Isolating cells from a heterogenous population is an important theme in stem cell biology. A number of cell isolation techniques are available to researchers; however, they are often expensive and can have disruptive effects on cell viability post-isolation.
The EasySep® SSEA4+ Kit is optimised for the positive selection the embryonic stem cell (ESC) marker SSEA4 and is very straightforward in its execution. The first step involves applying a SSEA4 selection cocktail to your cell suspension. This is followed by the addition of magnetic beads which subsequently attach to successfully labelled cells. The second stage involves a series of incubations of the magnetically labelled cell solution within a magnet. Upon inversion of the magnet, unlabelled cells are washed away while any labelled cells remain within the magnet. If conducted under sterile conditions the isolated cells can be successfully maintained post-isolation with little effect on cell viability. As the SSEA4 antigen is present on the surface of pluripotent stem cells, such as human ESCs and induced pluripotent stem cells (iPSCs), this system can be successfully used to isolate small numbers of iPSCs or alternatively to purify a population of hESCs.
I have been using this system for the past year on a monthly basis and have found this technique to be a reproducible and reliable way of isolating populations of pluripotent stem cells. The main advantages of this system are the efficiency of the isolation procedure with a high purity (98-99%) achieved post-isolation, as identified through fluorescence activated cell sorting. Also, the passive nature of this procedure allows isolated cells to be cultured without detrimentally affecting cell viability. Since the antibody-magnetic bead complex remains attached to the cells post-isolation, downstream applications could be affected; however, it did not appear to affect cell viability of hESCs post-isolation.
Overall, this system is an excellent way of isolating pluripotent stem cells based on the expression of the SSEA4 antigen.