Influential effect of age on oocyte morphometry, fertilization rate and embryo development following IVF in mice

Advanced maternal age affects their frozen-thawed embryo susceptibility to high oxygen environment

Preimplantation embryos can experience stress from laboratory interventions and a sub-optimal culture environment. Though research has demonstrated advanced maternal age impairs oocyte quality, the response of embryos derived from such oocytes to vitrification-thawing and culture in a high oxygen (O2) environment in the assisted reproductive technology laboratory is unknown. Therefore, in this study, embryos produced by in vitro fertilization (IVF) using oocytes from two- and eight-month-old Swiss albino mice were vitrified and thawed during their 6-8 cell stage. and cultured at low oxygen (5%) tension (LOT) and high oxygen (20%) tension (HOT). Embryo development, apoptosis, inner cell mass (ICM) outgrowth proliferation ability in vitro and pluripotency were assessed. Embryos from advanced maternal age cultured at HOT showed reduced fertilizing ability (p < 0.05), poor survival post-thawing (p < 0.05), and increased apoptosis (p < 0.01) in comparison to sibling embryos cultured at LOT. Importantly, the extended culture of vitrified-thawed embryos from advanced maternal age led to a significant (p < 0.001) reduction in complete ICM outgrowth formation at HOT in comparison to the LOT environment. The findings of this study suggest that HOT is detrimental to embryos from advanced maternal age, and importantly, vitrified-thawed embryos are more susceptible to stress, which could have negative implications, especially during the peri-implantation developmental period.

The impact of mitochondrial impairments on sperm function and male fertility: a systematic review

BACKGROUND

Besides adenine triphosphate (ATP) production for sustaining motility, the mitochondria of sperm also host other critical cellular functions during germ cell development and fertilization including calcium homeostasis, generation of reactive oxygen species (ROS), apoptosis, and in some cases steroid hormone biosynthesis. Normal mitochondrial membrane potential with optimal mitochondrial performance is essential for sperm motility, capacitation, acrosome reaction, and DNA integrity.

RESULTS

Defects in the sperm mitochondrial function can severely harm the fertility potential of males. The role of sperm mitochondria in fertilization and its final fate after fertilization is still controversial. Here, we review the current knowledge on human sperm mitochondria characteristics and their physiological and pathological conditions, paying special attention to improvements in assistant reproductive technology and available treatments to ameliorate male infertility.

CONCLUSION

Although mitochondrial variants associated with male infertility have potential clinical use, research is limited. Further understanding is needed to determine how these characteristics lead to adverse pregnancy outcomes and affect male fertility potential.

Unique Deep Radiomic Signature Shows NMN Treatment Reverses Morphology of Oocytes from Aged Mice

The purpose of this study is to develop a deep radiomic signature based on an artificial intelligence (AI) model. This radiomic signature identifies oocyte morphological changes corresponding to reproductive aging in bright field images captured by optical light microscopy. Oocytes were collected from three mice groups: young (4- to 5-week-old) C57BL/6J female mice, aged (12-month-old) mice, and aged mice treated with the NAD+ precursor nicotinamide mononucleotide (NMN), a treatment recently shown to rejuvenate aspects of fertility in aged mice. We applied deep learning, swarm intelligence, and discriminative analysis to images of mouse oocytes taken by bright field microscopy to identify a highly informative deep radiomic signature (DRS) of oocyte morphology. Predictive DRS accuracy was determined by evaluating sensitivity, specificity, and cross-validation, and was visualized using scatter plots of the data associated with three groups: Young, old and Old + NMN. DRS could successfully distinguish morphological changes in oocytes associated with maternal age with 92% accuracy (AUC~1), reflecting this decline in oocyte quality. We then employed the DRS to evaluate the impact of the treatment of reproductively aged mice with NMN. The DRS signature classified 60% of oocytes from NMN-treated aged mice as having a ‘young’ morphology. In conclusion, the DRS signature developed in this study was successfully able to detect aging-related oocyte morphological changes. The significance of our approach is that DRS applied to bright field oocyte images will allow us to distinguish and select oocytes originally affected by reproductive aging and whose quality has been successfully restored by the NMN therapy.