Visualization of bioavailable liposomal doxorubicin using a non-perturbing confocal imaging technique

Commonly employed tissue processing techniques can significantly alter tissue drug distribution patterns for liposomal encapsulated drugs by virtue of drug leakage via loss of membrane integrity. We report here a method that has been developed to determine the fluorescence of bioavailable doxorubicin (DOX) in tissues after administration of liposomal DOX formulations. A non-perturbing confocal fluorescence microscopy (CFM) technique with image processing analysis was used with unprocessed fresh tissues. This method takes advantage of the fact that considerable quenching occurs when DOX is within liposomes, leading to the selective visualization of the fluorescence due to DOX released from liposomes. We demonstrate that fresh tissue confocal imaging can be applied to provide detailed drug distribution information with improved accuracy and is a superior method for analyzing tissue distribution of liposome entrapped fluorescent agents.