MACS

What is MACS

MACS stands for Magnetic Activated Cell Sorting (i.e., magnetic separation by annexin columns).

Sperm quality is one of the factors that help determine the success of assisted reproduction treatments. Proper fertilisation requires that the spermatozoa have plasma membrane integrity and normal function. Membrane alterations have been linked to spermatozoa that have initiated the apoptosis process, which could be partially responsible for the low fertilisation and implantation rates found in the corresponding assisted reproduction cycles.

Magnetic separation by Annexin V columns (MACS) is a selection technique that, when applied to sperm samples, can eliminate apoptotic spermatozoa from the ejaculate, i.e., spermatozoa that have initiated the programmed cell death cycle.

This is achieved by incubating the semen sample with Annexin V conjugated to biodegradable iron spheres and then making it go through a column subjected to a magnetic field. Thanks to Annexin V, a protein with a high affinity for phosphatidylserine (an apoptotic marker), apoptotic spermatozoa bind to Annexin V and are retained on the column wall, while non-apoptotic spermatozoa are recovered by elution at the column exit.

The fraction of non-apoptotic spermatozoa is used in assisted reproduction treatments to improve the spermatozoa’s fertilising capacity and thus obtain a higher pregnancy rate.

This technique can be applied in couples where the male partner has high sperm DNA fragmentation.