Bioinspired Nanomaterials for Bone Tissue Engineering

The loss or failure of an organ or tissue is one of the most frequent, devastating, and costly problems in human health care [1, 2]. Existing approaches to repair or replace damaged bone have focused on bone grafting techniques; however, they are limited by supply problems, disease transmission, immune responses, and cost [3]. The need for high-quality bone graft substitutes has resulted in research focusing on tissue engineering using biomaterials to provide alternatives to support bone regeneration [4, 5]. Tissue engineering typically utilizes suitable biomaterials to prepare a scaffold support that is implanted and subsequently facilitates remodeling of the defect site. However, the regeneration of natural bone tissue is a complex, coordinated temporal process involving molecular, cellular, biochemical, and mechanical cues [6]. Most biomaterials alone cannot match the efcacy of bone grafts because they lack both the osteogenic cells and osteoinductive proteins that make autograft bone so advantageous [7, 8]. In the pursuit of a clinically effective alternative to bone grafting, current state of the art envisages the use of tissue-engineered constructs that play a more active role in the regenerative process [9]. Different approaches are being explored including using biomaterials that act as mimetics of the extracellular matrix (ECM), to design multifunctional constructs that combine stem or progenitor cells to support osteogenesis, facilitate the spatial and temporal presentation of signaling molecules including growth factors (GFs) to promote osteoinduction, respond to environmental stimuli, and support revascularization of the de novo tissue [3, 10-12]. Alternatively, another promising approach-focusing on the implantation of acellular scaffolds to recruit cells into the substrate and stimulate tissue development, circumventing the need to culture and expand cell-seeded scaffolds ex vivo prior to implantation [13].