Targeting Bone

Creative Biolabs has persisted for many years in the field of targeted delivery to develop the proper bone-targeted carrier and module delivery systems for mutiple usage. Scientists at Creative Biolabs have developed computational models to rapidly screen and identify bone-specific targeting module. Armed with the advanced platform and professional scientist team, Creative Biolabs has accumulated abundant experience in the successful completion of many targeted delivery projects. We provide clients customized services and products with the best quality and the most competitive prices.

The treatment of bone tumors remains to be a challenging issue due to the inefficient delivery of therapeutics to the bone and the bone microenvironment-associated tumor resistance to chemo-and radiotherapy. The leading cause of the cancer death is not the tumor in the primary site, but the one spread to other sites, despite the bone is the most common organ to be affected. Cancer-induced bone metastases often lead to substantial morbidity and mortality and patients with bone metastases generally cannot be treated curatively. Non-specific drug delivery using high-dose systemic administration may decrease the therapeutic efficacy of drugs and increase the risk of toxic effects in non-skeletal tissues. This circumstance poses a significant therapeutic challenge for bone disease treatment. Thus, targeted delivery systems are urgently needed to achieve higher drug delivery efficiency, improve therapeutic efficacy in the targeted cells/tissues, and minimize toxicities in non-targeted cells/tissues.

Fig.1 Mechanism of bone metastasis. (Adjei, 2018)

Targeting Strategy for Bone

The targeting modules could facilitate its cargoes, such as drugs or drug carriers, to the targeted tissues or cells. Therefore, the targeting moiety is one of the essential components in the targeted delivery systems. According to their targeting specificity, the targeting moieties can be classified into the following two types.

• Bone Tissue-targeting Moieties

Targeted delivery of drugs to bone pathological locations is an alternative strategy to overcome the unfavorable adverse effects. Many different bone-seeking chemicals have been identified and used in the targeted delivery system as bone targeting moieties. These chemicals can be classified into two types, biological molecules such as peptides, scaffold proteins and synthetic compounds such as bisphosphonates, tetracycline and so forth.

• Cell-specific Targeting Moieties

The skeletal systems are made up of different functional cells and ingredients. The bone tissue-targeting moieties could target the entire skeletal systems, rather than only the functional cells in bone. According to different targeted cells, the cell-specific targeting moieties in a targeted delivery system could be divided into three types: osteoclast-targeting, osteoblast-targeting, and bone marrow mesenchymal stem cell-specific moiety.

Fig.2 Targeted delivery systems carrying drugs extravasated from bone sinusoid or blood vessels to different target cells in bone. (Dang, 2016)

Application Example

To improve bone metastasis chemotherapy, a bone targeting moiety-conjugated diblock copolymer consisting of a chimeric peptide, poly (ethylene glycol) and poly (trimethylene carbonate) is fabricated as a drug carrier to ensure effective cellular uptake at the lesion sites. The chimeric peptide segment consisted of three main functional modules: the anionic Asp₈ is responsible for the direction and accumulation of particles into the skeletal tissues, the HPGGPQ serves as the CTSK-cleavable substrate and the remaining cationic residue is chemically conjugated to the PEG shell of the micelles. In this way, the combination of the targeting function of the targeting moiety and the stealth effect of the PEG shell would help the drug-loaded nano micelles prolong the circulation time and minimize the undesirable cellular uptake by healthy cells.

What Can We Do for You?

The new generation of targeting modules, such as aptamers and peptides, appeared to improve the accuracy of targeting to increase the therapeutic efficiency and reduce adverse effects to the untargeted cells. As a long-term expert in targeted delivery services, Creative Biolabs is proficient in the development of bone-targeted delivery system services and products. Our recent exploration of various targeted delivery systems for molecular therapy is worthy of your note. If you are interested in our services, please contact us for more information.

References

1. Adjei, Isaac M., et al. "Targeted nanomedicine to treat bone metastasis." Pharmaceutics 10.4 (2018): 205.
2. Dang, Lei, et al. "Targeted delivery systems for molecular therapy in skeletal disorders." International journal of molecular sciences 17.3 (2016): 428.

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