Culture time to optimize embryo cell-free DNA analysis for frozen-thawed blastocysts undergoing noninvasive preimplantation genetic testing for aneuploidy.

OBJECTIVE: To investigate the ideal time in culture to optimize embryo cell-free deoxyribonucleic acid (cfDNA) analysis in frozen-thawed blastocysts undergoing noninvasive preimplantation genetic testing for aneuploidy (PGT-A). Cell-free DNA is released into the spent blastocyst media (spent media) by the embryo. However, the optimal timing to determine maximal cfDNA in the case of frozen-thawed blastocysts undergoing noninvasive PGT-A remains to be elucidated. DESIGN: In this prospective observational study, 135 spent media and corresponding whole blastocysts were collected from January 2021 through March 2022. SETTING: Private fertility clinics. PATIENTS: Day-5 frozen-thawed blastocysts were cultured for 8 hours (Day-5 Short) or 24 hours (Day-5 Long), whereas day-6 frozen-thawed blastocysts were cultured for 8 hours (Day-6 Short). The spent media and whole blastocysts were then collected for further analysis. Spent media and whole blastocysts were amplified using whole genome amplification and sequenced using next-generation sequencing. MAIN OUTCOME MEASURES: Informativity and concordance rates between cfDNA in spent media and whole blastocyst DNA were compared according to the different times in culture. RESULTS: When comparing time in culture, informativity rates for spent media were significantly higher for Day-5 Long and Day-6 Short (>91%) compared with the Day-5 Short group (<60%). A similar trend was observed for cases with and without a previous PGT-A. Regarding blastocyst expansion grade, informativity rates were lower on Day-5 Short compared with Day-5 Long and Day-6 Short, regardless of expansion degree. This decrease was significant for Gardner-grade expansion grades 3, 4, and 5-6. In addition, for a similar time in culture, the grade of expansion did not have an impact on the informativity rates. For concordance rates, no significant differences were observed among the 3 groups. In all cases, concordance rates were 90.5% for Day-5 Short, 93.6% for Day-5 Long, and 92.3% for Day-6 Short. No impact of the expansion grade was observed on concordance rates. CONCLUSION: Noninvasive PGT-A in frozen-thawed blastocysts yields very high concordance rates with whole blastocysts, possibly limiting the need for invasive PGT-A and making it available for a wider range of patients.

Human embryo live imaging reveals nuclear DNA shedding during blastocyst expansion and biopsy.

Proper preimplantation development is essential to assemble a blastocyst capable of implantation. Live imaging has uncovered major events driving early development in mouse embryos; yet, studies in humans have been limited by restrictions on genetic manipulation and lack of imaging approaches. We have overcome this barrier by combining fluorescent dyes with live imaging to reveal the dynamics of chromosome segregation, compaction, polarization, blastocyst formation, and hatching in the human embryo. We also show that blastocyst expansion mechanically constrains trophectoderm cells, causing nuclear budding and DNA shedding into the cytoplasm. Furthermore, cells with lower perinuclear keratin levels are more prone to undergo DNA loss. Moreover, applying trophectoderm biopsy, a mechanical procedure performed clinically for genetic testing, increases DNA shedding. Thus, our work reveals distinct processes underlying human development compared with mouse and suggests that aneuploidies in human embryos may not only originate from chromosome segregation errors during mitosis but also from nuclear DNA shedding.

Cell-free deoxyribonucleic acid analysis in preimplantation genetic testing.

Detection of chromosomal aneuploidies and monogenic disorders in preimplantation embryos is essential for selecting the best embryo for transfer during in vitro fertilization to achieve a healthy pregnancy. Preimplantation genetic testing (PGT) is typically performed on preimplantation embryos to select a genetically normal embryo for transfer. A trophectoderm biopsy is necessary for PGT; this is an invasive procedure to the embryo that requires specialized equipment and highly trained embryologists, resulting in high costs associated with in vitro fertilization treatment. Moreover, the biopsy procedure may increase the likelihood of developing pregnancy complications, such as preeclampsia and hypertensive disorders. Therefore, there is a need for noninvasive embryo screening strategies. The presence of cell-free deoxyribonucleic acid in the embryo culture medium presents an opportunity to screen for genetic abnormalities. Cell-free deoxyribonucleic acid is released by embryos in the latter stages of preimplantation development, and its analysis has been proposed as a noninvasive approach for PGT. Here, we review studies reporting the concordance rates between cell-free deoxyribonucleic acid and trophectoderm biopsies, or whole blastocysts, in couples undergoing PGT. Noninvasive PGT results are promising for aneuploidy detection, with some early evidence of successful clinical application. Further research is required to explore its application for the detection of structural rearrangements and monogenic disorders.

Non-invasive preimplantation genetic testing for aneuploidies: an update.

Aneuploidy is common among preimplantation human embryos used in assisted reproductive technology. Because abnormal chromosome number can negatively affect reproductive outcome, in-vitro-fertilized embryos routinely undergo aneuploidy testing before transfer into the uterus. This testing typically involves an invasive trophectoderm biopsy of a blastocyst-stage embryo. However, emerging evidence indicates that, during in-vitro development, embryos secrete cell-free DNA into their culture medium; this phenomenon suggests the potential for an alternative, non-invasive assay for aneuploidy. Embryonic cell-free DNA-based assays exhibit high concordance with trophectoderm biopsies, inner cell mass and the whole blastocyst. Yet informativity and concordance rates may be influenced by several factors: the culture day when the medium is collected, contamination with external and/or cumulus cell DNA, and previous manipulation of the embryos. This review discusses non-invasive embryonic cell-free DNA analysis as a biomarker to prioritize blastocysts for transfer to help increase implantation rates and reduce miscarriage rates and time to achieve pregnancy. Ongoing research on the mechanisms underlying embryonic cell-free DNA secretion and how this impacts its role as a biomarker of aneuploidy are also discussed.

Optimized NGS Approach for Detection of Aneuploidies and Mosaicism in PGT-A and Imbalances in PGT-SR.

The detection of chromosomal aneuploidies and mosaicism degree in preimplantation embryos may be essential for achieving pregnancy. The aim of this study was to determine the robustness of diagnosing homogenous and mosaic aneuploidies using a validated algorithm and the minimal resolution for de novo and inherited deletions and duplications (Del/Dup). Two workflows were developed and validated: (a,b) preimplantation genetic testing for uniform whole and segmental aneuploidies, plus mixtures of euploid/aneuploid genomic DNA to develop an algorithm for detecting mosaicism; and (c) preimplantation genetic testing for structural rearrangements for detecting Del/Dup ≥ 6 Mb. Next-generation sequencing (NGS) was performed with automatic library preparation and multiplexing up to 24-96 samples. Specificity and sensitivity for PGT-A were both 100% for whole chromosomes and segmentals. The thresholds stablished for mosaicism were: euploid embryos (<30% aneuploidy), low mosaic (from 30% to <50%), high mosaic (50-70%) or aneuploid (>70%). In the PGT-SR protocol, changes were made to increase the detection level to ≥6 Mb. This is the first study reporting an accurate assessment of semiautomated-NGS protocols using Reproseq on pools of cells. Both protocols allow for the analysis of homogeneous and segmental aneuploidies, different degrees of mosaicism, and small Del/Dup with high sensitivity and specificity.

The dawn of the future: 30 years from the first biopsy of a human embryo. The detailed history of an ongoing revolution.

Following early studies showing no adverse effects, cleavage stage biopsy by zona drilling using acid Tyrode's solution, and removal of single blastomeres for preimplantation genetic testing (PGT) and identification of sex in couples at risk of X-linked disease, was performed by Handyside and colleagues in late 1989, and pregnancies reported in 1990. This method was later used for specific diagnosis of monogenic conditions, and a few years later also for chromosomal structural and/or numerical impairments, thereby establishing a valuable alternative option to prenatal diagnosis. This revolutionary approach in clinical embryology spread worldwide, and several other embryo biopsy strategies developed over three decades in a process that is still ongoing. The rationale of this narrative review is to outline the different biopsy approaches implemented across the years in the workflow of the IVF clinics that provided PGT: their establishment, the first clinical experiences, their downsides, evolution, improvement and standardization. The history ends with a glimpse of the future: minimally/non-invasive PGT and experimental embryo micromanipulation protocols. This grand theme review outlines a timeline of the evolution of embryo biopsy protocols, whose implementation is increasing worldwide together with the increasing application of PGT techniques in IVF. It represents a vade mecum especially for the past, present and upcoming operators and experts in this field to (re)live this history from its dawn to its most likely future.

Multicenter prospective study of concordance between embryonic cell-free DNA and trophectoderm biopsies from 1301 human blastocysts.

BACKGROUND: The recent identification of embryonic cell-free DNA in spent blastocyst media has opened a new era of possibilities for noninvasive embryo aneuploidy testing in assisted reproductive technologies. Yet, previous studies assessing a limited number of embryos reported variable concordance between embryonic cell-free DNA and trophectoderm biopsies, thus questioning the validity of this approach. OBJECTIVE: This study aimed to evaluate the concordance and reproducibility of testing embryonic cell-free DNA vs trophectoderm DNA obtained from the same embryo in a large sample of human blastocysts and to assess the contribution of the inner cell mass and trophectoderm to embryonic cell-free DNA released to the culture media. STUDY DESIGN: This is an interim analysis of a prospective, observational study among 8 in vitro fertilization centers in 4 continents to assess consistency between noninvasive embryo aneuploidy testing of embryonic cell-free DNA and conventional trophectoderm biopsy. The analysis included 1301 day-6/7 blastocysts obtained in 406 in vitro fertilization cycles from 371 patients aged 20-44 years undergoing preimplantation genetic testing for aneuploidy. Fresh oocytes underwent intracytoplasmic sperm injection or in vitro fertilization. No previous assisted hatching or vitrification was allowed before media collection. Individual spent blastocyst medium was collected from embryos cultured at least 40 hours from day 4. After media collection, conventional preimplantation genetic testing for aneuploidy, comprising trophectoderm biopsy and blastocyst vitrification, was performed. Embryonic cell-free DNA was analyzed blindly after embryo transfer. Inner cell mass and trophectoderm biopsies were also performed in a subset of 81 aneuploid blastocysts donated for research. RESULTS: Embryonic cell-free DNA analyses were 78.2% (866/1108) concordant with the corresponding trophectoderm biopsies. No significant differences were detected among centers ranging from 72.5% to 86.3%. Concordance rates exceeded 86% when all defined steps in the culture laboratory were controlled to minimize the impact of maternal and operator contamination. Sensitivity per center ranged from 76.5% to 91.3% and specificity from 64.7% to 93.3%. The false-negative rate was 8.3% (92/1108), and false-positive rate was 12.4% (137/1108). The 2 fertilization techniques provided similar sensitivity (80.9% vs 87.9%) and specificity (78.6% vs 69.9%). Multivariate analysis did not reveal any bias from patient clinical background, ovarian stimulation protocols, culture conditions, or embryo quality on testing accuracy of concordance. Moreover, concordances of embryonic cell-free DNA with trophectoderm and inner cell mass suggest that the embryonic cell-free DNA originates from both compartments of the human embryo. CONCLUSION: Noninvasive analysis of embryonic cell-free DNA in spent blastocyst culture media demonstrates high concordance with trophectoderm biopsy results in this large multicenter series. A noninvasive approach for prioritizing embryo euploidy offers important advantages such as avoiding invasive embryo biopsy and decreased cost, potentially increasing accessibility for a wider patient population.

Embryonic cell-free DNA versus trophectoderm biopsy for aneuploidy testing: concordance rate and clinical implications.

OBJECTIVE: To study whether embryonic cell-free DNA (cfDNA) in spent blastocyst media is representative of the chromosomal constitution of a blastocyst. DESIGN: Pilot prospective blinded study. SETTING: In vitro fertilization center and genetics laboratory. PATIENT(S): A total of 115 trophectoderm (TE) biopsies and spent blastocyst media (SBM) from 46 patients with ages ranging from 32 to 46 years, whose indications for preimplantation genetic testing of aneuploidy (PGT-A) were advanced maternal age, recurrent miscarriage, or recurrent implantation failure. INTERVENTIONS(S): Spent blastocyst media collection and TE biopsy. MAIN OUTCOME MEASURE(S): Concordance rates, sensitivity, and specificity between TE biopsies and SBM. Clinical outcomes in cases with euploid TE biopsies and euploid SBM compared with cases with euploid TE and aneuploid SBM. RESULT(S): In general, the total concordance rate for ploidy and sex was 78.7%, and sensitivity and specificity were 94.5% and 71.7%, respectively. A significant increase for all parameters was observed for day 6/7 samples compared with day 5 samples, with day 6/7 samples showing total concordance for ploidy and sex of 84%, and sensitivity and specificity of 95.2% and 82.1%, respectively. Ongoing implantation rates in euploid TE/euploid SBM showed a threefold increase compared with euploid TE/aneuploid SBM (52.9% vs. 16.7%, respectively), without reaching significant differences. Interestingly, no miscarriages were observed when TE and SBM were euploidy concordant. CONCLUSION(S): These results offer a better understanding of the dynamics of cfDNA during embryo development and despite more basic research being needed, they are reassuring to consider in the future this noninvasive approach as an alternative to TE biopsy for PGT-A.

Clinical application of embryo aneuploidy testing by next-generation sequencing.

We review here the evolution in the field of embryo aneuploidy testing over the last 20 years, from the analysis of a subset of chromosomes by fluorescence in situ hybridisation to the transition toward a more comprehensive analysis of all 24 chromosomes. This current comprehensive aneuploidy testing most commonly employs next-generation sequencing (NGS). We present our experience in over 130 000 embryo biopsies using this technology. The incidence of aneuploidy was lower in trophectoderm biopsies compared to cleavage-stage biopsies. We also confirmed by NGS that embryo aneuploidy rates increased with increasing maternal age, mostly attributable to an increase in complex aneuploid embryos. In contrast, the number of MII oocytes retrieved or the use of oocyte vitrification did not affect aneuploidy rates. Similarly, neither maternal age, oocyte number, nor oocyte vitrification affected the incidence of mosaicism. Analysis of clinical outcomes, indications, and potential benefits of embryo aneuploidy testing revealed advanced maternal age as the most favored group, with some evidence of improved delivery rate per transfer as well as decreased miscarriage rates and time to pregnancy. Other indications are: recurrent miscarriage, repetitive implantation failure, severe male factor, previous trisomic pregnancy, and good prognosis patients mainly undergoing single embryo transfer, with the latter indication used to reduce the occurrence of multiple pregnancies without compromising cycle outcome. In conclusion, NGS has become the most appropriate technology for aneuploidy testing in trophectoderm biopsies, with accurate results, high throughput, and cost efficiency. This technology can be also applied to the analysis of the embryonic cell free DNA released to the culture media at blastocyst stage. This is a promising approach towards a non-invasive preimplantation genetic testing of aneuploidy.

Evaluation of the antiproliferative, proapoptotic, and antiangiogenic effects of a double-stranded RNA mimic complexed with polycations in an experimental mouse model of leiomyoma.

OBJECTIVE: To assess the antiproliferative, proapoptotic, and antiangiogenic effects of the double-stranded RNA mimic polyinosine-polycytidylic acid (pIC) complexed with polyethylenimine [pIC(PEI)] in xenografted human leiomyomas. DESIGN: Heterologous leiomyoma mouse model. SETTING: University-affiliated infertility center. ANIMAL(S): Ovariectomized and hormone-replaced nude mice (n = 16) who received human leiomyoma fragment transplantation. INTERVENTION(S): Leiomyoma fragments placed in the peritoneum of 5-week-old nude female mice and treated with the vehicle (n = 8) or 0.6 mg/kg [pIC(PEI)] (n = 8) for 4 weeks. MAIN OUTCOME MEASURE(S): The size of the leiomyoma implants, and cellular proliferation (Ki67), vascularization (PECAM), and apoptosis (OH-ends) assessed by quantitative immunohistochemical/immunofluorescent analysis of the recovered implants. RESULT(S): No significant differences were observed in the size of the leiomyoma implants between groups. Vascularization and proliferation were significantly decreased, and apoptosis was increased in the [pIC(PEI)]-treated group versus control. CONCLUSION(S): We hypothesize that the antiangiogenic and apoptotic effects exerted by [pIC(PEI)] might lead to a decrease in lesion size in this animal model if the compound is administered for longer periods of time. This study provides promising data on [pIC(PEI)] as a potential novel therapeutic agent against human leiomyoma.

Dopamine agonist inhibits vascular endothelial growth factor protein production and secretion in granulosa cells.

BACKGROUND: Dopamine receptor 2 agonists (D2-ags) inhibit vascular endothelial growth factor (VEGF) secretion in luteinized granulosa cells (LGCs) both in vitro and in vivo. However, the mechanism of D2 regulation of the VEGF/VEGF Receptor 2 (VEGFR-2) pathway remains to be elucidated. We sought to determine the effects of D2 signaling on VEGF transcription and translation in LGCs, with the expectation of identifying potential D2-ag-based therapies for ovarian hyperstimulation syndrome (OHSS). FINDINGS: LGCs from egg donors were cultured with chorionic gonadotropin (hCG) in the presence of Actinomycin-D (ActD) or Brefeldin-A (BFA) to evaluate the effects of a D2-ag, cabergoline (Cb2), on VEGF secretion. The contribution of the conventional Gi/Go, Gz and AKT/ß-Arrestin pathways in the VEGF regulation was assessed by adding pertussis toxin (PTX), phorbol 12-myristate 13-acetate (PMA), or wortmannin (WT). While Cb2 inhibited VEGF secretion by interfering with VEGF peptide translation and secretion, inhibition of conventional D2 transduction pathways did not reverse Cb2-mediated inhibition of VEGF secretion. CONCLUSIONS: The effects of D2-ag on VEGF translation and secretion are mediated by D2 signaling pathways that have yet to be described. We found that D2-ag inhibits VEGF secretion at the post-transcriptional level, suggesting that D2-ag treatment should be combined with therapies that inhibit VEGF transcription, such as the employment of LH or GnRH for triggering ovulation, to improve the efficacy of OHSS prevention.

Evaluation of the potential therapeutic effects of a double-stranded RNA mimic complexed with polycations in an experimental mouse model of endometriosis.

OBJECTIVE: To assess the therapeutic potential of polyinosine-polycytidylic acid, a double-stranded RNA molecule with selective proapoptotic and antiangiogenic activity, complexed with polyethyleneimine (pIC(PEI)) in treating endometriosis. DESIGN: A heterologous mouse model of endometriosis was created by injecting human endometrial fragments into the peritoneum. Endometrial fragments were engineered to express the fluorescent protein mCherry as a reporter to monitor status over the course of the 4-week study. SETTING: University-affiliated infertility center. ANIMAL(S): Ovariectomized and hormone-replaced nude mice (n = 30) injected with fluorescent-labeled human endometrial fragments at 4-6 weeks of age. INTERVENTION(S): Animals (n = 10 per group) were injected with vehicle (control), the anti-VEGF compound CBO-P11 (0.6 mg/kg), or pIC(PEI) (0.6 mg/kg) twice weekly over the course of 4 weeks. MAIN OUTCOME MEASURE(S): Variations in the size of endometriotic implants were estimated by quantifying the expression of mCherry throughout the course of the experiment. Neovascularization, cellular proliferation, and apoptosis were estimated by quantitative immunofluorescence detection of PECAM, α-SMA, Ki67, and TUNEL. RESULT(S): pIC(PEI) promoted a significant increase in apoptosis and a decrease in neovascularization in human fragments, but did not reduce the size of endometriotic implants. CONCLUSION(S): While pIC(PEI) treatment had significant antiangiogenic and pro-apoptotic effects in this setting, longer periods of exposure than the ones supported by our heterologous model and/or assays in homologous mouse models of endometriosis may be necessary to detect an effect of this compound on lesion size.

Dopamine receptor 2 activation inhibits ovarian vascular endothelial growth factor secretion in an ovarian hyperstimulation syndrome (OHSS) animal model: implications for treatment of OHSS with dopamine receptor 2 agonists.

OBJECTIVE: To explore whether a dopamine receptor 2 agonist (D2-ag) can prevent ovarian hyperstimulation syndrome (OHSS) in a rat model by decreasing ovarian vascular endothelial growth factor (VEGF) production. DESIGN: Experimental study in an OHSS animal model. SETTING: University-affiliated infertility center. PATIENT(S): Immature Wistar rats. INTERVENTION(S): Immature rats were stimulated with gonadotropins to mimic OHSS and treated with a D2-ag and/or D2-antagonists (D2-ant). Vascular permeability (VP) was measured at the endpoint, and ovaries were collected to assess the effects of these drugs on VEGF production. MAIN OUTCOME MEASURE(S): VP was estimated by measuring the peritoneal extravasation of a previously injected dye. Ovarian VEGF mRNA expression and VEGF protein levels were assessed by quantitative real-time PCR and Western blots, respectively. RESULT(S): The D2-ag exerted a reduction in VP that was associated with a drastic decrease in VEGF protein production in OHSS rat ovaries. The effects of this D2-ag on VP and VEGF protein levels were partially reversed by concomitant administration of a D2-ant. Ovarian VEGF mRNA expression levels were unaffected by these drugs in OHSS rats. CONCLUSION(S): D2-ags prevent increased VP in OHSS rats by decreasing ovarian VEGF production, very likely through a D2-mediated post-transcriptional mechanism. Given the dose-dependent inhibitory effect of D2-ags on ovarian VEGF production reported herein, we infer that current OHSS therapies used in humans may be improved by increasing the intraovarian concentration of D2-ags in these patients.

Dopamine receptor 2 activation inhibits ovarian vascular endothelial growth factor secretion in vitro: implications for treatment of ovarian hyperstimulation syndrome with dopamine receptor 2 agonists.

OBJECTIVE: To ascertain whether vascular endothelial growth factor (VEGF) secretion by luteinized granulosa cells (GCs) is modulated by the dopaminergic system in a dose-dependent fashion and how this is related to the differential efficacy of dopamine receptor 2 (D2)-agonists (D2-ag) in preventing ovarian hyperstimulation syndrome (OHSS). DESIGN: The relationship between the dopaminergic system and VEGF secretion in luteinized GCs was evaluated. Archived human ovaries were immunostained to characterize D2 expression. SETTING: University affiliated infertility center. PATIENT(S): Premenopausal women and egg donors. INTERVENTION(S): Luteinized GCs were cultured with the D2-ag cabergoline. Human ovarian sections were immunostained for D2. MAIN OUTCOME MEASURE(S): The VEGF was measured by ELISA and D2 expression was evaluated by In-Cell ELISA. The D2 expression throughout the luteal phase was characterized by immunohistochemistry. RESULT(S): The VEGF secretion was decreased by the D2-ag in a dose-dependent fashion. The efficiency of this process was correlated with the amount of D2 expressed by luteinized GCs. A decrease in D2 expression in ovarian sections was observed during the late luteal phase. CONCLUSION(S): The efficacy of D2-ags in preventing OHSS might rely on their capacity to inhibit VEGF secretion by luteinized GCs. Because this capacity is dose-dependent, increasing the intraovarian concentration of D2-ags should be explored as a means of increasing the efficacy of these drugs in preventing OHSS.

Delta-like ligand 4 regulates vascular endothelial growth factor receptor 2-driven luteal angiogenesis through induction of a tip/stalk phenotype in proliferating endothelial cells.

OBJECTIVE: To explore whether the Dll4/Notch-1 signaling pathway modulates vascular endothelial growth factor (VEGF)-dependent luteal angiogenesis and related function, by inducing a tip/stalk phenotype in endothelial cells (ECs). DESIGN: Experimental laboratory animal study. SETTING: University-affiliated infertility center. ANIMAL(S): Immature female mice. INTERVENTION(S): The presence of leading tip ECs in growing luteal vessel was identified by immunofluorescent analysis of Dll4 in the ovaries of hormonally stimulated female mice. The effects of Dll4 inhibition on luteal vessels functionality and related corpus luteum function were assessed by administering a Dll4 blocking antibody or placebo to hormonally stimulated female mice. MAIN OUTCOME MEASURE(S): Alteration of the tip/stalk phenotype was identified by immunofluorescence analysis of luteal vascular density, Dll4, Notch-1, and VEGF receptor 2 expression. Lectin perfusion was used to assay blood vessel functionality, whereas apoptosis and P levels were quantified to determine the effects on luteal function. RESULT(S): Expression of Dll4 was restricted to the tip of growing vessels. Inhibition of Dll4 signaling promotes promiscuous Dll4 expression, leading to increased, but paradoxically, nonfunctional vascularization, which was associated with decreased P levels. CONCLUSION(S): The Dll4/Notch-1 signaling pathway has a modulatory role in VEGF-dependent luteal angiogenesis and related function through induction of a tip/stalk phenotype.

Efficiency and purity provided by the existing methods for the isolation of luteinized granulosa cells: a comparative study.

BACKGROUND: Several protocols for the isolation of luteinized granulosa cells (LGCs) contained in follicular fluid have been described but no previously published study has compared the relative efficiency of these protocols. Our objective is to obtain conclusive scientific evidence for the superiority of one method over another. METHODS: Different purification methods for LGCs based on the recognition of specific cell markers, aggregates, differential adhesion and LGC size were evaluated. We compared the levels of CD45 cell contamination and the percentage of total cell viability in paired aliquots of cells (before and after purification) derived from the follicular fluid obtained from women who were donating oocytes (n = 72). Each of the six purification methods was performed six times using pooled follicular fluids from two women. RESULTS: Samples processed by means of recognition of specific cell markers were characterized by their greater purity (0.1-1.33% CD45+) but low rate of LGC recovery (17.13-25.4%) when compared with the other methods (3.29-12% CD45+, P < 0.05 and 51.67-73.20% LGC, P < 0.05). It is noteworthy that the filter method, which is based on the LGC size, combined one of the highest rates of LGC recovery (∼70%) with acceptable low levels of contamination (<5%). CONCLUSIONS: There is currently no gold standard method for the isolation of LGCs, and protocols should be chosen depending on the purpose in question. We conclude that fluorescence-activated cell sorting is the best protocol for isolating LGCs when purity is the principal criterion, and magnetic separation when both purity and viability are essential. However, cell straining (filter) is probably the least laborious and, overall, the most efficient method to isolate LGCs.