Collagen-based materials in reproductive medicine and engineered reproductive tissues

Collagen, the main component of mammal skin, has been traditionally used in leather manufacturing for thousands of years due to its diverse physicochemical properties. Collagen is the most abundant protein in mammals and the main component of the extracellular matrix (ECM). The properties of collagen also make it an ideal building block for the engineering of materials for a range of biomedical applications. Reproductive medicine, especially human fertility preservation strategies and reproductive organ regeneration, has attracted significant attention in recent years as it is key in resolving the growing social concern over aging populations worldwide. Collagen-based biomaterials such as collagen hydrogels, decellularized ECM (dECM), and bioengineering techniques including collagen-based 3D bioprinting have facilitated the engineering of reproductive tissues. This review summarizes the recent progress in applying collagen-based biomaterials in reproductive. Furthermore, we discuss the prospects of collagen-based materials for engineering artificial reproductive tissues, hormone replacement therapy, and reproductive organ reconstruction, aiming to inspire new thoughts and advancements in engineered reproductive tissues research. Graphical abstract

Vitamin D effects on androgen levels in men

Background. Accumulating evidence from animal and human studies suggests that vitamin D is involved in many functions of the reproductive system. Considering the potential link between vitamin D and human fertility, authors performed this review summarizing current literature on vitamin D and possible mechanisms explaining the link of vitamin D with androgen metabolism in men. The purpose of this review was to provide an overview on the effects of vitamin D on androgen metabolism in men. Methods. Author performed a systematic literature search in PubMed for relevant English language publications published from January 2011 until September 2021. Results. The vitamin D receptor and vitamin D-metabolizing enzymes are found in reproductive tissues. In men, vitamin D status has been associated with androgen levels and hypogonadism. Further, there is some evidence for a favorable effect of vitamin D supplementation on testosterone concentrations, although others failed to show a significant effect on testosterone levels. Vitamin D might play an important role in androgen metabolism. Existing evidence from available trials evaluating the effect of vitamin D supplementation on androgen levels in men is insufficient to recommend measurement of 25(OH)D levels or vitamin D supplementation in hypogonadal men. We cannot exclude vitamin D effects on androgen levels in men with low TT levels or in men with severe vitamin D deficiency. This question remains to be answered in future investigations. Conclusions. Vitamin D deficiency is associated with adverse fertility outcomes including hypogonadism, but the evidence is insufficient to establish causality. High-quality trials are needed to further evaluate the effects of vitamin D supplementation on androgen levels in men.

Fertility and Child-Rearing

This chapter outlines the economic determinants of human fertility, and explores the demographic transition, and studies of child productivity. It offers an assessment of the costs of and returns from child production in Kala over the first 15 years of life, in terms of their costs and the contributions which they make to the family’s prosperity. Several aspects of child production are investigated, such as the opportunity cost of women’s time, children’s marriage and dowry costs, and the value of children’s labour. Risks to child-production include an understanding of survival rates for infants and children, sickness, and child-failure rates – as when a young man goes off on migration and does not return. The chapter concludes with a recognition of the limits to an economic understanding of high fertility, for example as shown by the political and religious importance of children, since children are not just economic assets but constitute “descendants”.

The Power of Fertility and Its Importance for the Concept of Sustainable Development

Demographic changes are one of the indicators of sustainable development, expressed by the value of the natural increase in the human population, resulting directly from the fertility level, which is the subject of this article. Human fertility is a complex potential conditioned by the environmental, social, and economic factors. The multi-dimensional relations of fertility that may affect its level, constitute an unlimited field of research, study, and analysis. The inter-disciplinary scope of fertility research conducted by the authors has shown that fertility is an issue that, in its historical, social, political, and medical aspects, has the potential of contributing to societal development and raising the standard of living. The aim of this article is to answer the question: whether and how the fertility of an individual has an impact on the idea of sustainable development. To achieve this, the available literature was analysed and synthesised, as well as supplemented with information provided by experts in the field. The article incorporates presentations of selected fertility determining factors, methods of measuring fertility potential, and diverse contexts, such as the impact of fertility on history and its relationship with the freedom of the human individual. Moreover, the authors present the relationship between the fertility of an individual, and the assumptions and postulates of the idea of sustainable development.

The Impact of SARS-CoV-2 Infection on Fertility and Female and Male Reproductive Systems

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection remains a huge challenge for contemporary healthcare systems. Apart from widely reported acute respiratory distress syndrome (ARDS), the virus affects many other systems inducing a vast number of symptoms such as gastrointestinal, neurological, dermatological, cardiovascular, and many more. Currently it has also been hypothesized that the virus might affect female and male reproductive systems; SARS-CoV-2 infection could also have a role in potential disturbances to human fertility. In this article, we aimed to review the latest literature regarding the potential effects of SARS-CoV-2 infection on female and male reproductive systems as well as fertility, in general.

Antioxidant and Infertility

Unexplained sub-fertility is commonly identified if couples fail to conceive after 1 yr. of everyday unprotected sexual intercourse even though investigations for ovulation, tubal patency and semen evaluation are ordinary. Many previous studies had shown that oxidative stress plays an important role in human fertility. Free radicals are neutralized by an elaborate antioxidant defense system. In a healthy body, pro-oxidants and antioxidants maintain a ratio and a shift in this ratio towards pro-oxidants gives rise to oxidative stress. There are two types of antioxidants in the human body: enzymatic and non-enzymatic antioxidants. Under normal conditions, antioxidants convert ROS to H2O to prevent overproduction of ROS. All cells in the human body are capable of synthesizing glutathione specially the liver. Free radicals appear to have a physiological role in female reproductive system in many different processes such as: oocyte maturation, fertilization, luteal regression, endometrial shedding and progesterone production by the corpus luteum. Protection from ROS is afforded by scavengers present in both male and female reproductive tract fluids, as well as in seminal plasma elevated concentrations of ROS in these environments may have detrimental effects on the spermatozoa, oocytes, sperm oocyte interaction and embryos both in the Fallopian tube and the peritoneal cavity; therefore oxidative stress modulates a host of reproductive pathologies affecting natural fertility in a woman’s life.