Tissue engineering was defined by Vacanti and Langer as the field combining engineering and the sciences to “restore, maintain, and improve tissue function or whole organ” function [2, 3]. This is done by observation of the relationship between structure of the tissue and the function that it then performs. After, a construct can be created to mimic those functions.
1.1 Need for Tissue Engineering
The field of tissue engineering is one that is crucially in demand today. Whether the defect is caused through disease, trauma, or other causes, the need for the regeneration of tissues and organs continues to become clearer. Typically, these defects and traumas involve procedures and treatment using the gold standard donor graft such as autografts or allografts [4-6]. An autograft is a graft that is taken from another place in the same person’s body while allografts are where the graft is taken from another human (typically a donor or cadaver) .
While these grafts are useful in the performance of the intended function, there are disadvantages that can be associated. These include transmission of diseases, donor site morbidity, pain and a possible immune response. In addition to this, there is often a shortage in terms of donor organs and tissues. In terms of immune response, rejection is also probable because the body is not acclimated with the new tissue or organ [4-6]. Thus, tissue engineering aims to provide the same intended function with use of biological substitutes instead .
1.1 Hard versus Soft Tissue Engineering
When studying tissues and looking at regeneration, it is important to specify whether it is a hard or soft tissue. The hard tissues typically include bone and cartilage and are more commonly studied in tissue engineering. For bone, osteoprogenitor or stem cells will be used as a cell source and the scaffold on which they are implanted acts to facilitate key cellular activities such as migration, proliferation and differentiation [8-10]. The scaffold environment needs to be like that of the native bone . It is important for the scaffold to have an interconnected pore structure for vascularization purposes [8, 9, 11-13]. For cartilage tissue engineering, the main challenge is in regenerating the complex structure. Embryonic stem cells have been studied in this application because they are said to be “immortal” which means that they will continue to self-renew and proliferate . In terms of scaffold structure, hydrogels have been studied frequently and determined as a good material for this application. The scaffold needs
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