Hong Kong Med J 2024;30(Suppl 3):S23-5
Sialyl-Lewis(x) interaction for sperm selection in assisted reproductive treatment: abridged secondary publication
PCN Chiu, WSB Yeung, EHY Ng, CL Lee
Department of Obstetrics and Gynaecology, The University of Hong Kong, Hong Kong SAR, China
 
 
  1. Capacitated human spermatozoa initiate fertilisation via binding to the zona pellucida (ZP). The sialyl-Lewis(x) (sLeX) sequence is the most abundant terminal sequence on the glycans of human ZP glycoproteins involved in spermatozoa-ZP binding. Compared with unbound spermatozoa, ZP- or sLeX-bound spermatozoa have better fertilisation potential and quality in terms of morphology, DNA integrity, chromatin integrity, protamination, and global methylation.
  2. Four sLeX-binding proteins of capacitated spermatozoa were identified: chromosome 1 open reading frame 56 (C1orf56), ZP-binding protein 1, heat shock-related 70 kDa protein 2, and sperm acrosome membrane–associated protein 1.
  3. Clorf56 translocated to the cell surface of the spermatozoa acrosomal region during capacitation. Treatment with anti-C1orf56 antibody inhibited spermatozoa-ZP binding and ZP-induced acrosomal reactions. Purified C1orf56 from capacitated spermatozoa were able to bind human ZP.
  4. The in vitro fertilisation rate was not associated with the percentage of capacitated spermatozoa expressing C1orf56. However, the percentage of C1orf56-positive spermatozoa in the acrosome-reacted population was significantly lower in cycles with a fertilisation rate <60% than in cycles with a fertilisation rate ≥60%. These results suggest that C1orf56 has important roles after ZP-binding and acrosomal reactions.
  5. Sperm quality can be significantly enhanced by selection methods involving ZP, sLeX, and annexin V microbeads.