The Preparation of 99mTc-GSA and its Instant Lyophilized Kit for Hepatic Receptor Imaging

The ligand GSA (DTPA-galactosyl-human serum albumin) was synthesized by first introducing bifunctional chelator DTPA (diethylenetriamine pentaacetic acid) to human serum albumin (HSA) via DTPA anhydride, and then coupling galactosyl units (2-imino-2-methoxyethyl-thio-galactose) to DTPA-HSA. GSA was labeled with technetium-99m by using SnCl2 as reductant and the labeling conditions of 99mTc-GSA were optimized. Lyophilized kit of GSA was also developed for instant preparing of 99mTc-GSA. Technetium labeling yields in excess of 96% by using both of liquid and lyophilized labeling methods. Biodistribution of 99mTc-GSA was investigated in both normal and liver-injury model mice. 99mTc-GSA showed high liver uptake in normal mice (> 70%ID•g-1 at 30 min after injection). The liver uptake in liver-injury model mice is lower than that of in normal mice (P=0.0324). The promising biological properties of 99mTc-GSA combined with the development of reliable and instant lyophilized GSA kit afford the opportunity of liver receptor imaging for routine clinical assessment of hepatocyte function.