Biochemical markers of sperm function: male fertility and sperm selection for ICSI

The expression of a 70 kDa chaperone protein, HspA2 (formerly called CK-M), has been identified in mature human spermatozoa. The central role of HspA2 has been established, as the expression level of this protein is related to sperm cellular maturity, DNA integrity, chromatin maturity, chromosomal aneuploidy frequency and sperm function, including fertilizing potential. The spermiogenetic events of cytoplasmic extrusion and remodelling of the plasma membrane, which facilitate the formation of zona pellucida binding site(s) in human spermatozoa, are related. Finally, the presence of the hyaluronic acid (HA) receptor on the plasma membrane of mature sperm coupled with the HA-coated slide sperm-binding assay, facilitates the testing of infertile men and the selection of single mature spermatozoa for ICSI. Because mature spermatozoa have no residual cytoplasm, the HA-bound sperm fraction is also enriched in spermatozoa that are normal by the Kruger strict morphology method.

FISH assessment of aneuploidy frequencies in mature and immature human spermatozoa classified by the absence or presence of cytoplasmic retention

Previously, a relationship has been found between diminished cellular maturity of human spermatozoa and low-level expression of the testis-specific chaperone protein, HspA2. Because HspA2 is a component of the synaptonemal complex in rodents, and assuming that this is also the case in men, it was postulated that the frequency of chromosomal aneuploidies would be higher in immature versus mature spermatozoa. This question was examined in spermatozoa from semen and from 80% Percoll pellets (enriched for mature spermatozoa) of the same ejaculate in 10 oligozoospermic men. Immature spermatozoa with retained cytoplasm, which signifies spermiogenetic arrest, were identified by immunocytochemistry. Using fluorescence in-situ hybridization (FISH), approximately 7000 sperm nuclei were evaluated in each of the 20 fractions (142 086 spermatozoa in all) using centromeric probes for the X, Y and 17 chromosomes. The proportions of immature spermatozoa were 45.4 +/- 3.4 versus 26.6 +/- 2.2% in the two semen versus the Percoll groups (medians: 48.2 versus 25%, P < 0.001, n = 300 spermatozoa per fraction, total 6000 spermatozoa). There was also a concomitant decline in total disomy, total diploidy and total aneuploidy frequencies in the 80% Percoll versus semen fractions (0.17 versus 0.54%, 0.14 versus 0.26% and 0.31 versus 0.81% respectively, P < 0.001 in all comparisons). The mean decline of aneuploidies was 2.7-fold. With regard to the hypothesis that aneuploidies are related to sperm immaturity, there was a close correlation between the incidence of immature spermatozoa and disomies (r = 0.7, P < 0.001) but no correlation with diploidies (r = 0.03), indicating that disomies originate primarily in immature spermatozoa. It is suggested that the common factor underlying sperm immaturity and aneuploidies is the diminished expression of HspA2. In addition, the lack of this chaperone may also cause diminished cellular transport of proteins, such as DNA-repair enzymes or of the retention of cytoplasm that is extruded from normally maturing spermatozoa during spermiogenesis.

Putative creatine kinase M-isoform in human sperm is identifiedas the 70-kilodalton heat shock protein HspA2

We previously described a putative creatine kinase M isoform in human sperm that is developmentally regulated and expressed during late spermiogenesis, simultaneous with cytoplasmic extrusion. We have now identified this protein as the testis-expressed 70-kDa heat shock protein chaperone known as HspA2 (the human homologue of mouse Hsp70-2). We have isolated and characterized HspA2 (formerly CK-M) by amino acid sequencing and have localized it by immunocytochemistry to spermatocytes at low levels, to spermatids, and in the tail of mature sperm. The specificity of the CK-M/HspA2 antiserum to HspA2 was demonstrated on immunoblots of one- and two-dimensional SDS-PAGE. In agreement with our earlier biochemical data, immunocytochemistry of testicular tissue indicated that HspA2 is selectively expressed in mature spermatids and in sperm about to be released in the seminiferous tubuli. The identity of HspA2 has been further confirmed by cross-absorption of the mouse HSP70-2 antibody by the HspA2/CK-M fraction, and by identical immunostaining patterns of human testicular tissue using either the anti-CK-M/HspA2 or an anti-mouse Hsp70-2 antisera. During spermiogenesis, both cytoplasmic extrusion and plasma membrane remodeling, which facilitate the formation of the zona pellucida binding site, involve major intrasperm protein transport, which may be chaperoned by HspA2. Accordingly, in immature human sperm, which fail to express HspA2, there is cytoplasmic retention and lack of zona pellucida binding. The present findings provide the biological rationale for the role of the human HspA2 as an objective biochemical marker of sperm function and male fertility, which we have established in earlier clinical studies.

Increased in vitro binding of fresh and frozen-thawed human sperm exposed to a synthetic peptide

Prosaposin is a well-characterized, approximately 68-kDa protein found in many tissues and as a normal component of human semen. A fragment of prosaposin apparently is involved in primary sperm-egg binding. We hypothesized that binding of sperm from some men to egg investments would be increased by in vitro exposure of their sperm to a synthetic fragment of human prosaposin (FertPlus peptide). Hence, we evaluated samples of washed fresh or frozen-thawed human sperm after a 10-minute exposure to synthetic FertPlus peptide at 0 (control), 80, 160, 320, 640, or 1280 pM, followed by 1:50 dilution for evaluation of binding. The criterion of response was mean percentage of sperm bound to a substrate prepared from chicken egg membranes after sperm were incubated for 60 minutes at 37 degrees C in substrate-coated wells of a sperm-binding assay plate. For each seminal sample, data were normalized against the percentage of sperm bound for control aliquots, providing values for relative binding. With fresh sperm, relative binding was increased (P < 0.01) by exposure of sperm to peptide, and the effect was especially obvious at 1280 pM. Higher doses were not tested. Collectively at three study sites, exposure of fresh sperm to 1280 pM peptide substantially increased (above 99% confidence interval; on the basis of duplicate control samples) percentage of sperm bound for 25 of 74 (34%) samples. For frozen-thawed sperm, exposure to 1280 pM peptide increased binding for 29 of 65 (45%) samples. We concluded that for >30% of men, exposure of their sperm to this synthetic fragment of prosaposin at 1280 pM increased binding of sperm to an egg membrane substrate similar to that offered by the zona pellucida.

In vitro sperm-binding assay to distinguish differences in populations of human sperm or damage to sperm resulting from cryopreservation

Annually, >1.3 million men are members of couples seeking help because of infertility. Semen from many of these men contains reasonable numbers of motile and normal sperm, but for a subset of individuals, many sperm are deficient in ability to bind to the zona pellucida during in vitro fertilization. Diagnosis of this defect has been hampered by lack of a low-cost test. Molecular similarity exists between the perivitelline membrane of a hen's egg and the mammalian zona pellucida. These facts and some preliminary data led to evaluation of binding of human sperm during incubation for 60 minutes at 37 degrees C to an extract of chicken perivitelline membrane coated in microwell assay plates. The sperm-binding assay had inter- and intraassay plate variations of 21 and 12%, respectively, using washed fresh sperm. All seminal samples were normal, except a few that had 36 to 50% motile sperm with a low rate of sperm movement (if there is a low rate of movement, World Health Organization [WHO] criterion for normalcy is >50% motile). Nevertheless, this sperm-binding assay detected differences among individuals in percentage of sperm bound. Based on data for two to four ejaculates from each of eight occasional sperm donors, the coefficient of variation for ejaculates within donor averaged 31%, and means for the donors differed (P < 0.02). Percentage of sperm bound ranged from <1 to 38% for fresh semen from 57 men and from <1 to 13% for frozen-thawed semen from 34 men. Percentage of motile sperm accounted for <30% of the variation in percentage of sperm bound. In a direct comparison based on 17 ejaculates, aliquots evaluated fresh averaged 13% sperm bound, versus 2% for frozen-thawed aliquots. We concluded that the egg membrane substrate used in these microwell assay plates might serve as the basis for a diagnostic assay. However, it remains to be established whether samples of human semen with a low percentage of sperm binding indeed have relatively low fertilizing potential.

Morphometric assessment of mature and diminished-maturity human spermatozoa: sperm regions that reflect differences in maturity

As part of our studies on sperm maturity and function, we examined the head, midpiece and tail of human spermatozoa using computerized morphometry in order to determine which regions reflect the differences between mature spermatozoa and spermatozoa of diminished cellular maturity. We studied 20 men, who were divided into two groups based on their lower (LCKM: 14.6 +/- 7.0%, n = 8) and higher sperm creatine kinase (CK-M) isoform ratios (HCKM: 48.0 +/- 4.3%, n = 12) in the initial semen. Using a sequential centrifugation method which relies on the lower density of immature spermatozoa with retained extra cytoplasm, we prepared three sperm fractions with progressively declining maturity, as confirmed with CK-M isoform ratio measurements. Following the sequential fractionation, we affixed the spermatozoa to glass slides, stained the midpiece and the sperm contour, and photographed 25 spermatozoa in each of the 60 fractions (1509 spermatozoa in all). The spermatozoa were then individually digitized on the Image-1 system, and the dimensions of the head, midpiece, and tail were determined. While the data showed significant differences in the midpiece and tail dimensions between the mature and diminished-maturity sperm fractions, the head dimensions were similar and did not reflect sperm maturity. We postulated that the relationship between the biochemical markers of sperm maturity and sperm morphology is based on common spermiogenic events. The data support this idea. In immature spermatozoa in which cytoplasmic extrusion, CK-M isoform expression, and tail sprouting are all diminished, the retained extra cytoplasm in the midpiece and shorter tail length contribute to the morphological variations that we identified by morphometry and considered in sperm morphology. These morphometric features, in association with fluorochrome-coupled biochemical probes, can facilitate the identification of mature spermatozoa in computer-assisted semen analysis.

Sperm creatine kinase activity in normospermic and oligozospermic Hungarian men

PURPOSE

Our purpose was to measure sperm creatine phosphokinase (CK) activity, which reflects cytoplasmic retention in immature spermatozoa, in normospermic and oligozospermic Hungarian men.

METHODS

A study of 109 randomly selected men in a university-based andrology laboratory was done.

RESULTS

CK activity differed between normospermic and oligozospermic men (0.21 +/- 0.02 vs. 1.19 +/- 0.15 CK IU/10(8) sperm; n = 56 and n = 53; mean +/- standard error of the mean, respectively). There was an inverse correlation between sperm concentration and CK activity (r = -0.70; n = 109). However, 28% of men in the range with less than 10 million sperm/ml had normal sperm CK activity (below the mean + 2 standard deviations of the group with greater than 30 x 10(6) sperm/ml), whereas 36% of men in the group with 20-30 million sperm/ml and 5% in the group with greater than 30 million sperm/ml had elevated CK activities, indicating that the incidence of mature and immature spermatozoa in specimens is independent from the sperm concentrations.

CONCLUSIONS

The improved facility of sperm CK activity measurements, compared with sperm concentrations, in the assessment of sperm maturity was confirmed in a Hungarian population. The CK measurements aid the selection of the most efficient treatment for couples with male-factor or unexplained infertility, particularly when considering the options of intrauterine insemination, varicocelectomy followed by a waiting period, or ovulation workup/induction in wives of men who are oligozospermic but may have fertile sperm.

Optimal utilization of cryopreserved human semen for assisted reproduction: recovery and maintenance of sperm motility and viability

PURPOSE

Our purpose was to evaluate sperm motility and viability and the maintenance of these parameters in already cryopreserved semen samples following repeated freezing/thawing cycles.

METHODS

Human spermatozoa were subjected to five cycles of cryopreservation/thawing. Recovery of sperm motility and viability and the proportion of viable nonmotile sperm were determined up to 6 hr after thaw.

RESULTS

Sperm motilities (prefreeze motility, 70.1%; n = 9 samples) after each of five freeze/thaw cycles were 24.4, 8.0, 3.5, 1.5 and 1.8%. The recovery of sperm viability was higher than that of motility after each cycle: 39.1, 25.3, 22.6, 17.8, and 16.5%. Recoveries of motility and viability were improved if the thawed samples were left in the original cryopreservation medium prior to refreezing vs. if a washing/ resuspension step was included. The recovery of sperm motility in the first thawing cycle was indicative of the expected motile sperm recovery in the second thawing cycle.

CONCLUSIONS

Cryopreserved semen that is intended to be reused in future assisted reproduction treatments should be thawed only once and aliquoted in the original freezing medium before refreezing. The recovery of sperm motility and viability in the second thawing cycle, thus the applicability of the sample in conventional in vitro fertilization or intracytoplasmic sperm injection may be anticipated in > 90% of the samples. In view of intracytoplasmic sperm injection it is important that sperm viability is maintained better than motility; after the first, second, and third thawing cycles the ratios of motile:nonmotile viable sperm were 1:1, 1:4, and 1:7, respectively.

Cell and molecular biological challenges of ICSI: ART before science?

Authors discuss the possible genetic and cell biological risks to offspring conceived by ICSI in relation to the lack of fundamental research using relevant animal models.

Cytoplasmic extrusion and the switch from creatine kinase B to M isoform are completed by the commencement of epididymal transport in human and stallion spermatozoa

Although in several species there is a relationship between epididymal sperm transport and fertility, in human in vitro fertilization (IVF), spermatozoa recovered from the caput epididymidis or even the rete testis are fertile. We studied two objective markers of sperm maturity in the sperm of men and stallions: creatine kinase (CK) concentrations, which are a measure of cytoplasmic retention in immature spermatozoa, and the ratio of CK-M and CK-B isoforms (% CK-M/[CK-M + CK-B]), which is proportional to the incidence of mature sperm. The CK markers and the fertilizing function are closely related: Immature sperm with cytoplasmic retention do not bind to the zona, because during cytoplasmic extrusion, the sperm plasma membrane is also remodeled. We examined whether changes in sperm CK values are still ongoing during epididymal transport, or if cellular maturation is completed prior to the arrival of sperm in the caput epididymidis. The incidences of mature sperm in human caput and corpus epididymidis (studied in six men with obstructive azoospermia of various pathogeneses) were (mean+/-SEM) 55.7+/-2.2 and 49.3+/-7.6%, respectively; and the sperm CK-M ratios in the caput epididymidis of three men were 72, 75, and 70%, values that are similar to those of ejaculated sperm. In four segments of the proximal and distal epididymis of three stallions (the origin of sperm was also verified by the position of the cytoplasmic droplet) and in ejaculate of five stallions, the incidences of mature sperm were 88.2+/-6.2, 89.0+/-6.7, 90.3+/-7.8, 87.6+/-5.9, and 86.7+/-0.8%, and the respective CK-M ratios were 75.0+/-8.7, 84.2+/-2.9, 87.9+/-1.2, 92.5+/-1.5, and 69.3+/-3.5%. There were no differences in the incidences of mature and immature spermatozoa or in CK-M ratios among sperm arising from the various epididymal regions or from the ejaculate in men or stallions. Thus, the cellular maturation events in sperm, as detected by the CK markers, are completed by the time the sperm commences epididymal transport. These findings are in agreement with the IVF fertility of sperm aspirated from the male reproductive tract. The data may also suggest that the primary role of sperm epididymal transport in men is to remodel the plasma membrane to enhance sperm functional integrity in the diverse environments of the male and female reproductive tracts prior to fertilization.

Hyaluronic acid substantially increases the retention of motility in cryopreserved/thawed human spermatozoa

We have demonstrated previously that hyaluronic acid (HA) improves the velocity and the retention of motility in freshly ejaculated human spermatozoa. In the present work, we examined the effect of HA on cryopreserved/ thawed spermatozoa in four paradigms: (i) effect of HA on sperm motility and velocity in semen; (ii) stabilizing effect of HA after 4 h of incubation when the decline of sperm motility is already detectable; (iii) the duration of improved motility after the separation of spermatozoa from HA by Percoll gradient centrifugation; and (iv) motility of sperm cryopreserved in the presence of HA. HA improved the retention of sperm motility in thawed spermatozoa. Indeed, the motility values after 30 h were approximately 100% higher in the HA compared with the control samples. This effect of HA was also evident in the stabilization of spermatozoa with already declining motility. After removal of the HA from the incubation medium, significantly increased motility in the HA-exposed spermatozoa was still detectable for at least 4 h. Cryopreservation of spermatozoa in the presence of HA did not improve the recovery of motility. The data indicate that HA improves the retention of motility of cryopreserved/thawed spermatozoa, even after the removal of HA from the incubation medium. The utilization of HA will probably prove beneficial in assisted reproduction: in intrauterine insemination and in in-vitro fertilization (IVF), the extended sperm motility and velocity will enhance the fertilizing efficiency; in intracytoplasmic sperm injection (ICSI), the improved motility will facilitate the identification of viable spermatozoa. Because HA is a physiological component of the cumulus and of the female and male reproductive tracts, administration of HA should not cause ethical concerns.

Sperm plasma membrane remodeling during spermiogenetic maturation in men: relationship among plasma membrane beta 1,4-galactosyltransferase, cytoplasmic creatine phosphokinase, and creatine phosphokinase isoform ratios

Sperm creatine phosphokinase (CK) concentrations and the synthesis of the CK-M isoform reflect normal spermiogenesis and predict maturity and fertilizing potential of ejaculated human spermatozoa. Immature spermatozoa, characterized by cytoplasmic retention and low CK-M to CK-B isoform ratios, are deficient in zona binding and fail to cause pregnancies. Because these sperm lack zona-binding ability, we examined in this study whether beta 1,4-galactosyltransferase (GalTase), a key element of sperm-zona interactions in mice, is diminished in immature human sperm. Unexpectedly, GalTase was overexpressed in immature sperm relative to mature sperm: the levels of cytoplasmic CK and plasma membrane GalTase were positively correlated (r = 0.78, p < 0.001, n = 88). Sperm populations with various levels of cellular maturity, prepared by Percoll gradients, had different CK and GalTase concentrations, but within each subpopulation the relationship between CK and GalTase was maintained (p < 0.01-0.001). GalTase activities in intact and vortex-disrupted sperm fractions were similar, showing that GalTase is present on the surface membrane of human sperm--similar to the situation in all other species assayed. The changes previously reported by our laboratory in zona-binding ability and lipid peroxidation rates (which occur simultaneously with cytoplasmic extrusion), decline in CK activity, and increased expression of the CK-M isoform are suggestive of a remodeling of the sperm surface concomitant with cytoplasmic maturation. The changes reported here in GalTase expression on the surface of maturing spermatozoa prove this hypothesis.

Assessment of reproductive disorders and birth defects in communities near hazardous chemical sites. III. Guidelines for field studies of male reproductive disorders

Exposures to environmental toxicants can have detrimental effects on several aspects of human male reproduction: fertility, sexual function, hormone status, and pregnancy/birth outcomes. However, no simple prescreening methods are available for reliably identifying potential hazards; questionnaires alone are relatively imprecise and inefficient in the absence of field data. Multidisciplinary field studies are required that include detailed exposure information, health and reproductive histories, physical examinations, semen analyses, and possibly, hormone analyses. Semen analysis is a critical component of field studies for evaluating two aspects of male reproduction: 1) changes in sperm or seminal content, which may be indicative of adverse effects on the male reproductive system with possible implications for fertility potential; and 2) defects in sperm DNA or chromosomes, which may be associated with subsequent changes in viability during embryonic development and health risks to the offspring. Semen analyses may be tiered: 1) initially, each semen study may include conventional semen assays (concentration, motility, and morphology) as well as specific biomarkers indicated by the health effect of concern in the study cohort: and 2) archived samples (i.e., frozen, videotaped, or smeared) may be utilized in later second-tier analyses to further characterize specific findings. Before initiating any field study, it is cost effective to critically evaluate the suitability of the cohort by confirming exposure and determining that there are adequate numbers of male participants in each exposure category. Such evaluations must be based on the statistical sensitivities of the specific tissue biomarkers and health endpoints for detecting changes. This article summarizes the components of the ideal field study and identifies research needs for improving field studies of male effects and for understanding the mechanisms of male reproductive toxicity. Several promising semen methods currently under development are also discussed.

Peritoneal fluid from women with moderate or severe endometriosis inhibits sperm motility: the role of seminal fluid components

OBJECTIVE

To examine the mechanism of sperm motility inhibition by peritoneal fluid (PF) from women with endometriosis.

DESIGN

Prospective, randomized study.

SETTING

University-based andrology laboratory.

PATIENTS

Women with and without endometriosis.

INTERVENTIONS

Fresh semen or Percoll-purified sperm fractions were combined with PF from women with endometriosis (n = 20), from fertile women without endometriosis (n = 10), or with physiological saline.

MAIN OUTCOME MEASURE

Sperm motility parameters were determined with computer assisted semen analysis. Data were evaluated by the analysis of variance and the Student's t-test.

RESULTS

Peritoneal fluid from women with minimal or mild endometriosis did not inhibit sperm motility in semen. Peritoneal fluid from women with moderate or severe endometriosis caused approximately 40%, 50%, and 80% declines in sperm motility and in percent progressive motile sperm after 4,7, and 24 hours, respectively. Sperm velocity was inhibited by approximately 30% and 60% after 7 and 24 hours, respectively. However, in the Percoll-purified sperm fractions the same PF did not inhibit sperm motility within the 4- to 7-hour time frame, and only a 17% to 42% inhibition occurred after the overnight incubation. Sperm velocity was not affected.

CONCLUSION

Cellular components of seminal fluid appear to mediate the inhibitory action of PF. Assuming that the leukocyte components of semen and PF are common, the cell-mediated inhibition of sperm motility is a likely contributor to endometriosis related infertility.

Biochemical markers of early and late spermatogenesis: relationship between the lactate dehydrogenase-X and creatine kinase-M isoform concentrations in human spermatozoa

As part of our research program on biochemical markers of sperm maturity, we have studied sperm creatine kinase (CK) and lactate dehydrogenase (LDH) concentrations and the isoform ratios of the CK-M [% CK-M/(CK-M + CK-B)] and LDH-X [% LDH-X/(LDH-X + LDH-a)] in 50 oligospermic and 95 normospermic men [corrected]. Because the synthesis of LDH-X is initiated in early spermatogenesis, and that of CK-M commences in late spermiogenesis simultaneously with cytoplasmic extrusion, we proposed two working hypotheses:(1) LDH and CK concentrations reflect the retained cytoplasm in sperm, thus the activities of both enzymes will be related and will be higher in oligospermic specimens, which have a higher incidence of immature spermatozoa; and (2) because in normally developed sperm both LDH-X and CK-M are present, there will be a correlation between LDH-X and CK-M ratios in the mature sperm populations. However, among men with immature sperm samples with late spermiogenetic defect and diminished CK-M ratios, there will be two groups: one which completed spermatogenesis prior to spermiogenetic failure (normal LDH-X and diminished CK-M ratios), and another group with defects in both spermatogenesis and spermiogenesis (low LDH-X and diminished CK-M ratios). Because of this heterogeneity, LDH-X ratios will be a poor predictor of sperm maturity. The data support the hypotheses: (1) LDH and CK concentrations were higher in oligospermic vs. normospermic men (P < 0.001). (2) The LDH and CK concentrations were related (r = 0.65, P < 0.001, N = 145), and there were inverse correlations between CK, LDH, LDH-X, or CK-M ratios vs. sperm concentrations (P < 0.001 in all four). (3) The CK-M and LDH-X ratios were different between the oligospermic and normospermic groups (P < 0.001), although the means of the LDH-X ratios were narrower (LDH-X:1:1.3; CK-M:1:1.9). (4) Dividing the 145 samples by the cut-off value of mean minus 1 SD of the CK-M and LDH-X ratios (11% and 32%, respectively) demonstrated that the CK-M ratios discriminated better than LDH-X ratios between the samples with mature and immature sperm. These data on the biochemical markers of early and late spermatogenesis support the studies in which CK better reflected sperm quality than LDH or LDH-X (Orlando et al., 1994: Int J Androl 17:13-18) and the > 10% sperm CK-M ratio predicted with a rate of 30.4% per cycle in the occurrence of pregnancies in a blinded study of 84 IVF couples (Huszar et al., 1992: Fertil Steril 57:882-888).

Sperm function and choice of preparation media: comparison of Percoll and Accudenz discontinuous density gradients

We compared the sperm populations prepared by Accudenz (35-65%) and Percoll (40-80%) density gradients in 21 normospermic specimens (concentration, 53.6 +/- 3.8 x 10(6) sperm/ml; motility, 44.5 +/- 3.5%). Accudenz facilitated a higher recovery of sperm and motile sperm (68.4 +/- 6.6% vs. 49.3 +/- 4.9%, P < 0.001, and 87.8 +/- 4.1% vs. 77.8 +/- 3.7%, P < 0.01, respectively). Sperm motility was lower in the Accudenz compared to the Percoll pellets; thus the values of total motile sperm recovered were not different (17.1 +/- 2.4 vs. 15 + /- 1 2.2 x 10(6) sperm/ml). The long term retention of sperm motility was substantially improved in Accudenz (at 24 hours, 34.9 +/- 2.8% vs. 26.3 +/- 1.5%; 60% vs. 40% of the initial motility, P < 0.001), and the Accudenz vs. Percoll samples also exhibited a higher retention of total motile sperm (at 24 hours, 9.8 +/-.2 vs. 6.1 = 0.5 x 10(6) motile sperm/ml, P < 0.05). The sperm motility index, a multiple of velocity and motility in the sample that reflects the efficiency of the sperm population in sperm-oocyte interaction, was 75% higher in the Accudenz samples at 24 hours (3.6 +/- 0.4 vs. 2.1 +/- 0.2, mu m/second, P < 0.01). Sperm cellular maturity by the creatine phosphokinase (CK) activity and CK-M to CK-B isoform ratio parameters (in the original samples 0.14 +/- 0.02 lU CK/100 x 10(6) sperm and 57.9 +/- 3.7%, respectively) were improved in both the Accudenz and Percoll pellets (P < 0.001), with no difference between the two sperm fractions. Sperm activation status monitored by chlortetracycline fluorescence indicated that after 4 hours of incubation the incidence of fully acrosome-reacted spermatozoa in the Accudenz versus Percoll pellets was 6.2 +/- 0.3% versus 13.1 +/- 1.0% (P < 0.001), a 100% increase in Percoll. We can conclude that Accudenz yields a higher concentration of motile spermatozoa, with improved retention of motility, velocity, and acrosomal integrity and without an increase of sperm with diminished cellular maturity. Thus, in sperm preparation for intrauterine insemination, in which the timing of ovulation and insemination frequently do not correspond, Accudenz-prepared sperm, with a better retention of motility/velocity and acrosomal integrity and with a consequential higher resistance to activation by the female reproductive tract, are expected to be more effective.

A follicular fluid chondroitin sulfate proteoglycan improves the retention of motility and velocity of human spermatozoa

OBJECTIVE

To examine the effects of two proteoglycans of different structure, isolated from human follicular fluid (FF), on the motility of human spermatozoa.

DESIGN

Normozoospermic semen samples and their swim-up sperm fractions were incubated in the presence of 0.4 mg/mL of a larger chondroitin sulfate proteoglycan (CS-PG) for 0, 3, 7, and 16 hours. The effects of a smaller heparan-CS-PG and the chondroitin sulfate side chains of the larger proteoglycan were also investigated in the same conditions. Sperm motility parameters were analyzed using a computer-aided sperm analysis system (CASA; Cryo Research Inc., New York, NY) RESULTS: The larger CS-PG caused an immediate increase in sperm linearity. After 3 and 7 hours, the retention of sperm motility, velocity, linearity, and amplitude of lateral head displacement have increased by an average of 13% compared with the control samples. After a 16-hour incubation, the retention of the motility properties was improved by approximately 40% (range, 27% to 50%) in the samples containing proteoglycan. The effects of the isolated glycosaminoglycan side chains were much lower than those of the intact proteoglycan. The heparan-CS-PG did not affect sperm motility.

CONCLUSION

A CS-PG from FF increases retention of motility and velocity of human sperm. These physiological effects may enhance the fertilizing efficiency of spermatozoa in the female reproductive tract.

Creatine kinase immunocytochemistry of human sperm-hemizona complexes: selective binding of sperm with mature creatine kinase-staining pattern

OBJECTIVE

To examine the clinical significance of the increased sperm cytoplasmic content that is due to a fault of spermatogenesis, we have further studied the relationship between increased sperm creatine kinase (CK) concentrations and diminished fertilizing potential in men. In the present work, we used CK immunocytochemistry of human sperm-hemizona (HZ) complexes to examine whether the distribution of mature (clear heads), intermediate (sperm heads with light stippling), and immature (heads with heavy stippling or with solid CK staining) spermatozoa bound to the HZ would follow the incidence of these sperm in the samples tested, or if there is a preferential binding by the mature sperm.

DESIGN

Two pairs of HZ were exposed to washed semen and to their swim-up sperm fractions. The sperm and sperm-HZ complexes were treated with a CK antibody followed by horseradish peroxidase immunostaining, and the sperm were evaluated for maturity.

SETTING

Men presenting for fertility evaluation were studied in two university-based andrology laboratories.

RESULTS

The binding of the HZ was selective for mature sperm as indicated by the incidence of intermediate and immature sperm in washed semen versus bound to the HZ (intermediate: 20.0% versus 1.4%; immature: 7.6% versus 0.5% [mean +/- SEM]) or in swim-up sperm fractions versus the HZ (intermediate: 18.7% versus 3.4%; immature: 2.5% versus 0.2%). The binding was almost exclusive to normal sperm (96.4% to 98.1%) whether the HZ were exposed to washed semen or swim-up fractions in spite of the five to ten times higher incidence of intermediate and immature sperm.

CONCLUSIONS

Mature sperm selectively bind to the zona. We suggest that spermatozoa with immature CK-staining patterns are deficient in the site(s) of oocyte recognition and binding.

Correlation between the rate of lipid peroxidation and cellular maturity as measured by creatine kinase activity in human spermatozoa

We have demonstrated previously that creatine kinase (CK) activity is a measure of cellular maturity and fertilizing potential in human spermatozoa. In the present work we have examined whether there is a relationship between sperm CK activity and the rate of lipid peroxidation (LP) as measured by malondialdehyde (MDA) formation. Both MDA production and CK activity were higher in oligospermic than in normospermic specimens (P < 0.001, N = 41 and 101, respectively), and there was a close correlation (R = 0.43, P < 0.001) between these two biochemical parameters. As demonstrated previously with the CK measurements, there was a heterogeneity among the groups: About 40% of the oligospermic men had MDA and CK activity values similar to that of the normospermic group, and 12% of the normospermic men had MDA and CK activity values similar to that of the oligospermic group. We have also examined in three experimental paradigms the question of sperm-to-sperm propagation of increased LP and the possible increase in LP following centrifugation as used in sperm preparation for assisted reproduction: The MDA differences among Percoll sperm fractions originating within the same specimens, the lack of change in MDA production after co-centrifugation and co-incubation of samples with high and low sperm LP rates, and the repeated centrifugation of the same specimens without an increase in MDA production all indicated the lack of sperm-to-sperm propagation of LP or increase in LP due to mechanical stress.(ABSTRACT TRUNCATED AT 250 WORDS)

Incomplete development of human spermatozoa is associated with increased creatine phosphokinase concentration and abnormal head morphology

Our previous creatine phosphokinase (CK) activity studies in human sperm revealed differences among men and among sperm populations within the same specimen. Samples with low sperm concentrations, high incidence of abnormal sperm morphology, and diminished fertility had higher per sperm CK activity. In the present work, we demonstrated, with 14C-FDNB covalent CK active site modification and with direct CK immunocytochemistry, that the higher CK activity is related to an increased content of CK and of other proteins in sperm. Also, sperm heads with higher CK content were significantly larger and rounder and showed a higher incidence of amorph configuration. We suggest that these biochemical and morphological irregularities are related and are due to a failure of spermatogenesis, more specifically, to a higher retention of cytoplasm, which in normal sperm development is lost to the Sertoli cells as residual bodies. Thus higher CK activity and larger or irregular head size in human sperm signify cellular immaturity and a failure to complete spermatogenesis.

Adenosine triphosphate (ATP) concentrations and ATP/adenosine diphosphate ratios in human sperm of normospermic, oligospermic, and asthenospermic specimens and in their swim-up fractions: lack of correlation between ATP parameters and sperm creatine kinase concentrations

The authors had previously found an inverse correlation between per sperm creatine phosphokinase activity and sperm concentrations in men. Because creatine phosphokinase is a key enzyme in sperm energy transport, the possible relationship of sperm creatine phosphokinase activity, sperm adenosine triphosphate (ATP) concentrations, sperm ATP/ADP (adenosine diphosphate) ratios, and computer-aided semen analysis sperm motility parameters were then studied. The ATP concentrations and ATP/ADP ratios, measured by high-pressure liquid chromatography in washed sperm, were similar in normospermic and oligospermic specimens (ATP: 123.1 +/- 21.6 vs. 90.0 +/- 24.5 pmol/10(6) sperm; ATP/ADP: 2.8 +/- 0.4 vs. 2.1 +/- 0.4, N = 32 and 17, mean +/- SEM), and in samples with normal and less than 40% sperm motility (ATP: 96.8 +/- 27.2 vs. 122.2 +/- 19.6 pmol/10(6) sperm; ATP/ADP: 2.4 +/- 0.5 vs. 2.8 +/- 0.4, n = 26 and 23). In the swim-up sperm fractions, which showed improved motility, the ATP concentrations, but not the ATP/ADP ratios, were lower than in the initial semen samples (ATP: 152.9 +/- 28.4 vs. 90.3 +/- 10.6 pmol/10(6) sperm, P less than 0.05; ATP/ADP: 3.3 +/- 0.5 vs. 3.9 +/- 0.7, N = 18 pairs of samples). This is consistent with our previous finding of a lower cytoplasmic content in sperm in swim-up fractions.(ABSTRACT TRUNCATED AT 250 WORDS)

Sperm creatine phosphokinase M-isoform ratios and fertilizing potential of men: a blinded study of 84 couples treated with in vitro fertilization

OBJECTIVE

To examine the value of sperm creatine phosphokinase M-isoform (CK-MM) measurements toward predicting fertilizing potential of men.

DESIGN

In 84 in vitro fertilization (IVF) couples without knowing the semen parameters, reproductive history or the outcome of the IVF cycles, we determined the sperm CK-MM ratios (the proportion of sperm CK-MM versus CK-MM+CK-BB). Husbands with less than 10% or greater than or equal to 10% CK-MM ratios were classified as "low likelihood for fertilization" (CKMM-Infertile, n = 22) or "high likelihood for fertilization" (CKMM-Fertile, n = 62), respectively.

RESULTS

Both the CKMM-Infertile and CKMM-Fertile groups (CK-MM ratios: 4.9% +/- 0.6% versus 31.1% +/- 1.8%) were in the normospermic range (31.5 +/- 6.9 versus 78.4 +/- 5.9 x 10(6) sperm/mL and 45.6% +/- 5.0% versus 54.0% +/- 2.0% motility). The fertilization rates (6.2 versus 4.9 oocytes inseminated) were 14.2% versus 53.4%, and 72.7% versus 25.8% of the couples failed to achieve any oocyte fertilization. All 14 pregnancies (16.7% rate) occurred in the CKMM-Fertile group. The pregnancy rate in the 62 CKMM-Fertile couples was 22.6%, and considering only the 46 CKMM-Fertile women in whom oocyte fertilization occurred, it was 30.4%. Among the 22 CKMM-Infertile men, 9 were normospermic and 9 of the 62 CKMM-Fertile men were oligospermic. Within the CKMM-Fertile group, 12 and 2 of the 14 pregnancies occurred by the 53 normospermic and 9 oligospermic men (22.6% versus 22.2% rate).

CONCLUSIONS

Sperm CK-MM ratios, a measure of normal sperm development, predict fertilizing potential independently from sperm concentrations. Sperm CK-MM ratios also detect unexplained male infertility (infertile men with normospermic semen), a diagnosis that until now could not be substantiated.

Hyaluronic acid (Sperm Select) improves retention of sperm motility and velocity in normospermic and oligospermic specimens

The effects of Sperm Select (Pharmacia AB, Uppsala, Sweden), a hyaluronic acid medium, on the motility and membrane integrity properties of sperm were studied. In 15 normospermic specimens after overnight incubation, the motility parameters in the control versus the Sperm Select group were as follows (mean +/- SEM): motility, 18.8% +/- 2.8% versus 27.4% +/- 2.9%; velocity, 21.5 +/- 2.4 versus 27.2 +/- 2.2 microns/s; linearity, 3.8 +/- 0.3 versus 4.4 +/- 0.2; lateral head displacement, 1.5 +/- 0.2 versus 1.9 +/- 0.1 microns; and tail beat/cross frequency, 8.8 +/- 1.3 versus 10.8 +/- 1.4 Hz. The density of motile sperm was 10.8 +/- 2.3 versus 18.5 +/- 2.5 X 10(6) sperm/mL. Finally, the velocity coefficient, the multiple of the sperm motility and linear velocity, was 4.6 +/- 1.1 versus 8.1 +/- 1.4. However, we found no Sperm Select related differences when testing sperm membrane integrity with hypoosmotic swelling and supravital staining. Thus, Sperm Select improves the retention of sperm motility (most prominently velocity) apparently due to a direct action of hyaluronic acid on sperm metabolism or contractility rather than to preservation of sperm membrane integrity. In 20 oligospermic specimens, Sperm Select caused similar improvements in sperm motility, and the duration of motility could be predicted from the degree of enhancement in sperm velocity after short-term Sperm Select exposure. A modified Sperm Select protocol is described that further increases motile sperm yield without a centrifugation step.

Spermatogenesis-related change in the synthesis of the creatine kinase B-type and M-type isoforms in human spermatozoa

We have demonstrated earlier that the per sperm creatine-N-phosphotransferase (CK) activity was increased in oligospermic vs. normospermic men. The increased sperm CK activity is related to higher concentrations of cellular CK, which may indicate a defect of cytoplasmic extrusion during spermatogenesis. In the present work, we examined whether in spermatozoa, similar to muscle, there is a change in the synthesis of B-CK and M-CK isoforms during cellular differentiation. In 109 normospermic and 50 oligospermic specimens (sperm concentrations 60.6 +/- 3.7 vs. 8.8 +/- 1.3 million sperm/ml; all values expressed as mean +/- SEM), the relative concentrations of the M-CK isoform (M-CK/M-CK + B-CK) were 27.2% +/- 2.1% vs. 6.7% +/- 0.9% (P less than 0.001). The per sperm CK activities showed comparable differences (0.21 +/- 0.02 vs. 0.89 +/- 0.1 CK IU/100 million sperm; P less than 0.001) in the two groups, and there was a close correlation between per sperm CK activities and M-CK concentrations (R = 0.69, P less than 0.001, N = 159). This indicates that the loss of cytoplasm and the commencement of M-CK isoform synthesis are related events during the last phase of spermatogenesis, also that the incidence of spermatozoa with incomplete cellular maturation is higher in oligospermic specimens. In characterizing the M-CK, we found that sperm (unlike muscle tissue) lack the MB hybrid of CK dimers. However, in the presence of muscle M-CK, the muscle-sperm MB-CK hybrid has formed. Thus in sperm and muscle the M-CK isoforms are structurally different, whereas the B-CKs are apparently homologous.(ABSTRACT TRUNCATED AT 250 WORDS)

Sperm creatine kinase activity in fertile and infertile oligospermic men

The authors examined the value of sperm creatine-kinase (CK) activity parameters to predict sperm fertilizing potential of oligospermic men. Two patient groups from our intrauterine insemination program were studied: fertile oligospermic (32 men/46 specimens) and infertile oligospermic (19 men/82 specimens). In the initial specimens, the CK activities were (mean + SEM IU CK/10(8) sperm): 0.53 +/- 0.09 and 1.17 +/- 0.19 (P less than 0.001). The corresponding values in the swim-up fractions were 0.32 +/- 0.06 and 0.67 +/- 0.08 (P less than 0.001). In a subset of samples by fertile (N = 33) and infertile (N = 66) oligospermic men who had close to identical sperm concentrations (11.9 +/- 0.9 vs. 11.9 +/- 0.5 million sperm/ml) and motility values (23.7 +/- 1.7 vs. 23.0 +/- 1.3%), the CK activities were significantly lower in the fertile group in both the initial (P = 0.02) and in the swim-up (P = 0.002) samples. A logistic regression analysis of all 160 study samples (including 21 normal men/32 samples) further demonstrated that CK activities were predictive of fertilizing potential, whereas sperm concentrations of the samples provided no additional contribution. Sperm CK and similar biochemical markers will facilitate selection of men for various approaches in assisted reproduction.

Sperm creatine phosphokinase activity as a measure of sperm quality in normospermic, variablespermic, and oligospermic men

We have found a significant inverse correlation between sperm concentrations and sperm creatine N-phosphotransferase (CPK) activities in oligospermic and normospermic human specimens. In the present work, we carried out serial CPK determinations to assess whether there is a relationship between fluctuating sperm concentrations and sperm quality in consistently oligospermic and variablespermic (sperm concentrations are occasionally in the greater than 20 million/ml range) husbands of 65 couples (23 normospermic men/51 samples, 25 consistently oligospermic men/80 samples, and 17 variablespermic men/68 samples). The sperm CPK activities were significantly lower in the normospermic vs. the oligospermic or variablespermic groups (p less than 0.001), but there were no differences between the latter two (p greater than 0.25). The mean CPK values of migrated sperm fractions in both the oligospermic and variablespermic populations were improved (at least 20% decline in CPK values) compared to those of the initial specimens (1.27 +/- 0.38 vs. 0.68 +/- 0.37 and 0.77 +/- 0.32 vs. 0.46 +/- 0.24 SEM U/100 million sperm, respectively, p less than 0.001 in both pairs) and the incidence of the "failed-to-improve" samples was also similar in the two groups (44/36 vs. 45/23, p greater than 0.2). The lack of differences in the mean CPK activities, in the distribution of CPK values under and over 0.250 U/100 million sperm level, and in the ratio of migrated samples with improved or with failed-to-improve CPK activities suggests that sperm quality is not different between men who are consistently oligospermic and those who occasionally produce normospermic specimens.(ABSTRACT TRUNCATED AT 250 WORDS)

Correlation between sperm creatine phosphokinase activity and sperm concentrations in normospermic and oligospermic men

Toward the development of biochemical probes for the assessment of sperm function we have measured the activities of sperm creatine-N-phosphotransferase (CPK). There was a highly significant inverse correlation (P less than 0.001 in all comparisons) between sperm CPK activities and sperm concentrations in specimens of normospermic and oligospermic men with greater than 30 million sperm/ml (0.106 +/- 0.01 SEM, N = 90, expressed as CPK U/100 million sperm), 20-30 million sperm/ml (0.333 +/- 0.07 SEM, N = 30) and 10-20 million sperm/ml (0.583 +/- 0.12 SEM, N = 30) when compared with the CPK values of the less than 10 million/ml specimens (2.242 +/- 0.46 SEM, N = 30). Furthermore, the distribution of CPK activities within these four groups showed that 96%, 67%, 43%, and 4% of the samples, respectively, were in the less than 0.250 CPK U/100 million sperm normal range (mean + 2 SD of the greater than 30 million sperm/ml group). However, there was no relationship between sperm CPK activities and the values of sperm motility (P greater than 0.15) or morphology (P = 0.38) in the samples. The migrated sperm fractions (significantly improved in motility and velocity parameters) showed CPK activities lower than the initial semen specimens (P less than 0.01, N = 150). In fact, in some oligospermic men the CPK activities of the migrated sperm fractions were within the range of normospermic samples.(ABSTRACT TRUNCATED AT 250 WORDS)

Enhancement of human sperm motility and velocity in vitro: effects of calcium and creatine phosphate

Because of their roles in motility regulation and energy transport, calcium and creatine phosphate were examined for their effects on sperm motility and velocity in specimens of normal donors. Semen or migrated sperm fractions were incubated with of 1 mmol of calcium, 5 mmol magnesium, and 10 mmol of creatine phosphate (n = 28) or in the presence of 4 mumol of Verapamil, calcium, and creatine phosphate (n = 10). The samples were subjected to multiple exposure photography (four picture frames of two different drops) at 0, 1, 4, or 5 and at 10 hours and sperm motility and velocity were analyzed. In both calcium and calcium-creatine phosphate conditions, sperm motility and velocity were significantly increased, compared with control values (P = between less than 0.001 and 0.05). Sperm motility declined following Verapamil exposure, but the motility values remained at the level of the control in the presence of additional calcium or creatine phosphate. The effects of calcium and creatine phosphate take place rapidly; within 1 minute all improvements in sperm velocity and motility are fully achieved. There is no loading effect of calcium, and when the sperm is transferred into media without the additional calcium, the velocity decreased to that of the initial control value. Magnesium alone had no effect on motility or velocity. These experiments indicate that calcium or creatine phosphate can support sperm motility and velocity at a significantly increased level. Thus the addition of calcium or creatine phosphate to the insemination media may enhance the fertilizing capacity of sperm during in vitro fertilization or gamete intrafallopian transfer procedures.