Both techniques allow the selection of the best spermatozoa to carry out the microinjection into the egg. It is usually said that both sperm selection techniques have the same purpose, that is, the selection of spermatozoa with less DNA fragmentation. However, this is not exactly the case.
The columns of adnexins or MACS serve to filter apoptotic spermatozoa. Apoptosis or programmed cell death is a phenomenon that acts as a defense mechanism in our body by eliminating unwanted cells, and can occur as a result of injury or cellular stress.
The reason why it is said that MACS can help us eliminate fragmented sperm is because DNA fragmentation will eventually lead to sperm apoptosis. What is not entirely clear is whether all sperm with fragmentation will express markers of apoptosis and whether this will occur in both single and double stranded sperm. In fact, the scientific evidence is quite dubious in this regard, since few studies have found a significant improvement in gestation rates using this technique.
Instead, the Fertile Chip is specifically designed to filter sperm with fragmentation, both single and double chain. The mechanism uses microfluidic dynamics that mimics the conditions that occur within the female genital tract.
Furthermore, although the Fertile Chip is a relatively new technique, several studies have been published in which it has been found that the Fertile Chip is capable of reducing spermatozoa with fragmentation and increasing the percentage of good quality embryos obtained.
Thus, we could say that the Fertile Chip is better for men with sperm DNA fragmentation, especially double-stranded. It is also true that in order to use this filter a certain quality of the sperm is necessary in terms of sperm concentration and motility parameters, so in very altered samples it will not be possible to use the Fertile Chip. In this case, as an alternative, MACS or other types of filters can be used which, even if only partially, will help us to reduce the number of spermatozoa with fragmentation.