Biodistribution studies of 99mTc-labeled myoblasts in a murine model of muscular dystrophy.

The purpose of this study was twofold: first, to evaluate the myoblast labeling of various 99mTc complexes and to select the complex that best accomplishes this labeling, and second to evaluate the biodistribution of myoblasts labeled with this complex using mice with MDX muscular dystrophy (the murine homologue of Duchenne's muscular dystrophy). The following ligands were used to prepare the corresponding 99mTc complexes: hexakis-methoxy-isobutyl-isonitrile (MIBI), bis(2-ethoxyethyl)diphosphinoethane (Tf), (RR,SS)-4,8-diaza-3,6,6,9-tetramethyl-undecane-2,10-dione-bisoxime (HM-PAO), bis(N-ethyl)dithiocarbamate (NEt), and bis(N-ethoxy, N-ethyl)dithiocarbamate (NOEt). One million murine myoblasts were incubated for 30-60 minutes with 5 mCi of each of the 99mTc complexes prepared from the above ligands. Viability was assessed by microscopic counting after trypan blue staining, and the radioactivity absorbed in the cells was measured after centrifugation. The compound with the highest uptake in cellular pellets was [99mTc]N-NOEt. The biodistribution of myoblasts labeled with this complex was evaluated after intraaortic injection in dystrophic mice. Such an approach has the potential of effecting widespread gene transfer through the bloodstream to muscles lacking dystrophin.

Quality control of 99Mo/99Tcm generators: results of a survey of the Radiopharmacy Working Group of the Italian Association of Nuclear Medicine (AIMN).

A multicentre survey of the quality control of 99Tcm generators has been completed: 245 generators from seven different commercial sources were tested over a period of 2 years. The results indicate that the mean pH of the eluates was 5.8 +/- 0.6; the aluminium contents were typically < 10 ppm; the radiochemical purity was 99.8 +/- 0.4% and the median 99Mo content was 3.8 x 10(-4) percent. The elution profiles gave a volume of 1.9 ml to obtain 50% of the total eluted activity and of 4.9 ml to obtain 95%. Other radionuclide impurities and heavy metal breakthrough were evaluated by graphite furnace absorption spectrometry and inductively coupled plasma mass spectrometry. National guidelines for the standardization of radiopharmacy procedures are currently being compiled.