Purifying Cell Populations
Flow cytometry represents an irreplaceable tool that allows researchers to identify and purify cell populations to homogeneity. This aspect is of particular interest in stem cell biology, where cell population heterogeneity poses major challenges for downstream applications, which often require pure cell populations. At the International Society for Stem Cell Research meeting held in Barcelona, Nil Emre, Ph.D., stem cell scientist at BD Biosciences, presented a recent approach that she and collaborators developed to define a cell-surface signature for neurons derived from human embryonic stem cells and subsequently separate different cell populations on this basis.
“I predict that there will be defined cell signatures for numerous cell types, and there will be methods to enable their purification, and this will help develop better and more robust in vitro assays,” said Christian Carson, Ph.D., senior author on the study. “I also think that using flow cytometry to define cell-surface signatures will provide great tools for quality control, enabling us to quantify purity of cell preparations.”
While flow cytometry allows high-quality data to be obtained in a more time-efficient and cost-effective manner as compared to other techniques, for certain applications it represents one of the few available methodologies. One example is protein glycosylation, a well-known post-translational modification during malignant development. Overexpression, loss of expression, and the incomplete synthesis of glycosylated structures have long been described in various tumors, and some of these changes represent valuable progression markers with prognostic value.
Glycosylation can be examined with two main approaches—mass spectrometry and flow cytometry. Flow cytometry can be used for routine clinical laboratory applications since it is possible to have antibodies that recognize specific glycosylation epitopes and differentiate cells on this basis. “It’s hard to beat flow cytometry for this approach if the cells are amenable to it and the antibodies are available,” emphasized Dr. Carson.
Flow cytometry has undergone exciting changes in its approximately 40 years of existence. While initially used mostly to quantitate the DNA content of malignant tumor cells, this approach is increasingly becoming an indispensable tool in medical sciences, food microbiology, ecology, drug design, and population biology and, in all likelihood, the next few years will witness many novel and more sophisticated applications.