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Injectable Scaffolds for Bone Tissue Repair and Augmentation
Published in Naznin Sultana, Sanchita Bandyopadhyay-Ghosh, Chin Fhong Soon, Tissue Engineering Strategies for Organ Regeneration, 2020
Subrata Bandhu Ghosh, Kapender Phogat, Sanchita Bandyopadhyay-Ghosh
Bone is the primary structural and supportive connective tissue of the body which protects various organs and enable mobility. It comprises of relatively hard and lightweight composite material (Dinopoulos et al. 2012, Boskey 2007). From the material point of view, bone could be simplified as a three-phase material formed by organic phase, an inorganic nanocrystalline phase and a bone matrix (Boskey 2007, Boskey and Coleman 2010, Bigham et al. 2008). Bone has a hierarchical structure, where each level is designed to perform a range of mechanical, biological, and chemical functions (Wang et al. 2016). The hierarchical structure of bone consists of macroscale, microscale, sub-microscale, nanoscale, and sub-nanoscale (Fig. 7.1). In the macrostructure of bone, a smooth, dense, and continuous external layer forms the compact or cortical bone, while, the interior layer of bone is known as spongy or trabecular bone (Zhao 2010, Bigham et al. 2008, Dinopoulos et al. 2012). Compact bone consists of closely packed osteons or haversian systems and surrounds the medullary cavity, or bone marrow. It provides strength and protection to bones. Spongy (cancellous) bone on the other hand, is lighter and less dense than compact bone (Merolli and Leali 2012). Spongy bone consists of trabeculae, which are lamellae that are arranged as rods or plates and are adjacent to irregular cavities that contain red bone marrow. In bone, osteoblasts are bone-forming cell, osteoclasts resorb or break down bone, and osteocytes are mature bone cells. Osteoblasts produce a matrix that is eventually mineralized, or hardened, to become bone (Florencio-Silva et al. 2015, Buckwalter et al. 1996, SEER Training Modules 2019). At the micron- and nano-scales, reinforced collagen mainly consisting of aggregated type-I collagen and hydroxyapatite (HAp) form the building blocks for both compact and trabecular bones (Buckwalter et al. 1996, Dinopoulos et al. 2012, Bigham et al. 2008, Wang et al. 2016).
Transformation of acellular dermis matrix with dicalcium phosphate into 3D porous scaffold for bone regeneration
Published in Journal of Biomaterials Science, Polymer Edition, 2021
Weixu Li, Kunkun Sheng, Yongfeng Ran, Jingyi Zhang, Bo Li, Yuqing Zhu, Jiayu Chen, Qianhong He, Xin Chen, Jianwei Wang, Tao Jiang, Xiaohua Yu, Zhaoming Ye
Figure 6(B) showed the X-ray images of one representative rabbit in each group over time. At 4 weeks post implantation, opaque calcified shadows were observed in some animals of the ADM/DCP and Bongold® group, with similar calcified density, indicating a 25–50% bridging bone forming at the broken ends toward the middle of the defect; however, new bone formation was barely observed in the NC (negative control) group, and the boundaries were visible as well. Furthermore, at 8 weeks, new bone in the ADM/DCP and Bongold® group were both close to 50% of the defect, forming a good bridging tissue, while the new bone formation was still less than 25% in the NC group. Meanwhile, the fracture lines were blurred or disappeared in the ADM/DCP group and the Bongold® group, but were still clearly visible in the NC group. At 12 weeks, defects were healed the most in ADM/DCP group that achieved fine connection. The bone formation accounted for nearly 75% of the defects. The cancellous bone started to remodel to cortical bone and medullary cavity started to form. In the Bongold® group, the bone formation accounted for about 50% of the defects, and the cortical bone was not seen to be fully regenerated. In the NC group, the degree of bone remodeling was weak, half of the animals had minimal new bone formation, and the rest showed no more than 50% bone formation.
A new small-sized penguin from the late Eocene of Seymour Island with additional material of Mesetaornis polaris
Published in GFF, 2021
Piotr Jadwiszczak, Marcelo Reguero, Thomas Mörs
The micro-CT scanning revealed that the compact (cortical) and trabecular bone tissues left relatively little room for significant volumes of hollow spaces accounting for metatarsal medullary cavities (Fig. 3M–T). However, they can be observed along the distal second metatarsal, the distal two thirds of the fourth metatarsal, and, as several separate air spaces of highly diverse sizes, in the third metatarsal. The largest continuous empty volume appears to be inside the fourth metatarsal bone. The medullary cavity of the third tarsometatarsal, together with the associated trabecular bone, are characterized by a large content of some hyperdense material (Fig. 3M–P, R–T). This material has also spread into the trochlea, penetrating much of its dense spongy-bone meshwork (Fig. 3O, P, T). Trabecular bone within the proximal tarsometatarsus (the tarsal part and adjacent fragments of metatarsals) is devoid of such an infill/coating (Fig. 3O, P, Q). The tarsal/metatarsal transition zone is clearly visible (Fig. 3M, O, P).
Fabrication of cationic polymer surface through plasma polymerization and layer-by-layer assembly
Published in Materials and Manufacturing Processes, 2020
Rui Chen, Changgui Shi, Yanhai Xi, Peng Zhao, Hailong He
H&E staining was performed to evaluate the in vivo antibacterial capability of cationic polymer-coated titanium alloys after 6 weeks of implantation. A very large number of neutrophils (indicated by black arrow) between the bone and implant were observed from tibia medullary cavity for the UT sample, which suggested the severe bacterial infection (Fig. 8). For the PAA implantation, a reduced number of neutrophils were observed in the medullary cavity as compared to the UT group, which should be ascribed to the slight infiltration of bacterial infection. In sharp contrast, nearly no neutrophils were detected in the medullary cavity after LbL-10 implantation and some osteocytes (indicated by white arrow) could be observed, suggesting the effective inhibition of bacterial infection. The in vivo data indicated that the antibacterial capability of titanium alloys was significantly improved after surface cationic polymer coating, allowing for safety implantation.