Experimental Study Of The Biological Properties Of ～(153)Sm-nano- Hydroxyapatite

Objective We have developed two new agents ¹⁵³Sm—citrate— nano-Hydroxyapatite(nano-HA) and ¹⁵³Sm—EDTMP—nanoHA and the aim of this study was to investigate the in vitro and in vivo performance of these new agents, aiming to explore a new radiopharmaceutical for target therapy of bone metastases.Methods The nano-Hydroxyapatite(nano-HA) was synthesized by collosol-gelatum method, and evaluated by TEM and XRD. ¹⁵³Sm was produced at a high specific activity and excellent radionuclidic purity; adopting independent variable method, that nano-HA was labeled with ¹⁵³Sm by citrate and EDTMP tansfer ligands in the best enviroment was investigated. We studied the stability of ¹⁵³Sm — citrate-nano-HA and ¹⁵³Sm-EDTMP-nano-HA in vitro. ¹⁵³Sm-citrate — nano-HA and ¹⁵³Sm — EDTMP — nano-HA have beenrespectively injiected into normal rabbits that were subsequently performed scanning. SMMC-7721 and MCF-7 cell lines were devided into three groups, treated with nano-HA, 153Sm—citrate—nano-HA and 153Sm—EDTMP—nano-HA in vitro respectively, survival rate was measured by MTT methods.Results The detections of TEM, XRD showed that nano-HAconsisted of needle-like microcrystals. The label rate of' Sm—citrate —nano-HA and 153Sm—EDTMP—nano-HA were repectively more than 95%, and extremely stable in vitro. The scanning of normal rabbits showed skeletal system clearly, but other systems, such as liver, spleen and kidney also were seen. The cell culture experiments in vitro indicted that 153Sm — citrate — nano-HA and 153Sm — EDTMP — nano-HA strongly inhibited the proliferation of SMMC-7721 and MCF-7 cells. 153Sm — citrate — nano-HA's half effective inhibition concentrations were 1.89g/l and 0.094g/l respectively; 153Sm — EDTMP — nano-HA's half effective inhibition concentrations were 1.98g/l and 0.075g/l respectively; nano-HA's half effective inhibition concentrations were 3.31 g/1 and 0.52g/l respectively.Conclusions I53Sm — citrate — nano-HA and 153Sm —EDTMP — nano-HA showed fine biological properties, especially 153Sm—EDTMP—nano-HA ;and it is well worth further researching as a promising radiopharmaceutical in radioactive treatment for bone metastases.