In utero detection of T7 phage after systemic administration to pregnant mice.

The phage is used as a scaffold to display recombinant libraries of peptides, which provides the means to rescue and amplify peptides that bind target macromolecules. Many reports showed that the T7 phage display method can be used to obtain a ligand-binding peptidefor tissue-targeted therapies in adult animals. In utero tissue targeting of fetal tissues may help in the correction of many genetic and metabolic diseases. Here we demonstrate the distribution and detection of T7 phage displaying the C-X7-C peptide library in mouse fetal tissues after systemic injection of T7 phage into pregnant mouse tail vein. T7 phage was recovered from fetal tissues 15 min after injection of T7 phage. Our results suggest that T7 phage may be a useful tool in selecting the tissue-specific ligand-binding peptide for fetal tissues. This approach may be helpful in designing in utero tissue-targeted therapies.