Maternal non-Mendelian inheritance of a reduced lifespan? A hypothesis

An Update on Planned Oocyte Cryopreservation (POC) in Italy: Medical, Epidemiological and Legal Consideration

Starting with a brief socioeconomic analysis of the phenomenon of female fertility, this narrative review aims to provide an analysis of the use and possibilities of medically assisted reproductive technology in combating fertility issues, adopting socioeconomic, legal and medical perspectives in Italy. The authors mainly employ data from the annual reports of the National Registry of Medically Assisted Reproduction (PMA Registry) and the Italian Statistical Institute (ISTAT) to understand the evolution of oocyte use in medically assisted reproductive technology in Italy from 2015 to 2018 and in particular to dissect the possibilities of oocyte cryopreservation as a measure to counteract age-related infertility, specifically through Planned Oocyte Cryopreservation (POC), also known as “social freezing”. It seems that the best course of action in the context of medically assisted reproduction would be the use of young and healthy cryopreserved oocytes (autologous or donated), preferably before the age of 40, while encouraging donation of oocytes whenever possible. Italy’s dependence on foreign biobanks for donated oocytes calls for the institution of a national biobank and further specific regulation of gamete donation. For this reason, it would be useful to encourage the acceptance of Planned Oocyte Cryopreservation to allow greater availability of healthy, younger oocytes.

Advanced maternal age causes adverse programming of mouse blastocysts leading to altered growth and impaired cardiometabolic health in post-natal life

STUDY QUESTION

Does advanced maternal age (AMA) in mice affect cardiometabolic health during post-natal life in offspring derived from an assisted reproduction technology (ART) procedure?

SUMMARY ANSWER

Offspring derived from blastocysts collected from aged female mice displayed impaired body weight gain, blood pressure, glucose metabolism and organ allometry during post-natal life compared with offspring derived from blastocysts from young females; since all blastocysts were transferred to normalized young mothers, this effect is independent of maternal pregnancy conditions.

WHAT IS KNOWN ALREADY

Although studies in mice have shown that AMA can affect body weight and behaviour of offspring derived from natural reproduction, data on the effects of AMA on offspring cardiometabolic health during post-natal development are not available. Given the increasing use of ART to alleviate infertility in women of AMA, it is pivotal to develop ART-AMA models addressing the effects of maternal aging on offspring health.

STUDY DESIGN, SIZE, DURATION

Blastocysts from old (34-39 weeks) or young (8-9 weeks) C57BL/6 females mated with young CBA males (13-15 weeks) were either subjected to differential cell staining (inner cell mass and trophectoderm) or underwent embryo transfer (ET) into young MF1 surrogates (8-9 weeks) to produce young (Young-ET, 9 litters) and old (Old-ET, 10 litters) embryo-derived offspring. Offspring health monitoring was carried out for 30 weeks.

PARTICIPANTS/MATERIALS, SETTING, METHODS

All animals were fed with standard chow. Blood pressure was measured at post-natal Weeks 9, 15 and 21, and at post-natal Week 30 a glucose tolerance test (GTT) was performed. Two days after the GTT mice were killed for organ allometry. Blastocyst cell allocation variables were evaluated by T-test and developmental data were analysed with a multilevel random effects regression model.

MAIN RESULTS AND THE ROLE OF CHANCE

The total number of cells in blastocysts from aged mice was decreased (P < 0.05) relative to young mice due to a lower number of cells in the trophectoderm (mean ± SEM: 34.5 ± 2.1 versus 29.6 ± 1.0). Weekly body weight did not differ in male offspring, but an increase in body weight from Week 13 onwards was observed in Old-ET females (final body weight at post-natal Week 30: 38.5 ± 0.8 versus 33.4 ± 0.8 g, P < 0.05). Blood pressure was increased in Old-ET offspring at Weeks 9-15 in males (Week 9: 108.5 ± 3.13 versus 100.8 ± 1.5 mmHg, Week 15: 112.9 ± 3.2 versus 103.4 ± 2.1 mmHg) and Week 15 in females (115.9 ± 3.7 versus 102.8 ± 0.7 mmHg; all P < 0.05 versus Young-ET). The GTT results and organ allometry were not affected in male offspring. In contrast, Old-ET females displayed a greater (P < 0.05) peak glucose concentration at 30 min during the GTT (21.1 ± 0.4 versus 17.8 ± 1.16 mmol/l) and their spleen weight (88.2 ± 2.6 ± 105.1 ± 4.6 mg) and several organ:body weight ratios (g/g × 10(3)) were decreased (P < 0.05 versus Young-ET), including the heart (3.7 ± 0.06 versus 4.4 ± 0.08), lungs (4.4 ± 0.1 versus 5.0 ± 0.1), spleen (2.4 ± 0.06 versus 3.2 ± 0.1) and liver (36.4 ± 0.6 versus 39.1 ± 0.9).

LIMITATIONS, REASONS FOR CAUTION

Results from experimental animal models cannot be extrapolated to humans. Nevertheless, they are valuable to develop conceptual models that can produce hypotheses for eventual testing in the target species (i.e. humans).

WIDER IMPLICATIONS OF THE FINDINGS

Our data show that offspring from mouse embryos from aged mothers can develop altered phenotypes during post-natal development compared with embryos from young mothers. Because all embryos were transferred into young mothers for the duration of pregnancy to normalize the maternal in vivo environment, our findings indicate that adverse programming via AMA is already established at the blastocyst stage. Whilst human embryos display increased aneuploidy compared with mouse, we believe our data have implications for women of AMA undergoing assisted reproduction, including surrogacy programmes.

STUDY FUNDING/COMPETING INTERESTS

This work was supported through the European Union FP7-CP-FP Epihealth programme (278418) to T.P.F. and the BBSRC (BB/F007450/1) to T.P.F. The authors have no conflicts of interest to declare.

Trends, fads and ART!

Morphological selection techniques of gametes and embryos are of current interest to clinical practice in ART. Although intracytoplasmic morphologically selected sperm injection (IMSI), time lapse imaging morphometry (TLIM) or quantification of chromosome numbers (PGS) are potentially useful in research, they have not been shown to be of statistically predictive value and, thus, have only limited clinical usefulness. We make the point that morphological markers alone cannot predict the success of the early embryo, which depends on the correct orchestration of a myriad of physiological and biochemical activation events that progress independently of the maternal or zygotic genome. Since previous attempts to identify metabolic markers for embryo quality have failed and there is no evidence that the intrinsic nature of gametes and embryos can be improved in the laboratory, embryologists can only minimize environmental or operator induced damage while these cells are manipulated ex vivo.

New Developments in the Biodemography of Aging and Longevity

Biodemography is a promising scientific approach based on using demographic data and methods for getting insights into biological mechanisms of observed processes. Recently, new important developments have happened in biodemographic studies of aging and longevity that call into question conventional aging theories and open up novel research directions. Recent studies found that the exponential increase of the mortality risk with age (the famous Gompertz law) continues even at extreme old ages in humans, rats, and mice, thus challenging traditional views about old-age mortality deceleration, mortality leveling-off, and late-life mortality plateaus. This new finding represents a challenge to many aging theories, including the evolutionary theory that explains senescence by a declining force of natural selection with age. Innovative ideas are needed to explain why exactly the same exponential pattern of mortality growth is observed not only at reproductive ages, but also at very-old postreproductive ages (up to 106 years), long after the force of natural selection becomes negligible (when there is no room for its further decline). Another important recent development is the discovery of long-term 'memory' for early-life experiences in longevity determination. Siblings born to young mothers have significantly higher chances to live up to 100 years, and this new finding, confirmed by two independent research groups, calls for its explanation. As recent studies found, even the place and season of birth matter for human longevity. Beneficial longevity effects of young maternal age are observed only when children of the same parents are compared, while the maternal age effect often could not be detected in across-families studies, presumably being masked by between-family variation. It was also found that male gender of centenarian has a significant positive effect on the survival of adult male biological relatives (brothers and fathers) but not of female relatives. Finally, large gender differences are found in longevity determinants for males and females, suggesting a higher importance of occupation history for male centenarians as well as a higher importance of home environment history for female centenarians.

Can we define maternal age as a genetic disease?

>Maternal age is strongly associated with a decrease in the probability of achieving pregnancy and the birth of a healthy child. Among current theories of the mechanism of this decrease is the hypothesis that a progressive degeneration of the respiratory capacity of mitochondria in eggs of women of advanced age leads to an energy deficit and consequent secondary effects on the oocyte and developing embryo. Mitochondria are uniquely inherited through the female germ line and these organelles contain DNA sequences that are independent from the genome. It is therefore possible that offspring born to females of advanced age inherit suboptimal mitochondria and that these persist throughout the life of the new being. This could in turn lead to long-term consequences for the offspring of females of advanced age such as a reduced potential lifespan in relation to the age of the mother at conception. In this review and hypothesis, we discuss the evidence relating to this theory and suggest that on this basis the maternal age effect could be classified as an inheritable genetic disease.