Transfection microarray of human mesenchymal stem cells and on-chip siRNA gene knockdown.

The transfection efficiency of primary cells is the bottleneck for their use with miniaturized formats for gene validation assays. We have found that when formulations containing various reporter plasmids were microarrayed on glass slides (chips), hMSCs cultivated on the chip incorporated and expressed the microarrayed plasmid DNAs with high efficiency and virtually total spatial resolution. Fibronectin, as the key formulation component, was found to significantly increase the on-chip transfection efficiency in hMSCs as well as many other cells. Further, we have conclusively proven that when siRNA was co-arrayed with the target plasmid DNA, a concentration-dependent gene knockdown was observed. Thus, massively miniaturized RNAi gene knockdown experiments can now be performed in primary cells, previously unusable with transfection microarrays (TMA).