Nanotechnology in the targeted drug delivery for bone diseases and bone regeneration

Abstract

Nanotechnology is a vigorous research area and one of its important applications is in biomedical sciences. Among biomedical applications, targeted drug delivery is one of the most extensively studied subjects. Nanostructured particles and scaffolds have been widely studied for increasing treatment efficacy and specificity of present treatment approaches. Similarly, this technique has been used for treating bone diseases including bone regeneration. In this review, we have summarized and highlighted the recent advancement of nanostructured particles and scaffolds for the treatment of cancer bone metastasis, osteosarcoma, bone infections and inflammatory diseases, osteoarthritis, as well as for bone regeneration. Nanoparticles used to deliver deoxyribonucleic acid and ribonucleic acid molecules to specific bone sites for gene therapies are also included. The investigation of the implications of nanoparticles in bone diseases have just begun, and has already shown some promising potential. Further studies have to be conducted, aimed specifically at assessing targeted delivery and bioactive scaffolds to further improve their efficacy before they can be used clinically.

Keywords: bone diseases; bone regeneration; cancer bone metastasis; nanoparticles; nanostructured scaffold; target drug delivery.

Figure 1

Multifunctional NPs for targeted delivery to bone metastasized cancer cells. Notes: A schematic figure shows the use of a multifunctional NP to deliver anticancer reagents and gene therapy (eg, siRNA). In this scheme, the NP of a mesoporous silica NP is loaded with anticancer drugs in the pore, and the NP surface is grafted with BPs or other bone-specific markers to target bone cells or tissues. Because of the positive charge of the NP surface, it can also carry negatively charged siRNA for gene therapy. When the NP is administered, it will specifically remain at the sites of bone cells where/with which the metastasized cancer cells are closely associated. The cancer cells will be killed by the released drugs or siRNAs. Abbreviations: NP, nanoparticle; BP, bisphosphonate; siRNA, small interfering ribonucleic acid.

Figure 2

Biodegradable (polymer-based) NP-targeted local delivery in bone. Notes: A schematic diagram shows an ideal NP that can load multiple cargos, including targeting molecules that have an affinity to bone tissue or cells such as BPs, siRNA for gene therapy, and drugs for bone diseases. These kinds of NPs are better and readily biodegradable, such as polymer-based NPs or some kinds of inorganic NPs like layered double hydroxides. They can be further modified to be multifunctional NP carriers, but will not be silica based particles to increase the roughness of the interaction surface of joints for local delivery. Abbreviations: NP, nanoparticle; siRNA, small interfering ribonucleic acid; BP, bisphosphonate.

Figure 3

Porous mesoporous bioactive glass scaffolds with large pores (several hundred micrometers, left) and well-ordered mesoporous channel structures (5 nm, right).