Objective: To determine the content of sperm mitochondrial DNA (mtDNA) in patients with asthenospermia or with poor sperm motility.
Design: Analysis of the content of mtDNA as the ratio between the amount of mtDNA and nuclear DNA by using a new concurrent polymerase chain reaction.
Setting: University hospital infertility center.
Patient(s): Eighty-six men who sought infertility therapy.
Intervention(s): Moving characteristics of sperm were examined with a computer-assisted semen analyzer.
Main outcome measure(s): Sperm samples were classified into two groups, one with asthenospermia and the other with normal moving characteristics. The content of mtDNA in sperm was determined by polymerase chain reaction. We analyzed the mitochondrial mass by MitoTracker Green staining and analyzed DNA content with propidium iodide staining by flow cytometry.
Result(s): A decrease in sperm mtDNA content was detected in patients with asthenospermia or with poor sperm motility (<20% motility). The relative mtDNA contents in the asthenospermia and normal groups were 7.2 +/- 1.3 (mean +/- SD, n = 23) and 74.1 +/- 2.0 (n = 29), respectively. Lower intensities of propidium iodide staining were detected in patients with asthenospermia or poor motility, but there was no significant difference in MitoTracker Green staining between the sperm with different motility.
Conclusion(s): We suggest that mtDNA content may serve as a useful indicator of sperm quality and that mtDNA depletion may play an important role in the pathophysiology of some male infertility.