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Category Archives: Human Reproduction

Natural killer cells and pregnancy outcomes in women with recurrent miscarriage and infertility: a systematic review

BACKGROUND

Peripheral natural killer (pNK) and uterine NK (uNK) cells have been associated with reproductive failure. We systematically reviewed the literature to assess whether numbers or activity of pNK or uNK cells predicted subsequent pregnancy and outcome.

METHODS

We searched the electronic MEDLINE database from 1950 to April 2010 for relevant publications by using MeSH terms ‘natural killer cells’, ‘reproduction’ and ‘pregnancy complications’. We included studies that measured pre-pregnancy pNK and uNK cell numbers or activity in women with recurrent miscarriage (RM) or infertility, and reported subsequent pregnancy outcomes of miscarriage or failure to conceive after assisted reproductive technology (ART).

RESULTS

The search identified 783 publications and 12 fulfilled the inclusion criteria. There were too few women entered into the observational studies to assess whether high pNK cell percentages or activity predicted subsequent miscarriage in women with idiopathic RM (numbers: n = 32, OR 17, 95% CI 0.82–350.6, activity: n = 92, OR 2.51, 95% CI 0.16–40.29), or implantation failure (n = 203, OR 1.35, 95% CI 0.28–6.46), or miscarriage in infertile women after ART (n = 79, OR 2.48, 95% CI 0.50–12.32). Similarly, the studies of uNK cells were not large enough to assess whether abnormal uNK cell density predicted subsequent miscarriage in women with idiopathic RM (n = 72, OR 1.33, 95% CI 0.16–11.11). None of the uNK cell studies in women with infertility reported pregnancy outcomes dichotomized for uNK cell numbers.

CONCLUSIONS

The prognostic value of measuring pNK or uNK cell parameters remains uncertain. More studies are needed to confirm or refute the role of NK cell assessments as a predictive test for screening women who may benefit from immunotherapy.

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Selective karyotyping in recurrent miscarriage: are recommended guidelines adopted in daily clinical practice?

BACKGROUND

Couples with recurrent miscarriage (RM) have an increased risk of one of the partners carrying a structural chromosome abnormality. On the basis of four independent risk factors, an evidence-based model was developed, which allows limiting karyotyping to high-risk couples. The aim of this study was to assess the level of adoption of selective karyotyping, its clinical consequences and the factors at the patient and hospital level that determine adoption.

METHODS

A retrospective cohort study was performed in nine Departments of Obstetrics and Gynaecology, the Netherlands, in 2006. Selective karyotyping was defined as offering karyotyping to high-risk couples and refraining from karyotyping in low-risk couples. Data were collected for risk factors as described in the model for selective karyotyping, cytogenetic results as a measure for clinical consequences, and information about determinants and costs.

RESULTS

A total of 530 couples were included; 252 (48%) high-risk couples and 278 (52%) low-risk couples. Among the high-risk couples, 186 (74%) were offered karyotyping. Although not advised, karyotyping was still performed in 198 (71%) low-risk couples. Overall, selective karyotyping was offered to 50% of the couples. The main determinants for adoption of the model were maternal age, obstetric history, treatment by specialists in RM and the number of patients per centre. If selective karyotyping was adopted adequately, a potential reduction of 34% of all karyotyping tests performed is possible.

CONCLUSION

Selective karyotyping is applied in only half of the couples with RM in daily practice. Implementation of selective karyotyping should be a topic of future research.

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Electrophoretic sperm isolation: optimization of electrophoresis conditions and impact on oxidative stress

BACKGROUND

The purpose of this study was to optimize the electrophoretic conditions that should be used for the effective isolation of functional human spermatozoa and to determine whether this method of isolating cells was associated with oxidative stress and DNA damage.

METHODS

Human spermatozoa were prepared by repeated centrifugation, discontinuous density gradient centrifugation and electrophoresis followed by assessments of sperm quality.

RESULTS

Systematic analysis of optimal electrophoresis conditions demonstrated that field strength was positively correlated with sperm recovery rates but negatively correlated with sperm movement, irrespective of whether the current or the voltage was held constant. This loss of functionality observed at high power settings was not associated with a major increase in superoxide generation or the induction of oxidative DNA damage. In contrast, discontinuous Percoll gradient centrifugation was shown to produce a significant rise in oxidative DNA base adduct expression in live cells (P < 0.05). As a result of these analyses, optimized electrophoretic conditions were defined that permitted sperm recovery rates of around 20%. These electrophoretically isolated cells were not only free of oxidative stress but exhibited significantly enhanced motility (P < 0.01) and vitality (P < 0.001) compared with the original samples.

CONCLUSIONS

We conclude that while field strength is positively correlated with sperm recovery rates; it is negatively associated with sperm motility. Optimized conditions are described that represent a balance between these opposing forces and permit the isolation of highly motile, vital sperm populations, free from the oxidative DNA damage associated with conventional density gradient centrifugation technologies.

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Testicular recovery after irradiation differs in prepubertal and pubertal non-human primates, and can be enhanced by autologous germ cell transplantation

BACKGROUND

Although infertility is a serious concern in survivors of pediatric cancers, little is known about the influence of the degree of sexual maturation at the time of irradiation on spermatogenic recovery after treatment. Thus, we address this question in a non-human primate model, the rhesus monkey (Macaca mulatta).

METHODS

Two pubertal (testis size 3 and 6.5 ml, no sperm in ejaculate) and four prepubertal (testis size 1 ml, no sperm in ejaculate) macaques were submitted to a single fraction of testicular irradiation (10 Gy). Unilateral autologous transfer of cryopreserved testis cells was performed 2 months after irradiation. Testicular volume, histology and semen parameters were analyzed to assess irradiation effects and testicular recovery.

RESULTS

Irradiation provoked acute testis involution only in the two pubertal monkeys. Subsequently, testis sizes recovered and sperm was present in the ejaculates. Longitudinal outgrowth of seminiferous tubules continued, and, in testes without autologous cell transfer, 4–22% of tubular cross sections showed spermatogenesis 2 years after irradiation. In contrast, the four prepubertal monkeys showed neither a detectable involution as direct response to irradiation, nor a detectable growth of seminiferous tubules later. However, two of these animals showed spermarche 2 years after irradiation, and 8–12% of tubules presented spermatogenesis. One prepubertally irradiated monkey presented fast growth of one testis after cell transfer, and showed spermarche 1 year after irradiation. The infused testis had spermatogenesis in 70% of the tubules. The contralateral testis remained smaller.

CONCLUSION

We conclude that irradiation before puberty has a severe detrimental effect on outgrowth of seminiferous tubules. But, within the seminiferous epithelium, spermatogenetic recovery occurs at a low rate with no detectable relation to the maturity of the epithelium at irradiation. We also show that autologous testis cell transplantation can enhance spermatogenesis, but only in isolated cases.

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Increased frequency of occult fragile X-associated primary ovarian insufficiency in infertile women with evidence of impaired ovarian function

BACKGROUND

The FMR1 premutation is associated with overt primary ovarian insufficiency (POI). However, its prevalence in women with occult POI (i.e. menstrual cycles, but impaired ovarian response) has not been examined. We hypothesized that both the FMR1 premutation and intermediate allele is more frequent in infertile women with occult POI than in controls, and that a repeat length cutoff might predict occult POI.

METHODS

All subjects were menstruating women <42 years old and with no family history of unexplained mental retardation, autism or fragile X syndrome. Cases had occult POI defined by elevated FSH or poor response to gonadotrophin therapy (n= 535). Control subjects (n= 521) had infertility from other causes or were oocyte donors. Prevalence of the FMR1 premutation and intermediate alleles was examined and allele length was compared between controls and women with occult POI.

RESULTS

The frequency of the premutation (7/535 versus 1/521; P< 0.05) and intermediate alleles (17/535 versus 7/521; P< 0.05) was higher in women with occult POI than in controls. The allele with the greatest number of CGG repeats was longer in women with occult POI compared with controls (32.7 ± 7.1 versus 31.6 ± 4.3; P< 0.01). A receiver operating characteristic curve examining repeat length as a test for occult POI had an area of 0.56 ± 0.02 (P< 0.01). A repeat cutoff of 45 had a specificity of 98%, but a sensitivity of only 5% to identify occult POI. The positive predictive value was only 21% for a fertility population that has ~22% of its patients with occult POI.

CONCLUSIONS

The data suggest that FMR1 premutations and intermediate alleles are increased in women with occult POI. Thus, FMR1 testing should be performed in these women as some will have fragileX-associated POI. Although the FMR1 repeat lengths were longer in women with occult POI, the data do not support the use of a repeat length cutoff to predict occult POI.

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Tubal factor infertility is associated with antibodies against Chlamydia trachomatis heat shock protein 60 (HSP60) but not human HSP60

BACKGROUND

Serum antibodies against major outer membrane protein (MOMP) and heat shock protein 60 (HSP60) from Chlamydia trachomatis are correlated with sequelae following infection. Since bacterial and human HSP60 share considerable sequence homology, cross-reactivity to human HSP60 is suggested as being involved in tubal factor infertility (TFI). The aim was to investigate whether antibodies to human HSP60 are associated with TFI, and to evaluate antibody testing in TFI diagnosis.

METHODS

Serum levels of antibodies against chlamydial MOMP and HSP60 from C. trachomatis, Salmonella enterica Enteritidis, Campylobacter jejuni and human HSP60 were analysed by enzyme-linked immunosorbent assay in three groups of infertile women: women with TFI (n= 70), controls with normal fallopian tubes (control group 1, n= 92) and a subgroup of women with normal fallopian tubes and sero-positive for either chlamydial MOMP or chlamydial HSP60 (control group 2, n= 28).

RESULTS

Serum levels of immunoglobulin (Ig)G1 and IgG3 antibodies against MOMP and HSP60 from C. trachomatis were elevated in patients with TFI compared with non-TFI individuals (group 1; P <0.001), while levels of IgG3 against MOMP and IgG1 against HSP60 were higher in the TFI group compared with control group 2 (P= 0.04 and P= 0.03, respectively). Levels of antibodies against human HSP60 did not differ between groups.

CONCLUSIONS

Our findings confirm an association between TFI and antibodies to MOMP and HSP60 from C. trachomatis, suggesting antibody testing as a supplement in TFI diagnosis. No connection was observed between TFI and antibodies to human HSP60, pointing to an infectious rather than an autoimmune inflammation as the cause of TFI.

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