Soluble transferrin receptor-1 (sTfR1) concentrations are increased in the 
plasma under two conditions that are associated with increased iron absorption, 
i.e. iron deficiency and increased erythropoiesis. To determine the possible 
role of sTfR1 as a signaling mechanism for iron absorption, a hydrodynamic gene 
transfer technique was established to express transfected plasmid constructs of 
human sTfR1 (hsTfR1) and murine sTfR1 (msTfR1) from the livers of C57BL/6 mice. 
Iron absorption, serum iron levels and hepcidin expression were then measured. 
The hydrodynamic gene transfer technique proved to be an effective approach to 
achieving sustained expression of sTfR1 in mice. Although expression of high 
levels of sTfR1 significantly increased serum iron levels, repeated experiments 
showed that neither hsTfR1 nor msTfR1 had any effect on iron absorption or 
hepcidin mRNA expression levels. Thus, despite its attractiveness as a potential 
modifier of iron absorption, sTfR1 levels do not exert a regulatory effect on 
iron absorption.