ABSTRACT
Objective To prepare a novel dual-modality imaging probe based on Cerasome nano-materials, and evaluate its in vivo biodistribution and pharmacokinetic properties. Methods ICG encapsu-lated Cerasome was modified with chelating agent DOTA for 111 In-labeling. Normal mice firstly were used for in vivo studies. Animals were sacrificed at different time points after tail vein administration, blood samples were taken and the organs of interest were captured to evaluate the pharmacokinetic properties and in vivo biodistribution of 111 In-ICG-DPDCs. The subcutaneous Lewis lung carcinoma ( LLC ) tumor model in C57BL/6 mouse was established. The tumor-bearing mice were subjected to optical imaging in small animal IVIS and SPECT imaging in small animal nanoScanSPECT/CT system for tumor uptake of 111 In-ICG-DPDCs. Results The size of the nanoparticle probe was about 90 nm, and the 111 In-labeling was successfully per-formed with 99.93% radiochemical purity after purification. 111 In-ICG-DPDCs showed excellent in vitro sta-bility with 97.10% radiochemical purity at 48 h post-purification. In vivo blood clearance experiments showed that 111 In-ICG-DPDCs had a relative long blood circulation time with the fast and slow phase half-lives of 40 and 132.7 min. 111In-ICG-DPDCs accumulated mainly in the liver and spleen, with long retention time. NanoScanSPECT/CT imaging showed that LLC tumors were significantly visualized at 4 h post-injection, and the other major accumulated organs were the liver and spleen, which were consistent with the results of biodistribution. Optical imaging showed significant uptake of the nanoparticle probe in the tumor, confirming the SPECT imaging results. Conclusion The Cerasome based probe designed could be used for tumor SPECT and optical dual-modality imaging, and has potential for therapeutic use.
ABSTRACT
Objective To prepare 99 Tcm-HYNIC-c( isoDGRKy) as a SPECT/CT imaging molecu-lar probe targeting integrin αvβ3 , and evaluate its biodistribution and feasibility on SPECT/CT imaging for integrinαvβ3-positive tumor in U87MG human glioma xenograft mouse models. Methods The bifunctional chelator HYNIC was conjugated to c( isoDGRKy) , and tricine and TPPTS were used as coligands for 99 Tcm labeling to prepare 99 Tcm-HYNIC-c( isoDGRKy) . The radiochemical purity and stability of the product were measured. The expression of integrin αvβ3 and binding affinity ( half maximal inhibitory concentration, IC50 ) of c ( isoDGRKy ) was detected in U87MG cells by cell experiments in vitro. Biodistribution and SPECT/CT imaging of 99 Tcm-HYNIC-c( isoDGRKy) including blocking experiments were performed respec-tively in nude mice bearing U87MG human glioma xenografts. Results The radiochemical purity of 99 Tcm-HYNIC-c( isoDGRKy) was over 99%, and was still over 99% after 4 h incubation in saline at room temper-ature. Flow cytometry assay showed that U87MG cells were integrinαvβ3-positive ( expressive rate:70%) . The IC50 of c(isoDGRKy) was 6.67×10-8 mol/L. Biodistribution results showed 99Tcm-HYNIC-c(isoDGRKy) with a rapid clearance from blood was excreted mainly via the kidneys. The 99 Tcm-HYNIC-c( isoDGRKy) uptake values in U87MG tumors were (7.31±1.42) and (1.09±0.11) %ID/g at 15 and 45 min post-injection re-spectively, and tumor-to-muscle ratio reached 5.01±1.47 at 15 min post-injection. The tumors were clearlyvisualized with low background from 0.5 to 1 h post-injection in tumor bearing mice. In the blocking experi-ment, the tumor was barely visualized after co-injection of excess cold c(RGDfK) peptide with 99Tcm-HYNIC-c(isoDGRKy). Conclusions 99Tcm-HYNIC-c(isoDGRKy) may be easily and steadily prepared. It may be a RGD-like promising SPECT/CT imaging probe for integrinαvβ3-positive tumor.