title: Integration of sperm motility and chemotaxis screening with a microchannel-based device.
abstract: BACKGROUND
  Sperm screening is an essential step in in vitro fertilization (IVF) procedures. The swim-up method, an assay for sperm motility, is used clinically to select the ideal sperm for subsequent manipulation. However, additional parameters, including acrosome reaction capability, chemotaxis, and thermotaxis, are also important indicators of mammalian sperm health. To monitor both sperm motility and chemotaxis simultaneously during sperm screening, we designed and constructed a microdevice comprising a straight channel connected with a bibranch channel that mimics the mammalian female reproductive tract.
  
  
  METHODS
  The width and length of the straight channel were optimized to select the motile sperms. We selectively cultured cumulus cells in the bibranch channel to generate a chemoattractant-forming chemical gradient. Sperm chemotaxis was represented by the ratio of the sperm swimming toward different branches.
  
  
  RESULTS
  The percentage of motile sperms improved from 58.5% (3.8%) to 82.6% (2.9%) by a straight channel 7 mm in length and 1 mm in width. About 10% of sperms were found to be chemotactically responsive in our experiment, which is consistent with previous studies.
  
  
  CONCLUSIONS
  For the first time, we achieved the combined evaluation of both sperm motility and chemotaxis. The motile and chemotactically responsive sperms can easily be enriched on a lab-on-a-chip device to improve IVF outcome.
authors.affiliation: Medical Systems Biology Research Center, Department of Biomedical Engineering, Tsinghua University School of Medicine, Beijing, China.
authors.forename: Lan
authors.initials: L
authors.lastname: Xie
authors.forename: Rui
authors.initials: R
authors.lastname: Ma
authors.forename: Chao
authors.initials: C
authors.lastname: Han
authors.forename: Kai
authors.initials: K
authors.lastname: Su
authors.forename: Qiufang
authors.initials: Q
authors.lastname: Zhang
authors.forename: Tian
authors.initials: T
authors.lastname: Qiu
authors.forename: Lei
authors.initials: L
authors.lastname: Wang
authors.forename: Guoliang
authors.initials: G
authors.lastname: Huang
authors.forename: Jie
authors.initials: J
authors.lastname: Qiao
authors.forename: Jundong
authors.initials: J
authors.lastname: Wang
authors.forename: Jing
authors.initials: J
authors.lastname: Cheng
mesh_terms: D000818:Animals; D002478:Cells, Cultured; D002633:Chemotaxis; D005260:Female; D006801:Humans; D008297:Male; D051379:Mice; D008813:Mice, Inbred ICR; D044085:Microfluidics / Q000295:instrumentation; D013081:Sperm Motility; D013094:Spermatozoa / Q000502:physiology*