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Orthopedic implants have faced challenges in treating bone defects due to various factors, including inadequate osseointegration, oxidative stress, bacterial infection, immunological rejection, and poor individualized treatment. These challenges profoundly affect both the results of treatment and patients' daily lives. There is great promise for the layer-by-layer (LbL) assembly method in tissue engineering. The method primarily relies on electrostatic attraction and entails the consecutive deposition of electrolyte complexes with opposite charges onto a substrate, leading to the formation of homogeneous single layers that can be quickly deposited to produce nanolayer films. LbL has attracted considerable interest as a coating technology because of its ease of production, cost-effectiveness, and capability to apply diverse biomaterial coatings without compromising the primary bio-functional properties of the substrate materials. This review will look into the fundamentals and evolution of LbL in orthopedics, provide an analysis of the chemical strategy used to prepare bone implants with LbL and introduce the application of LbL bone implants in orthopedics over recent years. Among the many potential uses of LbL, such as the implementation of sustained-release and programmed drug delivery, which in turn promotes the osseointegration and the development of new blood vessels, as well as antibacterial, antioxidant, and other similar applications. In addition, we offer a thorough examination of cell behavior and biomaterial interaction to facilitate the advancement of next-generation LbL films for tissue engineering. [ABSTRACT FROM AUTHOR]

Bone defects pose significant challenges in healthcare, with over 2 million bone repair surgeries performed globally each year. As a burgeoning force in the field of bone tissue engineering, 3D printing offers novel solutions to traditional bone transplantation procedures. However, current 3D-printed bone scaffolds still face three critical challenges in material selection, printing methods, cellular self-organization and co-culture, significantly impeding their clinical application. In this comprehensive review, we delve into the performance criteria that ideal bone scaffolds should possess, with a particular focus on the three core challenges faced by 3D printing technology during clinical translation. We summarize the latest advancements in non-traditional materials and advanced printing techniques, emphasizing the importance of integrating organ-like technologies with bioprinting. This combined approach enables more precise simulation of natural tissue structure and function. Our aim in writing this review is to propose effective strategies to address these challenges and promote the clinical translation of 3D-printed scaffolds for bone defect treatment. [ABSTRACT FROM AUTHOR]

Background: Mesenchymal stem cells (MSCs) can be differentiated into an osteoblastic lineage in the presence of growth factors (GFs). Platelet-rich plasma (PRP), which can be easily isolated from whole blood, contains a large amount of GFs, and, therefore, promotes bone growth and regeneration. The main goal of this work was to develop and investigate the effect of a new sandwich-like bone scaffold which combines a nano-calcium sulfate (nCS) disc along with PRP fibrin gel (nCS/PRP) with BMP2-modified MSCs on bone repair and regeneration in rat critical-sized calvarial defects. Methods: We evaluated the cytotoxicity, osteogenic differentiation and mineralization effect of PRP extract on BMP2-modified MSCs and constructed a sandwich-like nCS/PRP scaffold (mimicking the nano-calcium matrix of bone and carrying multi GFs in the PRP) containing BMP2-modified MSCs. The capacity of this multifunctional bone regeneration system in promoting bone repair was assessed in vivo in a rat critical-sized (8 mm) calvarial bone defect model. Results: We developed an optimized nCS/PRP sandwich-like scaffold. Scanning electron microscopy (SEM) results showed that nCS/PRP are polyporous with an average pore diameter of 70-80 µm and the cells can survive in the nCS/PRP scaffold. PRP extract dramatically stimulated proliferation and differentiation of BMP2-modified MSCs in vitro. Our in vivo results showed that the combination of BMP2-modified MSCs and nCS/PRP scaffold dramatically increased new bone regeneration compared with the groups without PRP and/or BMP2. Conclusions: nCS/PRP scaffolds containing BMP2-modified MSCs successfully promotes bone regeneration in critical-sized bone defects. This system could ultimately enable clinicians to better reconstruct the craniofacial bone and avoid donor site morbidity for critical-sized bone defects. [ABSTRACT FROM AUTHOR]

Background: Mesenchymal stem cells (MSCs) can be differentiated into an osteoblastic lineage in the presence of growth factors (GFs). Platelet-rich plasma (PRP), which can be easily isolated from whole blood, contains a large amount of GFs, and, therefore, promotes bone growth and regeneration. The main goal of this work was to develop and investigate the effect of a new sandwich-like bone scaffold which combines a nano-calcium sulfate (nCS) disc along with PRP fibrin gel (nCS/PRP) with BMP2-modified MSCs on bone repair and regeneration in rat critical-sized calvarial defects., Methods: We evaluated the cytotoxicity, osteogenic differentiation and mineralization effect of PRP extract on BMP2-modified MSCs and constructed a sandwich-like nCS/PRP scaffold (mimicking the nano-calcium matrix of bone and carrying multi GFs in the PRP) containing BMP2-modified MSCs. The capacity of this multifunctional bone regeneration system in promoting bone repair was assessed in vivo in a rat critical-sized (8 mm) calvarial bone defect model., Results: We developed an optimized nCS/PRP sandwich-like scaffold. Scanning electron microscopy (SEM) results showed that nCS/PRP are polyporous with an average pore diameter of 70-80 μm and the cells can survive in the nCS/PRP scaffold. PRP extract dramatically stimulated proliferation and differentiation of BMP2-modified MSCs in vitro. Our in vivo results showed that the combination of BMP2-modified MSCs and nCS/PRP scaffold dramatically increased new bone regeneration compared with the groups without PRP and/or BMP2., Conclusions: nCS/PRP scaffolds containing BMP2-modified MSCs successfully promotes bone regeneration in critical-sized bone defects. This system could ultimately enable clinicians to better reconstruct the craniofacial bone and avoid donor site morbidity for critical-sized bone defects.