A therapy based on modified RNA, which limits therapeutic protein expression to a few days, has been shown to work better in a mouse model of heart attack compared to a traditional DNA delivery method that provides longer-term protein expression. The study, published online this week in Nature Biotechnology, suggests that modified RNA could be a useful approach for therapies designed to activate resident stem cells to repair damaged tissues.

Kenneth Chien and colleagues treated mice subjected to coronary artery ligation, an experimental model of heart attack, with an RNA that was chemically modified to be stable in the body and that expressed a growth factor known to stimulate blood-vessel growth. They found that expressing the growth factor for only a few days using this RNA improved the survival of mice for up to one year and was superior to longer-term expression of the growth factor by a DNA-based method. The treatment also promoted the differentiation of resident heart tissue stem cells into cells that form the inner layer of blood vessels, which are needed to counteract ischemic tissue damage from heart attack.