Preparation and imaging of rhenium-188 labeled human serum albumin microsphere in orthotopic hepatoma rats

• The present study relates to a method for preparing 188Re-labeled human serum albumin microspheres (HSAM) by 188Re(I)-tricarbonyl ion(188Re(OH2)3(CO)3)+).
• This radioactive particle can be subjected to radioembolization for liver tumor.
• The method of 188Re(I)-tricarbonyl ion labeled HSAM can proceed with high labeling yield.
• We believe this work is important and benefit for the future research and application of cancer radiotherapeutics.
• Furthermore, this method provided a convenient method for radio-labeling of HSAM with 188Re as well as a kit for manufacturing.

ObjectiveThe present study relates to a method for preparing 188Re-labeled human serum albumin microspheres (HSAM) by 188Re(I)-tricarbonyl ion(188Re(OH2)3(CO)3)+). This radioactive particle can be subjected to radioembolization for liver tumor.MethodsThe particle sizes and conformations of HSA microspheres were analyzed by Particle sizes-Malvern mastersizer and Scanning Electron Microscope (SEM). For preparing 188Re(I)-tricarbonyl ion, the 188ReO4- was eluted from a 188W/188Re generator with saline. The radio labeling efficiency was analyzed with high-performance liquid chromatography (HPLC). Amino borane-reduced 188ReO4-was interacted with carbon oxide to form (188Re(OH2)3(CO)3]+). For preparing 188Re-HSA microspheres, the 188Re(I)-tricarbonyl ion was added into a vial with HSA microspheres. The in vitro stability was investigated. The rat was injected with 188Re-HSA microspheres via hepatic artery route. Nano-SPECT/CT Imaging was acquired after injection of 188Re-HSA microspheres.ResultsThe shape of HSA microsphere was rough surfaced sphere or oval-shaped. The particle size was distributed between 20 and 35 μm. In the RP-HPLC-UV chromatography, the yield of 188Re(I)-tricarbonyl ion was 75–80%. The labeling efficiency of 188Re-HSA microspheres in this method was more than 85%. After incubation, the 188Re(I)-tricarbonyl ion labeled HSA microspheres were found to be stable in vitro in normal saline and rat plasma. The result of Nano-SPECT/CT Imaging quantification analysis indicated that the percentage of injection dose %ID was maintained at 95% ID-88% ID from 2 to 72 h after injection with 188Re- HSA microspheres.ConclusionsThe method of 188Re(I)-tricarbonyl ion labeled HSA microspheres can proceed with high labeling yield. Furthermore, this method provided a convenient method for radio-labeling of HSA microspheres with 188Re as well as a kit for manufacturing.