Cellular uptake of polymeric nanoparticles by bovine cumulus-oocyte complexes and their effect on in vitro developmental competence

Magnetotactic Sperm Cells for Assisted Reproduction

Biohybrid micromotors are active microscopic agents consisting of biological and synthetic components that are being developed as novel tools for biomedical applications. By capturing motile sperm cells within engineered microstructures, they can be controlled remotely while being propelled forward by the flagellar beat. This makes them an interesting tool for reproductive medicine that can enable minimally invasive sperm cell delivery to the oocyte in vivo, as a treatment for infertility. The generation of sperm-based micromotors in sufficiently large numbers, as they are required in biomedical applications has been challenging, either due to the employed fabrication techniques or the stability of the microstructure-sperm coupling. Here, biohybrid micromotors, which can be assembled in a fast and simple process using magnetic microparticles, are presented. These magnetotactic sperm cells show a high motility and swimming speed and can be transferred between different environments without large detrimental effects on sperm motility and membrane integrity. Furthermore, clusters of micromotors are assembled magnetically and visualized using dual ultrasound (US)/photoacoustic (PA) imaging. Finally, a protocol for the scaled-up assembly of micromotors and their purification for use in in vitro fertilization (IVF) is presented, bringing them closer to their biomedical implementation.

Magnetic-Assisted Control of Eggs and Embryos via Zona Pellucida-Linked Nanoparticles

Eggs and embryo manipulation is an important biotechnological challenge to enable positioning, entrapment, and selection of reproductive cells to advance into a new era of nature-like assisted reproductive technologies. Oviductin (OVGP1) is an abundant protein in the oviduct that binds reversibly to the zona pellucida, an extracellular matrix that surrounds eggs and embryos. Here, the study reports a new method coupling OVGP1 to magnetic nanoparticles (NP) forming a complex (NPOv). NPOv specifically surrounds eggs and embryos in a reversible manner. Eggs/embryos bound to NPOv can be moved or retained when subjected to a magnetic force, and interestingly only mature-competent eggs are attracted. This procedure is compatible with normal development following gametes function, in vitro fertilization, embryo development and resulting in the birth of healthy offspring. The results provide in vitro proof-of-concept that eggs and embryos can be precisely guided in the absence of physical contact by the use of magnets.

Superior performance of biocomposite nanoparticles PLGA-RES in protecting oocytes against vitrification stimuli

Irreversible cryogenic damage caused by oocyte vitrification limits its widespread use in female fertility preservation. In recent years, nanoparticles (NPs) have gained great attention as potential alternatives in protecting oocytes against cryoinjuries. In this paper, a novel composite nanoparticle, poly (lactic-co-glycolic acid)-resveratrol (PLGA-RES) was designed to improve the biocompatibility and sustained release properties by encapsulating natural antioxidant RES into PLGA NPs. Firstly, biotoxicity and oxidation resistance of PLGA-RES were determined, and the results showed that PLGA-RES had nontoxic effect on oocyte survival during in vitro maturation (IVM) (97.08% ± 0.24% vs. 98.89% ± 1.11%, p > 0.05). Notably, PLGA-RES even increased maturation (65.10% ± 4.11% vs. 52.85% ± 2.87%, p < 0.05) and blastocyst rate (56.13% ± 1.36% vs. 40.91% ± 5.85%, p < 0.05). Moreover, the reduced reactive oxygen species (ROS) level (13.49 ± 2.30 vs. 34.07 ± 3.30, p < 0.01), increased glutathione (GSH) (44.13 ± 1.57 vs. 37.62 ± 1.79, p < 0.01) and elevated mitochondrial membrane potential (MMP) levels (43.10 ± 1.81 vs. 28.52 ± 1.25, p < 0.01) were observed in oocytes treated with PLGA-RES when compared with that of the control group. Subsequently, the role of PLGA-RES played in oocytes during vitrification was systematically evaluated. The results showed that the addition of PLGA-RES during vitrification and thawing significantly improved the survival rate (80.42% ± 1.97% vs. 75.37% ± 1.3%, p < 0.05). Meanwhile, increased GSH (15.09 ± 0.86 vs. 14.51 ± 0.78, p < 0.01) and mitochondrial membrane potential (22.56 ± 3.15 vs. 6.79 ± 0.60, p < 0.01), decreased reactive oxygen species levels (52.11 ± 2.95 vs. 75.41 ± 7.23, p < 0.05) and reduced mitochondrial abnormality distribution rate (25.00% ± 0.29% vs. 33.33% ± 1.15%, p < 0.01) were assessed in vitrified MII oocytes treated with PLGA-RES. Furthermore, transcriptomic analyses demonstrated that PLGA-RES participated in endocytosis and PI3K/AKT/mTOR pathway regulation, which was verified by the rescued expression of ARRB2 and ULK3 protein after PLGA-RES treatment. In conclusion, PLGA-RES exhibited potent antioxidant activity, and could be used as an efficacious strategy to improve the quality of vitrified oocytes.

Trehalose delivered by cold-responsive nanoparticles improves tolerance of cumulus-oocyte complexes to microwave drying

PURPOSE

Trehalose is a non-permeable protectant that is the key to preserve live cells in a dry state for potential storage at ambient temperatures. After intracellular trehalose delivery via cold-responsive nanoparticles (CRNPs), the objective was to characterize the tolerance of cat cumulus-oocyte complexes (COCs) to different levels of microwave-assisted dehydration.

METHODS

Trehalose was first encapsulated in CRNPs. After exposure to trehalose-laden CRNPs, different water amounts were removed from cat COCs by microwave drying. After each dehydration level, meiotic and developmental competences were evaluated via in vitro maturation, fertilization, and embryo culture. In addition, expressions of critical genes were assessed by quantitative RT-PCR.

RESULTS

CRNPs effectively transported trehalose into COCs within 4 h of co-incubation at 38.5 °C followed by a cold-triggered release at 4 °C for 15 min. Intracellular presence of trehalose enabled the maintenance of developmental competence (formation of blastocysts) as well as normal gene expression levels of HSP70 and DNMT1 at dehydration levels reaching up to 63% of water loss.

CONCLUSION

Intracellular trehalose delivery through CRNPs improves dehydration tolerance of COCs, which opens new options for oocyte storage and fertility preservation at ambient temperatures.

Maternal metabolic health and fertility: we should not only care about but also for the oocyte!

Metabolic disorders due to obesity and unhealthy lifestyle directly alter the oocyte's microenvironment and impact oocyte quality. Oxidative stress and mitochondrial dysfunction play key roles in the pathogenesis. Acute effects on the fully grown oocytes are evident, but early follicular stages are also sensitive to metabolic stress leading to a long-term impact on follicular cells and oocytes. Improving the preconception health is therefore of capital importance but research in animal models has demonstrated that oocyte quality is not fully recovered. In the in vitro fertilisation clinic, maternal metabolic disorders are linked with disappointing assisted reproductive technology results. Embryos derived from metabolically compromised oocytes exhibit persistently high intracellular stress levels due to weak cellular homeostatic mechanisms. The assisted reproductive technology procedures themselves form an extra burden for these defective embryos. Minimising cellular stress during culture using mitochondrial-targeted therapy could rescue compromised embryos in a bovine model. However, translating such applications to human in vitro fertilisation clinics is not simple. It is crucial to consider the sensitive epigenetic programming during early development. Research in humans and relevant animal models should result in preconception care interventions and in vitro strategies not only aiming at improving fertility but also safeguarding offspring health.

Biocompatible Nanomaterials as an Emerging Technology in Reproductive Health; a Focus on the Male

A growing body of research has confirmed that nanoparticle (NP) systems can enhance delivery of therapeutic and imaging agents as well as prevent potentially damaging systemic exposure to these agents by modifying the kinetics of their release. With a wide choice of NP materials possessing different properties and surface modification options with unique targeting agents, bespoke nanosystems have been developed for applications varying from cancer therapeutics and genetic modification to cell imaging. Although there remain many challenges for the clinical application of nanoparticles, including toxicity within the reproductive system, some of these may be overcome with the recent development of biodegradable nanoparticles that offer increased biocompatibility. In recognition of this potential, this review seeks to present recent NP research with a focus on the exciting possibilities posed by the application of biocompatible nanomaterials within the fields of male reproductive medicine, health, and research.

Benefits and challenges of nanomaterials in assisted reproductive technologies

Assisted reproductive technology (ART) have contributed to preserve fertility in humans and to increase multiplication of genetically superior animals. Despite being highly practiced worldwide, ART presents some challenges, especially because gametes and embryos are kept in vitro for a variable period of time, and the oxidative stress in vitro can have negative impact on oocyte competence and embryo development. Nanotechnology needs to be considered to help overcome some of those impairments, since it can provide strategies to deliver antioxidants and hormones to gametes and embryos in vitro. The application of nanotechnology to ART can allow the development of new protocols using nanomaterials to improve in vitro oocyte competence and embryo production. This review discusses the applicability of nanomaterials to improve sperm selection, to deliver antioxidants and hormones to preantral follicles, oocytes, and embryos in vitro, as well as the concerns about using nanotechnology in ART.