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Farrell KB, Karpeisky A, Thamm DH, Zinnen S. Bisphosphonate conjugation for bone specific drug targeting. Bone Rep 2018; 9:47-60. [PMID: 29992180 PMCID: PMC6037665 DOI: 10.1016/j.bonr.2018.06.007] [Citation(s) in RCA: 105] [Impact Index Per Article: 17.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/21/2017] [Revised: 06/28/2018] [Accepted: 06/29/2018] [Indexed: 12/26/2022] Open
Abstract
Bones provide essential functions and are sites of unique biochemistry and specialized cells, but can also be sites of disease. The treatment of bone disorders and neoplasia has presented difficulties in the past, and improved delivery of drugs to bone remains an important goal for achieving effective treatments. Drug targeting strategies have improved drug localization to bone by taking advantage of the high mineral concentration unique to the bone hydroxyapatite matrix, as well as tissue-specific cell types. The bisphosphonate molecule class binds specifically to hydroxyapatite and inhibits osteoclast resorption of bone, providing direct treatment for degenerative bone disorders, and as emerging evidence suggests, cancer. These bone-binding molecules also provide the opportunity to deliver other drugs specifically to bone by bisphosphonate conjugation. Bisphosphonate bone-targeted therapies have been successful in treatment of osteoporosis, primary and metastatic neoplasms of the bone, and other bone disorders, as well as refining bone imaging. In this review, we focus upon the use of bisphosphonate conjugates with antineoplastic agents, and overview bisphosphonate based imaging agents, nanoparticles, and other drugs. We also discuss linker design potential and the current state of bisphosphonate conjugate research progress. Ongoing investigations continue to expand the possibilities for bone-targeted therapeutics and for extending their reach into clinical practice.
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Affiliation(s)
- Kristen B Farrell
- MBC Pharma Inc., 12635 East Montview Blvd., Aurora, CO 80045-0100, United States of America
| | - Alexander Karpeisky
- MBC Pharma Inc., 12635 East Montview Blvd., Aurora, CO 80045-0100, United States of America
| | - Douglas H Thamm
- Flint Animal Cancer Center, Colorado State University, 300 West Drake Road, Fort Collins, CO 80523-1620, United States of America
| | - Shawn Zinnen
- MBC Pharma Inc., 12635 East Montview Blvd., Aurora, CO 80045-0100, United States of America
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2
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Newman MR, Russell SG, Schmitt CS, Marozas IA, Sheu TJ, Puzas JE, Benoit DSW. Multivalent Presentation of Peptide Targeting Groups Alters Polymer Biodistribution to Target Tissues. Biomacromolecules 2017; 19:71-84. [PMID: 29227674 DOI: 10.1021/acs.biomac.7b01193] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Drug delivery to bone is challenging, whereby drug distribution is commonly <1% of injected dose, despite development of several bone-targeted drug delivery systems specific to hydroxyapatite. These bone-targeted drug delivery systems still suffer from poor target cell localization within bone, as at any given time overall bone volume is far greater than acutely remodeling bone volume, which harbors relevant cell targets (osteoclasts or osteoblasts). Thus, there exists a need to target bone-acting drugs specifically to sites of bone remodeling. To address this need, this study synthesized oligo(ethylene glycol) copolymers based on a peptide with high affinity to tartrate-resistant acid phosphatase (TRAP), an enzyme deposited by osteoclasts during the bone resorption phase of bone remodeling, which provides greater specificity relevant for bone cell drugging. Gradient and random peptide orientations, as well as polymer molecular weights, were investigated. TRAP-targeted, high molecular weight (Mn) random copolymers exhibited superior accumulation in remodeling bone, where fracture accumulation was observed for at least 1 week and accounted for 14% of tissue distribution. Intermediate and low Mn random copolymer accumulation was lower, indicating residence time depends on Mn. High Mn gradient polymers were cleared, with only 2% persisting at fractures after 1 week, suggesting TRAP binding depends on peptide density. Peptide density and Mn are easily modified in this versatile targeting platform, which can be applied to a range of bone drug delivery applications.
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Affiliation(s)
- Maureen R Newman
- Biomedical Engineering and ‡Chemical Engineering, University of Rochester , Rochester, New York 14627, United States.,Center for Musculoskeletal Research, ∥Department of Orthopaedics, ¶Center for Oral Biology, and ⊥Department of Biomedical Genetics, University of Rochester Medical Center , Rochester, New York 14642, United States
| | - Steven G Russell
- Biomedical Engineering and ‡Chemical Engineering, University of Rochester , Rochester, New York 14627, United States.,Center for Musculoskeletal Research, ∥Department of Orthopaedics, ¶Center for Oral Biology, and ⊥Department of Biomedical Genetics, University of Rochester Medical Center , Rochester, New York 14642, United States
| | - Christopher S Schmitt
- Biomedical Engineering and ‡Chemical Engineering, University of Rochester , Rochester, New York 14627, United States.,Center for Musculoskeletal Research, ∥Department of Orthopaedics, ¶Center for Oral Biology, and ⊥Department of Biomedical Genetics, University of Rochester Medical Center , Rochester, New York 14642, United States
| | - Ian A Marozas
- Biomedical Engineering and ‡Chemical Engineering, University of Rochester , Rochester, New York 14627, United States.,Center for Musculoskeletal Research, ∥Department of Orthopaedics, ¶Center for Oral Biology, and ⊥Department of Biomedical Genetics, University of Rochester Medical Center , Rochester, New York 14642, United States
| | - Tzong-Jen Sheu
- Biomedical Engineering and ‡Chemical Engineering, University of Rochester , Rochester, New York 14627, United States.,Center for Musculoskeletal Research, ∥Department of Orthopaedics, ¶Center for Oral Biology, and ⊥Department of Biomedical Genetics, University of Rochester Medical Center , Rochester, New York 14642, United States
| | - J Edward Puzas
- Biomedical Engineering and ‡Chemical Engineering, University of Rochester , Rochester, New York 14627, United States.,Center for Musculoskeletal Research, ∥Department of Orthopaedics, ¶Center for Oral Biology, and ⊥Department of Biomedical Genetics, University of Rochester Medical Center , Rochester, New York 14642, United States
| | - Danielle S W Benoit
- Biomedical Engineering and ‡Chemical Engineering, University of Rochester , Rochester, New York 14627, United States.,Center for Musculoskeletal Research, ∥Department of Orthopaedics, ¶Center for Oral Biology, and ⊥Department of Biomedical Genetics, University of Rochester Medical Center , Rochester, New York 14642, United States
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Nadar RA, Margiotta N, Iafisco M, van den Beucken JJJP, Boerman OC, Leeuwenburgh SCG. Bisphosphonate-Functionalized Imaging Agents, Anti-Tumor Agents and Nanocarriers for Treatment of Bone Cancer. Adv Healthc Mater 2017; 6. [PMID: 28207199 DOI: 10.1002/adhm.201601119] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2016] [Revised: 11/23/2016] [Indexed: 12/14/2022]
Abstract
Bone metastases result from the invasion of primary tumors to bone. Current treatment modalities include local treatments such as surgery and radiotherapy, while systemic treatments include chemotherapy and (palliative) treatment of skeletal metastases. Nevertheless, once bone metastases have been established they remain incurable leading to morbidity and mortality. Bisphosphonates are a well-established class of drugs, which are increasingly applied in the treatment of bone cancers owing to their effective inhibition of tumor cells and suppression of bone metastases. The increased understanding of the mechanism of action of bisphosphonates on bone and tumor cells has prompted the development of novel bisphosphonate-functionalized imaging and therapeutic agents. This review provides an update on the preclinical efficacy of bisphosphonate-functionalized fluorophore, anti-tumor agents and nanocarriers for the treatment of bone metastases. After an overview of the general characteristics of bisphosphonates and their mechanisms of action, an outline is provided on the various conjugation strategies that have become available to functionalize imaging agents, anti-tumor agents and nanocarriers with bisphosphonates. Finally, the efficacy of these bisphosphonate-modified agents and carriers in preclinical studies is evaluated by reviewing their potential to target tumors and inhibit tumor growth in clinically relevant animal models for the treatment of bone cancer.
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Affiliation(s)
- Robin A. Nadar
- Department of Biomaterials; Radboud University Medical Center; Philips van Leydenlaan 25 6525 EX Nijmegen The Netherlands
| | - Nicola Margiotta
- Dipartimento di Chimica; Università degli Studi di Bari Aldo Moro; Via E. Orabona 4 70125 Bari Italy
| | - Michele Iafisco
- Institute of Science and Technology for Ceramics (ISTEC); National Research Council (CNR); Via Granarolo 64 48018 Faenza Italy
| | | | - Otto C. Boerman
- Department of Nuclear Medicine; Radboud University Medical Center; Geert Grooteplein Zuid 10 6525 AG Nijmegen The Netherlands
| | - Sander C. G. Leeuwenburgh
- Department of Biomaterials; Radboud University Medical Center; Philips van Leydenlaan 25 6525 EX Nijmegen The Netherlands
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4
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Cole LE, Vargo-Gogola T, Roeder RK. Targeted delivery to bone and mineral deposits using bisphosphonate ligands. Adv Drug Deliv Rev 2016; 99:12-27. [PMID: 26482186 DOI: 10.1016/j.addr.2015.10.005] [Citation(s) in RCA: 125] [Impact Index Per Article: 15.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2015] [Revised: 10/01/2015] [Accepted: 10/09/2015] [Indexed: 01/07/2023]
Abstract
The high concentration of mineral present in bone and pathological calcifications is unique compared with all other tissues and thus provides opportunity for targeted delivery of pharmaceutical drugs, including radiosensitizers and imaging probes. Targeted delivery enables accumulation of a high local dose of a therapeutic or imaging contrast agent to diseased bone or pathological calcifications. Bisphosphonates (BPs) are the most widely utilized bone-targeting ligand due to exhibiting high binding affinity to hydroxyapatite mineral. BPs can be conjugated to an agent that would otherwise have little or no affinity for the sites of interest. This article summarizes the current state of knowledge and practice for the use of BPs as ligands for targeted delivery to bone and mineral deposits. The clinical history of BPs is briefly summarized to emphasize the success of these molecules as therapeutics for metabolic bone diseases. Mechanisms of binding and the relative binding affinity of various BPs to bone mineral are introduced, including common methods for measuring binding affinity in vitro and in vivo. Current research is highlighted for the use of BP ligands for targeted delivery of BP conjugates in various applications, including (1) therapeutic drug delivery for metabolic bone diseases, bone cancer, other bone diseases, and engineered drug delivery platforms; (2) imaging probes for scintigraphy, fluorescence, positron emission tomography, magnetic resonance imaging, and computed tomography; and (3) radiotherapy. Last, and perhaps most importantly, key structure-function relationships are considered for the design of drugs with BP ligands, including the tether length between the BP and drug, the size of the drug, the number of BP ligands per drug, cleavable tethers between the BP and drug, and conjugation schemes.
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Affiliation(s)
- Lisa E Cole
- Department of Aerospace and Mechanical Engineering, Bioengineering Graduate Program, University of Notre Dame, Notre Dame, IN 46556, United States; Harper Cancer Research Institute, University of Notre Dame, Notre Dame, IN 46556, United States
| | - Tracy Vargo-Gogola
- Department of Biochemistry and Molecular Biology, Indiana University Simon Cancer Center, Indiana University School of Medicine-South Bend, South Bend, IN 46617, United States; Harper Cancer Research Institute, University of Notre Dame, Notre Dame, IN 46556, United States
| | - Ryan K Roeder
- Department of Aerospace and Mechanical Engineering, Bioengineering Graduate Program, University of Notre Dame, Notre Dame, IN 46556, United States; Harper Cancer Research Institute, University of Notre Dame, Notre Dame, IN 46556, United States.
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5
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Ossipov DA. Bisphosphonate-modified biomaterials for drug delivery and bone tissue engineering. Expert Opin Drug Deliv 2015; 12:1443-58. [PMID: 25739860 DOI: 10.1517/17425247.2015.1021679] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
INTRODUCTION Bisphosphonates (BPs) were introduced 45 years ago as anti-osteoporotic drugs and during the last decade have been utilized as bone-targeting groups in systemic treatment of bone diseases. Very recently, strategies of chemical immobilization of BPs in hydrogels and nanocomposites for bone tissue engineering emerged. These strategies opened new applications of BPs in bone tissue engineering. AREAS COVERED Conjugates of BPs to different drug molecules, imaging agents, proteins and polymers are discussed in terms of specific targeting to bone and therapeutic affect induced by the resulting prodrugs in comparison with the parent drugs. Conversion of these conjugates into hydrogel scaffolds is also presented along with the application of the resulting materials for bone tissue engineering. EXPERT OPINION Calcium-binding properties of BPs can be successfully extended via different conjugation strategies not only for purposes of bone targeting, but also in supramolecular assembly affording either new nanocarriers or bulk nanocomposite scaffolds. Interaction between carrier-linked BPs and drug molecules should also be considered for the control of release of these molecules and their optimized delivery. Bone-targeting properties of BP-functionalized nanomaterials should correspond to bone adhesive properties of their bulk analogs.
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Affiliation(s)
- Dmitri A Ossipov
- Uppsala University, Division of Polymer Chemistry, Department of Chemistry-Ångström, Science for Life Laboratory , Uppsala, SE 751 21 , Sweden +46 18 417 7335 ;
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6
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Biomedical applications of bisphosphonates. J Control Release 2013; 167:175-88. [PMID: 23395668 DOI: 10.1016/j.jconrel.2013.01.032] [Citation(s) in RCA: 114] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2012] [Revised: 12/24/2012] [Accepted: 01/30/2013] [Indexed: 02/08/2023]
Abstract
Since their discovery over 100 years ago, bisphosphonates have been used industrially as corrosion inhibitors and complexing agents. With the discovery of their pharmacological activity in the late 1960s, implicating their high affinity for hydroxyapatite, bisphosphonates have been employed in the treatment of bone diseases and as targeting agents for colloids and drugs. They have notably been investigated for the treatment of Paget's disease, osteoporosis, bone metastases, malignancy-associated hypercalcemia, and pediatric bone diseases. Currently, they are first-line medications for several of these diseases and are taken by millions of patients worldwide, mostly postmenopausal women. A major problem associated with their use is their low oral bioavailability. Several delivery systems have been proposed to improve their absorption and to direct them to sites other than bone tissues. Beyond their important pharmacological role, the medical applications of bisphosphonates are numerous. In addition, their metal-chelating properties have been exploited to coat and stabilize implants, nanoparticulates, and contrast agents. In this contribution, we review the pharmacological and clinical uses of bisphosphonates and highlight their novel applications in the pharmaceutical and biomedical fields.
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7
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Mucha A, Kafarski P, Berlicki Ł. Remarkable potential of the α-aminophosphonate/phosphinate structural motif in medicinal chemistry. J Med Chem 2011; 54:5955-80. [PMID: 21780776 DOI: 10.1021/jm200587f] [Citation(s) in RCA: 480] [Impact Index Per Article: 36.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Affiliation(s)
- Artur Mucha
- Department of Bioorganic Chemistry, Faculty of Chemistry, Wrocław University of Technology, Wybrzeże Wyspiańskiego 27, 50-370 Wrocław, Poland
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8
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Zhang S, Kucharski C, Doschak MR, Sebald W, Uludağ H. Polyethylenimine-PEG coated albumin nanoparticles for BMP-2 delivery. Biomaterials 2009; 31:952-63. [PMID: 19878992 DOI: 10.1016/j.biomaterials.2009.10.011] [Citation(s) in RCA: 70] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2009] [Accepted: 10/05/2009] [Indexed: 01/24/2023]
Abstract
Bone Morphogenetic Protein-2 (BMP-2) plays an important role in stimulating new bone formation, and has been utilized in clinical bone repair by implantation. In this study, we report a nanoparticulate (NP) system for BMP-2 delivery based on bovine serum albumin (BSA) NPs stabilized with a poly(ethylene glycol) modified polyethylenimine (PEI-PEG) coating. PEI-PEG with different PEG substitutions were synthesized, and the cell viability assay showed PEG substitution greatly reduced the cytotoxicity of the native PEI. Furthermore, PEI-PEG coated BSA NPs demonstrated smaller size and decreased zeta potential compared to PEI-coated NPs. The bioactivity of the encapsulated BMP-2 and the toxicity of PEI-PEG coated NPs were examined by the alkaline phosphatase (ALP) induction assay and the MTT assay, respectively, using human C2C12 cells. The results indicated that BMP-2 remained bioactive in NPs and PEI-PEG coating was advantageous in reducing the NP toxicity as compared to PEI. A 7-day pharmacokinetics study showed the BMP-2 retention in PEI-PEG coated NPs was similar to the uncoated NPs, but lower than that of the PEI-coated NPs. The osteoinductivity of BMP-2 delivered in NPs was determined by subcutaneous implantation in rats, and the results revealed that PEI-PEG coated BSA NPs induced significant de novo bone formation after implantation, while PEI-coated NPs demonstrated much less bone formation. We conclude that BMP-2 delivered by PEGylated PEI-coated BSA NPs displays favorable biocompatibility and promotes new bone formation after implantation.
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Affiliation(s)
- Sufeng Zhang
- Department of Chemical and Materials Engineering, University of Alberta, Canada
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9
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Doschak MR, Kucharski CM, Wright JEI, Zernicke RF, Uludağ H. Improved bone delivery of osteoprotegerin by bisphosphonate conjugation in a rat model of osteoarthritis. Mol Pharm 2009; 6:634-40. [PMID: 19718808 DOI: 10.1021/mp8002368] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
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.
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Affiliation(s)
- Michael R Doschak
- Faculty of Pharmacy & Pharmaceutical Sciences and Department of Chemical & Materials Engineering, University of Alberta, Edmonton, Alberta, Canada.
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Zhang S, Doschak MR, Uludağ H. Pharmacokinetics and bone formation by BMP-2 entrapped in polyethylenimine-coated albumin nanoparticles. Biomaterials 2009; 30:5143-55. [PMID: 19540582 DOI: 10.1016/j.biomaterials.2009.05.060] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2009] [Accepted: 05/21/2009] [Indexed: 11/29/2022]
Abstract
The osteoinductive growth factor, bone morphogenetic protein-2 (BMP-2), is capable of inducing de novo bone formation after implantation. A nanoparticulate (NP) system was developed for BMP-2 delivery based on NPs fabricated from bovine serum albumin (BSA) and stabilized by polyethylenimine (PEI) coating. In this study, the pharmacokinetics and osteoinductivity of BMP-2 delivered with different BSA NP formulations were determined by subcutaneous implantation in rats. A 7-day pharmacokinetics study showed that PEI coating on NPs effectively reduced the initial burst release of BMP-2 and prolonged the BMP-2 retention at implantation site. However, the uncoated BMP-2 NPs (BMP-2 loading of 1.44% w/w) were able to induce a robust ectopic bone formation, while no bone formation was found by the BMP-2 NPs coated with PEI. The toxicity of the PEI used for NP coating was determined to be the reason for lack of osteoinduction. Increasing BMP-2 loading (up to 5.76% w/w) was then employed to formulate NPs with lower PEI content; the higher BMP-2 loading was found to better promote induction of de novo bone. Our findings indicated that PEI coating on BSA NPs was effective for controlling BMP-2 release from NPs, but the toxicity of cationic PEI was a concern for the osteoinductive activity, which should be alleviated by further optimization of NP formulations.
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Affiliation(s)
- Sufeng Zhang
- Department of Chemical and Materials Engineering, Faculty of Engineering, University of Alberta, Edmonton, AB, Canada
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Zhang S, Wang G, Lin X, Chatzinikolaidou M, Jennissen HP, Laub M, Uludağ H. Polyethylenimine-coated albumin nanoparticles for BMP-2 delivery. Biotechnol Prog 2009; 24:945-56. [PMID: 19194903 DOI: 10.1002/btpr.12] [Citation(s) in RCA: 79] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Nanoparticle (NP)-based delivery has gained importance for improving the potency of therapeutic agents. The bovine serum albumin (BSA) NPs, obtained by a coacervation process, was modified by electrostatic adsorption of cationic polyethylenimine (PEI) to NP surfaces for delivery of bone-inducing growth factor, bone morphogenetic protein-2 (BMP-2). Different concentrations of PEI were utilized for coating BSA NPs to stabilize the colloidal system and to control the release of BMP-2. The NPs were characterized by size and zeta potential measurements, as well as by Scanning Electron Microscopy and Atomic Force Microscopy. The encapsulation efficiency was typically >90% in all NP preparations. In vitro release kinetics showed that the PEI concentration used for coating the NPs efficiently controlled the release of BMP-2, demonstrating a gradual slowing, sustained release pattern during a 10-day study period. The bioactivity of the encapsulated BMP-2 and the toxicity of the NPs were examined by the alkaline phosphatase (ALP) induction assay and the MTT assay, respectively, using C2C12 cells. The results indicated that PEI was the primary determinant of NP toxicities, and BSA NPs coated with 0.1 mg/mL PEI demonstrated tolerable toxicity, retained the bioactivity of BMP-2, and efficiently slowed the release rate of BMP-2. We conclude that BMP-2 encapsulated in BSA NPs might be an efficient way to deliver the protein for in vivo bone induction.
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Affiliation(s)
- Sufeng Zhang
- Faculty of Engineering, Dept. of Chemical and Materials Engineering, University of Alberta, Edmonton, AB, Canada
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El-Mabhouh AA, Mercer JR. 188Re-labelled gemcitabine/bisphosphonate (Gem/BP): a multi-functional, bone-specific agent as a potential treatment for bone metastases. Eur J Nucl Med Mol Imaging 2008; 35:1240-8. [PMID: 18265977 DOI: 10.1007/s00259-008-0728-y] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2007] [Accepted: 01/22/2008] [Indexed: 10/22/2022]
Abstract
PURPOSE This study investigated the bone-binding affinity and biodistribution of a (188)Re-labelled gemcitabine/bisphosphonate (Gem/BP) conjugate, a multi-functional drug designed to deliver tumour-specific combined radiotherapy and chemotherapy to the bone using the high bone-binding affinity of the bisphosphonate group. METHODS The Gem/BP conjugate was labelled at high radiochemical purity with (188)Re. The bone-binding affinity of the (188)Re-Gem/BP was studied in vitro in purified hydroxyapatite emulsion and powdered bovine bone. In vivo biodistribution studies were carried out in normal BALB/c mice. RESULTS (188)Re-Gem/BP demonstrated strong and stable binding in both in vitro systems. In vivo (188)Re-Gem/BP showed bone uptake, rapid blood clearance and rapid elimination of unbound activity. The bone tissue demonstrated the highest concentration of bound radioactivity exempting the kidneys. Approximately 67% of retained whole-body activity was bound to the bone at 8 h after (188)Re-Gem/BP administration. CONCLUSIONS (188)Re-Gem/BP demonstrated high, selective and persistent bone binding and can be considered as a model compound for multi-functional bone-specific therapy for bone metastases.
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Affiliation(s)
- Amal A El-Mabhouh
- Faculty of Pharmacy and Pharmaceutical Sciences, University of Alberta, Edmonton, AB, Canada T6G-2N8
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13
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Murphy MB, Hartgerink JD, Goepferich A, Mikos AG. Synthesis and in vitro hydroxyapatite binding of peptides conjugated to calcium-binding moieties. Biomacromolecules 2007; 8:2237-43. [PMID: 17530891 DOI: 10.1021/bm070121s] [Citation(s) in RCA: 77] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
To confer bone-binding properties to proteins and other biological agents that lack specific targeting capacity, model peptide-based molecules were synthesized containing poly(aspartic acid), poly(glutamic acid), or a bisphosphonate (pamidronate). These motifs have well-documented affinities to hydroxyapatite, a property desirable for the targeting of molecules to bone for drug delivery and tissue engineering applications. Model peptides of increasing molecular mass (5-33 amino acids) were directly conjugated to eight aspartic acids (Asp8), eight glutamic acids (Glu8), or pamidronate, purified by high-performance liquid chromatography, and characterized by matrix-assisted laser desorption ionization time-of-flight (MALDI-TOF) mass spectroscopy. The modified peptides were incubated with hydroxyapatite in phosphate-buffered saline at physiological conditions over 24 h. This study revealed a significant amount (>90%) of conjugated peptides adsorbed to the hydroxyapatite as compared to unmodified peptides (<5%). It was found that while there were significant differences between the different hydroxyapatite-binding and control groups for all time points, the size of the peptide had no statistical effect on peptide-hydroxyapatite binding. These results demonstrate that bisphosphonate and oligopeptide conjugates hold great promise for the development of new bioactive molecules for bone-specific applications.
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Affiliation(s)
- Matthew B Murphy
- Department of Bioengineering, Rice University, Houston, TX 77251-1892, USA
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14
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Zhang S, Wright JEI, Ozber N, Uludağ H. The Interaction of Cationic Polymers and Their Bisphosphonate Derivatives with Hydroxyapatite. Macromol Biosci 2007; 7:656-70. [PMID: 17457941 DOI: 10.1002/mabi.200600286] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Conjugating proteins with bisphosphonates (BPs), a class of molecules with exceptional affinity to hydroxyapatite (HA), is a feasible means to impart bone affinity to protein-based therapeutic agents. To increase the targeting effectiveness while minimizing protein modification, a polymeric linker containing multiple copies of BPs could be constructed for protein conjugation and targeting to bone. Towards this goal, poly(L-lysine) (PLL) and poly(ethylenimine) (PEI) were utilized as the polymeric backbones to incorporate a BP, namely 2-(3-mercaptopropylsulfanyl)-ethyl-1,1-bisphosphonic acid (thiolBP), by using N-hydroxysuccinimidyl polyethylene glycol maleimide and succinimidyl-4-(N-maleimidomethyl)-cyclohexane-1-carboxylate, respectively. In vitro and in vivo mineral affinity of the polymer-BP conjugates were determined in comparison with the unmodified polymers. The in vitro results indicated strong binding of the cationic polymers to HA in their unmodified form. BP conjugation did not enhance the inherent mineral affinity of the polymers; in contrast, certain modifications negatively affected the polymers' binding to the HA. In vivo results from a subcutaneous implant model in rats also showed no significant difference in mineral affinity of the BP modified and unmodified PEI. We conclude that thiolBP conjugation to the cationic polymers PLL and PEI was not beneficial for increasing the mineral affinity of the polymeric molecules. The strong interaction between the cationic polymers and HA may make the polymers suitable for imparting mineral affinity to bone-acting therapeutics.
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Affiliation(s)
- Sufeng Zhang
- Department of Chemical and Materials Engineering, Faculty of Engineering, University of Alberta, Edmonton, AB, T6G 2G6, Canada
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15
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Zhang S, Gangal G, Uludağ H. 'Magic bullets' for bone diseases: progress in rational design of bone-seeking medicinal agents. Chem Soc Rev 2006; 36:507-31. [PMID: 17325789 DOI: 10.1039/b512310k] [Citation(s) in RCA: 200] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
An ideal therapeutic agent for bone diseases should act solely on bone tissue with no pharmacological activity at other anatomical sites. Current therapeutic agents, however, do not usually display a preferential affinity to bones and non-specifically distribute throughout the body after administration. Attempts to design bone-specific agents have relied on engineering a desired therapeutic agent with bone-seeking molecules so that the latter delivers the therapeutic agents specifically to bones. In this critical review, we summarize the latest attempts to engineer bone-seeking therapeutic agents based on formulating therapeutic agents with bisphosphonates, a class of compounds with high affinity to biological apatite. We first provide a relevant summary of the structure of bone mineral and bisphosphonates, highlighting the mode of interaction between these two entities. The use of bisphosphonates in the diagnosis of bone diseases is then presented, since this application helps us to understand the bone-carrier properties of bisphosphonates under physiological conditions. A summary of recent attempts to formulate bisphosphonates with traditional therapeutic agents to restrict their activities to bone tissues is then provided, with special emphasis on the structure-function relationships of the engineered compounds. Finally, attempts to use bisphosphonates to deliver macromolecular therapeutics (i.e., proteins) are summarized, based on recent data from the authors' lab. The collective research into bone-seeking medicinal agents is progressively laying the foundation for next-generation 'magic bullets' that display desirable activities at the disease sites with no undesirable activity on other organ systems. (164 references.).
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Affiliation(s)
- Sufeng Zhang
- Department of Chemical & Materials Engineering, Faculty of Engineering, University of Alberta, Edmonton, Alberta, Canada T6G 2G6
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