Donald P. Evenson

Sperm Chromatin Structure Assay is useful for fertility assessment.

The Sperm Chromatin Structure Assay (SCSA) serves as a tool for measuring clinically important properties of sperm nuclear chromatin integrity. The assay utilizes the metachromatic features of Acridine Orange (AO), a DNA probe, and the principles of flow cytometry (FCM). SCSA data are not well correlated with classical sperm quality parameters and have been solidly shown to predict sub/infertility. This assay is ideally suited to human and animal fertility clinics to assess male sperm DNA integrity as related to fertility potential and embryo development as well as effects of reproductive toxicants. A detailed description of the SCSA follows.

Relationship between the outcomes of assisted reproductive techniques and sperm DNA fragmentation as measured by the sperm chromatin structure assay

OBJECTIVE To investigate how moderate and/or high levels of DNA fragmentation (DFI), as measured by the sperm chromatin structure assay (SCSA), affect either IVF or IVF with intracytoplasmic sperm injection (ICSI) fertilization, cleavage, blastulation, implantation, and pregnancy. DESIGN Retrospective clinical study. SETTING Academic human reproduction laboratory. PATIENT(S) Eighty-nine couples undergoing IVF with conventional fertilization or ICSI. INTERVENTION(S) Sperm chromatin structure assay testing (SCSA) of semen aliquot taken from ejaculate used for assisted reproductive technology (ART). MAIN OUTCOME MEASURE(S) Related DFI to conventional semen parameters and cycle-specific outcomes after ART. RESULT(S) No patients achieved clinical pregnancy if SCSA values exceeded the DFI (27%, P<.01), moderate DFI (15%, P<.01), or high DFI (15%, P<.05) thresholds. Dividing the DFI sperm population into moderate-fragmentation and high-fragmentation categories did not improve the prognostic value of the SCSA. No coefficient of determination (r(2)) between SCSA parameters and conventional parameters exceeded 0.29. CONCLUSION(S) Sperm chromatin structure assay identified thresholds for negative pregnancy outcome after ART not identified using conventional semen parameters. This is the first study analyzing the clinical value of sperm DFI to [1] include a large number of ART patients (n = 89), [2] perform SCSA analysis on a semen aliquot from the ejaculate used for ART, and [3] examine how the extent (moderate and high DFI) of DFI influenced ART outcomes.

Individuality of DNA denaturation patterns in human sperm as measured by the sperm chromatin structure assay.

Eight monthly semen samples from 45 men not known to be exposed to industrial toxicants were measured by the flow cytometric sperm chromatin structure assay (SCSA). This assay determines susceptibility of sperm DNA to in situ, acid-induced denaturation and is quantitated by the metachromatic shift of acridine orange fluorescence from green (native DNA) to red (denatured DNA). The observed green versus red fluorescence scattergram (cytogram) patterns were generally unique between donors and homogeneous within a donor over time. Within a donor, the cytogram patterns were the same whether intact sperm cells or detached nuclei were measured. For some individuals the cytogram patterns differed for some months and then returned to the original pattern. Intraclass correlations for mean and standard deviation of alpha t [alpha t = red/(red + green) fluorescence] were higher (.67 to .90) than any classically measured semen variables, suggesting that SCSA results within an individual were more consistent than other measures. Furthermore, average within-donor CV of alpha t parameters expressed as a percent of any given individuals means was around 10%, which is significantly lower than those derived from common semen measures. The SCSA is an objective, technically sound, biologically stable, sensitive, and feasible measure of semen quality.

Leukocytospermia is associated with increased reactive oxygen species production by human spermatozoa

To investigate the role of increased seminal leukocytes in enhancing reactive oxygen species (ROS) production by human spermatozoa.A prospective study. Male infertility clinic.Forty-eight infertile men. Standard semen analysis. Assessment of sperm nuclear DNA damage by sperm chromatin structure assay. Incubation of spermatozoa from nonleukocytospermic samples with blood neutrophils. Spontaneous and phorbol 12-myristate 13-acetate (PMA)-induced ROS production in pure-sperm suspensions (after removal of leukocytes) as measured by a chemiluminescence assay. Levels of spontaneous and PMA-induced ROS production in pure-sperm suspensions from the infertile men with a diagnosis of leukocytospermia (n = 16) were significantly higher compared with the case of infertile men without leukocytospermia (n = 32) and with the case of a control group of healthy volunteers (n = 13). A similar pattern of increased ROS was observed when spermatozoa were incubated with blood neutrophils. Leukocytospermia was associated with a significant decrease in sperm motility and increase in DNA damage. Increased seminal leukocytes may play a role in stimulating ROS production by human spermatozoa. Such stimulation may be mediated via direct cell-cell contact or by soluble products released by leukocytes. Poor sperm quality in leukocytospermic samples may be due to leukocyte-mediated oxidative stress.

Flow cytometric evaluation of boar semen by the sperm chromatin structure assay as related to cryopreservation and fertility.

Boar semen from a heterospermic mating trial and semen cryopreserved by various methods were evaluated by the flow cytometric sperm chromatin structure assay (SCSA), which measures the susceptibility of sperm nuclear DNA to acid-induced denaturation in situ. Spermatozoa were treated with a pH 1.4 buffer and then stained with the metachromatic dye acridine orange. Acridine orange intercalated into double-stranded DNA (native) fluoresces green while single-stranded DNA (denatured) fluoresces red when excited with 488 nm light. The ratio of red to total fluorescence provides an index of normality/abnormality. The SCSA data on neat boar semen or semen in either Kiev-Merck or Pursel-Johnson extender and frozen directly on dry ice blocks or plunged into LN2 did not differ within individual boars. Therefore, chromatin structure, as measured by the SCSA, was not influenced differently by these 2 methods of semen cryopreservation. When semen from 6 boars was mixed in equal sperm numbers in six 3-way combinations and inseminated into at least 3 Duroc gilts per combination, 4 of the 6 combinations yielded 2 litters, while the remaining 2 combinations yielded 3 litters. The SCSA correctly predicted both the high and low fertility boars based on a ratio of offspring as deviated from the theoretical percentage. Thus, the SCSA was found to be a valuable adjunct method for evaluating boar semen quality.

Meta-analysis of sperm DNA fragmentation using the sperm chromatin structure assay.

Meta-analyses were conducted to investigate the relationship of sperm DNA fragmentation on pregnancy outcome using in-vivo fertilization, IUI, routine IVF and ICSI. Couples with no known infertility problems were 7.0 times (CI 3.17, 17.7) more likely to achieve a pregnancy/delivery if the DNA fragmentation index (DFI) was <30% (n = 362, P = 0.0001) using in-vivo fertilization. Infertile couples using IUI were 7.3 times (CI 2.88, 18.3) more likely to achieve a pregnancy/delivery if their DFI was <30% (n = 518, P = 0.0001). With routine IVF, infertile couples were approximately 2.0 times (CI 1.02, 2.84) more likely to become pregnant if their DFI was <30% (n = 381, P = 0.03). For ICSI and/or routine IVF, the results showed a non-significant trend where infertile couples were 1.6 times (CI 0.92, 2.94) more likely to achieve a pregnancy/delivery if the DFI was <30% (n = 323,P = 0.06). The in-vivo and IUI meta-analyses were similar, indicating that IUI infertility patients with <30% DFI have as good a statistical probability of obtaining a pregnancy/delivery as in-vivo presumably fertile couples with the same DFI. These meta-analyses show that the Sperm Chromatin Structure Assay infertility test was significantly predictive for reduced pregnancy success using in-vivo, IUI and routine IVF, and to a lesser extent ICSI fertilization.

Rapid analysis of normal and abnormal cell types in human semen and testis biopsies by flow cytometry.

A simple, rapid procedure is described that quantitates RNA content and DNA content/chromatin condensation for each of many possible cell types and differentiation levels of the cells present in human semen. A fresh semen sample (1-6 hr postemission) or frozen sample (allowing samples to be accumulated and sent to a laboratory) is treated with a detergent solution, stained with acridine orange (AO), and measured by flow cytometry (FCM); approximately 10 minutes are required to measure 5,000 cells per sample and analyze the data with computer assistance. The following can be learned from a single measurement: a) the percentage of each cell type in semen including, i) mature sperm, ii) immature sperm precursor cells, representing all stages of development from spermatogonia to mature sperm, iii) somatic cells, e.g., leukocytes; b) normality/abnormality of sperm nuclear chromatin condensation. These measurements can be correlated with cell types in testis biopsies identified by two-parameter FCM measurements (RNA versus DNA) using AO as the fluorescent probe.

Increased DNA damage in sperm from leukocytospermic semen samples as determined by the sperm chromatin structure assay

OBJECTIVE To determine DNA damage as measured by the sperm chromatin structure assay (SCSA) in subsets of human spermatozoa at different stages of maturation in patients who are undergoing infertility evaluation. DESIGN Prospective study. SETTING Andrology laboratory at a tertiary care hospital. PATIENT(S) Fifty-six patients undergoing infertility evaluation. Patients with normal semen parameters (n = 17), abnormal semen parameters (n = 29), leukocytospermia (n = 10), and a group of healthy fertile men (n = 18) were included in the study. INTERVENTION(S) None. MAIN OUTCOME MEASURE(S) The shift of green (native DNA) to red (denatured, single-stranded DNA) fluorescence was measured and quantified using the expression alpha(t) (red fluorescence/[red + green fluorescence] per cell). Sperm DNA damage was examined in subsets of spermatozoa isolated by a three-step density gradient. The DNA damage was correlated with classic semen characteristics. RESULT(S) Leukocyte concentration in semen was directly correlated with chromatin alterations in immature and mature sperm. Leukocyte concentration in semen was also directly correlated with immature germ cell concentration and the percentage of abnormal forms in semen. CONCLUSION(S) The increase in chromatin alterations and DNA damage in sperm, as defined by the sperm chromatin structure assay from leukocytospermic samples may be related to alterations in the regulation of spermatogenesis.

Bull sperm head morphometry related to abnormal chromatin structure and fertility.

This study investigated the relationship between morphologically abnormal sperm, sperm chromatin structure, and fertility. Semen samples were obtained from 13 bulls. The sperm chromatin structure assay (SCSA), a sensitive measure of denaturability of sperm nuclear DNA in situ following acid treatment, was performed on each sample to quantitate abnormal chromatin structure. Feulgenstained sperm head morphology was measured by computerized image analysis (ONCOR-Image): Sixteen parameters were measured for each of 200 nuclei per sample. Fertility estimates were available for nine of the bulls. The SCSA variable SD alpha t was correlated with fertility ranking (r = 0.617, P < 0.01). No correlations were seen between means of the imaging variables and SCSA variables % COMP alpha t or SD alpha t. Significant correlations (P < 0.05) were seen between SD alpha t and the variation of imaging variables eccentricity, width, and light blobs. Significant correlations (P < 0.05) were seen between % COMP alpha t and the variation of imaging variables area, perimeter, p2a, bending energy, nmac, sphericity, eccentricity, length, and width. A regression model for fertility rankings incorporating the standard deviation of the imaging variables area, bending energy, nmac, eccentricity, condensity, light blobs, and dark blobs was highly significant (r2 = 0.999, P < 0.05). These results indicate that variation of morphometry measurements is likely a sensitive biomarker related to fertility potential and abnormal chromatin structure.

Flow cytometric analysis for reproductive biology

Summary— Flow cytometric studies of spermatogenesis have been advanced by the need for: i) rapid, sensitive, objective and multiparameter measurements of reproductive effects due to environmental, occupational, and therapeutic exposure to toxicants; and ii) assessment of fertility potential of human and animal sperm. As a consequence, various flow cytometric techniques are already available to identify germ cell subpopulations undergoing both proliferative and maturative processes in normal and perturbed conditions. Significant improvements have been introduced in order to investigate the spermatogenic complex differentiation pathway and the apparent uniformity of mature sperm. Flow cytometry (FCM) has been applied to the measurement of both testis and sperm cells in a variety of species, including man. End points considered in toxicology studies are: altered testicular germ cell ratios, DNA and RNA content, increase of the coefficient of variation, induction of diploid elongated spermatids and diploid sperm, altered nuclear morphology, sperm cell viability, mitochondrial function and sperm chromatin structure. Precise DNA content measurements allow accurate analysis to determine the proportion of X‐ and Y‐chromosome bearing sperm and sorting of these subpopulations for gender preselection. FCM technology has reached a maturation level that allows its inclusion in the list of available and routine methods for reproductive studies in human and animal populations.