Chapter 7 - Polymeric nanoparticles used in tissue engineering

Repair of defects in articular joints

Chapter 3 - Emerging trends of nanobiomaterials in hard tissue engineering

The decellularized extracellular matrix in regenerative medicine.

Hard tissues and organs, including the bones, teeth and cartilage, are the most extensively exploited and rapidly developed areas in regenerative medicine field. One prominent character of hard tissues and organs is that their extracellular matrices mineralize to withstand weight and pressure. Over the last two decades, a wide variety of 3D printing technologies have been adapted to hard tissue and organ engineering. These 3D printing technologies have been defined as 3D bioprinting. Especially for hard organ regeneration, a series of new theories, strategies and protocols have been proposed. Some of the technologies have been applied in medical therapies with some successes. Each of the technologies has pros and cons in hard tissue and organ engineering. In this review, we summarize the advantages and disadvantages of the historical available innovative 3D bioprinting technologies for used as special tools for hard tissue and organ engineering.

Introduction to Tissue Engineering -- Biomaterials for cranio-maxillo-facial bone engineering -- Cells -- Physical stimulation in tissue engineering -- Growth factors -- Tissue Engineering of Composite Soft Tissue Grafts for Craniomaxillofacial Reconstruction -- Hard tissue engineering -- Vascularization in Oral and Maxillofacial Tissue Engineering -- 3-D Computer Aided Design and Manufacturing -- Safety, Efficacy and Regulation of Mesenchymal Stromal/Stem Cells -- Future perspectives - with special emphasis on extracellular vesicles.

Recently, much attention has been paid to tissue engineering and local gene delivery system in periodontal tissue regeneration. Gene-activated matrix (GAM) blends these two strategies, serving as a local bioreactor with therapeutic gene expression and providing a structural template to fill the lesion defects for cell adhesion, proliferation and synthesis of extracellular matrix (ECM). In this study, we designed a novel GAM with embedded chitosan/plasmid nanoparticles encoding platelet derived growth factor (PDGF) based on porous chitosan/collagen composite scaffold. The chitosan/collagen scaffold acted as three-dimensional carrier and chitosan nanoparticles condensed plasmid DNA. The plasmid DNA entrapped in the scaffolds showed a sustained and steady release over 6 weeks and could be effectively protected by chitosan nanoparticles. MTT assay demonstrated that periodontal ligament cells (PDLCs) cultured into the novel GAM achieved high proliferation. Luciferase reporter gene assay displayed that the novel GAM could express 1.07 x 10(4) LU/mg protein after 1 week and 8.97 x 10(3) LU/mg protein after 2 weeks. The histological results confirmed that PDLCs maintained a fibroblast figure and the periodontal connective tissue-like structure formed in the scaffolds after 2 weeks. Semi-quantitative immunohistochemical results suggested that PDGF protein expressed at a relatively high level after 2 weeks. From this study, it can be concluded that the novel GAM had potential in the application of periodontal tissue engineering.

Porous chitosan-gelatin scaffold containing plasmid DNA encoding transforming growth factor- β1 for chondrocytes proliferation

In this article, we introduce some of the more extensively evaluated technologies using concepts of tissue engineering. We report on hard tissue engineering and soft tissue engineering and their utility for dental implant therapy. For hard tissue engineering, we evaluated human recombinant bone morphogenetic protein-2 and marrow mesenchymal stem cells using a model of sinus augmentation procedure in rabbit. We also describe distraction osteogenesis as another category for hard tissue engineering. In addition, we evaluate soft tissue management using cultured epithelial grafting for soft tissue engineering. The results of our tissue regeneration materials and methods in this study are positive. When the tissue engineering materials are used in clinics in the future, implant surgery could be the leading field.

Tissue engineering: the design and fabrication of living replacement devices for surgical reconstruction and transplantation

Three-dimensional (3D) printing is a versatile technique used for various tissue-engineering applications and regenerative medicine. Tissue engineering comprises three primary components used with the aim of restoring, maintaining, or replaceing organs. Three-dimensional printing techniques have significant capability in creating three-dimensional scaffolds for tissue engineering and employing variety of biomaterials for scaffold fabrication. Three-dimensional scaffolds have an important role in cellular attachment, proliferation, nutrient transportation and vascularization. This review aims to introduce 3D printing techniques in hard-tissue engineering (bones and teeth) and soft-tissue engineering (cardiovascular system, nerves, cartilage, liver, skin and trachea) including scaffolds, applications and recent advances.

Currently, scientists are on the cutting edge of inventing many novel biomaterials from various sources for selection in tissue engineering and controlled drug delivery systems to improvise the patient surgical and treatment processes. This article focuses on the significant improvements made in the design of natural, biodegradable polymer‐based biomaterials and their applications in biomedical and tissue engineering areas. Polysaccharide and protein‐based hydrogels are suitable for soft and hard biomaterials. The soft biomaterial is made of biodegradable natural or synthetic or in a combination of both polymers that can be utilized for a stipulated time and cleared partly or whole of the system that it treats, enhance the rate of healing or replace tissues or organs. Soft biomaterials fabricated for muscle, ligament, tendon, articular cartilage tissue engineering exhibit valuable properties, such as biocompatibility, biodegradability, flexible, renewability, and cheaper. The combination of the polysaccharides and proteins with synthetic biodegradable polymers improved the mechanical strength and when added with inorganic calcium compounds could be exploited in hard tissue engineering, such as bone tissue engineering. The development of biomaterial for scaffolding in tissue engineering using polysaccharides and proteins could lead to the emergence of a new era of safer material to replace the damaged tissues in the body without suffering inflammation. Polysaccharides and proteins are consumed as food, and treating damaged tissue with food‐based biomaterial would not harm the humankind. In the near future, the development of natural polymer‐based biodegradable biomaterials by interdisciplinary and multidisciplinary research scientists is highly important.

Nanoparticles (NPs) are strong colloidal particles with diameters ranging from 1nm–100 nm. They comprise of macromolecular materials and can be utilized therapeutically as adjuvant in immunizations or as medication transporters. In this paper two fundamental sorts of nanoparticles are discussed i.e., metallic nanoparticle and polymeric nanoparticle. Metallic nanoparticle is nano-sized metals with measurements (length, width, thickness) inside the size range of 1nm - 100nm. The properties, advantages, disadvantages and characteristics of metal nanomaterials are discussed in brief in this review. Polymers are the most common materials for constructing nanoparticle-based drug carriers. Polymers used to form nanoparticles can be both synthetic and natural polymers. This review summarizes the synthesis and fabrication of nanomaterials. It describes about synthesis of metallic and polymeric nanomaterials as well as synthesis of quantum dots. It gives insights of fabrication of nanomaterials. Applications of nanomaterials are also included in this review mainly focusing on biosensor, gas sensor, wastewater treatment and environmental applications. The tunable surface and optical properties of nanomaterials make the perfect contender for biosensing including the analysis of ailments, cellular imaging of cancerous cell and so on. Gas sensors have been utilized in numerous applications like monitoring the oxygen content in fuel mixture, observing food decay, health monitoring etc. Nanomaterials offer the potential for the productive expulsion of pollutants and biological contaminants thus extremely valuable in environment and wastewater treatment. Nanomaterials are highly recommended in future for these properties, mainly for their use in healthcare sector.

The significance of three-dimensional (3D) bioprinting in the domain of regenerative medicine and tissue engineering is readily apparent. To create a multi-functional bioinspired structure, 3D bioprinting requires high-performance bioinks. Bio-inks refer to substances that encapsulate viable cells and are employed in the printing procedure to construct 3D objects progressive through successive layers. For a bio-ink to be considered high-performance, it must meet several critical criteria: printability, gelation kinetics, structural integrity, elasticity and strength, cell adhesion and differentiation, mimicking the native ECM, cell viability and proliferation. As an exemplar application, tissue grafting is used to repair and replace severely injured tissues. The primary considerations in this case include compatibility, availability, advanced surgical techniques, and potential complications after the operation. 3D printing has emerged as an advancement in 3D culture for its use as a regenerative medicine approach. Thus, additive technologies such as 3D bioprinting may offer safe, compatible, and fast-healing tissue engineering options. Multiple methods have been developed for hard and soft tissue engineering during the past few decades, however there are many limitations. Despite significant advances in 3D cell culture, 3D printing, and material creation, a gold standard strategy for designing and rebuilding bone, cartilage, skin, and other tissues has not yet been achieved. Owing to its abundance in the human body and its critical role in protecting and supporting human tissues, soft and hard collagen-based bioinks is an attractive proposition for 3D bioprinting. Collagen, offers a good combination of biocompatibility, controllability, and cell loading. Collagen made of triple helical collagen subunit is a protein-based organic polymer present in almost every extracellular matrix of tissues. Collagen-based bioinks, which create bioinspired scaffolds with multiple functionalities and uses them in various applications, is a represent a breakthrough in the regenerative medicine and biomedical engineering fields. This protein can be blended with a variety of polymers and inorganic fillers to improve the physical and biological performance of the scaffolds. To date, there has not been a comprehensive review appraising the existing literature surround the use of collagen-based bioink applications in 'soft' or 'hard' tissue applications. The uses of the target region in soft tissues include the skin, nerve, and cartilage, whereas in the hard tissues, it specifically refers to bone. For soft tissue healing, collagen-based bioinks must meet greater functional criteria, whereas hard tissue restoration requires superior mechanical qualities. Herein, we summarise collagen-based bioink's features and highlight the most essential ones for diverse healing situations. We conclude with the primary challenges and difficulties of using collagen-based bioinks and suggest future research objectives.

10 - Use of nanostructured materials in hard tissue engineering

Tissue engineering is a novel and multidisciplinary field that intends to remake functional, sound tissues and organs to supplant unhealthy or dead tissues. The advancement of tissue engineering for dental tissues is promising, and different dental soft and hard tissues have been regenerated effectively in vitro, utilizing stem cells and scaffolds. In almost any tissue engineering application, there are various challenges and unanswered inquiries that should be settled for further advancements. It is expected that in the next few decades, the field of dentistry will be altered remarkably by the accessibility of novel tissue-engineered products in the dental industry. This book chapter aims to address the advancement of tissue engineering for different dental hard and soft tissues, such as enamel, dentin, bone, periodontium, oral mucosa, and salivary glands. Additionally, challenges in the advancement of tissue engineering and future trends have been summarized in this book chapter.