Dissection autoradiography: a screening technique using storage phosphor autoradiography to detect the...

This study reports an alternative, rapid, whole body autoradiography technique which utilises storage-phosphor imaging technology. Conventionally, tissue or whole body sections have been used to examine the distribution of radiolabelled test compounds. However, the information acquired relates only to the sections examined, and the amount of radioactivity within the whole organ cannot be quantified. We have developed a rapid semi-quantitative technique that produces a concise visual representation of the distribution of the isotope throughout the entire animal: dissection autoradiography (DAR).

By dissecting a mouse which has been administered 14C-labelled methotrexate (MTX) and drying the tissues on a gel dryer, whole organs and aliquots of body fluids can be exposed to a phosphor imaging plate. The data obtained was analysed with the software associated with the phosphor imaging system and, by using 14C standards, the amount of 14C per total organ or tissue was quantified relative to other samples. Another widely used method to detect radiolabelled material in vivo is tissue solubilisation (TS) followed by liquid scintillation counting (LSC). This conventional method was compared with DAR.

The new technique described in this communication was found to have a high level of reproducibility (R(2)= 88-95%). Whilst DAR was less sensitive than TS and LSC, trends over time in the biodistribution of 14C-MTX throughout most tissues were consistent between techniques.

Whilst TS and LSC was a more sensitive technique, it was labour intensive and expensive in terms of consumables and time when compared with DAR. Dissection autoradiography has the potential to be used to screen quickly large numbers of samples in the biodistribution studies of various conjugates, isomers, derivatives or formulations of a parent compound, following a variety of routes of administration.