title: Characterization of chemical, radiochemical and optical properties of a dual-labeled MMP-9 targeting peptide.
abstract: Optical imaging possesses similar sensitivity to nuclear imaging and has led to the emergence of multimodal approaches with dual-labeled nuclear/near-infrared (NIR) agents. The growing impact of (68)Ga (t(1/2)=68 min) labeled peptides on preclinical and clinical research offers a promising opportunity to merge the high spatial resolution of NIR imaging with the clinically-accepted positron emission tomography (PET). Previously, dual-labeled agents have been prepared with longer-lived radiometals and showed no detrimental effects on optical properties as a result of radiolabeling. In this study, we selected a peptide (M(2)) that targets MMP-2/9 and is dual-labeled with IRDye 800 CW and (68)Ga. Since (68)Ga chelation typically requires low pH (3.5-4) and elevated heating temperatures (95 °C), we sought to evaluate the impact of (68)Ga labeling on the optical properties of M(2). An efficient method for preparation of (68)Ga-M(2) was developed and reaction conditions were optimized. Stability studies in PBS, DTPA, and serum were performed and high levels of intact agent were evident under each condition. The addition of multiple reporters to a targeting agent adds further complexity to the characterization and validation and thus requires not only testing to ensure the agent is stable chemically and radiochemically, but also optically. Therefore, fluorescence properties were evaluated using a spectrofluorometer as well as by fluorescence detection via HPLC. It was determined that (68)Ga-labeling conditions did not impair the fluorescent properties of the agent. The agent was then used for in vivo imaging in a mouse model of heterotopic ossification (HO) with activated MMP-9 expression as an early biomarker which precedes mineralization. Although (68)Ga-complexation greatly reduced binding affinity of the peptide and negated tracer uptake on PET, NIR imaging showed consistent fluorescent signal that correlated to MMP-9 expression. This attests to the feasibility of using (68)Ga/NIR for dual-labeling of other peptides or small molecules for multimodality molecular imaging.
authors: Center for Molecular Imaging, The Brown Foundation Institute of Molecular Medicine, The University of Texas Health Science Center, Houston, TX 77030, USA. ali.azhdarinia@uth.tmc.edu
authors: Ali
authors: A
authors: Azhdarinia
authors: Nathaniel
authors: N
authors: Wilganowski
authors: Holly
authors: H
authors: Robinson
authors: Pradip
authors: P
authors: Ghosh
authors: Sunkuk
authors: S
authors: Kwon
authors: Zawaunyka W
authors: ZW
authors: Lazard
authors: Alan R
authors: AR
authors: Davis
authors: Elizabeth
authors: E
authors: Olmsted-Davis
authors: Eva M
authors: EM
authors: Sevick-Muraca
references: J Nucl Med. 2007 Oct;48(10):1741-8
references: 17873136
references: Biochem Biophys Res Commun. 2009 Dec 18;390(3):624-9
references: 19818734
references: Eur J Nucl Med Mol Imaging. 2004 Aug;31(8):1097-104
references: 15029459
references: Surgery. 2008 Jul;144(1):39-48
references: 18571583
references: J Cell Biochem. 2001 Apr 2-27;82(1):11-21
references: 11400159
references: J Nucl Med. 2007 Sep;48(9):1501-10
references: 17785729
references: Bioconjug Chem. 2010 Mar 17;21(3):436-44
references: 20131753
references: J Nucl Med. 2008 Feb;49(2):169-72
references: 18199608
references: Curr Pharm Biotechnol. 2008 Feb;9(1):34-46
references: 18289055
references: J Nucl Med. 2005 Jan;46 Suppl 1:172S-8S
references: 15653666
references: J Biomed Opt. 2005 Sep-Oct;10(5):054010
references: 16292970
references: Eur J Nucl Med. 2001 Dec;28(12):1751-7
references: 11734911
references: J Med Chem. 2002 May 9;45(10):2003-15
references: 11985468
references: Transl Oncol. 2010 Oct 01;3(5):307-217
references: 20885893
references: Thorax. 2006 Dec;61(12):1037-42
references: 16769715
references: J Biomed Opt. 2008 Jul-Aug;13(4):041312
references: 19021320
references: Amino Acids. 2011 Nov;41(5):1103-12
references: 20232090
references: Bioconjug Chem. 2004 May-Jun;15(3):554-60
references: 15149183
references: Mol Imaging Biol. 2009 Nov-Dec;11(6):424-33
references: 19424760
references: Bioconjug Chem. 2008 Jan;19(1):192-200
references: 18020401
references: Open Surg Oncol J. 2010;2(2):12-25
references: 22924087
references: Cancer Metastasis Rev. 2006 Mar;25(1):9-34
references: 16680569
references: Nat Biotechnol. 1999 Aug;17(8):768-74
references: 10429241
references: Bioconjug Chem. 2009 Nov;20(11):2177-84
references: 19919110
references: AJR Am J Roentgenol. 2010 Jan;194(1):W91-W103
references: 20028897
references: Nat Biotechnol. 2001 Apr;19(4):327-31
references: 11283589
references: Eur J Nucl Med Mol Imaging. 2007 Jul;34(7):982-93
references: 17225119
references: Nucl Med Biol. 2004 Apr;31(3):337-44
references: 15028246
references: Eur J Nucl Med Mol Imaging. 2010 Oct;37(10):2004-10
references: 20596866
references: Bioconjug Chem. 2010 Oct 20;21(10):1709-19
references: 20812730
references: Bone. 2009 Feb;44(2):251-65
references: 19027888
references: Nucl Med Biol. 2006 Feb;33(2):227-37
references: 16546677
references: Arterioscler Thromb Vasc Biol. 2008 Mar;28(3):425-32
references: 18258820
references: J Biomed Opt. 2007 Mar-Apr;12(2):024017
references: 17477732
references: Mol Imaging. 2010 Feb;9(1):21-9
references: 20128995
references: Clin Biochem. 2008 Aug;41(12):955-9
references: 18471998
references: Nucl Med Biol. 2006 Apr;33(3):349-58
references: 16631083
references: J Biomed Opt. 2008 Jul-Aug;13(4):041303
references: 19021311
references: Nucl Med Biol. 2007 Jul;34(5):503-10
references: 17591550
references: Eur J Nucl Med Mol Imaging. 2005 Apr;32(4):478-85
references: 15655678
references: Eur J Radiol. 2009 Jun;70(3):382-92
references: 19406595
references: Mol Imaging. 2004 Oct;3(4):343-51
references: 15802051