Biodistribution of 99mTc-HYNIC-lactadherin in mice--a potential tracer for visualizing apoptosis in vivo.

INTRODUCTION

The aim of this study was to establish a radio synthesis of (99m)Tc-HYNIC-lactadherin for in vivo studies and to perform biodistribution analysis studies in mice, comparing (99m)Tc-HYNIC-lactadherin to (99m)Tc-HYNIC-annexin V.

METHODS

The radiochemical purity of (99m)Tc-HYNIC-lactadherin was optimized by varying the amount of SnCl(2) in the synthesis. Furthermore, the need for bovine serum albumin (BSA) as a stabilizing agent was evaluated by following the stability by radiochemical purity measurement with and without the addition of BSA. A total of 24 mice were assigned to groups of 15 and nine mice, respectively. The animals were sacrificed at different time points; 10 min, 60 min, and 180 min.

RESULTS

The synthesis of (99m)Tc-HYNIC-lactadherin for in vivo studies has been optimized to give a stable product without addition of BSA and with a radiochemical purity of more than 95%. Approximately 60% of the injected dose of (99m)Tc-HYNIC-lactadherin was found in the liver and 4-5% could be assigned to kidneys. In contrast, (99m)Tc-HYNIC-annexin V distributes with around 13% and 45% of the injected dose in liver and kidneys, respectively. Over the experimental period (10-180 min) only small distributional changes were observed for both probes.

CONCLUSION

In conclusion, the biodistribution of (99m)Tc-HYNIC-lactadherin, a potential new tracer for in vivo quantification of apoptosis, was evaluated. The small renal uptake of (99m)Tc-HYNIC-lactadherin makes it possible to image apoptosis in the kidneys, but the high liver clearance may be a disadvantage during myocardial perfusion.