In nature, human oocytes are surrounded by Hyaluronic
Acid (HA), which is then involved in the mechanism of
sperm selection. In fact, only mature spermatozoa which
have extruded their specific receptors to bind to and digest
HA can reach the oocyte and fertilize it. HA’s role as
“physiologic selector” is now well recognized also in vitro:
it has been demonstrated that spermatozoa able to bind HA
in vitro are those that have completed plasma membrane
remodelling, cytoplasmic extrusion and nuclear maturation
[1–3]. Furthermore, these HA-bound spermatozoa show
low chromosomal aneuploidies and DNA fragmentation,
and good nuclear morphology [4, 5]. Thus, HA-sperm
selection prior to intracytoplasmic sperm injection (ICSI)
helps to optimize the outcome of the treatment, especially
when insemination of only a limited number of oocytes is
allowed by law [6].
In a previous prospective-randomized study, we demonstrated
that the injection of HA-bound spermatozoa (HA-ICSI
or Physiologic ICSI) improved embryo quality and development,
by favouring selection of spermatozoa with normal
nucleus and intact DNA [5]. The aim of the present study is
to verify the role of HA for sperm selection on a larger
number of HA-ICSI treatments.