Magnetic cell separation

This approach is useful if an important marker for the target cells is also expressed on a fraction of undesired cells. To enable positive selection of the target cells based on this marker, the fraction of undesired cells needs to be depleted first. To this end, the undesired cells are magnetically labeled via antigens distinct from that common marker. During separation, the labeled cells are retained in the column. The flow-through fraction contains the target cells. These cells can then be labeled with MACS MicroBeads for that marker, and the target cells are isolated by positive selection.
Sophisticated MACS Cell Isolation Kits based on this strategy are available for the fast and convenient isolation of specific cell subsets.

This option enables straightforward positive selection of target cells. Hundreds of reagents are available for the isolation of specific cell types and subsets. The strong magnetic field within a MACS Column allows for minimal cell labeling with nano-sized beads, thus preventing epitope saturation and non-specific labeling. Moreover, cells are not activated during the separation process. 

• The gentlest, least manipulative positive selection method available
• Preservation of cell functionality due to optimal labeling
• Labeled cells are ready for downstream applications as beads are biodegradable

MACS Cell Isolation Kits contain a cocktail of titrated antibodies and MACS MicroBeads for indirect magnetic labeling. They are the preferred choice if binding of antibodies to the target cells is not desired. Minimal labeling of unwanted cells with MACS MicroBeads avoids non-specific labeling of target cells, leaving the target cells truly untouched. In contrast, column-free methods based on nano-sized beads from other manufacturers require high concentrations of labeling reagents resulting in non-specific labeling of the target cell fraction (see figure below).

• High purity and recovery rates
• Fully compatible with any downstream application
• No non-specific labeling of target cells

StraightFrom® MicroBeads allow magnetic isolation of various leukocyte subsets from different blood-derived starting materials by positive selection. In contrast to conventional methods, StraightFrom Technology does not require density gradient centrifugation, thus resulting in a simple and short protocol (see figure below). 

• Cell isolation directly from whole blood, buffy coat, and leukocyte reduction system chamber (LRSC)
• Isolated target cells are immediately ready for any downstream application
• Simple protocol with only few handling steps

MACSxpress® Technology enables fast isolation of cells directly from whole blood, omitting all centrifugation steps. This method is independent of columns. However, MACSxpress Beads are micro-sized and therefore allow for minimal labeling of unwanted cells, preventing non-specific labeling and activation of target cells. Non-target cells are removed by immunomagnetic depletion. Simultaneously, erythrocytes are sedimented to obtain target cell populations of exceptional purity.

• Isolated cells from whole blood within 20 minutes
• No density gradient centrifugation
• High reproducibility due to minimal sample handling

REAlease® MicroBead Kits have been developed for positive selection of target cells from PBMCs. REAlease MicroBead Technology relies on recombinantly engineered antibody fragments instead of antibodies to label specific cell surface markers. The antibody fragments have a low affinity for cell surface epitopes. However, when the fragments are multimerized as a complex, they bind epitopes on target cells with high avidity and enable effective magnetic cell separation. REAlease Technology controls the multimer / monomer state of the fragments and thus triggers the release of monomerized antibody fragments from the cell surface after isolation. Ultimately, the isolated, positively selected target cells are free from antibody fragments and magnetic labels and are thus available for further separation steps (see figure below). Of course, the negative, i.e. non-labeled, cell fraction from this separation step is also available for further separation by positive selection (see figure below).

• Bead-free cells: suited for second round of magnetic labeling
• Label-free cells: the epitope of a marker becomes completely available again
• Recombinantly produced: lot-to-lot consistency allows for reproducible results

UltraPure MicroBeads have been particularly optimized for use with samples that contain large amounts of cell debris or low numbers of target cells. UltraPure MicroBeads greatly improve recovery and purity of the sorted population by specifically enriching viable target cells.

• Optimized formulation to minimize debris
• High cell purity, even from challenging starting materials
• As easy to use as the conventional MACS MicroBeads