Question

Why is it important to remove dead cells during sorting of eukaryotic cells?

Answer

Dead cells represent a significant issue in cell sorting. Generally, if a suspension contains more than 10% dead cells, they must be removed. Below this threshold, sorting performance may still be negatively affected.

The main reasons to eliminate dead cells are:

• Dead cells release free DNA, which can cause cell clumping.
• Dead cells can bind antibodies nonspecifically, leading to false positives.

The first problem can be mitigated by adding DNase I.
The second issue worsens especially in antibody-mediated separations, as dead non-target cells may still bind antibodies, compromising purity.

The most effective solution is to completely remove dead or dying cells via a pre-sorting purification step.