Whether in immunology, oncology or regenerative medicine - wherever cells are used, cell separation plays a crucial role. Blood and tissue samples contain a large number of different cell types, which together form a complex biological system. For research purposes, however, it is often necessary to isolate specific cells or cell populations . This is the only way to precisely investigate their properties, functions and interactions.
However, not every method is equally suitable. The choice of the right technique depends on the issue at hand - and also on the purity, viability and yield required. Here, it is not only know-how that is important, but also the right tools and reagents that enable standardized and reproducible separation.
Basics of cell separation
Cell separation is the separation of specific cells or cell groups from a heterogeneous mixture, such as occurs in blood (whole blood), bone marrow or tissue. The aim is to obtain the desired cells as unchanged and functional as possible.
There are different approaches to this:
- Physical properties: size, density or electrical charge
- Biological characteristics: Surface markers, receptors or antigens
- Mechanical separation: filtration through special sieves or membranes
The challenge lies in finding a balance between purity, speed and cell protection. While some methods deliver a high level of purity, they can also put more strain on the cells. Other methods are particularly gentle, but separate less specifically.
Methods of cell separation
Various methods are available for the separation of cells. Each method has its own strengths, limitations and typical areas of application.
Cell sieves or mesh screens are used to separate cells according to size or shape. This method is particularly practical for the preparation of single cell suspensions from tissue or for the purification of samples prior to subsequent analyses.
Advantage: quick, easy, gentle
Disadvantage: lower specificity compared to marker-based methods
Density gradient centrifugation is a classic technique that is primarily used to isolate peripheral blood mononuclear cells (PBMCs) from whole blood. The blood is layered onto a medium with a defined density (e.g. PBMC Spin or Ficoll) and centrifuged. The cell types accumulate in different layers according to their density so that the desired fraction can be easily extracted.
Advantage: reliable, cost-effective
Disadvantage: time-consuming, stress on the cells possible
The pluriBead technology enables the targeted enrichment or removal of specific cell types from complex samples such as blood (whole blood) or tissue. pluriBead is a combination of biological specificity and mechanical separation. Using specific antibodies, the desired cells are bound to small monodisperse beads and then selectively separated using filter processes - completely without a magnetic field. The process is fast, gentle and flexible: it is suitable for different cell types, can be easily scaled and preserves the functionality of the cells. Ideal for immune cell analysis, preparation for single cell studies or other applications where high purity cell populations are required.
Advantage: high specificity, good purity, fast
Disadvantage: more expensive reagents, marker dependency
Magnetic Activated Cell Sorting (MACS) uses magnetic particles that bind specifically to cell surface markers. The marked cells can then be specifically enriched or removed with the aid of a magnetic field. This technique is particularly useful when highly pure cell populations are required, e.g. for immune cell studies. This method is suitable for both positive and negative cell separation.
Advantage: high specificity, good purity
Disadvantage: more expensive reagents, marker dependency
Fluorescence-Activated Cell Sorting (FACS) is a method in which cells can be individually analyzed and sorted based on their surface markers and fluorescence signals. This technique not only allows separation, but also provides comprehensive data on each individual cell.
Advantage: high specificity, good purity, time-consuming
Disadvantage: more expensive reagents and devices, marker dependency