biomedical engineering tissue engineering scaffold

Further, the review also highlights the biomaterial scaffolds with additives. It aims to outline the history, types, properties and development methods of common biomaterials used to fabricate scaffolds. This article gives a brief introduction to the descriptions of the hierarchical structure, chemical composition of natural bone and strategies for bone tissue engineering. With the integration, intercrossing and development of the fields of medicine, biology, materials and other disciplines, biomaterials have been extensively used in the fabrication of bone tissue engineering scaffolds. Recent outstanding approaches include the addition of conductive polymers (CPs), inducerons (signaling molecules, unlike bone morphogenetic protein 2 (BMP-2)) and mechanical signals (elastic polymer networks such as hydrogels) to bone tissue engineering scaffolds. Numerous natural and synthetic polymers such as calcium phosphates, calcium carbonate, and bioactive glasses have been used to fabricate scaffolds. Due to the various needs of scaffolds, composite materials composed of two or more materials with excellent properties are widely used in bone tissue engineering. An ideal biomaterial should be non-cytotoxic, printable, biodegradable, bioactive, and osteoconductive in vivo. Ancient alternative materials are mostly bioinert (biologically inert), and these materials interact less with the surrounding tissues and are even toxic to humans. 7 Biomaterials are used for the evaluation, treatment, augmentation, repair or replacement of tissues or organs of the body. In the early 1960s, the limitations of biological bone substitute materials resulted in the emergence of a multidisciplinary field called “Biomaterials”. 6 For example, in the ancient times, the Etruscans learnt to replace damaged teeth with artificial graft obtained from the bones of oxen. Archaeological findings showed that materials such as human or animal bones and teeth, corals, shells, wood, and several metals (gold, silver and amalgam) were used for the replacement of missing human bones and teeth. The biomaterials (biomedical materials), which are basic components of scaffolds, play an important role in bone tissue engineering. Artificial bone scaffolds with biomaterials and additives, such as drugs, growth factors (GFs) and stem cells, have been useful for bone repair. An ideal scaffold should be biodegradable, biocompatible, bioactive, osteoconductive and osteoinductive. Their purpose is to mimic the structure and function of the natural bone extracellular matrix (ECM), which can provide a three-dimensional (3D) environment to promote the adhesion, proliferation, and differentiation and to have adequate physical properties for bone repair. Scaffolds play a crucial role in bone tissue engineering.

In recent years, with the rapid development of tissue engineering technology, bone tissue engineering has become a hopeful approach for repairing bone defects. 5 It is the utilization of a combination of multidisciplinary approaches to improve or replace biological tissues. The term “tissue engineering” was first used in 1987. These weaknesses limit its widespread use in clinical settings. However, the drawbacks of autologous bone grafting include secondary damages, high donor site morbidity, limitation of special shape, insufficiency of autogenous bone and so on. 3,4 Autologous bone grafting is still regarded as the “gold standard” for repairing bone defects. Large bone defects or injuries, caused by old age, traffic accident, fracture nonunion, bone tumor resection, etc., are serious problems in orthopaedics, and they bring great harms to health and the quality of life. 1,2 Although bones have a certain healing and/or regeneration capacity, it cannot be accomplished by itself for large segmental bone defects.

Bone and its associated diseases, accounting for half of chronic diseases in people over 50 years old, still remain an important clinical challenge.

Biomedical engineering tissue engineering scaffold