Transfection of cells in suspension by ultrasound cavitation

Abstract

Sonoporation holds many promises in developing an efficient, reproducible and permanent gene delivery vector. In this study, we evaluated sonoporation as a method to transfect nucleic acids in suspension cells, including the human follicular lymphoma cell line RL and fresh human Chronic Lymphocytic Leukemia (CLL) cells. RL and CLL cells were exposed to continuous ultrasound waves (445 kHz) in the presence of either plasmid DNA coding for green fluorescent protein (GFP) or fluorescent siRNA directed against BCL2L1. Transfection efficiency and cell viability were assessed using fluorescent microscopy and flow cytometry analysis, respectively. Knock-down of target protein by siRNA was assessed by immunoblotting. Moreover, sonoporation was used to stably transfect RL cells with a plasmid coding for luciferase (pGL3). These cells were then used for the non-invasive monitoring of tumorigenesis in immunodeficient SCID mice. Sonoporation allows a highly efficient transfection of nucleic acid in suspension cells with a low rate of mortality, both in a tumor cell line and in fresh human leukemic cells. It also allowed efficient transfection of BCL2L1 siRNA with efficient reduction of the target protein level. In conclusion, ultrasound cavitation represents an efficient method for the transfection of cells in suspension, including fresh human leukemic cells.