Advanced sperm selection methods: effects on sperm parameters and IVF outcomes

To date, human infertility is considered by World Health Organization (WHO) as a serious global problem. It affects 10-15% of couples worldwide and approximately 20-30% of infertility cases are related to a male infertility factor. Semen parameters have a direct relation to male infertility and the periodic updates of the WHO manual for the examination and processing of human semen highlight an important decline in semen quality during the last 50 years. Moreover, increasing evidence are suggesting that seminal fluids with normal sperm parameters can conceal underlying molecular abnormalities, as DNA damages, able to negatively affect in vitro fertilization (IVF) outcomes. DNA fragmentation may already exist in semen samples due to different conditions or can be induced or increased during assisted reproductive technologies (ART) semen manipulations. Traditional techniques of sperm selection aim to isolate the healthiest sperm in terms of vitality, motility and morphology, but can be inefficient in selecting spermatozoa without DNA fragmentation; furthermore, they often include centrifugation steps which may enhance DNA damages. In an attempt to optimize ART outcomes, alternative sperm selection methods have been proposed in the last years. This study evaluates the effect of two emerging sperm selection procedures, magnetic activated cell sorting (MACS) and microfluidics, on ART cycles in terms of sperm motility, fertilization rate, cleavage rate and pregnancy rate. Reported data are from couples who underwent one or more homologous or oocyte donation ART cycle at the Chianciano Salute clinic. The results from novel sperm selection techniques are compared to those of conventional methods. Collected data may inform ART clinical practice by clarifying the effectiveness of various sperm selection approaches, optimizing routinary used IVF laboratory protocols and improving ART treatments outcomes.