MACS and other sperm selection techniques
Selecting the best sperm increases the chances of achieving pregnancy
Techniques for sperm selection prior to performing ICSI have been evolving over the last years, and now they allow us to carry out a more focused selection to collect the best sperm. Today, a morphological assessment can be performed to select the sperm that will be microinjected by means of special optics with a magnification over x6000 (IMSI). Another option is to perform the so-called “physiological ICSI”, where hyaluronic acid is used, either on the microinjection dish (PICSI) or in the culture medium (“Sperm Slow”) to select mature sperm, which, in principle, carry fewer chromosomal alterations. Yet, recent studies have not proved the superiority of these methods and they remain experimental.
Using annexin columns (i.e. MACS) prior to performing ICSI also allows us to select pre-apopotic sperm, which would undergo programmed cellular death and could not produce developing embryos. These columns are also used in cases where sperm DNA is excessively fragmented, which relates to processes of fertilisation failure and embryo blockage.