Related Experiment Video
Updated: Jun 8, 2026
Flow Cytometric Analysis of Biomarkers for Detecting Human Sperm Functional Defects
Published on: April 21, 2022
TUNEL assay and SCSA determine different aspects of sperm DNA damage
Ralf Henkel1, C F Hoogendijk, P J D Bouic
1Department of Medical Biosciences, University of the Western Cape, Bellville, 7535, South Africa. rhenkel@uwc.ac.za
Abstract:
For the determination of sperm DNA damage, different assays are used. However, no further distinction is made and the literature generally speaks about DNA damage. Thus, this study aimed at comparing the sperm chromatin structure assay (SCSA) and the TUNEL assay. In 79 patients, sperm DNA damage was determined flow cytometrically using the SCSA and the TUNEL assay. Moreover, normal sperm morphology was evaluated according to strict criteria. A statistical comparison of the two methods was performed using standard correlations, Bland and Altman plots, Passing-Bablok regressions and concordance correlation. Results show a significant difference between P- and G-pattern morphology only for the mean channel fluorescence of the SCSA. Spearman's rank correlations between the different parameters of both assays, SCSA and TUNEL, revealed significant associations between the parameters of the assays. However, when applying Bland and Altman plots, Passing-Bablok regression and concordance correlation results showed that these methods are not comparable. These different techniques determine different aspects of sperm DNA damage, i.e. 'real' DNA damage for the TUNEL assay and 'potential' DNA damage in terms of susceptibility to DNA denaturation for the SCSA. Thus, one should clearly distinguish between the different assays, not only practically and methodologically but also linguistically.
Insights
The sperm chromatin structure assay (SCSA) and TUNEL assay both detect sperm DNA damage but measure different aspects. These methods are not interchangeable for assessing male fertility potential.
Area of Science:
- Reproductive Biology
- Genetics
- Clinical Diagnostics
Background:
- Sperm DNA damage is a critical factor in male infertility.
- Various assays exist for sperm DNA damage assessment, often used interchangeably.
- Lack of differentiation between assay methodologies can lead to misinterpretation.
Purpose of the Study:
- To compare the Sperm Chromatin Structure Assay (SCSA) and the TUNEL assay for determining sperm DNA damage.
- To evaluate the comparability of SCSA and TUNEL assay results in a patient cohort.
- To clarify the distinct aspects of sperm DNA damage measured by each assay.
Main Methods:
- Sperm DNA damage was assessed in 79 patients using flow cytometric SCSA and TUNEL assays.
- Normal sperm morphology was evaluated using strict criteria.
- Statistical analyses included Spearman's rank correlations, Bland and Altman plots, Passing-Bablok regressions, and concordance correlation.
Main Results:
- Significant associations were found between SCSA and TUNEL assay parameters.
- However, Bland and Altman plots, Passing-Bablok regression, and concordance correlation indicated the methods are not comparable.
- SCSA measures 'potential' DNA damage (susceptibility to denaturation), while TUNEL measures 'real' DNA damage.
Conclusions:
- SCSA and TUNEL assay are not interchangeable for assessing sperm DNA damage.
- The assays detect different biological phenomena related to DNA integrity.
- Clear distinction between assay methodologies and their linguistic representation is crucial for accurate interpretation.
