Knocking (Anti)-Sense into Cells: The Microsphere Approach to Gene Silencing

200 and 500 nm polymeric microspheres have been conjugated to siRNA targeted against EGFP expressed in human cervical cancer (HeLa) cells and shown to efficiently silence protein expression over 72 h, without detrimental cytotoxicity. Furthermore, with use of an independent Cy5 tracking label on the siRNA-laden microsphere, silencing of EGFP could be assessed by selecting only those cells that contained the delivery vehicle (and thus the siRNA) generating a more accurate picture of microsphere-induced gene silencing.