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Introduction
Published in Xiaolu Zhu, Zheng Wang, Self-Organized 3D Tissue Patterns, 2022
The strategy of tissue grafting and cell implantation could work for skin and cartilage because these tissues have a relative simpler inner microstructure and function mechanism. They do not require extensive vascularization and other significant tissue processes. Directly performing the tissue grafting from the autologous donor site is still facing the short supply of autologous donor tissue. Moreover, the skin substitutes also may lack native skin appendages and innate cell types, including sweat glands, sebaceous glands, and melanocytes, as well as langerhans or dendritic cells [4, 48]. The cell implantation-based method could alleviate the short supply of autologous donor tissue, because the cells could be significantly expanded in vitro before implantation. Yet, the cell implantation site would require the suitable clinical operation that still needs to be more standardized, and the patient-specific and cartilage defectspecific factors should be comprehensively considered. Sometimes, there will be chondrocyte leakage without the retention by an artificial scaffold, providing a uneven chondrocyte distribution, and it consequently results in graft hypertrophy [6, 7]. Nevertheless, largescale cohort studies are needed to be further investigated to develop rational methodology, aiming at advancing the consistency and longterm effectiveness of cartilage repairs.
Biomaterials and Immune Response in Periodontics
Published in Nihal Engin Vrana, Biomaterials and Immune Response, 2018
Sivaraman Prakasam, Praveen Gajendrareddy, Christopher Louie, Clarence Lee, Luiz E. Bertassoni
Resorbable membranes have been obtained from various sources, including12 autologous sources, allogeneic sources, xenogeneic sources and synthetic materials.13 The source from which the resorbable membrane is obtained determines the immunogenic potential. Autologous membranes, for example autologous palatal tissue, do not elicit any adverse immunological responses. Most allograft membranes, for example dermal allografts, are decellularised and have just the extracellular matrix, and they do not create any adverse reactions. Xenogeneic grafts, while having the theoretical potential of eliciting an immune response, generally do not elicit adverse immunological responses. This is primarily because, similar to allografts, these grafts are decellularised and, for the majority of these membranes, the collagen from the extracellular matrix is biochemically extracted and reconstituted as a membrane, thus significantly reducing immunogenicity. Alloplasts or synthetic membranes are designed with materials that are biocompatible and are selected for low immunogenicity. Thus, most resorbable membranes do not elicit a significant adverse immunological response. In fact, they take advantage of the inflammatory process for optimal function. Some membranes even possess the capability to reduce adverse inflammation by virtue of proteins embedded in their matrix.
Applications of extrusion bioprinting
Published in Ali Khademhosseini, Gulden Camci-Unal, 3D Bioprinting in Regenerative Engineering, 2018
G. Forgacs, F. Marga, K. Jakab
Expeditious reconstruction of damaged organs could be life saving in multiple scenarios, such as a traffic accident, battlefield injury, or burn wound. A bioprinter in the operating room could respond to such demands. The replacement tissue or organ structure could be prepared on the spot using autologous, allogeneic, or even xenogeneic cells if needed and could be immediately implanted into the patient for maturation, given that the body is the ideal bioreactor. Cubo and colleagues have recently used bioprinting to build functional human skin (Cubo et al., 2016). Setting up a similar process in surgical unit could be anticipated. Similarly, scientists at the Wake Forest University Institute of Regenerative Medicine have announced in February 2017 the printing of cells directly onto burn wounds (http://www.designindaba.com/articles/creative-work/3d-printing-skin-cells-directly-burn-wounds).
Bioinks—materials used in printing cells in designed 3D forms
Published in Journal of Biomaterials Science, Polymer Edition, 2021
Dilara Goksu Tamay, Nesrin Hasirci
Cell-based bioinks contain only cell aggregates without any polymeric support. Some scientists believe that the presence of a carrier affects the cell morphology, changes the cell-cell interaction and communication, and therefore does not reflect the real reactions taking place in the natural tissue. Studies on 3D printing of cell aggregates in predefined organization similar to the natural tissue are in process [191,192]. Although formation of 3D complex geometry is still challenging, printing of different live cells became possible. Formation of tissue mimics or organoids similar to the natural ones is expected with the growth of the cell groups. In the cases where the cells, such as adult mesenchymal stem cells or induced pluripotent stem cells derived from the patient are used, it would be possible to structure a fully autologous construct.