Intracervical insemination versus intrauterine insemination with cryopreserved donor sperm in the natural cycle: a randomized controlled trial.

STUDY QUESTION: Is intracervical insemination (ICI) non-inferior to IUI with cryopreserved donor sperm in the natural cycle in terms of live birth? SUMMARY ANSWER: ICI with cryopreserved donor sperm in the natural cycle was inferior to IUI in terms of live birth. WHAT IS KNOWN ALREADY: Both ICI and IUI in the natural cycle are performed as first-line treatments in women who are eligible for donor sperm treatment. High-quality data on the effectiveness of ICI versus IUI with cryopreserved donor sperm in the natural cycle in terms of live birth is lacking. STUDY DESIGN, SIZE, DURATION: We performed an open-label multicentre randomized non-inferiority trial in the Netherlands and Belgium. PARTICIPANTS/MATERIALS, SETTING, METHODS: We randomly allocated women who were eligible for donor sperm treatment with cryopreserved donor semen to six cycles of ICI in the natural cycle or six cycles of IUI in the natural cycle. The primary outcome was conception within 8 months after randomization leading to a live birth. Secondary outcomes were ongoing pregnancy, multiple pregnancy, clinical pregnancy, miscarriage and time to conception leading to live birth. We calculated relative risks (RRs) and risk differences (RDs) with 95% CI. Non-inferiority would be shown if the lower limit of the 95% RD CI was <-12%. MAIN RESULTS AND THE ROLE OF CHANCE: Between June 2014 and February 2019, we included 421 women, of whom 211 women were randomly allocated to ICI and 210 to IUI. Of the 211 women allocated to ICI, 2 women were excluded, 126 women completed treatment according to protocol and 75 women did not complete 6 treatment cycles. Of the 210 women allocated to IUI, 3 women were excluded, 140 women completed treatment according to protocol and 62 women did not complete 6 treatment cycles. Mean female age was 34 years (SD ±4) in both interventions. Conception leading to live birth occurred in 51 women (24%) allocated to ICI and in 81 women (39%) allocated to IUI (RR 0.63, 95% CI: 0.47 to 0.84). This corresponds to an absolute RD of -15%; 95% CI: -24% to -6.9%, suggesting inferiority of ICI. ICI also resulted in a lower live birth rate over time (hazard ratio 0.58, 95% CI: 0.41-0.82). Our per-protocol analysis showed that, within the 8 months treatment horizon, 48 women (38%) had live births after ICI and 79 women (56%) had live births after IUI (RR 0.68, 95% CI: 0.52-0.88; RD -18%, 95% CI: -30% to -6%). LIMITATIONS, REASONS FOR CAUTION: The study was non-blinded owing to the nature of the interventions. We consider it unlikely that this has introduced performance bias, since pregnancy outcomes are objective outcome measures. WIDER IMPLICATIONS OF THE FINDINGS: Since ICI in the natural cycle was inferior to IUI in the natural cycle with cryopreserved donor sperm in terms of live birth rate, IUI is the preferred treatment. STUDY FUNDING/COMPETING INTEREST(S): This trial received funding from the Dutch Organization for Health Research and Development (ZonMw project number 837002407). B.W.J.M. is supported by an NHMRC Investigator grant (GNT1176437), reports consultancy for ObsEva and has received research funding from Guerbet, Ferring and Merck. The other authors do not declare a COI. TRIAL REGISTRATION NUMBER: NTR4462. TRIAL REGISTRATION DATE: 11 March 2014. DATE OF FIRST PATIENT'S ENROLMENT: 03 June 2014.

Assessment of fresh and cryopreserved testicular tissues from (pre)pubertal boys during organ culture as a strategy for in vitro spermatogenesis.

STUDY QUESTION: Can the organ culture method be applied to both fresh and cryopreserved human (pre)pubertal testicular tissue as a strategy for in vitro spermatogenesis? SUMMARY ANSWER: Although induction of spermatogenesis was not achieved in vitro, testicular architecture, endocrine function and spermatogonial proliferation were maintained in both fresh and cryopreserved testicular tissues. WHAT IS KNOWN ALREADY: Cryopreservation of a testicular biopsy is increasingly offered as a fertility preservation strategy for prepubertal cancer patients. One of the proposed experimental approaches to restore fertility is the organ culture method, which, in the mouse model, successfully allows for in vitro development of spermatozoa from testicular biopsies. However, complete spermatogenesis from human prepubertal testicular tissue in such an organ culture system has not been demonstrated. STUDY DESIGN, SIZE, DURATION: Testicular tissue was collected from nine (pre)pubertal boys diagnosed with cancer (ranging from 6 to 14 years of age) admitted for fertility preservation before treatment. Testicular biopsies were either immediately processed for culture or first cryopreserved, using a controlled slow freezing protocol, and thawed before culture. Organ culture of testicular fragments was performed in two different media for a maximum period of 5 weeks, targeting early cellular events (viability, meiosis and somatic differentiation) in vitro. PARTICIPANTS/MATERIALS, SETTING, METHODS: Fresh and cryopreserved-thawed testis fragments (1-2 mm3) were cultured at a gas-liquid interphase (34°C, 5% CO2) in Minimum Essential Medium alpha + 10% knock-out serum replacement medium containing 10-7 M melatonin and 10-6 M retinoic acid, with or without 3 IU/L FSH/LH supplementation. The effect of culture conditions on testicular fragments was weekly assessed by histological evaluation of germ cell development and immunohistochemical identification of spermatogonia (using MAGEA4), proliferative status of spermatogonia and Sertoli cells (using proliferating cell nuclear antigen [PCNA]), intratubular cell apoptosis (by terminal deoxynucleotidyl transferase-mediated dUTP nick-end labelling) and Sertoli cells maturation (using Anti-Müllerian Hormone [AMH] versus Androgen Receptor [AR]). Additionally, Leydig cells' functionality was determined by measuring testosterone concentration in the culture media supernatants. MAIN RESULTS AND THE ROLE OF CHANCE: Neither fresh nor cryopreserved human (pre)pubertal testicular fragments were able to initiate spermatogenesis in our organ culture system. Nonetheless, our data suggest that fresh and cryopreserved testicular fragments have comparable functionality in the described organ culture conditions, as reflected by the absence of significant differences in any of the weekly evaluated functional parameters. Additionally, no significant differences were found between the two tested media when culturing fresh and cryopreserved human testicular fragments. Although spermatogonia survived and remained proliferative in all culture conditions, a significant reduction of the spermatogonial population (P ≤ 0.001) was observed over the culture period, justified by a combined reduction of proliferation activity (P ≤ 0.001) and increased intratubular cell apoptosis (P ≤ 0.001). We observed a transient increase in Sertoli cell proliferative activity, loss of AMH expression (P ≤ 0.001) but no induction of AR expression. Leydig cell endocrine function was successfully stimulated in vitro as indicated by increased testosterone production in all conditions throughout the entire culture period (P ≤ 0.02). LARGE SCALE DATA: N/A. LIMITATIONS, REASONS FOR CAUTION: Although not noticeable in this study, we cannot exclude that if an optimized culture method ensuring complete spermatogenesis in human testicular fragments is established, differences in functional or spermatogenic efficiency between fresh and cryopreserved tissue might be found. WIDER IMPLICATIONS OF THE FINDINGS: The current inability to initiate spermatogenesis in vitro from cryopreserved human testicular fragments should be included in the counselling of patients who are offered testicular tissue cryopreservation to preserve fertility. STUDY FUNDING/COMPETING INTEREST(S): This project was funded by EU-FP7-PEOPLE-2013-ITN 603568 `Growsperm'. None of the authors have competing interests. TRIAL REGISTRATION NUMBER: Not applicable.

Development of the testis in pre-pubertal boys with cancer after biopsy for fertility preservation.

STUDY QUESTION: Is testicular growth affected by a testicular biopsy intended for fertility preservation in pre-pubertal boys with cancer? SUMMARY ANSWER: Testicular growth of the biopsied testis is not impeded in comparison to the non-biopsied contralateral testis up until 1 year after surgery. WHAT IS KNOWN ALREADY: Fertility preservation in pre-pubertal boys by means of testicular biopsy has been conducted for more than 15 years. Although immediate adverse effects of testicular biopsy are rare (1%), no data exist on the effect of biopsy on testicular growth. STUDY DESIGN, SIZE, DURATION: In this prospective cohort study, between March 2011 and February 2017, 93 parents of pre-pubertal boys were offered cryopreservation of testicular tissue of their son, of whom 78 consented. Sixty-four boys were included in this follow-up study. PARTICIPANTS/MATERIALS, SETTING, METHODS: All boys with cancer at the paediatric oncology department of the Academic Medical Center (AMC) who needed gonadotoxic therapy and were unable to ejaculate were offered cryopreservation of testicular tissue prior to treatment. By testicular ultrasound before and after biopsy (1, 6 and 12 months after biopsy), volume and parenchymal abnormalities were assessed. Data were analysed using mixed-effects modelling. MAIN RESULTS AND THE ROLE OF CHANCE: Of the 64 included boys all were followed up at 1 month, 58 at 6 months and 55 at 12 months. Mean testicular volumes after 1, 6 and 12 months after biopsy were 1.7 ± 2.1, 1.7 ± 2.2 and 1.9 ± 2.4 for the biopsied testis and 1.8 ± 2.2, 1.8 ± 2.3 and 2.0 ± 2.2 for the non-biopsied testis, respectively. Biopsy of the testis did not have a significant impact on testicular growth. Immediate adverse effects of the biopsy, i.e. wound infections, were seen in 3/78 boys (3.8%). LIMITATIONS, REASONS FOR CAUTION: Although it is the largest cohort available to date, the number of patients included in our follow-up is still relatively small. A larger cohort would be able to evaluate growth more precisely. Follow-up was discontinued in a significant portion of boys, 12/76 (15.8%), mainly because of death due to primary illness but also because they could not be reached or declined further follow-up. WIDER IMPLICATIONS OF THE FINDINGS: These reassuring data may be used in counselling future boys who are eligible for fertility preservation and their parents. STUDY FUNDING/COMPETING INTEREST(S): Study funded by KIKA Foundation (Kika 86), Grant from the Netherlands Organisation for Health Research and Development (ZonMW TAS-116003002). The authors declare no conflict of interest. TRIAL REGISTRATION NUMBER: CCMO-register: NL27690.000.09.

The addition of a low-quality embryo as part of a fresh day 3 double embryo transfer does not improve ongoing pregnancy rates.

STUDY QUESTION: Does the addition of a low-quality embryo in fresh Day 3 double embryo transfer (DET) affect the ongoing pregnancy rate (OPR) and multiple gestation rate in patients with only one or no high-quality embryos available? SUMMARY ANSWER: In patients with only one- or no high-quality embryo available, the addition of a low-quality embryo in fresh Day 3 DET does not improve the OPR but increases multiple gestation rates in fresh DET. WHAT IS KNOWN ALREADY: Pregnancy rates after DET are considered to be higher compared to single embryo transfer (SET) when analyzed per first embryo transfer only. However, these conclusions are based on RCTs in which mostly patients with two or more high-quality embryos were included, and can therefore not be applied to patients with only one or no high-quality embryo available. This is particularly relevant since it has been suggested that low-quality embryos could impair the implantation of simultaneously transferred embryos by paracrine signaling. Hence, we investigated in patients with only one or no high-quality embryo available whether the addition of a low-quality embryo in DET affects the OPR, multiple gestation rate and miscarriage rate. STUDY DESIGN SIZE DURATION: This was a retrospective cohort study of 5050 patients receiving 7252 fresh embryo transfers on Day 3 after fertilization in IVF/ICSI cycles from 2012 to 2015 in two academic hospitals. PARTICIPANTS/MATERIALS SETTING METHODS: We included all women that received fresh SET or DET with any combination of high-quality embryos (7, 8 or 9 blastomeres, with equal to or <20% fragmentation) or low-quality embryos (all other embryos). Outcomes were OPR (primary outcome, defined as a positive fetal heartbeat by transvaginal ultrasound at least 10 weeks after oocyte retrieval), miscarriage rate and multiple gestation rate. We used a generalized estimating equations model adjusting for maternal age, number of oocytes retrieved, center of treatment and the interaction between maternal age and number of oocytes retrieved. Other baseline characteristics, including infertility diagnosis, fertilization method and the number of consecutive fresh embryo transfers per patient, did not contribute significantly to the GEE model and were therefore excluded, and not adjusted for. MAIN RESULTS AND THE ROLE OF CHANCE: Compared to SET with one high-quality embryo, DET with two high-quality embryos resulted in a higher OPR (adjusted odds ratio (OR) 1.38, 95% CI 1.14-1.67), while DET with one high- and one low-quality embryo resulted in a lower OPR (adjusted OR 0.65, 95% CI 0.49-0.90). However, SET in patients with only one high-quality embryo available resulted in a lower OPR compared to SET in patients with two or more high-quality embryos available (adjusted OR 0.52, 95% CI 0.39-0.70). After adjusting for this confounding factor, we found that both DET with two high-quality embryos (adjusted OR 0.99, 95% CI 0.74-1.31) and DET with one high- and one low-quality embryo (adjusted OR 0.78, 95% CI 0.47-1.27) resulted in a not significantly different OPR compared to SET with one high-quality embryo. If only low-quality embryos were available, DET did not increase the OPR as compared to SET with one low-quality embryo (adjusted OR 0.84, 95% CI 0.55-1.28). Multiple gestation rates were higher in all DET groups compared to SET (DET with ≥1 high-quality embryo(s) compared to SET with one high-quality embryo; DET with two low-quality embryos compared to SET with one low-quality embryo; all comparisons P < 0.001). Miscarriage rates were not different in all DET groups compared to SET (DET with ≥1 high-quality embryo(s) compared to SET with one high-quality embryo; DET with two low-quality embryos compared to SET with one low-quality embryo; all comparisons P > 0.05). LIMITATIONS REASONS FOR CAUTION: Limitations to this study include the retrospective design and possible bias between study groups related to embryo transfer policies between 2012 and 2015. Consequently, we may have underestimated pregnancy chances in all DET groups. Furthermore, the OPR was calculated as a percentage of the number of fresh embryo transfers in each study group, and not the total number of started IVF/ICSI cycles. Therefore, the reported pregnancy outcomes may not truly reflect the pregnancy chances of couples at the start of treatment. A possible confounding effect of maternal age in our study is acknowledged but we could not compare clinical outcomes in different age groups separately owing to small sample sizes. Analysis of pregnancy outcomes in lower prognosis patients (higher maternal age, fewer oocytes retrieved) separately is an avenue for future research. WIDER IMPLICATIONS OF THE FINDINGS: The decision to perform DET rather than SET in order to increase the OPR per fresh embryo transfer seems not to be justified for those patients with only one or no high-quality embryo(s) available. However, owing to the limitations of this study, prospective RCTs are needed that specifically investigate pregnancy outcomes in patients with only one or no high-quality embryo(s) available in SET and DET. STUDY FUNDING/COMPETING INTERESTS: This study was funded by a grant from the joint Amsterdam Reproduction & Development Institute of the Academic Medical Center and VU University Medical Center (www.amsterdam-reproduction-and-development.org). The authors have no conflicts of interest to declare.

Prediction model for live birth in ICSI using testicular extracted sperm.

STUDY QUESTION: Which parameters have a predictive value for live birth in couples undergoing ICSI after successful testicular sperm extraction (TESE-ICSI)? SUMMARY ANSWER: Female age, a first or subsequent started TESE-ICSI cycle, male LH, male testosterone, motility of the spermatozoa during the ICSI procedure and the initial male diagnosis before performing TESE were identified as relevant and independent parameters for live birth after TESE-ICSI. WHAT IS KNOWN ALREADY: In reproductive medicine prediction models are used frequently to predict treatment success, but no prediction model currently exists for live birth after TESE-ICSI. STUDY DESIGN, SIZE, DURATION: A retrospective cohort study between 2007 and 2015 in two academic hospitals including 1559 TESE-ICSI cycles. The prediction model was developed using data from one centre and validation was performed with data from the second centre. PARTICIPANTS/MATERIALS, SETTING, METHODS: We included couples undergoing ICSI treatment with surgically retrieved sperm from the testis for the first time. In the development set we included 526 couples undergoing 1006 TESE-ICSI cycles. In the validation set we included 289 couples undergoing 553 TESE-ICSI cycles. Multivariable logistic regression models were constructed in a stepwise fashion (P < 0.2 for entry). The external validation was based on discrimination and calibration. MAIN RESULTS AND THE ROLE OF CHANCE: We included 224 couples (22.3%) with a live birth in the development set. The occurrence of a live birth was associated with lower female age, first TESE-ICSI cycle, lower male LH, higher male testosterone, the use of motile spermatozoa for ICSI and having obstructive azoospermia as an initial suspected diagnosis. The area under the receiver operating characteristic (ROC) curve was 0.62. From validation data, the model had moderate discriminative capacity (c-statistic 0.67, 95% confidence interval: 0.62-0.72) but calibrated well, with a range from 0.06 to 0.56 in calculated probabilities. LIMITATIONS, REASONS FOR CAUTION: We had a lack of data about the motility of spermatozoa during TESE, therefore, we used motility of the spermatozoa used for ICSI after freeze-thawing, information which is only available during treatment. We had to exclude data on paternal BMI in the model because too many missing values in the validation data hindered testing. We did not include a histologic diagnosis, which would have made our data set less heterogeneous and, finally, our model may not be applicable in centres which have a different policy for the indication for performing sperm extraction. The prognostic value of the model is limited because of a low 'area under the curve'. WIDER IMPLICATIONS OF THE FINDINGS: This model enables the differentiation between couples with a low or high chance to reach a live birth using TESE-ICSI. As such it can aid in the counselling of patients and in clinical decision-making. STUDY FUNDING/COMPETING INTERESTS: This study was partly supported by an unconditional grant from Merck Serono (to D.D.M.B. and K.F.) and by the Department of Obstetrics and Gynaecology of Radboud University Medical Center, Nijmegen, The Netherlands, the Department of Obstetrics and Gynaecology, Jeroen Bosch Hospital, Den Bosch, The Netherlands, and the Department of Obstetrics and Gynaecology, Academic Medical Center, Amsterdam, The Netherlands. Merck Serono had no influence in concept, design, nor elaboration of this study. TRIAL REGISTRATION NUMBER: Not applicable.

Prediction model for obtaining spermatozoa with testicular sperm extraction in men with non-obstructive azoospermia.

STUDY QUESTION: Can an externally validated model, based on biological variables, be developed to predict successful sperm retrieval with testicular sperm extraction (TESE) in men with non-obstructive azoospermia (NOA) using a large nationwide cohort? SUMMARY ANSWER: Our prediction model including six variables was able to make a good distinction between men with a good chance and men with a poor chance of obtaining spermatozoa with TESE. WHAT IS KNOWN ALREADY: Using ICSI in combination with TESE even men suffering from NOA are able to father their own biological child. Only in approximately half of the patients with NOA can testicular sperm be retrieved successfully. The few models that have been developed to predict the chance of obtaining spermatozoa with TESE were based on small datasets and none of them have been validated externally. STUDY DESIGN, SIZE, DURATION: We performed a retrospective nationwide cohort study. Data from 1371 TESE procedures were collected between June 2007 and June 2015 in the two fertility centres. PARTICIPANTS/MATERIALS, SETTING, METHODS: All men with NOA undergoing their first TESE procedure as part of a fertility treatment were included. The primary end-point was the presence of one or more spermatozoa (regardless of their motility) in the testicular biopsies.We constructed a model for the prediction of successful sperm retrieval, using univariable and multivariable binary logistic regression analysis and the dataset from one centre. This model was then validated using the dataset from the other centre. The area under the receiver-operating characteristic curve (AUC) was calculated and model calibration was assessed. MAIN RESULTS AND THE ROLE OF CHANCE: There were 599 (43.7%) successful sperm retrievals after a first TESE procedure. The prediction model, built after multivariable logistic regression analysis, demonstrated that higher male age, higher levels of serum testosterone and lower levels of FSH and LH were predictive for successful sperm retrieval. Diagnosis of idiopathic NOA and the presence of an azoospermia factor c gene deletion were predictive for unsuccessful sperm retrieval. The AUC was 0.69 (95% confidence interval (CI): 0.66-0.72). The difference between the mean observed chance and the mean predicted chance was <2.0% in all groups, indicating good calibration. In validation, the model had moderate discriminative capacity (AUC 0.65, 95% CI: 0.62-0.72) and moderate calibration: the predicted probability never differed by more than 9.2% of the mean observed probability. LIMITATIONS, REASONS FOR CAUTION: The percentage of men with Klinefelter syndrome among men diagnosed with NOA is expected to be higher than in our study population, which is a potential selection bias. The ability of the sperm retrieved to fertilize an oocyte and produce a live birth was not tested. WIDER IMPLICATIONS OF THE FINDINGS: This model can help in clinical decision-making in men with NOA by reliably predicting the chance of obtaining spermatozoa with TESE. STUDY FUNDING/COMPETING INTEREST: This study was partly supported by an unconditional grant from Merck Serono (to D.D.M.B. and K.F.) and by the Department of Obstetrics and Gynaecology of Radboud University Medical Center, Nijmegen, The Netherlands, the Department of Obstetrics and Gynaecology, Jeroen Bosch Hospital, Den Bosch, The Netherlands, and the Department of Obstetrics and Gynaecology, Academic Medical Center, Amsterdam, The Netherlands. Merck Serono had no influence in concept, design nor elaboration of this study. TRIAL REGISTRATION NUMBER: Not applicable.

Psychosocial counselling of identifiable sperm donors.

STUDY QUESTION: What do identifiable sperm donors feel about psychosocial counselling? SUMMARY ANSWER: Identifiable sperm donors found it important that psychosocial counselling focused on emotional consequences and on rules and regulations and they expected to have access to psychosocial counselling at the time that donor-offspring actually sought contact. WHAT IS KNOWN ALREADY: Most studies on sperm donors are on anonymous donors and focus on recruitment, financial compensation, anonymity and motivations. There is limited knowledge on the value that identifiable sperm donors place on psychosocial counselling and what their needs are in this respect. STUDY DESIGN, SIZE AND DURATION: We performed a qualitative study from March until June 2014 with 25 identifiable sperm donors, who were or had been a donor at the Centre for Reproductive Medicine of the Academic Medical Centre in Amsterdam any time between 1989 and 2014. PARTICIPANTS/MATERIALS, SETTING AND METHODS: We held semi-structured in-depth interviews with identifiable sperm donors with an average age of 44 years. The interviews were fully transcribed and analysed using the constant comparative method of grounded theory. MAIN RESULTS AND THE ROLE OF CHANGE: Twelve out of 15 donors (former donors ITALIC! n = 8, active donors ITALIC! n = 7) who had received a counselling session during their intake procedure found it important that they had been able to talk about issues such as the emotional consequences of donation, disclosure to their own children, family and friends, future contact with donor-offspring and rules and regulations. Of the 10 former donors who had received no counselling session, 8 had regretted the lack of intensive counselling. In the years following their donation, most donors simply wanted to know how many offspring had been born using their sperm and had no need for further counselling. Nevertheless, they frequently mentioned that they were concerned about the well-being of 'their' offspring. In addition, they would value the availability of psychosocial counselling in the event that donor-offspring actually sought contact. LIMITATIONS, REASONS FOR CAUTION: A limitation of our study is its generalizability, since only a small number of identifiable donors at a single centre were studied. Variation in how donors are counselled upon intake may affect how donors value psychosocial counselling. WIDER IMPLICATIONS OF THE FINDINGS: This study reports on the issues that identifiable donors value being addressed during their intake procedure, as well as during counselling in the event that donor-offspring actually seek contact. These findings can be used to achieve a higher quality of care for identifiable sperm donors and may be the starting point for developing guidelines on psychosocial counselling for sperm donors. STUDY FUNDING/COMPETING INTERESTS: No funding was obtained for this study. The authors have no conflicts of interest to declare.

Intrauterine insemination or intracervical insemination with cryopreserved donor sperm in the natural cycle: a cohort study.

STUDY QUESTION: Does intrauterine insemination in the natural cycle lead to better pregnancy rates than intracervical insemination (ICI) in the natural cycle in women undergoing artificial insemination with cryopreserved donor sperm. SUMMARY ANSWER: In a large cohort of women undergoing artificial insemination with cryopreserved donor sperm, there was no substantial beneficial effect of IUI in the natural cycle over ICI in the natural cycle. WHAT IS KNOWN ALREADY: At present, there are no studies comparing IUI in the natural cycle versus ICI in the natural cycle in women undergoing artificial insemination with cryopreserved donor sperm. STUDY DESIGN, SIZE, DURATION: We performed a retrospective cohort study among all eight sperm banks in the Netherlands. We included all women who underwent artificial insemination with cryopreserved donor sperm in the natural cycle between January 2009 and December 2010. We compared time to ongoing pregnancy in the first six cycles of IUI and ICI, after which controlled ovarian stimulation was commenced. Ongoing pregnancy rates (OPRs) over time were compared using life tables. A Cox proportional hazard model was used to compare the chances of reaching an ongoing pregnancy after IUI or ICI adjusted for female age and indication. PARTICIPANTS/MATERIALS, SETTING, METHODS: We included 1843 women; 1163 women underwent 4269 cycles of IUI and 680 women underwent 2345 cycles of ICI with cryopreserved donor sperm. MAIN RESULTS AND THE ROLE OF CHANCE: Baseline characteristics were equally distributed (mean age 34.0 years for the IUI group versus 33.8 years for the ICI group), while in the IUI group, there were more lesbian women than in the ICI group (40.6% for IUI compared with 31.8% for ICI). Cumulative OPRs up to six treatment cycles were 40.5% for IUI and 37.9% for ICI. This corresponds with a hazard rate ratio of 1.02 [95% confidence interval (CI) 0.84-1.23] after controlling for female age and indication. Increasing female age was associated with a lower OPR, in both the IUI and ICI groups with a hazard ratio for ongoing pregnancy of 0.94 per year (95% CI 0.93-0.97). LIMITATIONS, REASONS FOR CAUTION: This study is prone to selection bias due to its retrospective nature. As potential confounders such as parity and duration of subfertility were not registered, the effect of these potential confounders could not be evaluated. WIDER IMPLICATIONS OF THE FINDINGS: In women inseminated with cryopreserved donor sperm in the natural cycle, we found no substantial benefit of IUI over ICI. A randomized controlled trial with economic analysis alongside, it is needed to allow a more definitive conclusion on the cost-effectiveness of insemination with cryopreserved donor sperm. STUDY FUNDING/COMPETING INTERESTS: No funding was used and no conflicts of interest are declared.

c-Cbl ubiquitinates the EGF receptor at the plasma membrane and remains receptor associated throughout the endocytic route.

Cbl family members have an evolutionarily conserved role in attenuating receptor tyrosine kinase function. Their negative regulatory capacity depends on a Ring finger domain that interacts with ubiquitin conjugating enzymes. Cbl molecules constitute a novel type of E3 or ubiquitin ligase family that is recruited to phosphotyrosine motifs. Ubiquitination of the receptor system is coupled to its downregulation, but it is unclear at which point in the endocytic pathway Cbl molecules come into play. Using low temperature and a dynamin mutant, we find that c-Cbl associates with and ubiquitinates the activated epidermal growth factor (EGF) receptor at the plasma membrane in the absence of endocytosis. With the aid of confocal microscopy and immunogold electron microscopy, we could demonstrate that c-Cbl associates with the EGF receptor at the plasma membrane prior to receptor recruitment into clathrin-coated pits and remains associated throughout the clathrin-mediated endocytic pathway. c-Cbl and the EGF receptor also colocalize in internal vesicles of multivesicular endosomes. Our data are consistent with a role for c-Cbl in clathrin-mediated endocytosis of tyrosine kinase receptors, as well as their intracellular sorting.

Integrins: alternative splicing as a mechanism to regulate ligand binding and integrin signaling events.

Integrins are a family of transmembrane proteins composed of heterodimers of alpha and beta subunits. With their extracellular domain they bind extracellular matrix proteins or other cell surface molecules, and their cytoplasmic domain binds to cytoskeletal and signaling proteins. Thus, they are in an ideal position to transfer information from the extracellular environment to the interior of the cell and vice versa. For several integrin subunits, alternative splicing of mRNA leads to variations in the sequence of both extracellular and cytoplasmic domains. Many integrin splice variants have specific expression patterns, but for some time, functional differences between these variants were not evident. Recent experiments using transfected cell lines and gene targeting of specific splice variants have contributed significantly to our understanding of the function of these splice variants. The results indicate that alternative splicing is a mechanism to subtly regulate the ligand binding and signaling activity of integrins.

Glomerular extracellular matrix components and integrins.

It has become apparent that extracellular matrix components and their cellular receptors, the integrins, are important regulators of glomerular development and function. In this rapidly evolving field we studied the production of extracellular matrix components and integrins by rat glomerular visceral epithelial and mesangial cells, using molecular probes and antibodies that have recently become available. Special attention was paid to laminin isoforms and to splice variants of the integrin subunits alpha 3 and alpha 6. Results were compared to the in vivo expression in human fetal, newborn and adult kidneys. The mesangial cells were found to produce laminin-1, nidogen and two as yet unidentified laminin isoforms with putative alpha chains of about 395 (alpha x) and of 375 kDa (alpha y), tentatively described before as bovine kidney laminin. Furthermore, they expressed the integrins alpha 1 beta 1, alpha 2 beta 1, alpha 3A beta 1, alpha 5 beta 1, alpha v beta 3, alpha v beta 5, and small amounts of alpha 6A beta 1 and alpha 6B beta 1. The glomerular visceral epithelial cells produced the two new laminin isoforms mentioned above, laminin-5, but no laminin-1 or nidogen. The integrins alpha 2 beta 1, alpha 3A beta 1, alpha 6A beta 4, alpha 6B beta 4 and the integrin subunit alpha v were found to be expressed. We show that during nephrogenesis, the laminin alpha 1 chain disappears and is replaced by another alpha chain, possibly one of the two as yet unidentified alpha chains mentioned above. The laminin beta 1 chain is replaced by the beta 2 chain somewhat later in glomerular development. In general, the integrins found to be expressed in glomeruli of adult kidney were consistent with those found in cultured glomerular visceral epithelial and mesangial cells. No splice variant switch of the integrin alpha 3 or alpha 6 subunits could be demonstrated during nephrogenesis. Our results suggest an important role for the mesangial cell in providing nidogen as a crucial component of the supramolecular structure of the glomerular basement membrane. Furthermore our results indicate that laminin alpha x beta 2 gamma 1 and alpha y beta 2 gamma 1 isoforms are important in the glomerulus of adult kidney and that the integrin alpha 3A beta 1 is the main integrin receptor for laminin isoforms on glomerular visceral epithelial and mesangial cells, both in vitro and in vivo.

Identification of the cleavage sites in the alpha6A integrin subunit: structural requirements for cleavage and functional analysis of the uncleaved alpha6Abeta1 integrin.

The alpha6A and alpha6B integrin subunits are proteolytically cleaved during biosynthesis into a heavy chain (120 kDa) that is disulphide-linked to one of two light chains (31 or 30 kDa). Analysis of the structure of the alpha6A subunit on the carcinoma cell line T24 and human platelets demonstrated that the two light chains of alpha6 are not differentially glycosylated products of one polypeptide. Rather they possess different polypeptide backbones, which presumably result from proteolytic cleavage at distinct sites in the alpha6 precursor. Mutations were introduced in the codons for the R876KKR879, E883K884, R890K891 and R898K899 sequences, the potential proteolytic cleavage sites, and wild-type and mutant alpha6A cDNAs were transfected into K562 cells. The mutant alpha6A integrin subunits were expressed in association with endogenous beta1 at levels comparable to that of wild-type alpha6Abeta1. A single alpha6 polypeptide chain (150 kDa) was precipitated from transfectants expressing alpha6A with mutations or deletions in the RKKR sequence. Mutations in the EK sequence yielded alpha6A subunits that were cleaved once into a heavy and a light chain, whereas alpha6A subunits with mutations in one of the two RK sequences were, like wild-type alpha6A, cleaved into one heavy and two light chains. Thus a change in the RKKR sequence prevents the cleavage of alpha6. The EK site is the secondary cleavage site, which is used only when the primary site (RKKR) is intact. Microsequencing of the N-termini of the two alpha6A light chains from platelets demonstrated that cleavage occurs after Arg879 and Lys884. Because alpha6(RKKG), alpha6(GKKR) and alpha6(RGGR) subunits were not cleaved it seems that both the arginine residues and the lysine residues are essential for cleavage of RKKR. alpha6A mutants with the RKKR sequence shifted to the EK site, in such a way that the position of the arginine residue after which cleavage occurs corresponds exactly to Lys884, were partly cleaved, whereas alpha6A mutants with the RKKR sequence shifted to other positions in the alpha6A subunit, including one in which it was shifted two residues farther than the EK cleavage site, were not cleaved. In addition, alpha6A mutants with an alpha5-like cleavage site, i.e. arginine, lysine and histidine residues at positions -1, -2 and -6, were not cleaved. Thus both an intact RKKR sequence and its proper position are essential. After activation by the anti-beta1 stimulatory monoclonal antibody TS2/16, both cleaved and uncleaved alpha6Abeta1 integrins bound to laminin-1. The phorbol ester PMA, which activates cleaved wild-type and mutant alpha6Abeta1, did not activate uncleaved alpha6Abeta1. Thus uncleaved alpha6Abeta1 is capable of ligand binding, but not of inside-out signalling. Our results suggest that cleavage of alpha6 is required to generate a proper conformation that enables the affinity modulation of the alpha6Abeta1 receptor by PMA.

The A and B variants of the alpha 3 integrin subunit: tissue distribution and functional characterization.

The alpha subunits of the laminin-binding integrins alpha 3 beta 1, alpha 6 beta 1, and alpha 7 beta 1 have homologous sequences and are similar in structure. Two cytoplasmic variants, A and B, have been identified for each of these alpha subunits, although the alpha 3B splice variant has been detected only at the mRNA level. We prepared a panel of mouse monoclonal antibodies specific for the A and B variants of the alpha 3 subunit to study their tissue distribution. Four monoclonal antibodies react with alpha 3A, one of which recognizes only the nonphosphorylated form; of the three anti-alpha 3B antibodies, one cross-reacts with alpha 6B. Reverse transcriptase-PCR analysis of various human tissues revealed the presence of alpha 3B mRNA in brain, heart, and skeletal muscle. Moreover, the alpha 3B protein was detected by immunoblotting in brain and heart tissue but not in skeletal muscle. In contrast, alpha 3A mRNA and protein were present in all tissues studied. Thus, the expression of alpha 3B in adult tissues is more restricted than that of alpha 3A. Immunohistochemical studies showed that in brain tissue, both variants are exclusively expressed on small blood-vessel endothelium, whereas in heart tissue their distribution patterns differ markedly. Although alpha 3A is strongly expressed on vascular smooth muscle cells, alpha 3B is detected only on endothelial cells of veins. Expression of the two variant forms of alpha 3 in K562 cells revealed that the ligand-binding specificities of alpha 3A beta 1 and alpha 3B beta 1 are identical: both bind human laminin-2 and -4, laminin-5, and laminins isolated from bovine kidney, but not bovine laminin-2 and -4, mouse laminin-1, or human fibronectin. In addition, adhesion mediated by both integrins is induced to the same extent by phorbol 12-myristate 13-acetate. The alpha 3A, but not the alpha 3B subunit, is phosphorylated; and phosphorylation of alpha 3A increases after phorbol 12-myristate 13-acetate stimulation. Thus, we found no differences between the adhesion functions of the A and B variants of alpha 3.

The two phenylalanines in the GFFKR motif of the integrin alpha6A subunit are essential for heterodimerization.

The membrane-proximal domain of the integrin alpha subunit contains a conserved motif of five amino acid residues, GFFKR. We deleted this motif from the human alpha6A subunit and found that in COS-7 cells this mutant cannot associate with the beta1 subunit and is retained in the endoplasmic reticulum. Point mutations in the GFFKR motif of the glycine residue or the two highly charged amino acids, or deletion of the lysine and arginine residues, had no effect on the ability of alpha6 to interact with beta1 and to be expressed at the cell surface. In contrast, by replacing either of the two phenylalanines with alanine, or by deletion of both of these residues, alpha6 was incapable of associating with beta1. The alpha6 point mutants that associated with beta1 were expressed in K562 cells and their responsiveness to integrin-activating factors was determined. None of these transfectants bound spontaneously to laminin-1, but binding could be induced by either PMA or the stimulating anti-beta1 antibody TS2/16 to the same extent as that of the wild-type transfectant. The ability of these mutants to initiate focal-contact formation in CHO cells plated on laminin-1 substrates also appeared to be unaltered. Thus the behaviour of alpha6 mutants involving the glycine, lysine or arginine residues was indistinguishable from that of wild-type alpha6 both in inside-out and outside-in signalling. In contrast, deletion of the cytoplasmic domain of alpha6 C-terminal of the GFFKR motif resulted in a loss of responsiveness of alpha6beta1 to PMA stimulation and formation of focal contacts on laminin-1. However, this mutant was targeted to focal contacts formed by other integrins, even when they had not bound ligand. Together, these results suggest that the two phenylalanine residues of the GFFKR motif provide a site for interaction of the alpha6A subunit with beta1, whereas the cytoplasmic domain C-terminal of this motif is involved in the regulation of bidirectional signalling via alpha6Abeta1.

Distribution of laminin variants and their integrin receptors in human secondary lymphoid tissue. Colocalization suggests that the alpha 6 beta 4-integrin is a receptor for laminin-5 in lymphoid follicles.

Laminins are a family of multifunctional basement membrane glycoproteins. Over the last years, many laminin isoforms have been characterized, which were shown to be composed of distinct combinations of variant alpha, beta and gamma chains. Some of these isoforms show remarkable tissue specificity, which suggests functional involvement in local processes. In this study the previously described mAb 4C7, which recognize epithelial basement membranes as well as endothelial basement membranes in lymphoid follicles, was identified as an anti-laminin-5 antibody. Using a set of mAbs against various variant laminin chains we established that specifically the gamma 2 chain of laminin-5 was confined to the endothelial basement membranes of vessels in lymphoid follicles, whereas other variant laminin chains were also expressed elsewhere in the lymphoid follicles, whereas other variant laminin chains were also expressed elsewhere in the lymphoid tissue. Additionally, the expression of the known integrin receptors of laminin-5 was also examined. The alpha 6 beta 4 integrin-receptor for laminin was found to be colocalized with the laminin-5 gamma 2 chain on the abluminal surface of endothelial cells, whereas the alpha 3 integrin chain could not be detected in lymphoid follicles. This finding suggests that the alpha 6 beta 4 integrin (and not the alpha 3 beta 1 integrin) serves as a laminin-5 receptor on endothelial cells in the follicular compartment of lymphoid tissue. Furthermore, alpha 6 beta 4 was also found in the same punctuated pattern on FDCs as laminin-5. The function of the laminin-alpha 6 beta 4 complex in this particular localisation is still obscure, but a role in the maintainance of the follicular compartment via hemidesmosome-like attachment sites is postulated.

The role of the cytoplasmic domain of alpha 6 integrin in the assembly and function of alpha 6 beta 1 and alpha 6 beta 4.

We have studied the role of the cytoplasmic domain of alpha 6 in the assembly and function of the alpha 6 beta 4 integrin, and compared it with the role of alpha 6 in the assembly and function of alpha 6 beta 1, by transfection of cDNAs encoding cytoplasmic mutants of alpha 6 into K562 cells with or without full-length beta 4 cDNA. Des-(1022-1050)-alpha 6, which contains a deletion C-terminal to the GFFKR motif, was expressed in association with beta 1, but associated preferentially with beta 4, whereas the wild-type alpha 6 subunit associated efficiently with beta 1 and beta 4. Des-(1016-1050)-alpha 6, which lacked also the GFFKR sequence, was only expressed at the cell surface when beta 4 was available. Transient expression in COS-7 cells showed that des-(1016-1050)-alpha 6 was retained in the endoplasmic reticulum as a monomer, which suggests that truncation of the cytoplasmic domain reduces the affinity of alpha 6 for beta 1, particularly when the GFFKR sequence is absent. Although the GFFKR motif is not essential for association of alpha 6 with beta 4, it increases the stability of the alpha 6 beta 4 integrin. The cytoplasmic domain of alpha 6 is essential for inside-out and outside-in signaling via the alpha 6 beta 1 receptor, but not for adhesion via alpha 6 beta 4. We show that alpha 6 beta 4 is a constitutively active receptor. Thus, unlike adhesion by most other integrins, adhesion by alpha 6 beta 4 does not seem to depend on any active cellular process. Binding of alpha 6 beta 4 to ligand was only slightly affected by truncation of the alpha 6 cytoplasmic domain N-terminal to the GFFKR sequence and became partially dependent on metabolic energy. These data indicate that truncations of the cytoplasmic domain of the alpha 6 subunit affect the assembly and function of alpha 6 beta 1 more strongly than those of alpha 6 beta 4. This difference may be due to the greater affinity of alpha 6 for beta 4 than for beta 1, which makes alpha 6 beta 4 less susceptible to the effect of truncations.

The alpha 6 beta 4 integrin is a receptor for both laminin and kalinin.

Previously, we have establish K562 transfectants that express either alpha 6A beta 1 or alpha 6B beta 1 (K alpha 6A or K alpha 6B) on their surface. Both cell lines bind to laminin and kalinin after treatment with the beta 1-stimulatory antibody TS2/16. Here we introduce the full-length beta 4 cDNA into the alpha 6A- and alpha 6B-expressing K562 cells and selected stably transfected cells. The beta 4 subunit was expressed on the surface of both transfectants and it formed dimers with the alpha 6A or alpha 6B subunits. Immunoprecipitation and preclearing analyses revealed that both transfectants expressed alpha 6 beta 1, in addition to alpha 6 beta 4. While K alpha 6A and K alpha 6B cells required TS2/16 stimulation for binding to laminin or kalinin, adhesion of the unstimulated beta 4-transfected K alpha 6A and K alpha 6B cells to these matrix components was already substantial. This adhesion was mediated by both alpha 6 beta 1 and alpha 6 beta 4 since it was completely blocked by an alpha 6-specific antibody or by a combination of anti-beta 1 and anti-beta 4 antibodies, but only partially by either of these latter two antibodies alone. Adhesion to laminin was completely blocked by an antiserum to laminin fragment E8 as was the adhesion to kalinin by an antibody to kalinin, demonstrating the specificity of adhesion. Both transfectants always adhered more strongly to kalinin than to laminin. Furthermore, binding to kalinin was less well blocked by antibodies to beta 4 than binding to laminin, indicating that the affinity of alpha 6 beta 4 for kalinin is higher than that for laminin. The fact that alpha 6 beta 1 mediated adhesion without TS2/16 stimulation on the beta 4-transfected K alpha 6A and K alpha 6B cells suggests that some activation of alpha 6 beta 1 had occurred in these cells, even though binding was increased when they were actively stimulated by the antibody TS2/16. Finally, we show that Mn2+ induced binding of solubilized alpha 6 beta 4 to matrix containing kalinin, deposited by the murine cell line RAC-11P/SD. This binding was inhibited by the anti-alpha 6 mAb GoH3. Together, these results indicate that both alpha 6 beta 1 and alpha 6 beta 4 are receptors for laminin and kalinin and that there are no differences in ligand specificity between the A and B variants of the alpha 6 subunit when associated with either beta 1 or beta 4.

Distinct and overlapping ligand specificities of the alpha 3A beta 1 and alpha 6A beta 1 integrins: recognition of laminin isoforms.

The ligand specificity of the alpha 3A beta 1 integrin was analyzed using K562 cells transfected with full-length alpha 3A cDNA and was compared with that of alpha 6A beta 1 in similarly transfected K562 cells. Clones were obtained that showed comparable surface expression of either alpha 3A beta 1 or alpha 6A beta 1 integrins. Those expressing alpha 3A beta 1 attached to and spread on immunopurified human kalinin and cellular matrices containing human kalinin, which is a particular isoform of laminin. In addition, alpha 3A transfectants adhered to bovine kidney laminins possessing a novel A chain variant. Binding to kalinin was blocked by a monoclonal antibody against the A chain constituent of kalinin and adhesion to both kalinin and kidney laminins by anti-alpha 3 and beta 1 monoclonal antibodies. The alpha 3A transfected cells bound more strongly to kalinin and bovine kidney laminins after treatment with the beta 1 stimulatory antibody TS2/16. A distinctly weaker and activation-dependent adhesion of alpha 3A transfectants was observed on human placental laminins possessing the Am chain variant (merosin), and no adhesion occurred on bovine heart laminins and murine EHS tumor laminin. Further inactive substrates were fibronectin, nidogen, and collagen types IV and VI, indicating that the alpha 3A beta 1 integrin is a much less promiscuous receptor than thought before. By contrast, alpha 6A transfected cells adhered to all laminin isoforms when stimulated with TS2/16. Adhesion also occurred only on bovine kidney laminins in the absence of TS2/16. These results demonstrate that both alpha 3A beta 1 and alpha 6A beta 1 integrins are typical laminin receptors but that their affinity and activation dependence for binding to various laminin isoforms differ considerably.

Formation of hemidesmosomes in cells of a transformed murine mammary tumor cell line and mechanisms involved in adherence of these cells to laminin and kalinin.

Keratinocytes attach to an underlying basement membrane by adhesion junctions called hemidesmosomes. We have characterized a cell line, RAC-11P/SD, established from a murine mammary tumor, which differentiates into squamous epithelium and forms well defined hemidesmosomes. These hemidesmosomes contain the integrin alpha 6 beta 4 as well as the hemidesmosomal plaque proteins BP230 and HD1 and are associated with a matrix containing kalinin and laminin. We examined how these cells adhere to laminin and to kalinin present in matrices as well as immunopurified kalinin. We show that adhesion to laminin is energy dependent but does not require an intact actin-containing cytoskeleton. The affinity for kalinin proved to be greater and binding to kalinin was still observed when cells had been treated with deoxyglucose and azide to inhibit metabolic energy. Binding to laminin (or fragment E8), but not to kalinin was partially blocked by a monoclonal antibody specific for the integrin alpha 6 subunit, and only in the initial phase of adhesion. The antibody efficiently blocked adhesion to laminin of cells treated with the microfilament disrupting drug cytochalasin B, but only partially blocked the adhesion of cytochalasin B-treated cells to kalinin, while adherence of cells treated with deoxyglucose and azide to kalinin was blocked completely. The integrin alpha 6 beta 4 is redistributed to the basal surface during adhesion and then is organized into ring-like structures when cells are bound to laminin and localized into hemidesmosomes in cells adhered to kalinin. We suggest that anti-alpha 6 hinders the binding of the alpha 6 beta 4 integrins to its ligands laminin and kalinin, but cannot prevent adhesion when clustering of the integrin has become complete. In addition, there is evidence that adhesion to kalinin is mediated by a second receptor, which associates with the actin-containing cytoskeleton. The presence of such a second receptor is suggested because the cells can spread on kalinin, but not when they have been treated with cytochalasin B. On laminin spreading does not occur, irrespective of whether cells have been treated with cytochalasin B or not. The integrin alpha 3 beta 1, which has been identified as a receptor for kalinin but not for laminin, is strongly expressed in RAC-11P/SD cells and it seems likely that this integrin is responsible for spreading of cells on kalinin.