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Functional 3D Tissue Engineering Scaffolds
The practice of medicine is an ever-growing arena of scientific intrigue, and a demanding one, as a growing population requires newer solutions that can address each individual’s specific problem. Tissue engineering is one such field that is working to meet these demands, but also aims to improve upon its treatment in the form of restoring quality of life. Through the development of a wide variety of biocompatible materials, the creation of specially designed structures called tissue engineering scaffolds has arrived for the purpose of regenerating a tissue or organ. This technology is already in use by today’s medical practitioners, and as this technology continues to evolve, there will be an increase in demand for this “gold standard” form of treatment, as it will do more than support the injured and afflicted, it will make them whole again.
The research dedicated to the creation and observation of tissue engineering scaffolds is incredibly vast and the authors of this book have formatted that collective knowledge into an educational tool. For tissue engineering scaffolds in the developmental stage, there are three things to consider about the nature of the scaffold: the biomaterial(s) being used, the techniques used to fabricate, and the target tissue. Biomaterials used for developing the tissue engineering scaffolds can fall into either natural, derived from flora or fauna, or synthetic polymers (i.e., polymers that were created in a laboratory environment). A polymer from either one of these two categories can have a wide array of strengths and weaknesses, thus making it important to consider the nature of the tissue being investigated, and the best polymer to use. A natural polymer may be easily acquired and have natural bioactivity, but a synthetic polymer could be more effective as its properties may be more easily adjusted for its intended role. After the polymer has been chosen, a method(s) of technological fabrication must be considered from the following: melt molding, phase separation, gas foaming, freeze drying, textile, 3D printing, extrusion based, and all of their varying derivatives. Each one of the aforementioned methods affects the scaffold fabrication process differently, and each one must be researched and carefully considered before any attempt is made. All of this information must be evaluated and understood as the best means of regenerating the target tissue; whether it be muscle, cardiovascular, skin, tendon, cartilage, dental, and others. From there comes the testing of the positive and negative bioactivity of not only the interaction between the scaffold and the tissue, but the bioactivity of the immune response it may provoke. All of these tissues have different attributes that will require the scaffolds to have a specific degree of porosity, tensile strength, degradation rate, and positive bioactivity to create a favorable environment for cells of that specific tissue type.
Tissue engineering scaffolds have more than just the biological aspect to contend with; the engineering part of the scaffold takes physical consideration as well. The physical design of a scaffold must fit its intended role; this means that a scaffold could be porous or solid, with a mix between elastic and tensile properties. An organ such as the esophagus, for example, would require a scaffold to be solid throughout so as to prevent leakage of water or food bolus into surrounding tissues with a mix of elastic and tensile properties to accommodate for the stretching of the organ. Whereas cancellous bone (spongy bone) tissue would require a scaffold to have a good degree of porosity for blood vessels and high tensile strength to endure the mechanical loads. For the surface of the material that will be interacting with the cells there is the question of its surface energy, surface topography, and the swelling of the scaffold. The scaffold’s level of surface energy (hydrophilicity versus hydrophobicity), will play an important role in how cells and the surrounding fluids will be able to spread and interact along the surface. Surface topography (i.e., the level of how rough a surface is), can have a significant effect on a cell’s adhesion properties. In such an aqueous environment, the fluids will invade the scaffold to supply it with water, nutrients, and other factors for cellular survival, with the invading fluid also changing the porosity, pore size, and other physical aspects. These factors are always considered, and tested before, during, and after interacting with living tissues to promote the “golden standard” that tissue engineering scaffolds have to offer.
For a tissue engineering scaffold to be considered ideal it has to be able to do the following: (1) be biocompatible with the target tissue with little to no detrimental effect to the surrounding tissues; (2) sustain itself and the newly-grown tissue from a wide variety of mechanical and chemical forces; (3) promote tissue regeneration at the same rate as material degradation; (4) have the interconnected pores of the scaffolds architecture allow for cells to enter and establish a means for those cells to receive nutrients and remove waste, while the fabrication process must offer an economically effective means of development, with a method of cleaning and sanitization. Confirming the integration or rejection of the tissue engineering scaffold at either the in vitro or in vivo stage can be done through a wide variety of quantitative or qualitative tests that are detailed within this book, with some aimed at specific tissues.
This book offers comprehensive knowledge of tissue engineering scaffolds that has been collected over decades of research and study, condensed into a useful tool. All of the polymers available as biomaterials, the crafting technologies used to shape them, and the wide variety of tissues that these scaffolds can influence are located within these pages, with the success of the tissue engineering scaffolds in full detail. This book was written at a level to be easily understandable and digestible at the undergraduate to graduate level, with the first chapters discussing the consideration and fabrications of tissue engineering scaffolds before transitioning to research in specific tissues. The audience for this book is the academic professor, career researcher, graduate and undergraduate student, and the curious alike. For this book shall offer use as a reference, an inspiration, a source of knowledge, and as the first stepping stone for those that choose this path.
- Provides a self-contained work for the field of biomaterials and tissue engineering
- Discusses all the requirements a scaffold must meet and a wide range of strategies to create them
- Highlights significant and successful applications of functional 3D scaffolds
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