Cytometry and Cell Sorting Core

The Cytometry and Cell Sorting Facility at Baylor College of Medicine provides training, instrumentation, technical expertise, and software for flow cytometric analysis and cell sorting. This site provides information about specific equipment, services, fees, training, methods, and resources.

Flow cytometry uses fluorescent probes to identify and characterize cells or particles. Cells or particles tagged with fluorescent molecules enter the cytometer via a fluid stream. The cells then pass by a laser, which emits a specific wavelength of light. The fluorescent probes are excited by the laser and then emit light. The fluorescent signal is detected and amplified, then translated into an electronic signal, which is sent to the computer. Information about the size and granularity of a cell is recorded, as well. The result is a visual presentation describing an individual or group of cellular events. The cells or particles can be separated by sorting, or the information can be collected and analyzed.

Cell sorting is the separation and isolation of various cell populations. There are two methods for performing cell sorting: One is by using flow cytometry and the other is by magnetically labeling the cells to differentiate and separate the cell populations. Using flow cytometry requires a Flow Cytometric Cell Sorter like the BD FACSAria.

Sorting on a cytometer is similar to standard flow cytometry except that after fluorescent analysis the stream is vibrated at a specific frequency to separate it into droplets. These droplets are then charged or not depending upon the fluorescent profile of the cell within. The drops go through an electric field that sends the charged drops of interest into a tube or plate leaving unwanted cells to go to the waste.

In contrast the magnetic separation uses a column that is placed under a magnetic field to retain cells labeled with magnetic beads. Cells are loaded onto the column and the labeled cells are retained in the magnetic field while the unlabeled cells pass through. The column can then be removed from the magnetic field to remove the labeled cells, and either the negative or positive fractions can be processed for experimental purposes.