Organ distributions of liposome-loaded rat platelets

Abstract

Past in vitro functional assays have demonstrated that platelet function is not inhibited by liposome uptake. In the present study, the organ distributions of control and liposome-loaded Sprague-Dawley rat platelets were examined to determine whether liposome uptake enhances RES uptake. Platelets were isolated using STRactan density gradient centrifugation, incubated with small unilamellar liposomes in vitro for 1 hour, labeled with 51Cr and injected into a cohort group of rats. One hour post-injection the spleen, liver, lungs, blood, kidneys and bladder contents were removed and the percentages of the recovered dose localized per total organ (%RD) were determined. The RES index, defined as %RDliver + %RDspleen, were 24.8 +/- 4.5 and 20.5 +/- 5.0 for the control platelets and liposome-loaded platelets, respectively. These results indicate that liposome uptake does not enhance RES uptake.