Improved Bone Delivery of Osteoprotegerin by Bisphosphonate Conjugation in a Rat Model of Osteoarthritis

Abstract

This study investigated the delivery of a model therapeutic protein, namely, osteoprotegerin (OPG), to bone sites in an animal model of osteoarthritis. The OPG was chemically conjugated to a "bone seeking" thiol-bisphosphonate (thiolBP) via a disulfide linkage. The BP conjugates of OPG were shown to display a higher hydroxyapatite affinity in vitro as compared to unmodified OPG. After intravenous injection, the bone uptake of OPG-thiolBP conjugate was increased 2-fold over that of control OPG under conditions of normal bone turnover. Furthermore, the retention of the OPG-thiolBP conjugate was significantly higher after 72 h. When administered to osteoarthritic rats undergoing active bone remodeling, the delivery of OPG-thiolBP conjugate to bone was increased more than 4-fold over that of control OPG after 24 h. These results suggest a significant advantage of BP conjugation as a drug delivery strategy for therapeutic cytokines in osteopenic bone diseases.

Bisphosphonate-modified biomaterials for drug delivery and bone tissue engineering

“…Osteoprotegerin Disulfide Prevention of bone resorption [32] Delivery of BP-modified protein was increased in osteoarthritis model Thiol-BP Salmon calcitonin Amide [33] Conjugate-induced reduction in loss of bone mineral density and bone volume in osteoporotic rats Carboxyl-BP Catalase Amide Reduce ROS in bone [34] Bone-specific anticancer activity was not clear BPpolymer…”

“…Despite that all bisphosphonated proteins showed high binding to HAP disks in vitro as compared to the control proteins, intravenous injection of only the amide-linked fetuin-BP resulted in its increased delivery to bone in rats. A significant advantage of BP conjugation for delivery to osteoarthritic bones was demonstrated with osteoprotegerin (OPG) that was linked to BP via a disulfide linkage [32]. OPG is a soluble circulating glycoprotein that interrupts receptor activator of nuclear factor kappa-B ligand--RANK intracellular signaling that is essential for osteoclast formation.…”

Synthesis, characterization and in vitro evaluation of a bone targeting delivery system for salmon Calcitonin

“…Nonetheless, our experience with BP conjugative strategies has amply demonstrated that each protein or peptide will behave differently during the conjugation process, with unique solubility, stability, and bioactivity issues (Doschak et al, 2009;Uludag et al, 2000a,b;Gittens et al, 2003). Accordingly, one "generalized" conjugation procedure will not work as a universal reaction scheme for all therapeutic peptides and proteins and individualized strategies will need to be considered and employed on a "case-by-case" basis for individual peptide or protein candidates, as previously hypothesized (Hirabayashi and Fujisaki, 2003).…”

Development of Bone-Targeted Catalase Derivatives for Inhibition of Bone Metastasis of Tumor Cells in Mice

“…13 Bisphosphonate derivatives have been used to deliver therapeutic compounds such as estradiol, diclofenac, and osteoprotegerin to bones by conjugation. [14][15][16][17] Results of these previous studies suggest that the conjugation of bisphosphonate is a promising approach for delivering catalase to the bones in individuals with bone metastasis. In this study, we conjugated bovine liver catalase with di(bisphosphonate) 3,5-di(ethylamino-2,2-bisphosphono)benzoic acid (Bip), a bisphosphonate derivative that has two bisphosphonate groups in one molecule, 18 to endow the enzyme with an affinity for bones.…”