Bulletin No. 2, 2014

Scientists, Muses and their Labs  15  Tackling the Problem of Male Infertility Infertility affects around 10% to 15% of couples worldwide, and male infertility contributes to approximately 50% of these infertile cases. Male infertility is attributed to multiple factors. Reduced sperm motility is a common cause of infertility and accounts for approximately 18% of male subfertility and infer tility cases. Another common cause of infertility, seminal tract infection, is observed in roughly 11% of infertile male patients. Interestingly, sperm with reduced motility is often associated with genital tract infection; however, the underlying cause and possible association between the two disorders remain largely unexplored. A collaborative research jointly conducted by the University’s Epithelial Cell Biology Re s earch Centre and Shenzhen Second People’s Hospital revealed that deficient human b -defensin-1 (DEFB1) underlies male infertility associated with poor sperm motility and genital tract infection. Prof. Chan Hsiao-chang , director of the centre and professor of physiology at CUHK, led the research. It was found that the amount of DEFB1 in sperm from infertile men exhibiting either genital tract infection or reduced sperm motility is much lower compared to that in normal fertile sperm. Interference with DEFB1 function also decreases both motility and bactericidal activity in normal sperm. The study further demonstrates that treatment with recombinant DEFB1 markedly restores DEFB1 expression, bactericidal activity, sperm quality, and egg-penetrating ability in sperm from infertile patients exhibiting poor sperm motility and genital tract infection, suggesting a feasible therapeutic approach for related male infertility.