Annexin A5–Conjugated Polymeric Micelles for Dual SPECT and Optical Detection of Apoptosis
Open Access
- 13 May 2011
- journal article
- Published by Society of Nuclear Medicine in Journal of Nuclear Medicine
- Vol. 52 (6), 958-964
- https://doi.org/10.2967/jnumed.110.083220
Abstract
Imaging of apoptosis can allow noninvasive assessment of disease states and response to therapeutic intervention for a variety of diseases. The purpose of this study was to develop and evaluate a multimodal nanoplatform for the detection of apoptosis. Methods: To modulate the pharmacokinetics of annexin A5, a 36-kDa protein that binds specifically with phosphatidylserine, annexin A5 was conjugated to polyethylene glycol–coated, core-cross-linked polymeric micelles (CCPMs) dually labeled with near-infrared fluorescence fluorophores and a radioisotope (111In). To evaluate the specificity of the binding of annexin A5-CCPM to apoptotic cells, both fluorescence microscopy and cell-binding studies were performed in vitro. Pharmacokinetics, biodistribution, dual nuclear and optical imaging, and immunohistochemical studies were performed in 2 xenografted tumor models to evaluate the potential applications of annexin A5-CCPM. Results: In cell-based studies, annexin A5-CCPM exhibited strongly specific binding to apoptotic tumor cells. This binding could be efficiently blocked by annexin A5. In mice, annexin A5-CCPM displayed a mean elimination half-life of 12.5 h. The mean initial concentration in blood was 22.4% of the injected dose/mL, and annexin A5-CCPM was mainly distributed in the central blood compartment. In mice bearing EL4 lymphoma treated with cyclophosphamide and etoposide and in mice bearing MDA-MB-468 breast tumors treated with poly(L-glutamic acid)-paclitaxel and cetuximab (IMC-C225) anti–epidermal growth factor receptor antibody, the tumor apoptosis was clearly visualized by both SPECT and fluorescence molecular tomography. In contrast, there was little accumulation of this nanoradiotracer in the tumors of untreated mice. The biodistribution data were consistent with the imaging data, with tumor-to-muscle and tumor-to-blood ratios of 38.8 and 4.1, respectively, in treated mice, and 14.8 and 2.2, respectively, in untreated mice bearing EL4 lymphoma. Moreover, further studies demonstrated that the conventional 99mTc-labeled hydrazinonicotinamide annexin A5 and the plain CCPM control exhibited significantly lower uptake in the tumors of the treated mice than annexin A5-CCPM. Immunohistochemistry staining study showed that radioactivity count correlated with fluorescence signal from the nanoparticles, and both signals colocalized with the region of tumor apoptosis. Conclusion: Annexin A5-CCPM allowed visualization of tumor apoptosis by both nuclear and optical techniques. The complementary information acquired with multiple imaging techniques should be advantageous in assessing and validating early response to therapy.This publication has 33 references indexed in Scilit:
- APOMAB®, a La-Specific Monoclonal Antibody, Detects the Apoptotic Tumor Response to Life-Prolonging and DNA-Damaging ChemotherapyPLOS ONE, 2009
- In Vivo Detection of ApoptosisJournal of Nuclear Medicine, 2008
- Long-Circulating Near-Infrared Fluorescence Core-Cross-Linked Polymeric Micelles: Synthesis, Characterization, and Dual Nuclear/Optical ImagingBiomacromolecules, 2007
- Diblock Copolymer Micellar Nanoparticles Decorated with Annexin-A5 ProteinsJournal of the American Chemical Society, 2006
- Dual optical and nuclear imaging in human melanoma xenografts using a single targeted imaging probeNuclear Medicine and Biology, 2006
- Improved Radiolabeling of PEGylated Protein: PEGylated Annexin V for Noninvasive Imaging of Tumor ApoptosisCancer Biotherapy & Radiopharmaceuticals, 2003
- Gone but not forgottenNature, 2000
- Apoptosis in the Pathogenesis and Treatment of DiseaseScience, 1995
- Annexins: the problem of assessing the biological role for a gene family of multifunctional calcium- and phospholipid-binding proteinsBiochimica et Biophysica Acta (BBA) - Reviews on Biomembranes, 1994
- Resistance of mitochondrial DNA to degradation characterizes the apoptotic but not the necrotic mode of human leukemia cell deathJournal of Cellular Biochemistry, 1993