PIXIES

PIXIE is a special method of sperm selection for the male factor of infertility. It is used as an adjunct to ICSI and is based on the physiological mechanisms of fertilization. The PIXIE method is designed to increase the probability of successful fertilization and consists in selecting the most healthy and high-quality spermatozoa.

During natural fertilization, spermatozoa bind to cumulus cells (these are auxiliary cells surrounding the egg inside the follicle) using special receptors sensitive to hyaluronate (hyaluronic acid). They split the top layer, “make their way” to the oocytes and fertilize them. It is the network of hyaluronate fibers that, in turn, connect cumulus molecules. The presence of hyaluronate receptors in spermatozoa indicates their maturity, and, consequently, their suitability for fertilization. It is this property that is used to filter spermatozoa within the framework of PIXIE technology.

A suspension of spermatozoa is placed in a cup that contains hyaluronate. Embryologists monitor which spermatozoa bind to hyaluronic acid and which do not. Due to the presence of receptors, the highest quality mature spermatozoa begin to attach to the bowl. Thus, an embryologist can identify the highest quality material for subsequent fertilization using ICSI based on three criteria - morphology, motility, and the presence of hyaluronate receptors.

It is recommended to pay attention to IVF with PIXIE for patients who, according to the results of the HBA test, have an abnormally low percentage of spermatozoa binding to hyaluronic acid. Normally, this indicator should be 80%. If this number is below 65% of motile spermatozoa, this can be considered a direct indication of PIXIE. In this group of patients, the use of PIXIES has been proven to reduce the risk of miscarriage (Worillow et al., 2013).