Peptide nucleic acid (PNA) is a peptide-like DNA mimic that was introduced
almost ten years ago. It was immediately predicted that PNA would have a br
ight future in gene therapeutic drug development, but progress in this dire
ction has been rather modest thus far. This is predominantly due to ineffic
ient uptake of PNA by most living cells. However, within the past couple of
years a variety of methods have been devised to address this problem and t
he stage should now be set for more rapid progress. Several studies have de
monstrated antisense effects ex vivo in cells in culture and two reports on
direct injection of PNA into the brain of rats are also interesting. Only
a few studies have addressed the possible exploitation of the antisense pri
nciple for development of antibacterial drugs. However, the first in vitro
results using antiribosomal RNA PNAs and antisense PNAs targeted to the bet
a -lactamase gene on Escherichia coli cultures were quite promising. Most r
ecently, these preliminary studies have been extended to demonstrate in viv
o efficacy of antibacterial PNAs in an E. coil peritonitis/sepsis mouse mod
el. Therefore, PNA drug development again is rapidly picking up pace.