In this study, AB-type carbonated hydroxyapatite (CHAp) nanosheet-assembled hollow microstructures were rapidly synthesized via a hydrothermal process without sintering. Urea was employed as both a pH adjusting agent and a CO 3 2− source during hydrothermal reaction. The influence of hydrothermal time on the final morphologies of the products was systematically investigated. The as-prepared CHAp hollow microstructures with a diameter of about 3-4 μm consist of numerous radially oriented CHAp nanosheets as building units with an average thickness of about 10 nm. The morphology of the product can vary from a hollow microstructure to a solid dandelion-like structure with increasing hydrothermal time. Possible mechanisms for the formation of a nanosheet-assembled CHAp hollow microstructure and a solid dandelion-like microstructure in the presence of both urea and ethylenediaminetetraacetic acid (EDTA) are illustrated. Moreover, the as-prepared CHAp hollow microstructures exhibit a high drug loading capacity and sustained drug release properties.
Purpose
To develop a method for labeling human bone marrow mesenchymal stem cells (hMSCs) with 89Zr-oxine to characterize the biodistribution characteristics of hMSCs in normal Sprague–Dawley (SD) rats in real-time by micro-PET–computed tomography (micro-PET/CT) imaging.
Methods
89Zr-oxine complex was synthesized from 89Zr-oxalate and 8-hydroxyquinoline (oxine). After hMSCs were labeled with the 89Zr-oxine complex, the radioactivity retention, viability, proliferation, apoptosis, differentiation, morphology, and phenotype of labeled cells were assessed. The biodistribution of 89Zr-oxine-labeled hMSCs in SD rats was tracked in real-time by micro-PET/CT imaging.
Results
The cell labeling efficiency was 52.6 ± 0.01%, and 89Zr-oxine was stably retained in cells (66.7 ± 0.9% retention on 7 days after labeling). Compared with the unlabeled hMSCs, 89Zr-oxine labeling did not affect the biological characteristics of cells. Following intravenous administration in SD rats, labeled hMSCs mainly accumulated in the liver (7.35 ± 1.41% ID/g 10 days after labeling, n = 6) and spleen (8.48 ± 1.20% ID/g 10 days after labeling, n = 6), whereas intravenously injected 89Zr-oxalate mainly accumulated in the bone (4.47 ± 0.35% ID/g 10 days after labeling, n = 3).
Conclusion
89Zr-oxine labeling and micro-PET/CT imaging provide a useful and non-invasive method of assessing the biodistribution of cell therapy products in SD rats. The platform provides a foundation for us to further understand the mechanism of action and migration dynamics of cell therapy products.
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