Molecular imaging of HPMA copolymers: Visualizing drug delivery in cell, mouse and man

N-(2-Hydroxypropyl)methacrylamide (HPMA) copolymers and their drug conjugates are some of the most intensively investigated drug delivery systems for over 30 years. Some of the HPMA copolymer drug conjugates have entered clinical trials. Various molecular imaging technologies have been used to investigate the mechanism of drug delivery with HPMA copolymers. Fluorescence imaging has been used for the study of the process of intracellular drug delivery, including cell binding, subcellular trafficking and intracellular fate, of HPMA copolymers and drug conjugates. Magnetic resonance imaging and nuclear medicine, including γ-scintigraphy, SPECT and PET, have been used for the non-invasive visualization of pharmacokinetics, biodistribution and drug targeting efficiency of HPMA copolymers in animal models. γ-Scintigraphy has been used to study HPMA copolymer drug conjugates in human patients. The application of imaging technologies in the study of HPMA copolymers and properties of the copolymers demonstrated by imaging is summarized in this review.