Carlos Simón

Testicular sperm extraction (TESE) and ICSI in patients with permanent azoospermia after chemotherapy

BACKGROUND Patients persistently azoospermic after chemotherapy have been considered traditionally as sterile unless sperm was frozen before therapy. Recent advances during the last decade combining testicular sperm extraction (TESE) and ICSI in patients with non-obstructive azoospermia allow these males to father their own genetic offspring. METHODS A retrospective study was conducted of 12 patients with non-obstructive azoospermia after chemotherapy undergoing TESE between 1995 and 2002. Cancer type and anti-neoplastic treatments were recorded, together with maximum testicular volume, serum FSH levels and testicular histopathology. When TESE was successful, spermatozoa were cryopreserved for performing ICSI later. RESULTS In five patients (41.6%) motile spermatozoa for cryopreservation and ICSI were retrieved. Four of them had received chemotherapy for testicular cancer, and one had been treated by chemotherapy/radiotherapy for Hodgkins disease. Clinical and histological parameters were unable to predict with certainty TESE outcome in an individual patient. Eight ICSI cycles were performed on five couples and one pregnancy was obtained which resulted in the delivery of a healthy girl. CONCLUSION Some patients with permanent azoospermia after chemotherapy can be successfully treated by TESE-ICSI. This procedure, however, may have potential genetic risks. Therefore, freezing semen before starting gonadotoxic therapy is the strategy of choice, and patients should be counselled accordingly.

Differentiation of germ cells and gametes from stem cells

BACKGROUND Advances in stem cell research have opened new perspectives for regenerative and reproductive medicine. Stem cells (SC) can differentiate under appropriate in vitro and in vivo conditions into different cell types. Several groups have reported their ability to differentiate SCs into germline cells, and some of them have been successful in obtaining male and female gamete-like cells by using different methodologies. METHODS This review summarizes the current knowledge in this field and emphasizes significant embryological, genetic and epigenetic aspects of germ cells and gametes in vitro differentiation in humans and other species, highlighting major obstacles that need to be overcome for successful gametogenesis in culture: studies reporting development of germ cell-like cells from murine and human embryonic (ESC) and somatic SCs are critically reviewed. RESULTS Published studies indicate that germ cells can be consistently differentiated from mouse and human ESC. However, further differentiation of germ cells through gametogenesis still has important genetic and epigenetic obstacles to be efficient. CONCLUSIONS Differentiation of germ cells from SCs has the potential of becoming a future source of gametes for research use, although further investigation is needed to understand and develop the appropriate niches and culture conditions. Additionally, if genetic and epigenetic methodological limitations could be solved, therapeutic opportunities could be also considered.

Proteomic analysis of the human receptive versus non-receptive endometrium using differential in-gel electrophoresis and MALDI-MS unveils stathmin 1 and annexin A2 as differentially regulated

BACKGROUND The transcriptome of the endometrium throughout the menstrual cycle has been described in recent years. However, the proteomic of the window of implantation remains unknown. The aim of this study was to compare the proteome of the human endometrium in the pre-receptive phase versus the receptive phase by identifying and quantifying the proteins differentially expressed using differential in-gel electrophoresis (DIGE) and mass spectometry (MS). METHODS Endometrial biopsies were collected at days 2 (pre-receptive) and 7 (receptive) after the urinary luteal hormone surge in the same menstrual cycle from eight fertile women (corresponding to days 16 and 21 of the menstrual cycle). Proteins were extracted and labeled with CyDye DIGE fluorofores and separated using two-dimensional gel electrophoresis. RESULTS Image analysis using the DeCyder software followed by protein identification by matrix-assisted laser desorption/ionization-MS and database searching revealed 32 differentially expressed proteins, although only annexin A2 and stathmin 1 were consistently regulated in the two experiments performed. Validation and localization of annexin A2 and stathmin 1 were performed by western blot and immunohistochemistry. Annexin A2 and stathmin 1 were investigated using an endometrial refractoriness model. The results highlight the key potential of these proteins as possible targets for human endometrial receptivity and interception. CONCLUSION This study shows that the human endometrium has a differential proteomic repertoire during the window of implantation. Consequently, we identified annexin A2 and stathmin 1 as differentially expressed molecules in the receptive endometrium.

Administration of Moderate and High Doses of Gonadotropins to Female Rats Increases Ovarian Vascular Endothelial Growth Factor (VEGF) and VEGF Receptor-2 Expression that Is Associated to Vascular Hyperpermeability

Abstract Convincing evidence supports the role of ovarian-origin vascular endothelial growth factor (VEGF) in inducing vascular permeability (VP) and ascites associated with ovarian hyperstimulation syndrome (OHSS) in mammals, including humans. A circulatory dysfunction has been described in every woman treated with gonadotropins for in vitro fertilization. It is not known, however, whether the action of gonadotropins also includes up-regulation of the VEGF receptor-2 (VEGFR-2) and whether increased VP is also found when milder stimulation is used. Thus, we applied an OHSS animal model to answer these questions. Immature female rats were stimulated with saline (control group) or with high (10 IU of eCG × 4 days + 30 IU hCG, OHSS group) or mild (10 IU of eCG + 10 IU of hCG, mild-stimulation group) doses of gonadotropins. The VP and the expression of whole-VEGF and VEGFR-2 mRNAs were analyzed through time-course experiments (0, 24, 48, and 96 h after hCG). Although eCG increased VP and the expression of VEGF and VEGFR-2 mRNAs in the ovaries of both mild- and OHSS-stimulated animals, hCG further augmented these parameters and produced the highest values after 48 h. A linear correlation was found between increased expression of VEGF and VEGFR-2 mRNAs and enhanced VP in both mild and OHSS groups. Immunohistochemistry showed the presence of VEGF and VEGFR-2 in the granulosa-lutein and endothelial cells of the entire corpus luteum. These studies confirm that in hyperstimulated animals as well as in mildly treated rats, VEGF and VEGFR-2 are overexpressed and associated with an increase in VP, which may be responsible for the accumulation of ascitic fluid in the syndrome.

Interleukin-1 type I receptor messenger ribonucleic acid expression in human endometrium throughout the menstrual cycle *

OBJECTIVE To investigate the messenger ribonucleic acid (mRNA) expression of interleukin-1 (IL-1) type I receptor in the endometrial tissue of normal patients during the menstrual cycle. DESIGN Prospective longitudinal study. SETTING Department of Obstetrics and Gynecology, Stanford University Medical Center, Stanford, California. PATIENTS Twenty fertile women between 19 and 41 years of age underwent hysterectomy for benign reasons (n = 9) and laparoscopy for tubal ligation (n = 11). In all cases, endometriosis was not visualized. INTERVENTIONS Endometrial biopsy using the Novak curette was obtained at the time of surgery. MAIN OUTCOME MEASURE Total RNA extracted from unfractioned endometrial tissue was analyzed on Northern blots by using specific complementary deoxyribonucleic acid probes. RESULTS We found IL-1 type I receptor mRNA expression in endometrial tissue throughout the entire menstrual cycle. However, IL-1 type I receptor mRNA levels were significantly higher during both early and late luteal phases than follicular and midluteal phases. CONCLUSIONS Our results demonstrate the presence of the IL-1 system in the human endometrium and that the receptor is regulated throughout the menstrual cycle with a 4.1-fold increased expression of the IL-1 receptor gene in the early luteal phase compared with preovulatory endometrium.

Leptin system in embryo development and implantation: a protein in search of a function

Implantation is a crucial moment in the reproduction process that requires perfect synchronization between the embryo and the maternal endometrium. The embryo must reach the blastocyst stage and the endometrium must be prepared to receive it. An appropriate and specific molecular dialogue must also take place between them. There is ample evidence to show that the leptin system is implicated in this cross-talk. Examples are described. Although there is some controversy surrounding the data, they are supported by the presence of leptin receptor mRNA in mouse and human oocytes and embryos throughout preimplantation development. Otherwise, the leptin mRNA is only detected at the blastocyst stage in both human and mouse. Furthermore, leptin is found at higher concentrations in the conditioned media from competent human blastocysts than in those from arrested embryos, suggesting that this molecule is a marker for blastocyst viability. Given that expression of the leptin receptor increases in the human endometrium during the luteal phase, the secreted leptin could trigger its activation. Finally, leptin and the leptin receptor have been detected in implantation sites. All these findings point to the involvement of the leptin system in the molecular mechanism of the implantation process and embryo development.

Highly purified hMG versus recombinant FSH in ovarian hyperstimulation with GnRH antagonists—a randomized study

BACKGROUND Highly purified hMG (hp-hMG) has recently shown better cycle outcome than the recombinant FSH (rFSH) when compared in GnRH agonist long protocol cycles. However, they have not yet been compared in GnRH antagonist cycles. METHODS A RCT comparing the ongoing pregnancy rate (primary end-point) in 280 patients undergoing IVF/ICSI after stimulation with hp-hMG or rFSH controlled with a GnRH antagonist. RESULTS No significant differences were observed between hp-hMG and rFSH in terms of the ongoing pregnancy rate per started cycle (35.0 versus 32.1%, respectively; P = 0.61); relative risk: 1.09 (95% confidence interval: 0.78-1.51; risk difference: 2.9%). No differences were observed for implantation, clinical pregnancy and pregnancy loss rates. More oocytes were obtained from patients receiving rFSH then hMG (14.4 +/- 8.1 versus 11.3 +/- 6.0, respectively; P = 0.001). Estradiol was higher at the end of stimulation in the hp-hMG group (P = 0.02), whereas progesterone was higher in patients stimulated with rFSH (P < 0.001). CONCLUSIONS A similar outcome was observed for hp-hMG and rFSH when used for stimulation in GnRH antagonist cycles. However, some differences were found in ovarian response in terms of oocyte yield and hormonal profile. Clinical Trials.gov TRIAL REGISTRATION NUMBER NCT00669786.

Hsa-miR-30d, secreted by the human endometrium, is taken up by the pre-implantation embryo and might modify its transcriptome

During embryo implantation, the blastocyst interacts with and regulates the endometrium, and endometrial fluid secreted by the endometrial epithelium nurtures the embryo. Here, we propose that maternal microRNAs (miRNAs) might act as transcriptomic modifier of the pre-implantation embryo. Microarray profiling revealed that six of 27 specific, maternal miRNAs were differentially expressed in the human endometrial epithelium during the window of implantation – a brief phase of endometrial receptivity to the blastocyst – and were released into the endometrial fluid. Further investigation revealed that hsa-miR-30d, the expression levels of which were most significantly upregulated, was secreted as an exosome-associated molecule. Exosome-associated and free hsa-miR-30d was internalized by mouse embryos via the trophectoderm, resulting in an indirect overexpression of genes encoding for certain molecules involved in the murine embryonic adhesion phenomenon – Itgb3, Itga7 and Cdh5. Indeed, this finding was supported by evidence in vitro: treating murine embryos with miR-30d resulted in a notable increase in embryo adhesion. Our results suggest a model in which maternal endometrial miRNAs act as transcriptomic modifiers of the pre-implantation embryo. Summary: Maternal miRNAs are differentially expressed in the human endometrium and are released into the endometrial fluid, suggesting that they may act as transcriptomic modifiers of the pre-implantation embryo.

PGE2 and PGF2α concentrations in human endometrial fluid as biomarkers for embryonic implantation.

BACKGROUND Prostaglandin (PG) signaling has been implicated in embryonic implantation in several animal species including humans; however, this knowledge has not yet been clinically translated. The objective of this work is to investigate whether PGE2 and PGF2α in endometrial fluid (EF) can be used as biomarkers of human embryonic implantation. PATIENTS AND METHODS Lipidomic profile of human EF (n = 173) obtained through natural cycles, hormonal replacement therapy, controlled ovarian stimulation, and refractory endometrium induced by the insertion of an intrauterine device was analyzed by liquid chromatography and tandem mass spectrometry. Immunohistochemistry, Western blotting, immunolocalization of PG receptors on mouse embryos, embryo adhesion assay, pharmacological interventions, and statistical analysis were conducted. RESULTS PGE2 and PGF2α concentrations increased significantly in the human EF during the window of implantation in natural cycles and assisted reproductive technologies patients undergoing in vitro fertilization and ovum donation. This profile was abrogated in the refractory endometrium. We also demonstrated that PGE2 and PGF2α synthases are located in the endometrial epithelium being hormonally regulated during the window of implantation, and PG receptors are expressed in the trophoectoderm and inner cell mass of mouse blastocysts. Using an in vitro model of embryo adhesion, we demonstrated that inhibition of PGE2 and PGF2α or PG receptors (EP2 and FP) prevents embryo adhesion, which can be overcome by adding these molecules back or using their agonists. Finally, in a pilot study, we demonstrated that PGE2 and PGF2α levels from EF 24 hours prior to embryo transfer could predict pregnancy outcome. CONCLUSIONS Our results suggest that PGE2 and PGF2α concentrations 24 hours prior to embryo transfer are potential noninvasive biomarkers of endometrial receptivity.

Human endometrial receptivity: a genomic approach

The endometrium is a specialized tissue, hormonally-regulated, that is non-adhesive for embryos throughout most of the menstrual cycle in humans and other primates. Thus, endometrial receptivity is a self-limited period in which the endometrial epithelium (EE) acquires a functional and transient ovarian steroid-dependent status. The luminal EE acquires the ability to adhere (receptivity) the developing human blastocyst during this period due mainly to the presence of progesterone after appropriate 17beta-oestradiol priming. This status is a key element for embryonic implantation and appears to be closely associated with morphological and biochemical changes of EE cells. This specific time window is thought to be open after 4-5 days and closes after 9-10 days of progesterone production or administration, creating a physiological window of receptivity limited to days 19-24 of the menstrual cycle in humans. The scientific knowledge of the endometrial receptivity process is fundamental for the understanding of the human reproduction, but, so far, none of the proposed biochemical markers for endometrial receptivity have been proved clinically useful. In this work new strategies are presented based on molecular biology technologies that aim to clarify the fragmented information in this field using differential display, quantitative PCR and cDNA microarray analysis of endometrial epithelial-derived cell lines and endometrial samples to investigate the hierarchy at the mRNA level of molecules implicated in the process of endometrial receptivity.