Cell sorting facs machine

The FACS (Fluorescence-Activated Cell Sorting) machine is an essential instrument in modern biology for isolating specific cell populations with high precision.

About this subject

FACS (Fluorescence-Activated Cell Sorting) is a specialized form of flow cytometry that allows the physical isolation of cells based on their optical properties. Cells are labeled with fluorophore-conjugated antibodies that bind to specific surface or intracellular markers. A laser beam excites the fluorophores, and detectors capture the emitted fluorescence and light scatter, enabling identification of cell size, granularity, and marker expression.

This technique is fundamental in biomedical research. In immunology, it is used to isolate rare lymphocyte subsets. In oncology, it helps purify circulating tumor cells for analysis. In stem cell biology, it enables sorting of hematopoietic stem cells for transplantation or gene editing. FACS is also critical for clinical applications, such as the production of CAR-T cell therapies, where precisely defined T cell populations are required.

The process begins with cells suspended in a sheath fluid that hydrodynamically focuses them into a single-file stream. As each cell passes through a laser interrogation point, optical signals are detected and analyzed in real time. A vibrating nozzle forms droplets, each typically containing a single cell. If the cell meets the sorting criteria, the droplet is electrically charged and then deflected by high-voltage plates into collection tubes. Uncharged droplets go to waste.

Historically, the first FACS instrument was built at Stanford University in the late 1960s by Leonard Herzenberg and colleagues. Modern instruments can sort up to 50,000 cells per second with greater than 99% purity while maintaining high viability. FACS is now a standard tool in research laboratories and clinical diagnostics, including routine immunophenotyping and monitoring of HIV patients through CD4+ T cell counts.

Frequently Asked Questions

What does FACS stand for?

FACS stands for Fluorescence-Activated Cell Sorting. It is a technique that uses fluorescence to identify and separate cells within a heterogeneous sample.

How is FACS different from flow cytometry?

Flow cytometry measures cellular properties, while FACS adds the ability to physically sort cells. FACS allows the isolation of live cells for further culture or analysis.

What are the main applications of FACS?

It is widely used in immunology for lymphocyte subset studies, oncology for isolating tumor cells, molecular biology for purifying transfected cells, and regenerative medicine.