Synthetic serum substitute (SSS): a globulin-enriched protein supplement for human embryo culture

Culture conditions in the IVF laboratory: state of the ART and possible new directions

In the last four decades, the assisted reproductive technology (ART) field has witnessed advances, resulting in improving pregnancy rates and diminishing complications, in particular reduced incidence of multiple births. These improvements are secondary to advanced knowledge on embryonic physiology and metabolism, resulting in the ability to design new and improved culture conditions. Indeed, the incubator represents only a surrogate of the oviduct and uterus, and the culture conditions are only imitating the physiological environment of the female reproductive tract. In vivo, the embryo travels through a dynamic and changing environment from the oviduct to the uterus, while in vitro, the embryo is cultured in a static fashion. Importantly, while culture media play a critical role in optimising embryo development, a large host of additional factors are equally important. Additional potential variables, including but not limited to pH, temperature, osmolality, gas concentrations and light exposure need to be carefully controlled to prevent stress and permit optimal implantation potential. This manuscript will provide an overview of how different current culture conditions may affect oocyte and embryo viability with particular focus on human literature.

Obstetric and perinatal outcomes after embryos cultured in one-step versus sequential culture media systems in vitrified-warmed single blastocyst transfer cycles

RESEARCH QUESTION

Does type of culture medium used influence obstetric and perinatal outcomes after vitrified-warmed single blastocyst transfers?

DESIGN

Retrospective cohort study involving singletons after vitrified-warmed single blastocyst embryo transfers, using embryos cultured in either Irvine Continuous Single Culture medium (CSC) or Vitrolife G5TM PLUS medium culture system between 2013 and 2020.

RESULTS

A total of 2475 women who had singleton deliveries were included for final analysis: 1478 had embryos cultured in CSC and 997 had embryos cultured in G5TM PLUS medium. Birth outcomes, including preterm birth, mean birth weight, gestational age- and sex-adjusted birth weight (Z-scores), rates of large-for-gestational-age, small-for-gestational-age, low birth weight and macrosomia, and the distribution of newborn gender did not differ significantly between groups in crude and adjusted analyses. Women whose embryos were cultured in G5TM PLUS frequently suffered from pregnancy-induced hypertensive disorders compared with those who had embryos cultured in CSC (4.7% versus 3.0%; P = 0.031). This difference was no longer significant after adjusting for several key confounders (adjusted odds ratio 1.49, 95% CI 0.94 to 2.38, P = 0.087). Other obstetric complications, including gestational diabetes mellitus, preterm premature rupture of membranes, abnormal placentation, postpartum haemorrhage and the mode of delivery were all similar between the two groups.

CONCLUSIONS

The present study adds new information to the current evidence by suggesting that the embryo culture medium does not affect birth outcomes and obstetric complications when comparison is limited to Irvine CSC and Vitrolife G5TM PLUS in vitrified-warmed single blastocyst transfer cycles.

Effect of antioxidants on preimplantation embryo development in vitro: a review

In vitro culture of the embryo is a useful method to treat infertility that shows embryo potential for selecting the best one to transfer and successfully implantation. However, embryo development in vitro is affected by oxidative stresses such as reactive oxygen species that may damage embryo development. Antioxidants are molecules found in fruits, vegetables, and fish that play an important role in reducing oxidative processes. In the natural environment, there is a physiological antioxidant system that protects embryos against oxidative damage. This antioxidant system does not exist in vitro. Antioxidants act as free radical scavengers and protect cells or repair damage done by free radicals. Various studies have shown that adding antioxidants into embryo culture medium improves embryo development in vitro. This review article emphasizes different aspects of various antioxidants, including types, functions and mechanisms, on the growth improvement of different species of embryos in vitro.

Systematic Development, Validation and Optimization of a Human Embryo Culture System

Objective: To develop and validate a reliable in vitro culture system for human embryos. Design: Retrospective analyses of a series of four studies were conducted between 2006 and 2010 to assess the effect of incubator type (CO2 box versus Tri-gas minibox), media type, oil type, and hyaluronate supplementation. Optimization of in vitro blastocyst development was verified by assessing our National CDC/ART Surveillance reports between 2010 and 2016. Material and Methods: All patients experienced controlled ovarian hyperstimulation, followed by egg retrieval 35 h post-hCG. Cumulus-oocyte complexes were temporarily cultured in P1 or LG Fert medium plus HSA. Eggs were moved to a more complex media (G-medium or Global®-LG medium) containing a synthetic protein and embryo adhesion supplement (SPS and EAS, respectively; mLG) post-ICSI insemination. Zygotes were assigned to group culture in 25 µl droplets under oil (light mineral oil or paraffin oil; 37 °C) and embryo development was evaluated on Days 3, 5, and 6 and transferred on Day 3 to 5 depending on the number/quality of embryos available and the IVF history of the patient. Transfers were performed under ultrasound guidance, primarily using a Sureview-Wallace catheter, and enriched ET medium containing 500 µg/mL EAS. Results: Pilot study results (Expt. 1) showed that a mLG single-step medium could be effectively used in combination with Sanyo MCO-5 tri-gas (TG) incubators. Once adapted to SCIRS Lab in 2007 (Expt. 2), the latter culture system yielded improved blastocyst production and pregnancy outcomes compared to CO2 in air sequential incubation in P1/Multi-blast medium. In Expt. 3, the mLG/TG system yielded high levels of ≥2BB quality blastocysts (51 to 66%) across all age groups, and greater (p < 0.05) pregnancy success/live birth rates using fewer embryos transferred on Day 5 versus Day 3. After validating its clinical effectiveness, mLG was then prospectively compared to a new generation G-media (1.5 & 2.5; Expt. 4) and determined that the crossover treatment using paraffin oil (Ovoil™) allowed the mLG system to be optimized. Subsequently, a compilation of our Annual CDC/ART reported data over six years verified the overall viability of in vitro cultured and vitrified blastocysts produced in the mLG/TG system. Conclusion: By systematically evaluating and implementing various components of an embryo culture system we were able to optimize blastocyst development over the last decade. Our mLG/TG culture system modified an exceptionally well designed KSOMAA LG medium using endotoxin-free EAS and SPS additives to support cellular membrane wellness under stressful in vitro conditions (e.g., culture, cell biopsy, vitrification). Our use of the mLG/TG culture system has proven to be effective, creating reliably high blastocyst production, implantation, and healthy live births.

Estimation of embryo transfer media viscosity and consideration of its effect on media and uterine fluid interactions

RESEARCH QUESTION

What are the viscosities of media used for human embryo transfer and what is the possible effect of viscosity as it relates to interactions between transfer media and uterine fluid.

DESIGN

Chamber slide filling times, in seconds, were used to calculate viscosity for each commercial and in-house modified medium, with 12 or 24 replicates per medium under standard operating procedure temperature and gas equilibration conditions used for embryo transfer. Means, standard deviations and coefficients of variation were calculated, and each viscosity was estimated using a regression equation; viscosities for each medium were presented for comparative purposes.

RESULTS

Complete culture media (G1-Plus, G2-Plus, G-TL, 1-Step, Global Total, Global Total HEPES, and Sperm Wash Medium) had viscosity estimates of 1.65 cP, 1.77 cP, 1.68 cP, 1.29cP, 1.18 cP, 1.15 cP, and 1.20 cP, respectively. Complete transfer media (EmbryoGlue, UTM), had viscosity estimates of 3.59 cP and 1.28 cP, respectively. Global HEPES medium with 10%, 20%, 30%, and 50% synthetic serum substitute (SSS) volume per volume had viscosity estimates 1.16 cP, 1.23 cP, 1.25 cP, and 1.34 cP, respectively. For reference, water had a viscosity estimate of 1.06 cP.

CONCLUSIONS

A relatively narrow distribution of viscosities was observed across several transfer media despite the various commercial or in-house modifications. These data demonstrate the vast difference between viscosities of embryo transfer media and the assumed viscosity of uterine fluid (1000 cP). Contemporary embryo transfer media may be well-suited for IVF, but evaluation of all variables, e.g. media viscosity in the context of embryo transfer, adds to the knowledge base that should be available to practitioners.

Stem cells: past, present, and future

In recent years, stem cell therapy has become a very promising and advanced scientific research topic. The development of treatment methods has evoked great expectations. This paper is a review focused on the discovery of different stem cells and the potential therapies based on these cells. The genesis of stem cells is followed by laboratory steps of controlled stem cell culturing and derivation. Quality control and teratoma formation assays are important procedures in assessing the properties of the stem cells tested. Derivation methods and the utilization of culturing media are crucial to set proper environmental conditions for controlled differentiation. Among many types of stem tissue applications, the use of graphene scaffolds and the potential of extracellular vesicle-based therapies require attention due to their versatility. The review is summarized by challenges that stem cell therapy must overcome to be accepted worldwide. A wide variety of possibilities makes this cutting edge therapy a turning point in modern medicine, providing hope for untreatable diseases.

Secretome of in vitro cultured human embryos contains extracellular vesicles that are uptaken by the maternal side

Communication between embryo and maternal endometrium occurs during a specific time frame in which implantation is possible. Here we demonstrate for the first time that conditioned media from non-manipulated human embryos cultured in vitro for 3 days or up to the blastocyst stage contain extracellular vesicles (EVs) with a diameter of 50 to 200 nm and bearing the traditional microvesicle and exosome marker proteins CD63, CD9 and ALIX. The embryonic origin of these EVs has been confirmed by the presence of stemness gene transcripts and their enrichment in the non-classical HLA-G protein. NANOG and POU5F1 transcripts were shown to be contained in vesicles deriving from embryos at different stages of development. In line with a higher detection rate of the HLA-G protein in blastocysts compared to cleavage stage embryos, a significantly higher amount of HLA-G was found in vesicles accumulated in spent media from day 3 to day 5 of development compared to those isolated from the earlier stage. Uptake of dye-labeled embryo-derived EVs by human primary endometrial epithelial and stromal cells was also demonstrated with a fluorescence intensity signal significantly higher for cells treated with vesicles derived from blastocysts. Based on these findings, EV exchange may be suggested as an emerging way of communication at the maternal-fetal interface.

Impact of the IVF laboratory environment on human preimplantation embryo phenotype

The phenotype of the human embryo conceived through in vitro fertilization (IVF), that is its morphology, developmental kinetics, physiology and metabolism, can be affected by numerous components of the laboratory and embryo culture system (which comprise the laboratory environment). The culture media formulation is important in determining embryo phenotype, but this exists within a culture system that includes oxygen, temperature, pH and whether an embryo is cultured individually or in a group, all of which can influence embryo development. Significantly, exposure of an embryo to one suboptimal component of the culture system of laboratory typically predisposes the embryo to become more vulnerable to a second stressor, as has been well documented for atmospheric oxygen and individual culture, as well as for oxygen and ammonium. Furthermore, the inherent viability of the human embryo is derived from the quality of the gametes from which it is created. Patient age, aetiology, genetics, lifestyle (as well as ovarian stimulation in women) are all known to affect the developmental potential of gametes and hence the embryo. Thus, as well as considering the impact of the IVF laboratory environment, one needs to be aware of the status of the infertile couple, as this impacts how their gametes and embryos will respond to an in vitro environment. Although far from straight forward, analysing the interactions that exist between the human embryo and its environment will facilitate the creation of more effective and safer treatments for the infertile couple.

MALDI mass spectrometry reveals that cumulus cells modulate the lipid profile of in vitro-matured bovine oocytes

The influence of cumulus cells (CC) on the lipid profile of bovine oocytes matured in two different lipid sources was investigated. Cumulus-oocyte complexes (COC) or denuded oocytes (DO) were matured in tissue culture medium (TCM) supplemented with fetal bovine serum (FBS) or serum substitute supplement (SSS). Lipid profiles of TCM, serum supplements, immature CC and oocyte (IO), and in vitro-matured oocytes from COC and DO were then analyzed by matrix assisted laser desorption ionization mass spectrometry (MALDI-MS) and submitted to partial least squares-discriminant analysis (PLS-DA). The developmental competence of such oocytes was also assessed. Differences in lipid composition were observed between two types of sera and distinctly influenced the lipid profile of CC. As revealed by PLS-DA, the abundance of specific ions corresponding to triacylglycerols (TAG) or phospholipids (PL) were higher in COC compared to DO both supplemented with FBS or SSS and to some extent affected the subsequent DO in vitro embryo development. DO exposed to SSS had however a marked diminished ability to develop to the blastocyst stage. These results indicate a modulation by CC of the oocyte TAG and PL profiles associated with a specific cell response to the serum supplement used for in vitro maturation.

Optimizing the culture environment and embryo manipulation to help maintain embryo developmental potential

With increased use of comprehensive chromosome screening (CCS), the question remains as to why some practices do not experience the same high levels of clinical success after implementation of the approach. Indeed, the debate surrounding the efficacy and usefulness of blastocyst biopsy and CCS continues. Importantly, several variables impact the success of an assisted reproductive technology cycle. Transfer of a euploid embryo is but one factor in an intricate system that requires numerous steps to occur successfully. Certainly, the culture environment and the manipulations of the embryo during its time in the laboratory can impact its reproductive potential. Environmental stressors ranging from culture media to culture conditions and even culture platform can impact biochemical, metabolic, and epigenetic patterns that can affect the developing cell independent of chromosome number. Furthermore, accompanying procedures, such as biopsy and vitrification, are complex and, when performed improperly, can negatively impact embryo quality. These are areas that likely still carry room for improvement within the IVF laboratory.

A combination of hydroxypropyl cellulose and trehalose as supplementation for vitrification of human oocytes: a retrospective cohort study

PURPOSE

This study aimed to determine whether the new formulation of vitrification solutions containing a combination of hydroxypropyl cellulose (HPC) and trehalose does not affect outcomes in comparison with using conventional solutions made of serum substitute supplement (SSS) and sucrose.

METHODS

Ovum donation cycles were retrospectively compared regarding the solution used for vitrification and warming of human oocytes. The analysis included 218 cycles (N = 2532 oocytes) in the study group (HPC + trehalose) and 214 cycles (N = 2353 oocytes) in the control group (SSS + sucrose).

RESULTS

No statistical differences were found in ovarian stimulation parameters and baseline characteristics of donors and recipients. The survival rate was 91.3% (95% confidence interval (CI) = 89.8-92.9) in the HPC + trehalose group vs. 92.1% (95% CI = 90.4-93.7) in the SSS + sucrose group (NS). The implantation rate (42.8%, 95% CI = 37.7-47.9 vs. 41.2%, 95% CI = 36.0-46.4), clinical pregnancy rate (CPR) per transfer (60.7%, 95% CI = 53.9-67.5 vs. 56.4%, 95% CI = 49.3-63.5), and ongoing pregnancy rate (OPR) per transfer (48.5%, 95% CI = 41.5-55.5 vs. 46.3%, 95% CI = 39.2-53.4) were similar for patients who received either HPC + trehalose-vitrified oocytes or SSS + sucrose-vitrified oocytes. Statistical differences were found when analyzing blastocyst rate both per injected oocyte (30.2%, 95% CI = 28.3-32.1 vs. 24.1%, 95% CI = 22.3-25.9) and per fertilized oocyte (40.8%, 95%CI = 38.5-43.1 vs. 33.2%, 95% CI = 30.8-35.5) (P < 0.0001). Delivery rate was comparable between groups (37.2%, 95% CI = 30.8-46.6 vs. 36.9%, 95% CI = 30.4-43.4; NS).

CONCLUSIONS

Our data demonstrate that HPC and trehalose are suitable and safe substitutes for serum and sucrose. Therefore, the new commercial media can be used efficiently in the vitrification of human oocytes avoiding viral and endotoxin contamination risk.

The impact of the protein stabilizer octanoic acid on embryonic development and fetal growth in a murine model

PURPOSE

The purpose of this study was to determine the effect of the protein stabilizer octanoic acid on blastocyst development, implantation, and fetal growth in a murine model.

METHODS

One-cell mouse embryos were collected and individually cultured in medium supplemented with recombinant human serum albumin for 96 h at 5 % oxygen in an EmbryoScope. Embryos were randomly allocated to four octanoic acid groups (0, 400, 800, or 1200 μM). Blastocyst development and cell cycle timings were calculated at 96 h of culture, and experiments were repeated in triplicate. Blastocysts were stained and fixed at 96 h for differential cell counts. Following 96 h of culture, blastocysts were transferred to recipients to determine implantation rates and fetal and placental weights.

RESULTS

Blastocyst development, hatching rates, developmental kinetics, and total number of cells were negatively affected by octanoic acid at concentrations commonly used in human IVF. Implantation was not affected by octanoic acid but fetal and placental weights at 800 μM octanoic acid were increased relative to control.

CONCLUSIONS

Octanoic acid, a standard additive to human protein supplements used in IVF, can have long-term negative effects on embryonic and fetal development. The use of octanoic acid for human embryo culture should be monitored and reduced.

The effects of chemical and physical factors on mammalian embryo culture and their importance for the practice of assisted human reproduction

BACKGROUND

Although laboratory procedures, along with culture media formulations, have improved over the past two decades, the issue remains that human IVF is performed in vitro (literally 'in glass').

METHODS

Using PubMed, electronic searches were performed using keywords from a list of chemical and physical factors with no limits placed on time. Examples of keywords include oxygen, ammonium, volatile organics, temperature, pH, oil overlays and incubation volume/embryo density. Available clinical and scientific evidence surrounding physical and chemical factors have been assessed and presented here.

RESULTS AND CONCLUSIONS

Development of the embryo outside the body means that it is constantly exposed to stresses that it would not experience in vivo. Sources of stress on the human embryo include identified factors such as pH and temperature shifts, exposure to atmospheric (20%) oxygen and the build-up of toxins in the media due to the static nature of culture. However, there are other sources of stress not typically considered, such as the act of pipetting itself, or the release of organic compounds from the very tissue culture ware upon which the embryo develops. Further, when more than one stress is present in the laboratory, there is evidence that negative synergies can result, culminating in significant trauma to the developing embryo. It is evident that embryos are sensitive to both chemical and physical signals within their microenvironment, and that these factors play a significant role in influencing development and events post transfer. From the viewpoint of assisted human reproduction, a major concern with chemical and physical factors lies in their adverse effects on the viability of embryos, and their long-term effects on the fetus, even as a result of a relatively brief exposure. This review presents data on the adverse effects of chemical and physical factors on mammalian embryos and the importance of identifying, and thereby minimizing, them in the practice of human IVF. Hence, optimizing the in vitro environment involves far more than improving culture media formulations.

Soluble ligands and their receptors in human embryo development and implantation

Extensive evidence suggests that soluble ligands and their receptors mediate human preimplantation embryo development and implantation. Progress in this complex area has been ongoing since the 1980s, with an ever-increasing list of candidates. This article specifically reviews evidence of soluble ligands and their receptors in the human preimplantation stage embryo and female reproductive tract. The focus will be on candidates produced by the human preimplantation embryo and those eliciting developmental responses in vitro, as well as endometrial factors related to implantation and receptivity. Pathways to clinical translation, including innovative diagnostics and other technologies, are also highlighted, drawing from this collective evidence toward facilitating joint improvements in embryo quality and endometrial receptivity. This strategy could not only benefit clinical outcomes in reproductive medicine but also provide broader insights into the peri-implantation period of human development to improve fetal and neonatal health.

Composition of protein supplements used for human embryo culture

PURPOSE

To determine the composition of commercially available protein supplements for embryo culture media and test if differences in protein supplement composition are biologically relevant in a murine model.

METHODS

Amino acid, organic acid, ion and metal content were determined for 6 protein supplements: recombinant human albumin (AlbIX), human serum albumin (HSA and Buminate), and three complex protein supplements (SSS, SPS, LGPS). To determine if differences in the composition of these supplements are biologically relevant, mouse one-cell embryos were collected and cultured for 120 hours in each protein supplement in Global media at 5 and 20 % oxygen in an EmbryoScope time-lapse incubator. The compositions of six protein supplements were analyzed for concentrations of 39 individual amino acids, organic acids, ions and elements. Blastocyst development and cell cycle timings were calculated at 96-hours of culture and the experiments were repeated in triplicate. Blastocyst gene expression was analyzed.

RESULTS

Recombinant albumin had the fewest undefined components , the lowest concentration of elements detected, and resulted in high blastocyst development in both 5 and 20 % oxygen. Buminate, LGPS and SPS had high levels of transition metals whereas SSS had high concentrations of amino acids. Pre-compaction mouse embryo development was delayed relative to embryos in AlbIX for all supplements and blastocyst formation was reduced in Buminate, SPS and SSS.

CONCLUSIONS

The composition of protein supplements are variable, consisting of previously undescribed components. High concentrations of pro-oxidant transition metals were most notable. Blastocyst development was protein dependent and showed an interaction with oxygen concentration and pro-oxidant supplements.

Media composition: macromolecules and embryo growth

Most embryo culture media are still supplemented with proteins rather than with nonprotein macromolecules or recombinant protein products. HSA is probably the most common supplement followed by globulin-enriched preparations. Serum supplementation and Co-Culture of embryos belong to the past. Defined nonprotein or recombinant protein supplements are becoming a viable alternative during gamete and embryo manipulation procedures. Biological protein supplements are still preferred for any extended period of embryo culture. Understanding the goals and purpose of supplemented macromolecules in embryo culture media during each step of the laboratory IVF process should assist us in choosing the safest and most consistent macromolecule for each step, but also selecting a product that has the capability of delivering the best clinical outcome. Each batch of biological protein supplement is unique, even if supplied by the same manufacturer. Each lot of protein supplement typically contains many lot-specific, potentially harmful, and unintended hormone and protein contaminants. Macromolecular embryo culture medium supplements should be identified as one of the highest risk factors in an IVF laboratory that may contribute towards clinical compromise. All efforts should be made to use a proven batch of supplement for as long as the expiration date will allow. The beneficial effect of more complex protein supplements is evident after the activation of the embryonic genome and probably due to the presence of growth factors. Lower live-birth rates due to suboptimum protein supplementation may be a direct result of the preferential loss of female embryos. When deciding on a culture system, thought should be given specifically to the interaction between the culture medium and the macromolecular supplement. Ready-to-use pre-supplemented culture media may be advisable over a more complex product if a comprehensive macromolecular quality management program is not feasible. However, the question remains as to whether the increasing simplification of embryo culture media supplements is ready for large-scale clinical use.

Quantitative analysis of perfluorinated chemicals in media for in vitro fertilization and related samples

The actual standard in vitro fertilization (IVF) protocol recommends an overnight gamete co-incubation. All of the culture media used for human IVF are supplemented with serum or albumin. In the present study, we determined the concentrations of perfluorinated chemicals (PFCs) in IVF media (IVFM) and related samples by liquid chromatography with tandem mass spectrometry (LC/MS/MS). The results indicated that the concentrations of PFOS and PFOA in the protein source were higher than those in the IVFM samples. Compared with human plasma concentrations of PFCs, PFCs in all of the IVFM samples, such as PFBS, PFHxS and PFOA, were either not detected or present at only trace levels, even when protein source was added. LC/MS/MS could be used to determine PFCs in IVFM samples in future studies of the effects of PFC exposure on intrauterine insemination.

Media composition: antioxidants/chelators and cellular function

Protection of embryos against oxidative insults during culture is necessary to maintain viability. Generation of excessive levels of reactive oxygen species (ROS) is triggered by various components of the in vitro environment, most of which embryos do not normally encounter in vivo. To compensate for these deficiencies in the culture environment, antioxidants and chelators are often used to control or suppress ROS levels as embryos develop. However, there is no consensus regarding dosage, time of exposure, or appropriate combinations of antioxidants and chelators in embryo culture. In order to elucidate this aspect of an embryo's chemical surroundings in vitro, we present the current knowledge on the function and effect of each antioxidant or chelator that is often included in an embryo culture medium.

Application of two different synthetic sequential media for the human IVF-ET program: a prospective, randomized, and comparative study

Objective

Since IVF program was first established, various types of media and culture systems have been developed either in-house or commercially. The aim of this study was to compare the efficacy of in-house Maria Research Center (MRC) media to that of commercially available Sydney IVF media in human day 3 embryo transfer cycles.

Methods

Three hundred sixty nine couples were included in this prospective, randomized, and comparative study. All couples undergoing IVF treatment at the Maria Fertility Hospital were randomly assigned to either Sydney IVF (n=178) or MRC (n=191) media.

Results

No difference was observed between the MRC media and Sydney IVF media groups with respect to fertilization rate (74.4% vs. 75.5%). The clinical pregnancy and implantation rates of MRC media (47.1% and 20.0%, respectively) were also similar to those of Sydney IVF media (44.4% and 19.4%, respectively). However, the proportion of embryos with good quality on day 3 was significantly higher in the MRC media group than the Sydney IVF media group (50.2% vs. 43.2%) (p<0.05).

Conclusion

MRC media were as effective as Sydney IVF media for sustaining embryo development and pregnancy rates. The present study implies that MRC media can be a suitable alternative to commercially available media for human IVF-ET program.

A randomized controlled study of human serum albumin and serum substitute supplement as protein supplements for IVF culture and the effect on live birth rates

BACKGROUND

It has been speculated that the addition of proteins more complex than human serum albumin (HSA) to culture media may improve IVF outcomes. Whether the expense, labor and risk of adding additional human-derived protein to IVF media are warranted is a question unanswered.

METHODS

In a randomized controlled trial with couples undergoing routine IVF or ICSI, 528 patients were assigned to one of two treatment groups. Embryos were cultured in either media supplemented with HSA as a solitary protein supplement or in media supplemented with HSA+serum substitute supplement (SSS) from the 2PN stage until the time of embryo transfer. Clinical end-points monitored included implantation (total 1151 embryos) and live birth rates (total 528 patients).

RESULTS

The transfer of embryos cultured in HSA+SSS resulted in higher embryo implantation (289/571, 50.6% versus 254/580, 43.8%; difference 6.8% with 95% CI 1.0-12.7, P = 0.042) and live birth rates (167/266, 62.8% versus 142/262, 54.2%; difference 8.6% with 95% CI 0.1-17.3, P = 0.043) when compared with those of women whose embryos were cultured with HSA as the sole protein supplement.

CONCLUSIONS

SSS added to commercial HSA-supplemented embryo culture media resulted in an overall increase in implantation and live birth rates. It remains uncertain whether the use of human-derived blood products in culture media and the requirement for ultra-rigorous quality control measures make these findings applicable to the average IVF laboratory. Protein enrichment of media may significantly improve the blastocyst implantation rate, creating opportunities to transfer single blastocysts without compromising the live birth rate. The study was registered at clinicaltrials.gov. NCT00708383.

Prospective randomized comparison of two embryo culture systems: P1 medium by Irvine Scientific and the Cook IVF Medium

PURPOSE

To compare the efficacy of two commercially available in vitro fertilization (IVF) and embryo culture media systems: the glucose-free P1 Medium supplemented with 20% synthetic serum substitute (SSS) (Irvine Scientific), and the Cook IVF Medium (Cook, Australia).

METHODS

A prospective randomized study. Medical center-based IVF Unit affiliated to the Faculty of Medicine of Tel Aviv University. IVF patients were randomly assigned to either P1 Medium supplemented with 20% SSS (182 patients, 196 cycles) or Cook Medium (167 patients, 179 cycles).

RESULTS

Fertilization rates were similar with both media (52.3 +/- 26.1 and 53.8 +/- 27.6, respectively). Likewise, no difference was found in morphological characteristics and grading of cultured embryos. However, a significantly higher proportion of the embryos incubated in the P1 Medium reached the four-cell stage on day 2 or the 6-cell stage on day 3 postfertilization, compared to those incubated in Cook Medium (54.3% vs. 41.9%, p < 0.0001). Clinical pregnancy and delivery rates were improved when oocytes and embryos were cultured in P1 Medium. Finally, Implantation rate was significantly higher in the P1 Medium Group (9.9% vs. 6%, respectively).

CONCLUSIONS

Our results suggest that the P1 Medium may be associated with a higher embryo cleavage rate and improved implantation rates compared to the Cook IVF Medium.

The use of an hydrogen peroxide multipurpose isolator for inhouse preparation of human embryo culture media: a unique successful Swiss randomized prospective study

PURPOSE

To develop inhouse made (IHM) embryo culture medium with a Multipurpose Isolator and compare the embryo development in a prospective randomized study with commercial media.

METHODS

Fertilization by intracytoplasmic single sperm injection (ICSI) of Metaphase II oocytes obtained after 96 controlled ovarian hyperstimulation cycles in patients not older than 37 years. Transfer of zygotes to IHM or commercial Cook Sydney IVF Cleavage medium (SIC) immediately after pronucleus observation. Evaluation of embryo cleavage and score, pregnancy, and implantation rate.

RESULTS

From 100 zygotes cultured in SIC, 61% were at the 4 cell stage 45 h after ICSI compared to 77% (78/101) in the IHM, P < 0.05. The mean embryo score with IHM was 3.9 +/- 0.9 compared to 3.5 +/- 1.2 with SIC, P < 0.05. The clinical pregnancy rate per transfer was 38.9% (37/95), the implantation rate was 23% (46/200), and no differences were observed between the groups.

Longevity of donor serum

PURPOSE

To determine the viability of long-term, stored serum, which is used in human in vitro production as a source of energy substrates, amino acids, vitamins, growth factors, and other nutrients.

METHOD

Two-cell mouse embryos were used in this prospective, cohort study. Serum stored for 1-, 5-, 10-, and 12-year intervals was subjected to four replications of mouse-embryo testing.

RESULT(S)

There were no significant differences in blastocyst rates between any of the replicates by year (80-100% blastocyst rate; P > 00.1) or between pooled replicate means by time period.

CONCLUSION(S)

Serum may be frozen up to 12 years.

Recombinant human albumin as protein source in culture media used for IVF: a prospective randomized study

Oocytes obtained from 85 women undergoing IVF/intracytoplasmic sperm injection (ICSI) treatment were randomly selected for culture in media containing either human serum albumin (HSA), (n = 42) or recombinant human albumin (rHA), (n = 43). At the time of transfer, the two embryos with the overall best morphology were selected on day 2, 3 or 5. Comparable rates of fertilization, cleavage, blastocyst formation and implantation were observed in both groups. The frequency of pregnancy and early pregnancy loss were also equal. It is concluded that culture media containing rHA seem to produce embryos of high quality comparable to media containing HSA. Therefore, rHA may replace HSA as a protein source in culture media for IVF and may reduce risks of prion contamination and transmission of plasma derived impurities.

Protein supplementation of human IVF culture media

This review travels the road of protein supplementation in embryo culture development-from whole crude plasma in the mid Twentieth century moving through to the completely genetically engineered human albumin with successful births at the beginning of the Twenty-first.

Large offspring syndrome and other consequences of ruminant embryo culture in vitro: relevance to blastocyst culture in human ART

In vitro production of embryos from domestic animals is used to augment conventional genetic improvement programmes in agriculture and to facilitate advances in gene transfer and cloning. However, production of embryos in vitro exposes them to hazards not normally encountered in vivo and, as a result, there have been unforeseen consequences including the large offspring syndrome. This syndrome is manifest as abnormal growth and development at fetal, neonatal and later stages after transfer of embryos cultured in vitro for up to 1 week after fertilization. Our embryo culture and fetal development studies have begun to characterize many of the genetic, metabolic and developmental features associated with the syndrome. This review considers the findings of these studies in the context of blastocyst production in vitro, emphasizing the impact of culture strategies on ruminant (cattle and sheep) embryo composition and developmental competence. The need to alter in vitro production strategies to safeguard oocytes and embryos during culture is discussed. Finally, the implications of experiences gained in domestic animal studies are considered in the context of current options for human embryo culture. The need for an appreciation of the sensitivity of the embryo to its environment and the possible short- and long-term consequences of inappropriate in vitro production strategies are considered.

Increasing synthetic serum substitute (SSS) concentrations in P1 glucose/phosphate-free medium improves implantation rate: a comparative study

PURPOSE

To assess the comparative efficacy of IVF medium (MediCult, with 5.2 mM glucose) and a glucose/phosphate-free medium, P1 (Irvine Scientific), and to investigate the influence of increasing the serum supplementation (synthetic serum substitute; SSS; Irvine Scientific) to P1 on embryo development and implantation.

METHODS

Patients were randomly assigned to IVF medium (Group 1, cycles n = 172) or P1 supplemented with 10% SSS (Group 2, cycles n = 229) according to the medium scheduled for use on the day of oocyte retrieval. Another 555 IVF consequent cycles (Group 3) were performed using increased SSS concentrations (20%) in P1 medium.

RESULTS AND CONCLUSION

In this large series of IVF cycles, we herein demonstrate that significantly higher pregnancy and implantation rates were found when embryos were cultured in glucose/phosphate-free medium P1 supplemented with 20% SSS compared to supplementation with the lower SSS concentration and with IVF medium.

A novel system for in vitro maturation of human oocytes

OBJECTIVE

To compare in vitro maturation of cumulus-free oocytes in glucose-free medium (P1) and standard medium (TC199).

DESIGN

Prospective, cohort study.

SETTING

Assisted reproductive technology program.

PATIENT(S)

One hundred eight patients undergoing ICSI.

INTERVENTION(S)

Germinal vesicle-stage or metaphase I--stage oocytes were allocated to culture with P1 or TC199. Metaphase II oocytes were fixed for immunofluorescence analysis or fluorescence in situ hybridization at 24 or 48 hours (or both). Media were compared by performing conditional logistic regression analysis that controlled for egg-specific factors.

MAIN OUTCOME MEASURE(S)

Proportion of mature oocytes and appearance of normal spindle-chromosome cytoarchitecture.

RESULT(S)

At 24 hours, more P1 oocytes than TC199 oocytes reached metaphase II (59.7% vs. 44.9%). At 48 hours, 71.7% of P1 oocytes and 61.0% of TC199 oocytes reached metaphase II, but this difference was not significant. Metaphase II oocytes in P1 were 34.3% more likely than those in TC199 to have a bipolar spindle with aligned chromosomes. Compared with oocytes at the germinal vesicle stage at 0 hour, those at metaphase I at 0 hour were more likely to progress to metaphase II (72.6% vs. 46.1% at 24 hours; 84.1% vs. 60.6% at 48 hours).

CONCLUSION(S)

P1 is superior to TC199 for in vitro maturation of granulosa-free human oocytes.

Development of a well-defined medium for the in vitro maturation of immature bovine cumulus-oocyte complexes

PURPOSE

Our purpose was to develop a well-defined medium for the in vitro maturation (IVM) of immature bovine cumulus-oocyte complexes (COC).

METHODS

The COC were cultured in the presence of three protein supplementations: fetal bovine serum (FBS), bovine serum albumin, and Synthetic Serum Substitute. The embryos obtained after in vitro fertilization of IVM oocytes were cocultured with Vero cells and their development to the morula and blastocyst stages was studied.

RESULTS

When FBS was absent from the IVM medium, a significantly lower fertilization rate was observed, followed by a decrease in the percentage of embryos reaching the blastocyst stage. When FBS was replaced by a defined protein supplementation, the best results were obtained with Synthetic Serum Substitute.

CONCLUSIONS

Adequate protein supplementation of the IVM medium optimizes the fertilization rate and the development of bovine IVM oocytes. The implication of these results in the human field is discussed.

Clinical outcome of day 2 versus day 3 embryo transfer using serum-free culture media: a prospective randomized study

PURPOSE

The objective was to evaluate whether extending the embryo culture period from 2 to 3 days would yield a more optimal selection of viable embryos, thereby increasing the implantation and live birth rates.

METHODS

Patients undergoing in vitro fertilization with at least one oocyte fertilized were prospectively randomized to 2 or 3 days of embryo culture in serum-free media. On the basis of their morphology and cleavage rate, a maximum of three embryos was selected for transfer.

RESULTS

Embryos transferred on day 2 or day 3 were similar morphologically, however, a higher proportion of retarded embryos was observed on day 3. The implantation rate was 15.8 and 14.3% for day 2 and day 3 transfers, respectively. The increase in live birth rate from 18.5 to 22.6%, possibly suggesting a better embryo selection on day 3, was not statistically significant.

CONCLUSIONS

Extending the embryo culture period from 2 to 3 days had no effect on implantation and live birth rates.

Impact of the "physician factor" on pregnancy rates in a large assisted reproductive technology program: do too many cooks spoil the broth?

OBJECTIVE

To determine whether in one program with unified treatment protocols, patients can expect varying treatment outcomes with different physicians.

DESIGN

Retrospective data analysis.

SETTING

University-affiliated infertility center with 14 physicians.

PATIENT(S)

One thousand eight hundred fifty IVF cycles performed consecutively between August 1995 and June 1997.

INTERVENTION(S)

The pregnancy rate and implantation rate per ET were evaluated for individual physicians between August 1995 and June 1996 (phase I). Physicians with lower success rates underwent strict supervision from July 1996 to June 1997 (phase II).

MAIN OUTCOME MEASURE(S)

Variations in success rates between physicians.

RESULT(S)

The pregnancy rate varied among the physicians from 13.2%-37.4%, and the implantation rate varied from 4.4%-14%. Some physicians' outcomes improved between phase I and phase II of the study, whereas others' did not. The pregnancy and implantation rates varied significantly for some physicians, depending on whether they were responsible for the choice of stimulation protocol, supervision of cycle monitoring, or ET in their own or other physicians' patients.

CONCLUSION(S)

Outcomes of IVF vary depending on the treating physician. Lower than expected pregnancy and implantation rates usually are not caused by poor ET techniques alone, but appear to be disproportionately the consequences of poor cycle stimulation.

Comparison of synthetic serum substitute and fetal cord serum as media supplements for in vitro fertilization: a prospective, randomized study

OBJECTIVE

To compare the value of synthetic serum substitute and fetal cord serum (FCS) as protein supplements in the media used for IVF.

DESIGN

Prospective, randomized study of 45 patients undergoing IVF.

SETTING

Private infertility practice.

INTERVENTION(S)

The protein supplement for use in IVF medium was randomized prospectively to synthetic serum substitute or FCS.

MAIN OUTCOME MEASURE(S)

Oocyte fertilization rate, incidence of embryo arrest, number of embryos transferred, ongoing pregnancy rate, and implantation rate were assessed.

RESULT(S)

There was no significant difference in the fertilization rate, incidence of embryo arrest, number of embryos transferred, ongoing pregnancy rate, and implantation rate.

CONCLUSION(S)

Synthetic serum substitute is a better alternative to FCS as a protein supplement for IVF because of its availability and cost effectiveness. Synthetic serum substitute can be used in culture medium for sperm washing, insemination, culture, and transfer translating to decreased technician time without a significant difference in fertilization, pregnancy, or implantation rate.

Globulin-enriched protein supplements shorten the pre-compaction mitotic interval and promote hatching of murine embryos

PROBLEM

To determine whether Synthetic Serum Substitute (SSS), which contains human globulins in addition to Human Serum Albumin (HSA), is superior to HSA alone as a protein supplement for embryo culture.

METHOD

Development of mouse zygotes to eight-cell/compacting morulae and to hatching/hatched blastocysts was assessed in Human Tubal Fluid (HTF) medium containing either SSS of HSA.

RESULTS

Although there was no difference in the overall blastocyst rate at 120 h in HTF+SSS versus HTF+HSA, significantly more embryos at 54 h were at the eight-cell/compacting morula stage in HTF+SSS. At 120 h, there were more hatching/hatched blastocysts in HTF+SSS, and hatching correlated with SSS concentration. Addition of isolated globulins to HSA significantly stimulated the number of hatching/hatched blastocysts. Hatching could be "rescued" by transfer of embryos grown in HTF+HSA to globulin-containing media and prevented by removal of globulins as late as the compacted morula stage (54 h).

CONCLUSIONS

SSS is superior to HSA alone for embryo culture. The stimulatory effects on mitosis and hatching may be mediated directly by globulins or by other components in the globulin-enriched fraction.

Optimizing tubal epithelial cell growth promotes mouse embryo hatching in coculture

PURPOSE

This study investigates the relationship between human tubal epithelial cell growth characteristics and mouse embryonic development to determine which cellular requirements should be preferentially provided in a coculture system.

METHODS

Cell growth and viability were assessed for 5 days in alpha-minimal essential medium or human tubal fluid supplemented with 10% human serum or 10% synthetic serum. Two-cell mouse embryo development to blastocyst and hatching blastocyst stages was also assessed with or without coculture.

RESULTS

Both epithelial cell growth and embryo development were dependent on serum supplementation with better cell viability and growth rates in human serum and better blastocyst development in synthetic serum. The highest proportion of hatching blastocysts was found in alpha-minimal essential medium and human serum with coculture.

CONCLUSIONS

Culture conditions which improve tubal epithelial cell growth also improve the hatching rate of mouse embryos in coculture. This indicates that by meeting the metabolic and nutritional demands for epithelial cell growth, the beneficial effects of coculture on embryo development may be optimized.