comment les Hommes conçoivent et estimentils ce milieu, quelles valeurs lui attribueton; en outre, sur la base de quels principes et d'après quels critères de préférence utilisentils leurs sols en tant que cultivateurs; quelles raisons déterminent-elles l'expansion des Mosi méridionaux dans cette aire géographique, la fondation des villages ainsi que leur dévéloppement démographique. Enfin quel est l'impact de tout cela sur l'environnement naturel, c'est-à-dire quelles sont les conséquences écologiques des conceptions et comportements susmentionnés. Nos recherches sur le terrain débutèrent en 1991 sous la forme d'une collaboration interdisciplinaire étroite entre l'ethnologie, la géographie physique et la botanique. L'objectif à long terme est une comparaison entre les Mosi méridionaux, leurs voisins bisa, les Gulmance et enfin un groupe mosi du nord.