title: Zeta Sperm Selection Improves Pregnancy Rate and Alters Sex Ratio in Male Factor Infertility Patients: A Double-Blind, Randomized Clinical Trial.
abstract: BACKGROUND
  Selection of sperm for intra-cytoplasmic sperm injection (ICSI) is usually considered as the ultimate technique to alleviate male-factor infertility. In routine ICSI, selection is based on morphology and viability which does not necessarily preclude the chance injection of DNA-damaged or apoptotic sperm into the oocyte. Sperm with high negative surface electrical charge, named "Zeta potential", are mature and more likely to have intact chromatin. In addition, X-bearing spermatozoa carry more negative charge. Therefore, we aimed to compare the clinical outcomes of Zeta procedure with routine sperm selection in infertile men candidate for ICSI.
  
  
  METHODS
  From a total of 203 ICSI cycles studied, 101 cycles were allocated to density gradient centrifugation (DGC)/Zeta group and the remaining 102 were included in the DGC group in this prospective study. Clinical outcomes were com- pared between the two groups. The ratios of Xand Y bearing sperm were assessed by fluorescence in situ hybridization (FISH) and quantitative polymerase chain reaction (qPCR) methods in 17 independent semen samples.
  
  
  RESULTS
  In the present double-blind randomized clinical trial, a significant increase in top quality embryos and pregnancy rate were observed in DGC/Zeta group compared to DGC group. Moreover, sex ratio (XY/XX) at birth significantly was lower in the DGC/Zeta group compared to DGC group despite similar ratio of X/Y bearings sper- matozoa following Zeta selection.
  
  
  CONCLUSIONS
  Zeta method not only improves the percentage of top embryo quality and pregnancy outcome but also alters the sex ratio compared to the conventional DGC method, despite no significant change in the ratio of Xand Ybearing sperm population (Registration number: IRCT201108047223N1).
authors.affiliation: Department of Reproductive Biotechnology, Reproductive Biomedicine Research Center, Royan Institute for Biotechnology, ACECR, Isfahan, Iran; Isfahan Fertility and Infertility Center, Isfahan, Iran.
authors.forename: Mohammad Hossein
authors.initials: MH
authors.lastname: Nasr Esfahani
authors.affiliation: Isfahan Fertility and Infertility Center, Isfahan, Iran.
authors.forename: Mohammad Reza
authors.initials: MR
authors.lastname: Deemeh
authors.affiliation: Department of Reproductive Biotechnology, Reproductive Biomedicine Research Center, Royan Institute for Biotechnology, ACECR, Isfahan, Iran.
authors.forename: Marziyeh
authors.initials: M
authors.lastname: Tavalaee
authors.affiliation: Department of Animal Science, Ferdowsi University of Mashhad, Mashhad, Iran; Embryonic and Stem Cell Biotechnology Research Group, Institute of Biotechnology, Ferdowsi University of Mashhad, Mashhad, Iran.
authors.forename: Mohammad Hadi
authors.initials: MH
authors.lastname: Sekhavati
authors.affiliation: Department of Genetics, Reproductive Biomedicine Research Center, Royan Institute for Reproductive Biomedicine, ACECR, Tehran, Iran.
authors.forename: Hamid
authors.initials: H
authors.lastname: Gourabi
keywords: Density Gradient Centrifugation; Embryo Quality; Pregnancy; Sex Ratio; Zeta Potential