Intraesophageal MnSOD-plasmid liposome enhances engraftment and self-renewal of bone marrow derived progenitors of esophageal squamous epithelium

We evaluated whether the improved esophageal radiation tolerance following Manganese Superoxide Dismutase (MnSOD)-Plasmid Liposomes was explained by improved engraftment of bone marrow-derived progenitors. C57BL/ 6NHsd female mice pretreated with intraesophageal MnSOD-PL were irradiated to 29 Gy to the esophagus and intravenously transplanted with marrow from male B6. 129S7-Gt (ROSA) 26S OR/J ROSA (Lac-Z+, G418-resistant) mice. After 14 days, esophagi were removed and side population and non-side population cells evaluated for donor multilineage (endothelin/vimentin/F480) positive esophageal cells. Serial intravenous transplantability was tested in second generation 29 Gy esophagus-irradiated mice. Esophagi from recipients receiving swallowed MnSOD-PL 24 h prior to irradiation demonstrated significantly increased esophageal repopulation with donor bone marrow-derived Lac-Z+, G418+, Y-probe+ multilineage cells (37.8 +/- 1.8 > 50 cell Lac-Z+ foci per esophagus) compared to irradiated controls (19.8 +/- 1.8) P < 0.0001. Serial transfer to second-generation irradiated C57BL/ 6NHsd mice of intravenously injected SP or NSP first generation recipient esophagus cells was also significantly enhanced by MnSOD-PL intraesophageal pretreatment (74.4 +/- 3.6 SP-derived Lac-Z+ foci per esophagus, 48.6 +/- 5.4 NSP-derived) compared to irradiation controls (23.4 +/- 1.8 SP, 6.0 +/- 3.0 NSP), P < 0.0001. Thus, intraesophageal MnSOD-PL administration enhances engraftment of marrow-derived progenitors.