Localization patterns of the ganglioside G_M1in human sperm are indicative of male fertility and independent of traditional semen measures

Abstract

Semen analysis lacks a functional component and best identifies extreme cases of infertility. The ganglioside GM1 is known to have functional roles during capacitation and acrosome exocytosis. Here, we assessed whether GM1 localization patterns (Cap‐Score™) correspond with male fertility in different settings: Study 1 involved couples pursuing assisted reproduction in a tertiary care fertility clinic, while Study 2 involved men with known fertility versus those questioning their fertility at a local urology center. In Study 1, we examined various thresholds versus clinical history for 42 patients; 13 had Cap‐Scores ≥39.5%, with 12 of these (92.3%) achieving clinical pregnancy by natural conception or ≤3 intrauterine insemination cycles. Of the 29 patients scoring <39.5%, only six (20.7%) attained clinical pregnancy by natural conception or ≤3 intrauterine insemination cycles. In Study 2, Cap‐Scores were obtained from 76 fertile men (Cohort 1, pregnant partner or recent father) and compared to 122 men seeking fertility assessment (Cohort 2). Cap‐Score values were normally distributed in Cohort 1, with 13.2% having Cap‐Scores more than one standard deviation below the mean (35.3 ± 7.7%). Significantly, more men in Cohort 2 had Cap‐Scores greater than one standard deviation below the normal mean (33.6%; p = 0.001). Minimal/no relationship was found between Cap‐Score and sperm concentration, morphology, or motility. Together, these data demonstrate that Cap‐Score provides novel, clinically relevant insights into sperm function and male fertility that complement traditional semen analysis. Furthermore, the data provide normal reference ranges for fertile men that can help clinicians counsel couples toward the most appropriate fertility treatment.

Timing of sperm capacitation varies reproducibly among men

“…Out of 123 samples, 84% had an increase in Cap‐Score™ from Day0 to Day1‐fix (103/123). A total of 44% (54/123) of the population had an increase in Cap‐Score™ greater than 1 SD (7.7%) defined previously in a population of men with proven fertility (Cardona et al, ). (b) The x‐axis shows the donor number and the y‐axis show the average Cap‐Rate™ of each donor (difference Day1‐fix−Day0).…”

“…When the average difference from Day0 to Day1‐fix was calculated for each donor, 94% of the individuals showed an increase in Cap‐Score™ (49/52) (Figure b). To put these changes into context, we compared the magnitude of the changes in Figure against data we previously collected from 76 fertile men, for whom 7.7 Cap‐Score™ units defined 1 SD in the Cap‐Scores™ which had a normal distribution (Cardona et al, ). We found that 44% (54/123) of the Day1‐fix samples had Cap‐Scores™ that increased more than 1SD from the Cap‐Score™ reported after the 3 hr, Day0, incubation.…”

“…Recently, we defined representative patterns of localization of the ganglioside G M1 that could be used to identify capacitated human sperm at the single cell level (Moody et al, ) and quantitatively provide information at the population level (Cardona et al, ). Based on multiple lines of investigation regarding these patterns, including the observation that sperm having “capacitated” patterns were in fact those cells that could undergo AE, and demonstrations of the precision and repeatability of the assay (Moody et al, ), we defined the Cap‐Score™ as the percentage of sperm having G M1 localization patterns consistent with capacitation in relation to the total number of sperm having G M1 localization patterns.…”

“…In an independently‐performed clinical study that was included in the recent papers, Cap‐Scores™ over a certain threshold were highly correlated with paternity by natural conception or within three or fewer cycles of intrauterine insemination, while those below that threshold were less likely to conceive (Cardona et al, ). Because that study was performed at a tertiary care fertility clinic with a patient base atypical for most urologists and local fertility clinics, we performed a cohort comparison trial, comparing Cap‐Scores™ in a population of 76 men with proven fertility versus 122 men questioning their fertility at a local urology center.…”

“…Because that study was performed at a tertiary care fertility clinic with a patient base atypical for most urologists and local fertility clinics, we performed a cohort comparison trial, comparing Cap‐Scores™ in a population of 76 men with proven fertility versus 122 men questioning their fertility at a local urology center. Significantly more men questioning their fertility had Cap‐Scores™ at or below one standard deviation (SD) below the mean of the fertile men (Cardona et al, ). These and other studies validated the use of the Cap‐Score™ to assay sperm capacitation/function and to reflect male fertility.…”