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

Proteomic analysis reveals the potential positive effects of Mito-TEMPO on ram sperm motility and fertility during cryopreservation

The aim of this study was to investigate the effects of mitochondria-targeted antioxidant Mito-TEMPO on the protein profile of ram sperm during cryopreservation and evaluate the cryoprotective roles of Mito-TEMPO on ram sperm quality and fertilization capacity. Semen collected from 8 Dorper rams was cryopreserved in TCG-egg yolk extender supplemented with various concentrations of Mito-TEMPO (0, 20, 40 and 60 μM). After thawing, sperm characteristics, antioxidant status and the abundance of hexose transporters (GLUT 3 and 8) were analyzed. The cervical artificial insemination (AI) was performed to evaluate the fertilization ability of cryopreserved ram sperm. The alterations of sperm proteomic profile between the control and MT₄₀ groups were determined using iTRAQ-coupled LC-MS. Supplementation with 40 μM of Mito-TEMPO resulted in the highest post-thaw sperm motility and kinematics. Sperm quality, antioxidant capacity and glucose transporter abundance of frozen-thawed ram sperm were elevated in the MT₄₀ group. The inclusion of 40 μM Mito-TEMPO in freezing extender also resulted in the higher pregnancy rate of ewes. A total of 457 proteins including 179 upregulated proteins and 278 downregulated proteins were defied as differentially expressed proteins (DEPs) using fold change (FC) > 1.2 with P < 0.05. Sixty-one DEPs with (FC > 1.5) were dramatically regulated by Mito-TEMPO. These DEPs are mainly involved in sperm motility, energy metabolism and capacitation. Our data suggest that the beneficial effects of Mito-TEMPO on sperm motility and fertility potential of cryopreserved ram semen are achieved by regulating sperm antioxidant capacity and sperm proteins related to energy metabolism and fertility.

Sperm Morphology Assessment in the Era of Intracytoplasmic Sperm Injection: Reliable Results Require Focus on Standardization, Quality Control, and Training

Semen analysis is the first, and frequently, the only step in the evaluation of male fertility. Although the laboratory procedures are conducted according to the World Health Organization (WHO) guidelines, semen analysis and especially sperm morphology assessment is very difficult to standardize and obtain reproducible results. This is mainly due to the highly subjective nature of their evaluation. ICSI is the choice of treatment when sperm morphology is severely abnormal (teratozoospermic). Hence, the standardization of laboratory protocols for sperm morphology evaluation represents a fundamental step to ensure reliable, accurate and consistent laboratory results that avoid misdiagnoses and inadequate treatment of the infertile patient. This article aims to promote standardized laboratory procedures for an accurate evaluation of sperm morphology, including the establishment of quality control and quality assurance policies. Additionally, the clinical importance of sperm morphology results in assisted reproductive outcomes is discussed, along with the clinical management of teratozoospermic patients.

First Evidence of DAAM1 Localization During the Post-Natal Development of Rat Testis and in Mammalian Sperm

Dishevelled-associated activator of morphogenesis 1 (DAAM1) is a formin-family protein involved in nucleation of unbranched actin filaments and in cytoskeletal organization through Wnt-Dishevelled PCP pathway, which participates in essential biological processes, such as cell polarity, movement, and adhesion during morphogenesis and organogenesis. While its role has been investigated during development and in somatic cells, its potential association with the germinal compartment and reproduction is still unexplored. In this work, we assessed the possible association of DAAM1 with the morphogenesis of rat testis. We studied its expression and profiled its localization versus actin and tubulin, during the first wave of spermatogenesis and in the adult gonad (from 7 to 60 dpp). We show that, in mitotic phases, DAAM1 shares its localization with actin in Sertoli cells, gonocytes, and spermatogonia. Later, during meiosis, both proteins are found in spermatocytes, while only actin is detectable at the forming blood-testis barrier. DAAM1, then, follows the development of the acrosome system throughout spermiogenesis, and it is finally retained inside the cytoplasmic droplet in mature gametes, as corroborated by additional immunolocalization data on both rat and human sperm. Unlike the DAAM1, actin keeps its localization in Sertoli cells, and tubulin is associated with their protruding cytoplasm during the process. Our data support, for the first time, the hypothesis of a role for DAAM1 in cytoskeletal organization during Mammalian testis morphogenesis and gamete progression, while also hinting at its possible investigation as a morphological marker of germ cell and sperm physiology. J. Cell. Physiol. 231: 2172-2184, 2016. © 2016 Wiley Periodicals, Inc.

Semen Characteristics After Overnight Shipping: Preservation of Sperm Concentrations, HspA2 Ratios, CK Activity, Cytoplasmic Retention, Chromatin Maturity, DNA Integrity, and Sperm Shape

We tested several approaches that can be used to preserve sperm attributes and the objective biochemical markers of sperm maturity and function for assessment in a remote centralized laboratory after overnight shipping of semen samples. Addition of phenyl-methyl-sulfonyl-fluoride (PMSF) to a final concentration of 20 microg/mL semen at 4 degrees C has preserved sperm concentrations and HspA2 isoform ratios, even at room temperature, simulating a shipping delay in moderate ambient temperatures. Regarding the attributes of individual spermatozoa, the patterns of CK-immunocytochemistry (demonstrates cytoplasmic retention in diminished-maturity spermatozoa); aniline blue staining pattern (tests chromatin maturity); sperm shape assessed by both Kruger strict morphology and computer assisted morphometry; and sperm DNA integrity, as tested by DNA nick translation, all remained unchanged. Thus, the PMSF-4 degrees C conditions preserved sperm concentrations and the cytoplasmic and nuclear biomarkers of sperm cellular maturity and function for next-day analysis. This shipping method will facilitate the early detection of subtle changes in semen quality that can affect sperm function, even when there has been no decline in sperm concentrations to signal possible toxic effects. Furthermore, sample preservation will enable investigators to evaluate semen for toxicology studies and for diagnosis of male infertility from remote locations. Home collection of semen should enhance study participation, and semen assessment in centralized laboratories will address concerns regarding interlaboratory variations and quality control.

An investigation of excess residual cytoplasm in human spermatozoa and its distinction from the cytoplasmic droplet

Recent studies have shown cytoplasmic droplets to be normal morphological occurrences in human male spermatozoa. When the cytoplasm around the sperm midpiece is present in large amounts, however, pathological effects may transpire. The cytoplasmic droplet then becomes known as excess residual cytoplasm, which can impair overall sperm function and produce higher levels of reactive oxygen species, potentially leading to male infertility. Though the distinction between cytoplasmic droplets and excess residual cytoplasm has been made, some studies fail to recognize the difference and incorrectly label the latter as a cytoplasmic droplet. This review attempts to clarify excess residual cytoplasm's effect on fertility, examine the enzymes responsible, and suggest tests and possible treatment options for those affected by this defect.

The expression pattern of SEPT7 correlates with sperm morphology

PURPOSE

To investigate the expression pattern of the SEPT7 protein during spermatogenesis and its potential role in sperm function.

METHODS

We first investigated the expression pattern of SEPT7 during different steps of mouse spermiogenesis using an immunofluorescence assay (IFA). IFA was also applied to study the expression pattern of SEPT7 in human ejaculated spermatozoa. Nine fertile men with normal semen parameters were used as the control group, and 21 infertile men with asthenozoospermia were recruited as the patient group. We assessed the frequency of the SEPT7 signal in the various morphological subgroups.

RESULTS

In humans, the frequency of a defective SEPT7 signal was significantly increased in men with asthenozoospermia. The absence of a SEPT7 signal was more prevalent in sperm containing morphological defects of various types.

CONCLUSIONS

The expression pattern of SEPT7 suggested that this protein may be involved in the regulation of subcellular-compartment formation during spermiogenesis in the mouse. The absence of a SEPT7 signal correlated with multiple sperm defects.

The role of sperm creatine kinase in the assessment of male fertility

The lack of reliable methods to assess sperm fertilizing potential has been a long-standing problem for infertile couples and for their physicians. The most widely used tests, the measurements of sperm concentrations, motility, velocity and morphology in the ejaculate, are of limited utility. Indeed, following intrauterine insemination, a treatment that compensates for low motile sperm concentrations, there were no significant differences found in semen parameters among those who did or did not achieve pregnancies. Other available assays probing for selected sperm functions, such as membrane integrity, acrosome enzyme activity, bovine cervical mucus penetration test, zona-free hamster oocyte penetration test and sperm binding to various carbohydrates,10–13 have all failed thus far to consistently predict male fertility. It became increasingly obvious that there was a need to identify cellular markers of sperm quality and fertilizing potential.

Fertility testing and ICSI sperm selection by hyaluronic acid binding: clinical and genetic aspects

The testis-expressed chaperone protein, HspA2 (previously creatine kinase M isoform) was established as a measure of human sperm cellular maturity, function and fertility. The presence of HspA2 in the synaptonemal complex is likely to link low HspA2 expression and increased frequency of chromosomal aneuploidies in arrested-maturity spermatozoa. A relationship also exists between HspA2 expression in elongating spermatids and the associated spermatogenetic events, including plasma membrane remodelling and the formation of zona pellucida and hyaluronic acid (HA) binding sites. The HA receptor of mature spermatozoa, when coupled with HA-coated slides and/or Petri dishes, allows visual observation of sperm-HA binding, providing a basis for sperm maturity testing, a major improvement in semen evaluation, and selection of mature spermatozoa for intracytoplasmic sperm injection (ICSI). Thus, in HA-selected spermatozoa the frequency of chromosomal disomy and diploidy is reduced 4- to 6-fold compared with semen sperm fractions. This reduction is similar to the increase in numerical chromosomal aberrations in ICSI children. Combined studies of sperm shape and chromosome probes demonstrated that sperm morphology does not aid selection of haploid spermatozoa. The HA-mediated sperm selection is a novel and efficient technique that may alleviate potential problems related to ICSI fertilization with visually selected spermatozoa.

Hyaluronic acid binding ability of human sperm reflects cellular maturity and fertilizing potential: selection of sperm for intracytoplasmic sperm injection

PURPOSE OF REVIEW

The current concepts of sperm biochemical markers and the central role of the HspA2 chaperone protein, a measure of sperm cellular maturity and fertilizing potential, are reviewed.

RECENT FINDINGS

Because HspA2 is a component of the synaptonemal complex, low HspA2 levels and increased frequency of chromosomal aneuploidies are related in diminished maturity sperm. We also suggest a relationship between HspA2 expression in elongating spermatids and events of late spermiogenesis, such as cytoplasmic extrusion and plasma membrane remodeling that aid the formation of the zona pellucida binding and hyaluronic acid binding sites. The presence of hyaluronic acid receptor on the plasma membrane of mature sperm, coupled with hyaluronic acid coated glass or plastic surfaces, facilitates testing of sperm function and selection of single mature sperm for intracytoplasmic sperm injection. The frequencies of sperm with chromosomal disomy are reduced approximately fourfold to fivefold in hyaluronic acid selected sperm compared with semen sperm, comparable to the increase in such abnormalities in intracytoplasmic sperm injection offspring. Hyaluronic acid binding also excludes immature sperm with cytoplasmic extrusion, persistent histones, and DNA chain breaks.

SUMMARY

Hyaluronic acid mediated sperm selection is a novel technique that is comparable to sperm zona pellucida binding. Hyaluronic acid selected sperm will also alleviate the risks related to intracytoplasmic sperm injection fertilization with sperm of diminished maturity that currently cause worldwide concern.

Oligozoospermia and heat-shock protein expression in ejaculated spermatozoa

BACKGROUND

Heat-shock protein A2 (HspA2) is correlated with sperm maturity, function and fertility, and a dysfunctional expression of such a gene results in abnormal spermatogenesis. The purpose of this study was to compare HspA2 gene expression in spermatozoa from oligozoospermic men and normozoospermic controls.

METHODS

Semen was obtained and analysed according to World Health Organization (World Health Organization, 1999) guidelines, morphology by Kruger's strict criteria. Seventeen patients with oligozoospermia and 21 fertile controls were studied. Total RNA was extracted from ejaculated and Percoll density-gradient-separated spermatozoa followed by semiquantitative RT-PCR analysis. The relative expression level of HspA2 was analysed according to the expression level of the housekeeping beta-actin gene. Serum hormonal profiles (FSH, LH and testosterone) and a peripheral karyotype were also performed.

RESULTS

All patients possessed normal karyotype, and no significant hormonal differences were found between the two groups. The study group had significantly lower sperm concentration and normal morphology than the controls. Semiquantitative RT-PCR analysis of HspA2 showed significantly lower expression levels in the oligoteratozoospermic men when compared to controls (P=0.0021).

CONCLUSIONS

The HspA2 gene was down-regulated in sperm from infertile men with idiopathic oligoteratozoospermia, suggesting that such anomalies of gene expression might be associated with pathogenesis in some subtypes of male infertility.

Effect of varicocelectomy on sperm creatine kinase, HspA2 chaperone protein (creatine kinase-M type), LDH, LDH-X, and lipid peroxidation product levels in infertile men with varicocele

OBJECTIVES

To determine the total sperm creatine kinase, HspA2 chaperone protein (creatine kinase-M isoform), lactate dehydrogenase (LDH), LDH-X activities, and lipid peroxidation product (malondialdehyde [MDA]) levels in infertile men with varicocele and to examine the possible effect of varicocelectomy on these parameters.

METHODS

Eighty-one men were enrolled in this study. The study population consisted of a control group (n = 25) and a varicocele group (n = 56). Of the 56 patients with varicocele, 26 underwent microsurgical subinguinal varicocelectomy at our institution between July 2002 and July 2003. The standard semen parameters (sperm concentration and motility and Kruger morphology) and total sperm creatine kinase, HspA2, LDH, and LDH-X activities, and MDA levels were assessed in the control and varicocele groups. The differences were compared between the two groups. The same parameters were repeated at 6 months postoperatively in the varicocelectomy group and the preoperative and postoperative results were compared.

RESULTS

The sperm concentration was significantly lower in the varicocele group than in the control group (P = 0.01). The mean sperm HspA2 activities were significantly lower and the LDH activities and MDA levels were significantly greater in the varicocele group than in the control group (P = 0.005 and P = 0.001, P < 0.001, respectively). No statistically significant difference was found in the semen parameters in the varicocelectomy group preoperatively and postoperatively. Sperm HspA2 activities increased significantly after varicocelectomy compared with preoperatively (P < 0.001).

CONCLUSIONS

Our data suggest that sperm HspA2 activities are lower and LDH activities and MDA levels are greater in infertile men with varicocele. These data also suggest that varicocelectomy increases HspA2 activities in these patients.

Human sperm maintain their shape following decondensation and denaturation for fluorescent in situ hybridization: shape analysis and objective morphometry

The relationship between abnormal sperm morphology and chromosomal aberrations has been of interest. Thus far, however, studies have focused on frequencies of sperm with either abnormal morphology or aneuploidies in semen samples, not on detection of individual spermatozoa exhibiting both abnormal morphology and aneuploidy. To assess the feasibility of simultaneous evaluation of both attributes in an individual sperm cell, we investigated whether sperm shape is preserved after decondensation and denaturation, procedures that are required for fluorescent in situ hybridization (FISH). On 21 slides, 395 sperm were fixed, photographed, and then digitized by the computer-assisted Metamorph morphometry program for individual evaluation before decondensation. To establish whether sperm of various shapes would behave in similar manners, the cells were also classified, according to their head shapes, into symmetrical (n = 115), asymmetrical (n = 115), irregular (n = 115), and amorphous (n = 50) categories. Following decondensation and subsequent denaturation, sperm that had been photographed initially were relocalized and digitized for morphometry. Head area, perimeter, long axis, short axis, shape factor, and tail length were evaluated in each of the 395 sperm in both the native and decondensed states. After the decondensation and denaturation protocol of the FISH procedure, the sperm exhibited a proportional increase in dimensions as compared to their original sizes. Their initial shapes were preserved with high fidelity whether the sperm were in the symmetrical, asymmetrical, irregular, or amorphous categories. Hybridization with the chromosome probes had no further effect on sperm shape or size. We provide images to demonstrate how these findings facilitate studies about the relationship between sperm shape and chromosomal content or aberrations in individual spermatozoa.

Hyaluronic acid binding by human sperm indicates cellular maturity, viability, and unreacted acrosomal status

OBJECTIVE

To test, both in semen and washed-sperm fractions, whether hyaluronic acid (HA) binding is restricted to sperm that have completed cellular maturation.

DESIGN

Comparisons of sperm in semen and in HA-bound sperm fractions.

SETTINGS

University-based diagnostic and research andrology laboratory.

PATIENT(S)

Semen samples originated in men being tested for infertility.

INTERVENTION(S)

The attributes of sperm maturity were tested by immunocytochemistry with creatine kinase and HspA2 antisera (highlights cytoplasmic retention in diminished-maturity sperm), aniline blue chromatin staining (detects persistent histones), pisum sativum lectin staining (reveals acrosomal integrity), and the FertiLight viability kit (highlights viable and nonviable sperm).

RESULT(S)

All markers of sperm maturity and immaturity supported the hypothesis that HA-bound sperm are mature. Nonbinding sperm exhibited cytoplasmic and nuclear properties of diminished maturity. The acrosomal status of HA-bound sperm was either unreacted or slightly capacitated, but not acrosome reacted. Only viable sperm exhibited HA binding.

CONCLUSION(S)

Sperm that are able to bind to HA are mature and have completed the spermiogenetic processes of sperm plasma membrane remodeling, cytoplasmic extrusion, and nuclear histone-protamine replacement. Hyaluronic acid-bound sperm show unreacted acrosomes. These studies provide further insights into the relationship between spermiogenesis and sperm function.

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.

Creatine phosphokinase in domestic cat epididymal spermatozoa

Mammalian spermatozoa that have not completed final testicular sperm maturation have residual cytoplasm and increased creatine phosphokinase (CK) content. This study determined: (1) if CK could be detected by immunostaining cat spermatozoa from the caput, corpus, and cauda epididymis, (2) fluctuations in the proportions of spermatozoa with mature or immature CK-staining patterns during epididymal sperm transit, and (3) how well sperm maturity (as determined by a CK marker) correlated with testicular or epididymal dysfunctions associated with morphological sperm abnormalities. One epididymis was collected from each of 37 cats after orchiectomy and processed immediately to allow sperm morphology evaluations on a 'regional' basis. Sperm released from the contralateral epididymis were evaluated for motility, sperm membrane integrity, and immunostaining with CK-B antibodies. Proportions of spermatozoa with malformed or detached heads, proximal droplets and acrosomal or midpiece abnormalities decreased (P < 0.05) from the caput to the cauda epididymis. In contrast, proportions of spermatozoa that were motile, membrane-intact or with flagellar abnormalities or distal droplets increased (P < 0.05) from the caput to cauda region. Percentages of spermatozoa with an immature CK-staining pattern also decreased (P < 0.05) with epididymal transit (which differs from that reported for the human and stallion). There was no correlation (P > 0.05) between sperm morphology and the CK-staining patterns. In summary, the results reveal that some specific sperm malformations in the domestic cat are of testicular origin, whereas others develop during epididymal transit.

Sperm maturity and treatment choice of in vitro fertilization (IVF) or intracytoplasmic sperm injection: diminished sperm HspA2 chaperone levels predict IVF failure

OBJECTIVE

To reexamine whether low sperm HspA2 ratios (formerly sperm CK-M ratio) are predictive for failure to cause pregnancies by in vitro fertilization (IVF) and to explore whether there are other male or female factors that may be predictive for IVF pregnancy outcome.

DESIGN

Retrospective, cohort study.

SETTING

University-based IVF program.

PATIENT(S)

In 119 IVF cycles, three patient groups were studied: 25 men had a <10% sperm HspA2 ratio and a lack of pregnancies (HS <10% group), 50 men had a >10% sperm HspA2 ratio and no pregnancies (HS >10%NP group), and another 44 couples had a >10% sperm HspA2 ratio but did achieve pregnancies (HS >10%P group).

INTERVENTION(S)

Sperm HspA2 ratio determinations within 1 year of the IVF cycles and analysis of male and female IVF cycle parameters.

MAIN OUTCOME MEASURE(S)

Sperm HspA2 ratio determinations within 1 year of the IVF cycles and analysis of male and female IVF cycle parameters.

RESULT(S)

In the three groups, male and female ages, number and maturation level of oocytes, and morphology of embryos were similar. In the HS < 10% group, mean sperm concentration and motility were close to normal, the fertilization and cleavage rates were lower, and cycles without any oocyte fertilization were higher. These parameters were similar in the two HS > 10% groups. The receiver operating characteristic curve in men with sperm HspA2 ratios of <17% (diminished and borderline sperm maturity) provided a cutoff value of 10.84% HspA2 ratio with a 100% positive predictive value for failure to achieve pregnancy, whether the men were oligospermic or normospermic.

CONCLUSION(S)

HspA2 ratios of <10% in the diminished sperm maturity range predict the failure to cause pregnancies by IVF. Thus, IVF should be bypassed in favor of ICSI. The occurrence of pregnancy with ICSI depends on the maturity of sperm selected, and it may not be as likely as in other indications for ICSI.

Creatine kinase as an indicator of sperm quality and maturity in men with oligospermia

OBJECTIVES

To determine the differences among the creatine kinase (CK) levels in the spermatozoa of subfertile men with mild, moderate, or severe oligospermia and to examine the differences in CK activity between infertile patients with various clinical diagnoses and a group of normal healthy donors (control). CK is a marker of sperm maturity that correlates with the sperm fertilizing capacity. Elevated levels are associated with an increased rate of functional abnormalities and increased cytoplasmic retention.

METHODS

We compared the CK levels in 51 oligospermic men who could not initiate a pregnancy. Patients were categorized according to their degree of oligospermia as defined by the total sperm count: mild (greater than 10 to 40 x 10(6); n = 30), moderate (5 to 10 x 10(6); n = 11), and severe (less than 5 x 10(6); n = 10). These patients were further classified according to their diagnosis (ie, varicocele, n = 24; unexplained infertility, n = 17; vasectomy reversal, n = 9; and unknown diagnosis, n = 1). A separate group consisting of 25 healthy donors was included as a control group. A computer-assisted semen analyzer assessed the sperm characteristics, and the CK levels were measured using a CK test kit after the enzyme was extracted with Triton-X.

RESULTS

The CK levels were significantly higher in the sperm of the severely oligospermic group (8.8 +/- 6.5 IU/10(8) sperm) than in the moderate (0.50 +/- 0.19 IU/10(8) sperm) and mild (0.49 +/- 0.15 IU/10(8) sperm) groups (P <0.0001). The mean CK level in the severely oligospermic group was 18-fold higher than that in the moderate (P = 0.03) and mild (P <0.001) groups. The CK levels were significantly higher in all three infertile groups compared with the donor group (0.06 +/- 0.01 IU/10(8) sperm). Patients with varicocele had the highest CK level (3.42 +/- 2.56 IU/10(8) sperm) compared with patients in the vasectomy reversal group (1.73 +/- 0.98 IU/10(8) sperm) and the idiopathic infertility group (0.26 +/- 0.08 IU/10(8) sperm).

CONCLUSIONS

Elevated CK levels are associated with severe oligospermia, irrespective of the clinical diagnosis. CK may be a sensitive indicator of sperm quality and maturity in the follow-up of patients treated for male factor infertility.

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.

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.

Clinical value of tests for assessing male infertility

The laboratory assessment of the male partner of an infertile couple is an important aspect of the overall investigation of that couple. The laboratory tests are designed essentially to determine whether (a) the semen samples contain adequate numbers of normal motile sperm, and the sperm are able (b) to migrate to the site of fertilization and (c) to fertilize oocytes. Within this framework, tests can be viewed as being either descriptive, in terms of describing the ejaculate and sperm, or assessing functional qualities of the sperm. Irrespective of the nature of the test, it must satisfy simple criteria, namely being reproducible and able to discriminate between the fertile and infertile populations reliably. External quality assurance programmes now exist for semen analysis and allied techniques to help laboratories to standardize their reporting and to identify the source of possible errors.

Creatine kinase level and lipid peroxidation rate in human spermatozoa from patients with cancer

PURPOSE

The present study assessed whether the poor semen quality in patients with cancer results from the inhibition of sperm maturation as indicated by creatine kinase or from increased oxidative stress as assessed by lipid peroxidation of the sperm membrane.

METHODS

Cryopreserved semen specimens from patients with testicular (n = 10) and nontesticular (n = 12) cancer and normal healthy donors (n = 14) were analyzed for lipid peroxidation and creatine kinase levels.

RESULTS

The levels of creatine kinase and malonaldehyde did not differ among testicular or nontesticular patients with cancer or normal healthy donors.

CONCLUSIONS

Poor semen quality in testicular and nontesticular patients with cancer is not related to creatine kinase or lipid peroxidation levels; it may be related to other factors.

Creatine kinase activity and isoenzymes in lung, colon and liver carcinomas

We have compared the levels of creatine kinase (CK) activity and the distribution of CK isoenzymes determined by agarose gel electrophoresis in normal colon, liver and lung tissues, and in colon, liver and lung adenocarcinomas, lung squamous cell carcinomas and lung carcinoids. Colon and lung adenocarcinomas, and squamous cell carcinomas presented lower CK activity than the normal tissues and no differences were found between hepatocarcinoma and normal liver tissue. In contrast, lung carcinoids had higher CK activity than normal lung tissue. Type BB-CK was the predominant isoenzyme in normal lung, colon and liver tissues. Type MM isoenzyme was detected in normal lung and type MB-CK was found in normal colon. In most lung tumours the CK isoenzyme electrophoretic pattern did not change. However, no type BB-CK was detected in some hepatocarcinomas, type MM-CK decreased in lung carcinoids and type MB isoenzyme was not observed in colon adenocarcinomas. It is concluded that in most tumours there is a decrease in the expression of type B- and type M-CK subunits, whereas in lung carcinoid the expression of type B-CK activity increases. Thus, the increase in type BB-CK observed in the serum of patients with lung and colon adenocarcinomas is probably due mainly to enhanced enzyme release as a result of tumour cell necrosis.

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).

Relationships between biochemical markers for residual sperm cytoplasm, reactive oxygen species generation, and the presence of leukocytes and precursor germ cells in human sperm suspensions

In this study, we have examined the relationship between creatine phosphokinase (CPK), a biochemical measure of human sperm quality (Huszar et al., 1988a,b, 1990; Huszar and Vigue, 1994), and a marker for the presence of residual cytoplasm in human spermatozoa, glucose-6-phosphate dehydrogenase (G6PDH). We then determined whether the diagnostic potential of these enzymes was related to the capacity of the sperm suspensions to generate reactive oxygen species (ROS) and/or the presence of leukocytes and precursor germ cells. Across the data set as a whole, G6PDH and CPK were highly correlated with each other and, to a lesser extent, with the generation of ROS. Contamination of the sperm suspensions with leukocytes might have contributed to these associations, since the presence of such cells was also significantly correlated with CPK, G6PDH, and ROS. However, even after the leukocytes had been carefully removed, G6PDH was still highly correlated with CPK (r = 0.794), indicating that both criteria were providing similar information of the cytosolic component of human sperm suspensions. In the absence of leukocyte contamination, CPK and G6PDH activities were also correlated with the presence of precursor germ cells, and this association may, in part, explain the diagnostic value of these criteria. An additional component of their prognostic value may be reflected in the statistically significant association observed between G6PDH activity and ROS generation. A possible mechanism for such an association is suggested, which should be amenable to experimental verification.

Maturation antigens present in epididymis of cynomolgus monkeys (Macaca fascicularis)

PROBLEM

The present study was carried out to evaluate the changes in morphology and motility of spermatozoa retrieved from different regions of the epididymis of the cynomolgus monkey. The role of the epididymis in sperm maturation is assessed by assaying protein synthesis within different regions of the epididymis and by correlating these with changes in spermatozoal membrane surface components.

METHOD

Spermatozoa retrieved from proximal caput (CP), midcorpus (CO), and distal cauda (CD) were assessed by morphological evaluation and computerized motion analysis. Membrane surface proteins of spermatozoa of different epididymal regions were extracted and separated on SDS-PAGE. Protein synthesis of different regions of the epididymis were assayed in vitro by [35S]-methionine incorporation.

RESULTS

Spermatozoa obtained from different regions of the epididymis differed morphologically only in the location of the cytoplasmic droplet. Specifically, from caput to corpus to cauda, sperm steadily exhibited a more distal cytoplasmic droplet. When the motion parameters of velocity and amplitude of the lateral head were examined, CP spermatozoa were not progressively motile, and poor duration of movement was most noticeable for CO spermatozoa compared with CD spermatozoa. Membrane extracts from CP, CO, and CD epididymal monkey spermatozoa differed in only several protein bands. Three major polypeptide bands (19, 30, and 60 kD) that were absent from CP sperm were present in CO and CD sperm, with the latter showing increased intensity. Several polypeptides were lost from the sperm during epididymal transit: a 25-kD band was lost in CD sperm; and bands at 27 kD, 50-52 kD, and 90 kD were only present for CP sperm. Additionally, regional differences exist for proteins secreted by the cynomolgus monkey epididymis. Proteins (15, 25 kD) were only secreted in the CP region; a 38-kD protein increased in intensity from the CP to CD regions, whereas a 21-kD protein was absent from CD-secreted medium.

CONCLUSION

These preliminary findings permitted the identification of several "maturational antigens" for cynomolgus monkey spermatozoa. Further characterization of these antigens that are modified during epididymal transit is warranted to determine their significance in the acquisition of progressive motility and fertilizing ability by epididymal spermatozoa.

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.

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.

Hemizona assay and its impact on the identification and treatment of human sperm dysfunctions

The HZA, a functional test for human gamete interaction, has become a useful and valuable experimental tool for physiological and cellular analysis of the early events leading to fertilization. The analysis of the conventional semen parameters with emphasis on sperm morphology (as judged by strict criteria) and motion characteristics (evaluated by computer assisted analysis) constitutes the first obligatory step for a critical evaluation of male-factor patients. Patients in whom fertilization disorders are suspected should be evaluated through bioassays of sperm function of established accuracy. The HZA, a bioassay of sperm-zona binding capacity is here proven to be highly predictive of IVF outcome. Ultimately, our increasing knowledge of sperm biology and dysfunction will provide a basis for a better diagnosis (membrane receptor defects and metabolic/biochemical abnormalities?) as well as better therapeutic interventions in patients with sperm disorders. It seems likely that the HZA may be eventually replaced by a standardized test kit in which recombinant human DNA-derived zona receptors mimic the natural function of the hemizonae currently used. This ZP3 reagent may also be a useful antigen for contraceptive development. The HZA therefore constitutes a useful adjuvant in the armentarium for the diagnosis and therapy of male-factor patients.

Developmental regulation of creatine kinase activity in cells of the epiphyseal growth cartilage

During the process of endochondral bone formation, the maturing chondrocyte exhibits profound changes in energy metabolism. To explore the mechanism of energy conservation in cartilage we examined the expression of creatine kinase, an enzyme that catalyzes the formation of ATP in tissues under oxygen stress. Measurement of creatine kinase activity and cytochemical assessment of enzyme distribution clearly showed that the level of enzyme activity was related to chondrocyte maturation. Thus, as the cells hypertrophied, there was a progressive increase in creatine kinase activity. Similarly, an elevation in creatine kinase activity was noted in chondrocyte cultures as the cells assumed an hypertrophic state. When cartilage calcification was disturbed by rickets, there was a decrease in enzyme activity in the hypertrophic region. Studies were performed to examine the creatine kinase isozyme profile of cells of the epiphysis. In resting and proliferating cartilage, the isoform was MM. In hypertrophic cartilage, the predominant isoforms were MB and BB. In terms of the creatine phosphate content, the highest values were seen in the proliferative region; lower amounts were present in hypertrophic and resting cartilage; and no creatine phosphate was detected in calcified cartilage. These data suggest that turnover of creatine phosphate is greatest in the mineralized region of the epiphysis. The results of these investigations point to creatine kinase as being under developmental control. The activity of the enzyme in cartilage cells should serve as a marker of developmental events associated with chondrocyte proliferation, hypertrophy, and mineralization.