Europium labeled lactosylated albumin as a model workflow for the development of biotherapeutics

Lactosylated albumin is currently used as a radiopharmaceutical agent to image the liver asialoglycoprotein receptors and quantify hepatic liver function in various diseases. A lactosylated protein (LACTAL) conjugate showed excellent liver uptake compared to non-lactosylated protein and a high signal to noise ratio, based on the biodistribution in mice using 99mTc-scintigraphy. However, in the laboratory, it is useful to have a method that can be used in daily practice to quantify cellular targeting or biodistribution. We propose a methodology from synthesis validation to pre-clinical demonstration and introduce a new practical detector (LACTAL.Eu) of the LACTAL molecule in biological media. We confirmed the purity and colloidal stability of the sample through physical analytical techniques, then showed the absence of in vitro toxicity of the agent and demonstrated in vitro targeting. Taking advantage of the fluorescence decay of the lanthanide, we performed measurements directly on the cell media without any further treatment. Finally, biodistribution in mice was confirmed by ex vivo measurements. Liver diseases are continuously progressing due to our habitual behaviors and have become a main public health issue. Unfortunately, imaging is unavailable to evaluate their stages. Macromolecular nanoprobes offer an interesting potential to overcome this shortcoming, but their development and pre-clinical evaluation in laboratories remain time-consuming and expensive. This study introduces an original rapid protocol to allow in vitro and ex vivo evaluation of liver cells specificity of a liver diagnostic agent using delayed fluorescence of Eu labeling. Secondly, the description of the methodological approach introduces a complete workflow, including “go” and “no go” criteria relying on physical analytical methods. As such, it addresses for the clinical translation, from bench to bedside, of emerging new contrast agent and biomacromolecules. [Display omitted]