Nano liposomes labeled with99mTC-HMPAO,a novel agent for blood pool imaging

In-vitro labeling of rbc with99mtc is an intricate procedure and there is always a need for an alternate blood pool imaging agent. the aim of this study was to prepare an effective nano sized liposome (nls) similar to human rbc for blood pool scintigraphy. this study formulates peg-nls and non-peg-nls using film method plus high pressure homogenization technique. biodistribution studies were performed on balb/c mice 1,4 and 24 h after tail vein injection of labeled nls with99mtc hexamethylpropylene-amine-oxime (99mtc-hmpao). planar images were acquired using a 256 × 256 matrix following99mtc-hmpao-nls injection into ear vein of rabbits 1,2 and 24 h later. spect images were obtained 15 minutes after the injection (64 slices,30 second/projection). the mean diameter,zeta potential and polydispersity index (pdi) of the peg-nls and the nls were (80.88 ± 0.594 nm,-12.5 ± 0.56 mv,0.158 ± 0.025) and (94.14 ± 0.114 nm,-35.5 ± 0.67 mv and 0.198 ± 0.007),respectively.99mtc-hmpao-peg-nls showed a significant circulation tracer activity (7.74 ± 1.63%id/g at 1 h and 4.9 ± 0.77 %id/g at 4 h),with low liver accumulation (12.07 ± 3.66 %id/g at 1 h and 14.85 ± 1.3 %id/g at 4 h). heart to liver,spleen and background rois (region of interests) for99mtc-hmpao-peg-nls were 1.25,4 and 4.28 respectively at 2 h which changed to 1.06,1.75 and 2.51 respectively at 24 h. the99mtc-hmpao-peg-nls with a prolonged blood circulation time could be an excellent rbc alternative for scintigraphy and gastrointestinal bleeding. © 2015 by school of pharmacy shaheed beheshti university of medical sciences and health services.