In vitro development of donated frozen-thawed human embryos in a prototype static microfluidic device: a randomized controlled trial

Opportunities involving microfluidics and 3D culture systems to the in vitro embryo production

Traditional methods of gamete handling, fertilization, and embryo culture often face limitations in efficiency, consistency, and the ability to closely mimic in vivo conditions. This review explores the opportunities presented by microfluidic and 3D culture systems in overcoming these challenges and enhancing in vitro embryo production. We discuss the basic principles of microfluidics, emphasizing their inherent advantages such as precise control of fluid flow, reduced reagent consumption, and high-throughput capabilities. Furthermore, we delve into microfluidic devices designed for gamete manipulation, in vitro fertilization, and embryo culture, highlighting innovations such as droplet-based microfluidics and on-chip monitoring. Next, we explore the integration of 3D culture systems, including the use of biomimetic scaffolds and organ-on-a-chip platforms, with a particular focus on the oviduct-on-a-chip. Finally, we discuss the potential of these advanced systems to improve embryo production outcomes and advance our understanding of early embryo development. By leveraging the unique capabilities of microfluidics and 3D culture systems, we foresee significant advancements in the efficiency, effectiveness, and clinical success of in vitro embryo production.

Microfluidic systems for modeling human development

The proper development and patterning of organs rely on concerted signaling events emanating from intracellular and extracellular molecular and biophysical cues. The ability to model and understand how these microenvironmental factors contribute to cell fate decisions and physiological processes is crucial for uncovering the biology and mechanisms of life. Recent advances in microfluidic systems have provided novel tools and strategies for studying aspects of human tissue and organ development in ways that have previously been challenging to explore ex vivo. Here, we discuss how microfluidic systems and organs-on-chips provide new ways to understand how extracellular signals affect cell differentiation, how cells interact with each other, and how different tissues and organs are formed for specialized functions. We also highlight key advancements in the field that are contributing to a broad understanding of human embryogenesis, organogenesis and physiology. We conclude by summarizing the key advantages of using dynamic microfluidic or microphysiological platforms to study intricate developmental processes that cannot be accurately modeled by using traditional tissue culture vessels. We also suggest some exciting prospects and potential future applications of these emerging technologies.

Organosilicon uptake by biological membranes

Organosilicon compounds are ubiquitous in everyday use. Application of some of these compounds in food, cosmetics and pharmaceuticals is widespread on the assumption that these materials are not systemically absorbed. Here the interactions of various organosilicon compounds (simeticone, hexamethyldisilazane and polydimethylsiloxane) with cell membranes and models thereof were characterized with a range of analytical techniques, demonstrating that these compounds were retained in or on the cell membrane. The increasing application of organosilicon compounds as replacement of other plastics calls for a better awareness and understanding of these interactions. Moreover, with many developments in biotechnology relying on organosilicon materials, it becomes important to scrutinize the potential effect that silicone leaching may have on biological systems.

Beekman et al. investigate whether low molecular weight organosilicon compounds leaching out of commonly used biological laboratory materials and household items can interact with molecules found in cellular membranes. The results suggest this is a passive process by physicochemical forces rather than active uptake.

Understanding and Assisting Reproduction in Wildlife Species Using Microfluidics

Conservation breeding and assisted reproductive technologies (ARTs) are invaluable tools to save wild animal species that are on the brink of extinction. Microfluidic devices recently developed for human or domestic animal reproductive medicine could significantly help to increase knowledge about fertility and contribute to the success of ART in wildlife. Some of these microfluidic tools could be applied to wild species, but dedicated efforts will be necessary to meet specific needs in animal conservation; for example, they need to be cost-effective, applicable to multiple species, and field-friendly. Microfluidics represents only one powerful technology in a complex toolbox and must be integrated with other approaches to be impactful in managing wildlife reproduction.

3D printed mold leachates in PDMS microfluidic devices

The introduction of poly(dimethylsiloxane) (PDMS) and soft lithography in the 90’s has revolutionized the field of microfluidics by almost eliminating the need for a clean-room environment for device fabrication. More recently, 3D printing has been introduced to fabricate molds for soft lithography, the only step for which a clean-room environment is still often necessary, to further support the rapid prototyping of PDMS microfluidic devices. However, toxicity of most of the commercial 3D printing resins has been established, and little is known regarding the potential for 3D printed molds to leak components into the PDMS that would, in turn, hamper cells and/or tissues cultured in the devices. In the present study, we investigated if 3D printed molds produced by stereolithography can leach components into PDMS, and compared 3D printed molds to their more conventional SU-8 counterparts. Different leachates were detected in aqueous solutions incubated in the resulting PDMS devices prepared from widely used PDMS pre-polymer:curing agent ratios (10:1, 15:1 and 20:1), and these leachates were identified as originating from resins and catalyst substances. Next, we explored the possibility to culture cells and tissues in these PDMS devices produced from 3D printed molds and after proper device washing and conditioning. Importantly, we demonstrated that the resulting PDMS devices supported physiological cultures of HeLa cells and ovarian tissues in vitro, with superior outcomes than static conventional cultures.

Mouse embryo assay to evaluate polydimethylsiloxane (PDMS) embryo-toxicity

In vitro embryo culture to support In Vitro Fertilization (IVF) procedures is a well-established but still critical technique. In the last decade first attempts to use microfluidic devices in IVF have shown positive results, enabling to control the culture conditions and to preserve the quality of the embryos during their development. In this study we completed an industry standard mouse embryo assay (MEA) to exclude potential toxic effects of PDMS.

The relationship between FSH receptor polymorphism status and IVF cycle outcome: a retrospective observational study

RESEARCH QUESTION

What is the association between FSH receptor (FSHR) gene polymorphism at position 680 and live birth in women undergoing IVF and intracytoplasmic sperm injection (ICSI).

DESIGN

In this retrospective cohort study, data were collected from the Electronic Patient Database of the VU University Medical Centre, Amsterdam, The Netherlands. Women undergoing their first IVF/ICSI cycle between January 2008 and March 2012, of whom the FSHR genotype was determined, were included. The main outcome was live birth rate. Secondary outcomes were ongoing pregnancy, total number of follicles, oocytes and embryos.

RESULTS

The FSHR genotype distribution was as follows: 334 women in the Asn/Asn group (28.2%), 617 in the Asn/Ser group (52.1%) and 234 in the Ser/Ser group (19.7%). Basal FSH concentration was highest in the Ser/Ser group (P = 0.006). The number of oocytes (P = 0.01) and number of embryos (P = 0.02) were lowest in the Ser/Ser group. The Asn/Asn group showed a significantly lower live birth rate. Live birth rates were 21.9% versus 31.1% and 27.6% (P = 0.009), for Asn/Asn, Asn/Ser and Ser/Ser, respectively. Logistic regression analysis, however, showed no significant difference on cumulative live birth rate between the three genotypes either unadjusted or when adjusted for age.

CONCLUSION

The homozygous Ser/Ser genotype of FSHR polymorphism at position 680 is associated with a reduced ovarian response to ovarian stimulation in IVF/ICSI. No difference in cumulative live birth rate was found.

Potential Health and Environmental Risks of Three-Dimensional Engineered Polymers

Polymer engineering, such as in three-dimensional (3D) printing, is rapidly gaining popularity, not only in the scientific and medical fields but also in the community in general. However, little is known about the toxicity of engineered materials. Therefore, we assessed the toxicity of 3D-printed and molded parts from five different polymers commonly used for prototyping, fabrication of organ-on-a-chip platforms, and medical devices. Toxic effects of PIC100, E-Shell200, E-Shell300, polydimethylsiloxane, and polystyrene (PS) on early bovine embryo development, on the transactivation of estrogen receptors were assessed, and possible polymer-leached components were identified by mass spectrometry. Embryo development beyond the two-cell stage was inhibited by PIC100, E-Shell200, and E-Shell300 and correlated to the released amount of diethyl phthalate and polyethylene glycol. Furthermore, all polymers (except PS) induced estrogen receptor transactivation. The released materials from PIC100 inhibited embryo cleavage across a confluent monolayer culture of oviduct epithelial cells and also inhibited oocyte maturation. These findings highlight the need for cautious use of engineered polymers for household 3D printing and bioengineering of culture and medical devices and the need for the safe disposal of used devices and associated waste.

Application of microfluidic technologies to human assisted reproduction

Microfluidics can be considered both a science and a technology. It is defined as the study of fluid behavior at a sub-microliter level and the investigation into its application to cell biology, chemistry, genetics, molecular biology and medicine. There are at least two characteristics of microfluidics, mechanical and biochemical, which can be influential in the field of mammalian gamete and preimplantation embryo biology. These microfluidic characteristics can assist in basic biological studies on sperm, oocyte and preimplantation embryo structure, function and environment. The mechanical and biochemical characteristics of microfluidics may also have practical and/or technical application(s) to assisted reproductive technologies (ART) in rodents, domestic species, endangered species and humans. This review will consider data in mammals, and when available humans, addressing the potential application(s) of microfluidics to assisted reproduction. There are numerous sequential steps in the clinical assisted reproductive laboratory process that work, yet could be improved. Cause and effect relations of procedural inefficiencies can be difficult to identify and/or remedy. Data will be presented that consider microfluidic applications to sperm isolation, oocyte cumulus complex isolation, oocyte denuding, oocyte mechanical manipulation, conventional insemination, intracytoplasmic sperm injection, embryo culture, embryo analysis and oocyte and embryo cryopreservation. While these studies have progressed in animal models, data with human gametes and embryos are significantly lacking. These data from clinical trials are requisite for making future evidence-based decisions regarding the application of microfluidics in human ART.