Strategies for Bone Regeneration: From Graft to Tissue Engineering

Abstract

Bone is a regenerative organ characterized by self-renewal ability. Indeed, it is a very dynamic tissue subjected to continuous remodeling in order to preserve its structure and function. However, in clinical practice, impaired bone healing can be observed in patients and medical intervention is needed to regenerate the tissue via the use of natural bone grafts or synthetic bone grafts. The main elements required for tissue engineering include cells, growth factors and a scaffold material to support them. Three different materials (metals, ceramics, and polymers) can be used to create a scaffold suitable for bone regeneration. Several cell types have been investigated in combination with biomaterials. In this review, we describe the options available for bone regeneration, focusing on tissue engineering strategies based on the use of different biomaterials combined with cells and growth factors.

Keywords: bio-materials; bone regeneration; mesenchymal stem cell; scaffolds; tissue engineering.

Figure 1

Representative scheme of available options for bone tissue regeneration. Natural bone grafts include autograft, allograft from human donors and xenograft from other species. Synthetic bone grafts can be obtained using metals (gray discs), ceramics (beige powder and gray microporous cylinder-shaped object) and polymers (green ribbon, green stiff cylinder-shaped hydrogel, light blue hydrogel mesh). Biomaterials can be functionalized with growth factors such as BMPs (bone morphogenetic proteins; BMP-2, BMP-7, BMP-9 here represented as blue and green circles and violet hexagon), TGFβ (transforming growth factor beta; pink hexagon), VEGF (vascular endothelial growth factor; blue ribbon) and PDGF (platelet-derived growth factor; light blue ribbon). Moreover, synthetic bone graft can be colonized by cells. The figure was created using BioRender (https://biorender.com/).