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Regeneration: Nanomaterials for Tissue Regeneration
Published in Harry F. Tibbals, Medical Nanotechnology and Nanomedicine, 2017
Trauma or infarction in the brain causes cell death, followed by necrosis with delayed cell death in adjacent tissue and formation of a lesion cavity surrounded by glial scar tissue. Biomaterial scaffolds are being evaluated for placement into damaged areas of the brain to provide support for the surrounding tissue, to act as a substrate for cell growth, axon regeneration and neurite formation, and to promote cell infiltration into the lesion. A number of different types of scaffolding are being investigated; most provide delivery of growth-promoting factors, cells, or both to the site of injury. Neurons or stem cells may be isolated from the host and incorporated into three-dimensional scaffoldings for transplantation.
The Igaki–Tamai stent: The legacy of the work of Hideo Tamai
Published in Yoshinobu Onuma, Patrick W.J.C. Serruys, Bioresorbable Scaffolds, 2017
Soji Nishio, Kunihiko Kosuga, Eisho Kyo, Takafumi Tsuji, Masaharu Okada, Shinsaku Takeda, Yasutaka Inuzuka, Tatsuhiko Hata, Yuzo Takeuchi, Junya Seki, Shigeru Ikeguchi
The objective for developing bioresorbable scaffolds (BRSs) devices has been to overcome the limitations of permanent metallic stents [1]. Metallic stents are effective for preventing acute occlusion and late restenosis following angioplasty. As these adverse events commonly occur within 1 year, the clinical need for scaffolding is reduced after this time. Considering the need for temporary scaffolding for atherosclerotic lesions, scaffolds made of a bioresorbable material have the potential to be preferable alternatives. The essential requirements for an ideal BRSs include those having sufficient radial force with minimum radial recoil, an appropriate bioresorption period for temporary scaffolding, antithrombogenic properties, and biocompatibility, which will collectively provide both short-term and long-term safety.
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
Every year, around millions of people suffer from bone fractures or other orthopedic-related injuries resulting from a variety of surgical, degenerative, and traumatic causes (Migliaresi et al. 2007, Lee et al. 2009, Bai et al. 2018). These result in increasing medical cost of treating bone related trauma, infection, and defects (Lee et al. 2009, Vo et al. 2012, Bai et al. 2018). Current clinical treatments for bone injuries such as autografts and allografts suffer from the potential risks of disease transmission, infection, and host rejection. Besides, there are additional problems related to insufficient bone cell availability and donor site morbidity (Lee et al. 2009, Bai et al. 2018, Gómez-Barrena et al. 2015, Kumawat et al. 2019). In this regard, synthetic bone scaffolds are gaining increased attention for repairing and regenerating defective bone tissues (Rose and Oreffo 2002, Winkler et al. 2018). These prefabricated scaffolds (preformed) aim to provide structural support and create appropriate environment for cell adhesion, migration, proliferation, and differentiation, while recapitulating the functional activity of the bone defects (Simeonov et al. 2016, Ghassemi et al. 2018, Bai et al. 2018). The various types of scaffold materials commonly used for bone scaffolding are based on metallic, polymeric, ceramic, and composite materials (Bandyopadhyay-Ghosh et al. 2008). Metallic materials although, have excellent mechanical properties, they usually cause stress-shielding due to their non-similar modulus of elasticity to that of bone (Ryan et al. 2006, Alvarez and Nakajima 2009). Besides, most of the metallic scaffolds are prone to corrosion, possess poor biological recognition on the material surface and are often known to release toxic ions (Ryan et al. 2006, Alvarez and Nakajima 2009, Navarro et al. 2008). Polymeric scaffolds on the other hand are easy to shape and light in weight, with the possibility to achieve tailored properties. However, they have insufficient mechanical properties and are not bioactive (Navarro et al. 2008, Bai et al. 2018). Bioceramic scaffold materials have the advantage that they can mimic the inorganic bone composition, and are usually bioactive (Bandyopadhyay-Ghosh 2008, Bandyopadhyay-Ghosh et al. 2008, Gerhardt and Boccaccini 2010). However, due to the difficulty in casting complex shapes and their poor fracture toughness, use of bioceramics as scaffold materials is restricted. Composite scaffold materials, in this regard, can play a vital role. Development of an interconnected polymer-inorganic (ceramics, glass, glass-ceramic) composite scaffold takes advantages of both polymer and inorganics to meet mechanical and physiological requirements of the host tissue (Fernandez-Yague et al. 2015). The new generation composite scaffolds contain bioactive components, which are released from the implant providing a supply of calcium and phosphate ions or other biologically active moieties, thereby accelerating the healing process. From a biological perspective, it also makes sense to combine biopolymers and inorganics to fabricate composite scaffolds for bone tissue engineering because native bone is the combination of a naturally occurring polymer and biological apatite (Bendtsen and Wei 2015).
Intervention of 3D printing in health care: transformation for sustainable development
Published in Expert Opinion on Drug Delivery, 2021
Sujit Kumar Debnath, Monalisha Debnath, Rohit Srivastava, Abdelwahab Omri
A lot of researches are carried out in the field of tissue engineering to generate new functional tissue using live cells and scaffolding. It comprises the development of a biological substitute to whole organs or tissue transplantation. 3D painting gives a potential solution for the growing concern of patients die due to a lack of organ transplantation and a shortage of organ donors [77]. The revolution of 3D printing technology helps to replicate natural skin structures at a lower price. This skin is successfully used in the testing of pharmaceutical products like cosmetics, chemical products. Thus, this advancement prevents the unnecessary use of animal skin to evaluate any product [46]. The importance of in vivo vascularization is increasing with micro-scale geometry. Microvasculature creates a complex network that exchanges nutrients to arterioles, capillaries, and venues. Therefore, the interest is growing to promote cell viability and drug response by incorporating vasculature [79]. 3D microfluidics prepared by digital light processing, stereolithography apparatus can be transparent and easy to observe. The micro-channel prepared by these techniques is accurate and suitable for varieties of module interfaces. 3D printing serves as a useful platform to analyze the drug penetration and metabolism by allowing dynamic dosing in cell culture (spheroids). Among the 3D cell cultures, multicellular tumor spheroid is the most commonly employed spheroids. These spheroids can grow to 1 mm in diameter and demonstrate heterogeneous microregions like in-vivo tumors [80].
Risk prediction of in-stent restenosis among patients with coronary drug-eluting stents: current clinical approaches and challenges
Published in Expert Review of Cardiovascular Therapy, 2021
Atsushi Sakamoto, Yu Sato, Rika Kawakami, Anne Cornelissen, Masayuki Mori, Kenji Kawai, Raquel Fernandez, Daniela Fuller, Neel Gadhoke, Liang Guo, Maria E. Romero, Frank D. Kolodgie, Renu Virmani, Aloke V. Finn
Stent fracture (SF) is another contributor to late adverse clinical events including ISR [137,138]. SF prevents metal scaffolding support at the site and results in non-uniform local drug delivery. Non-uniform stent expansion in a highly mobile and rigid arterial lesion (e.g. severe calcification or multiple stent implantation) may eventually cause increased non-uniform strut tension and separation. The incidence of SF in clinical settings has been reported to be 0.84 to 8.4% in first generation DES [139]. However, an autopsy study from our group including 140 consecutive cases (177 lesions) showed a much greater incidence of SF (29%) in first-generation DES [140], likely due to the insensitivity of angiography for SF detection. Severe SF was associated with the incidence of adverse pathologic findings involving ISR and thrombosis. Moreover, first-generation DES usage [thick strut (140 µm) with closed-cell design], longer implant duration, and longer stent length were noted to be independent risk factors for SF, suggesting greater metal fatigue as a cause of SF [140]. More recent clinical studies revealed that the incidence of SF in second generation DES was relatively lower than for first-generation DES (1.7 to 4.1%) but was still associated with a higher incidence of major adverse cardiac events, mainly TLR or ST [141,142], suggesting SF remains one cause of ISR in second-generation DES.
Recent advances in the local antibiotics delivery systems for management of osteomyelitis
Published in Drug Delivery, 2021
Reem Khaled Wassif, Maha Elkayal, Rehab Nabil Shamma, Seham A. Elkheshen
From the researchers’ overview, to be able to create a multipurpose scaffolding materials for managing different stages of osteomyelitis, many areas has to be tackled. The most important of which is creating reliable osteomyelitis models that imitates features of osteomyelitis conditions in humans’ bones which, continues to be a challenge to scientists (Roux et al., 2021). The current animal models employed to assess the efficacy of scaffolds for elimination of infection and regeneration of bone should be fully detailed and reproducible, with well-defined gold standard for the diagnosis of osteomyelitis, there originating sources and stage of infection in order to be able to simulate the clinical scenarios (Reizner et al., 2014). Furthermore, scaffolding materials have to offer multipurpose including eradication of infections, assisting the proliferation and healing of the bone tissues besides acting as internal mechanical supports.