Nanotechnology in bone tissue engineering

Abstract

Nanotechnology represents a major frontier with potential to significantly advance the field of bone tissue engineering. Current limitations in regenerative strategies include impaired cellular proliferation and differentiation, insufficient mechanical strength of scaffolds, and inadequate production of extrinsic factors necessary for efficient osteogenesis. Here we review several major areas of research in nanotechnology with potential implications in bone regeneration: 1) nanoparticle-based methods for delivery of bioactive molecules, growth factors, and genetic material, 2) nanoparticle-mediated cell labeling and targeting, and 3) nano-based scaffold construction and modification to enhance physicochemical interactions, biocompatibility, mechanical stability, and cellular attachment/survival. As these technologies continue to evolve, ultimate translation to the clinical environment may allow for improved therapeutic outcomes in patients with large bone deficits and osteodegenerative diseases.

From the clinical editor: Traditionally, the reconstruction of bony defects has relied on the use of bone grafts. With advances in nanotechnology, there has been significant development of synthetic biomaterials. In this article, the authors provided a comprehensive review on current research in nanoparticle-based therapies for bone tissue engineering, which should be useful reading for clinicians as well as researchers in this field.

Keywords: Bone; Nanoparticle; Nanotechnology; Osteogenesis; SPIONs; Scaffold.

Figure 1

Nanoparticle-based strategies to promote bone regeneration. Nanoparticles may be classified as either degradable (poly(l-lactide) (PLA), poly(l-lactide-co-glycolic) (PLGA), collagen, fibrin) or non-degradable (hydroxyapatite (HA), gold, dendrimer, silica), each with their own range of benefits and drawbacks. Loading of drugs, growth, factors, or genes can be employed to enhance bone formation at sites of pathology and fracture.

Figure 2

Nanoparticle-mediated stem cell labeling/targeting. A variety of nanoparticles including quantum dots, mesoporous silica, gold, and SPIONs have been used to tag cells, with uptake through clathrin- or caveolae-mediated endocytosis and macropinocytosis. In addition to MRI-based tracking, nanoparticles may be used to chaperon cells to desired sites through magnet- and antibody-based targeting.

Figure 3

Nano-based scaffold construction and modification. The material used for construction of a scaffold impacts many aspects of bone tissue engineering including cell survival, attachment, differentiation, and integration. Following construction, modification of scaffold surface topography to improve the physicochemical interaction between implanted materials and the native in vivo environment allows for enhancement of mechanical stability, biocompatibility, and cellular survival of implanted constructs. For example, metallic nanoparticles have also been incorporated into scaffolds to increase mechanical strength, cellular adhesion, and bone forming capacity.