Toward the identification of a subset of unexplained infertility: a sperm proteomic approach

Abstract

Objective: To investigate the male gamete proteome and its relation to blastocyst development and reproductive success.

Design: Experimental study.

Setting: Research laboratory.

Patient(s): Male infertility patients (n=12) with no known male factor infertility, donated motile sperm after intracytoplasmic sperm injection during an oocyte donor in vitro fertilization cycle.

Intervention(s): None.

Main outcome measure(s): Proteomic profiles of sperm from normozoospermic males.

Result(s): Patients were grouped based on day-5 embryo development: group A=good blastocyst development (>35%≥grade 3 BB) and group B=poor blastocyst development (<15%≥grade 3 BB). No differences between the groups were observed for sperm concentration, motility, or Kruger morphology. The in vitro fertilization outcome was statistically significantly different with higher viable implantation rates observed for group A (A=80% vs. B=48%). Proteomic analysis of the motile sperm samples revealed 49 proteins with statistically significantly differential abundance in relation to blastocyst development (>1.5-fold). Twenty-nine proteins showed decreased abundance for group B, including several proteins involved in spermatogenesis, and 20 proteins showed increased abundance for group B, including several heat shock proteins.

Conclusion(s): An altered sperm proteome was observed with respect to poor blastocyst development and in vitro fertilization outcome in donor oocyte cycles despite normal sperm testing parameters. These data could represent a novel subset of male factor infertility. Ongoing investigation into the male factor contribution to idiopathic infertility may result in improved patient care and enhanced outcomes.

Keywords: Proteomics; sperm; unexplained infertility.