Cell-Based Bone Tissue Engineering

T o restore skeleton function in the fi eld of orthopaedic and oral-maxillofacial surgery, bone tissue regeneration remains an important challenge. Spinal fusion, augmentation of fracture healing, and reconstruction of bone defects resulting from trauma, tumour, infections, biochemical disorders, or abnormal skeletal development are clinical situations in which surgical intervention is required. The types of graft materials available to treat such problems essentially include autologous bone (from the patient), allogeneic bone (from a donor), and demineralised bone matrices, as well as a wide range of synthetic biomaterials such as metals, ceramics, polymers, and composites. Until recently, the use of autologous bone grafts has been the number one choice for bone repair and regeneration [1–5]. A patient's own bone lacks immunogenicity and provides bone-forming cells, which are directly delivered at the implant site. Moreover, autologous bone grafts recruit mesenchymal cells and induce them to differentiate into osteogenic cells through exposure to osteoinductive growth factors [1,3,6,7]. Although there are many advantages to using autologous bone, there are major drawbacks to the harvesting procedure, and for centuries there has been a search for alternatives. The extra surgery involved in harvesting autologous bone causes morbidity at the donor site [1,3,6,8] and can cause post-operative continuous pain [3,9–11], hypersensitivity [3], pelvic instability [10–12], infection [6,9], and paresthesia [3,6]. These complications affect 10% to 30% of the patients [9]. Moreover, the amount of bone that can be collected is limited. As an alternative, the use of allografts (from human to human) eliminates the harvesting procedure and the quantity of available tissue is no longer an issue. Nevertheless, the quality of allografts is worse than that of autologous grafts. Allografts have a poor degree of cellularity, less revascularisation, and a higher resorption rate compared to autologous grafts [3,6], resulting in a slower rate of new bone tissue formation, as observed in several studies [11,13–15]. In addition, the immunogenic potential of these allografts and the risks of virus transmission to the recipient are serious disadvantages [2,14,16]. Although processing techniques such as demineralisation, freeze-drying, and irradiation have been shown to reduce the patient's immune response, processing also alters the structure of the graft and reduces its potential to induce bone healing (osteoinductivity), while the possibility of disease transmission still remains [3]. To overcome the drawbacks of the current bone graft materials, bone tissue engineering (BTE) using bone marrow stem cells has been suggested as a promising technique for reconstructing …