Quantitative selection of single human sperm with high DNA integrity for intracytoplasmic sperm injection.

OBJECTIVE

To study at the single-cell level whether a sperm's motility and morphology parameters reflect its DNA integrity, and to establish a set of quantitative criteria for selecting single sperm with high DNA integrity.

DESIGN

Prospective study.

SETTING

In vitro fertilization center and university laboratories.

PATIENT(S): Male patients undergoing infertility treatments.

INTERVENTION(S): None.

MAIN OUTCOME MEASURE(S): The motility and morphology parameters of each sperm were measured with the use of computer vision algorithms. The sperm was then aspirated and transferred for DNA fragmentation measurement by single-cell gel electrophoresis (comet assay).

RESULT(S): We adapted the World Health Organization criteria, which were originally defined for semen analysis, and established a set of quantitative criteria for single-sperm selection in intracytoplasmic sperm injection. Sperm satisfying the criteria had significantly lower DNA fragmentation levels than the sample population. Both normal motility and normal morphology were required for a sperm to have low DNA fragmentation. The quantitative criteria were integrated into a software program for sperm selection. In blind tests in which our software and three embryologists selected sperm from the same patient samples, our software outperformed the embryologists and selected sperm with the highest DNA integrity.

CONCLUSION(S): At the single-cell level, a sperm's motility and morphology parameters reflect its DNA integrity. The developed technique and criteria hold the potential to mitigate the risk factor of sperm DNA fragmentation in intracytoplasmic sperm injection.