Although gene therapy recently scored its first successÑcuring three French infants born with severe combined immune deficiency— delivering curative DNA to cells is still a problem. Last year, a modified virus designed for that purpose killed a volunteer in a gene therapy trial. That is why researchers at Washington University in St. Louis are so excited about their newly invented microscopic packages, which they call knedels.
Named after a Polish dumpling or matzo ball, knedels are virus-sized synthetic polymer particles that could be hollowed out and filled with DNA. Karen Wooley, the chemist who created them, has shown that her knedels can penetrate living cells when attached to a protein that acts as a key. And while viruses can prompt immune responses, knedels pose no such danger.
Wooley anticipates that the little hollow orbs will be used for gene therapy within about five years. They could be tailored to deliver drugs, to scavenge cholesterol from the blood, or even to deliver herbicides. "If you were coating a field with a toxic herbicide, these little capsules would trap the chemical and keep the action local, rather than dispersing it willy-nilly into the environment," says Wooley's colleague, physical chemist Ed Remsen.
A dumplinglike polymer (top) ferries therapeutic DNA into a cell (bottom).Image by Christopher G. Clark Jr./Washington University in St. Louis