Molecular Design of Bisphosphonate-Modified Proteins for Efficient Bone Targeting In Vivo.
To establish a rational molecular design for bisphosphonate (BP)-modified proteins for efficient bone targeting, a pharmacokinetic study was performed using a series of alendronate (ALN), a nitrogen-containing BP, modified proteins with various molecular weights and varying degrees of modification. Four proteins with different molecular weight-yeast glutathione reductase (GR; MW: 112,000 Da), bovine serum albumin (BSA; MW: 67,000 Da), recombinant human superoxide dismutase (SOD; MW: 32,000 Da), and chicken egg white lysozyme (LZM; MW: 14,000 Da)-were modified with ALN to obtain ALN-modified proteins. Pharmacokinetic analysis of the tissue distribution of the ALN-modified and unmodified proteins was performed after radiolabeling them with indium-111 (111In) by using a bifunctional chelating agent. Calculation of tissue uptake clearances revealed that the bone uptake clearances of 111In-ALN-modified proteins were proportional to the degree of ALN modification. 111In-GR-ALN and BSA-ALN, the two high-molecular-weight proteins, efficiently accumulated in bones, regardless of the degree of ALN modification. Approximately 36 and 34% of the dose, respectively, was calculated to be delivered to the bones. In contrast, the maximum amounts taken up by bone were 18 and 13% of the dose for 111In-SOD-ALN(32) and LZM-ALN(9), respectively, because of their high renal clearance. 111In-SOD modified with both polyethylene glycol (PEG) and ALN (111In-PEG-SOD-ALN) was efficiently delivered to the bone. Approximately 36% of the dose was estimated to be delivered to the bones. In an experimental bone metastasis mouse model, treatment with PEG-SOD-ALN significantly reduced the number of tumor cells in the bone of the mice. These results indicate that the combination of PEG and ALN modification is a promising approach for efficient bone targeting of proteins with a high total-body clearance.
Department of Biopharmaceutics, Kyoto Pharmaceutical University, Kyoto, Japan.
Hidemasa
H
Katsumi
Department of Biopharmaceutics, Kyoto Pharmaceutical University, Kyoto, Japan.
Jun-Ichi
J
Sano
Department of Biopharmaceutics and Drug Metabolism, Graduate School of Pharmaceutical Sciences, Kyoto University, Kyoto, Japan.
Makiya
M
Nishikawa
Department of Biopharmaceutics, Kyoto Pharmaceutical University, Kyoto, Japan.
Keiko
K
Hanzawa
Department of Biopharmaceutics, Kyoto Pharmaceutical University, Kyoto, Japan.
Toshiyasu
T
Sakane
Department of Biopharmaceutics, Kyoto Pharmaceutical University, Kyoto, Japan.
Akira
A
Yamamoto
D019386:Alendronate / Q000737:chemistry / Q000493:pharmacokinetics; D000818:Animals; D001842:Bone and Bones / Q000187:drug effects* / Q000378:metabolism; D004164:Diphosphonates / Q000737:chemistry*; D005260:Female; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D008970:Molecular Weight; D011092:Polyethylene Glycols / Q000737:chemistry; D011506:Proteins / Q000235:genetics* / Q000493:pharmacokinetics / Q000494:pharmacology*; D013482:Superoxide Dismutase / Q000737:chemistry / Q000378:metabolism; D014018:Tissue Distribution / Q000502:physiology
D004164:Diphosphonates; D011506:Proteins; D011092:Polyethylene Glycols; D013482:Superoxide Dismutase; C063471:polyethylene glycol-superoxide dismutase; D019386:Alendronate