[Preliminarily experimental study on biological properties of 153Sm-citrate-nano-Hydroxyapatite]

To investigate the biological character of new agent 153Sm-citrate-nano-Hydroxyapatite (nano-HA) in vitro and in vivo, and to explore a new radiopharmaceutical for the target therapy of bone metastasis cancer.

The nano-HA was synthesized by collosol-gelatum method, and evaluated by transmission electron microscopy (TEM) and X-ray diffraction (XRD). 153Sm was produced at a high specific activity and excellent radionuclidic purity, with which nano-HA was labeled by citrate transfer ligands in the best environment. By adopting the independent variable method, we also studied the optimally labeled condition and stability of 153Sm-citrate-nano-HA in vitro. And 153Sm-citrate-nano-HA was injected into normal rabbits for radio scanning performed. The cancer cell SMMC-7721 and MCF-7 cell lines were divided into two groups, and treated with nano-HA, 153Sm-citrate and 153Sm-citrate-nano-HA in vitro respectively, of which the cell survival rate was measured by MTT methods.

Through the detections of TEM, XRD showed that nano-HA consisted of needle-like microcrystals. The label rate of 153Sm-citrate-nano-HA was more than 95%, and extremely stable in vitro. The radio scanning of normal rabbits showed the skeletal system to be clear, and other systems, for example liver, spleen and kidney, could also be seen. The cell culture experiments in vitro indicated that 153Sm-citrate-nano-HA strongly inhibited the proliferation of SMMC-7721 and MCF-7 cells. 153Sm-citrate-nano-HA's half effective inhibition concentrations were 1.89 mg/L and 0.094 mg/L respectively; nano-HA's half effective inhibition concentrations were 3. 31 mg/L and 0.52 mg/L respectively; 153Sm-citrate's half effective inhibition concentrations were 4. 32 mg/L and 0. 67 mg/L respectively.

Sm-citrate-nano-HA shows fine biological properties, and is well worth for further researched and prepared as a promising potential radiopharmaceutical in nuclidic treatment for cancer bone metastases.