Reproductive biology and medicine 2015—the year in review

It would be an understatement to suggest that the discoveries in reproductive biology and medicine during 2015 were anything short of remarkable. And to rank these according to potential impact on our field would be a disservice to the groups that have persevered in tackling fundamental questions with the most sophisticated of techniques ensconced in the biomedical research enterprise of this decade. And so, with a measure of humility, a sense of awe, and the poetic license liberally taken by your EIC, a short summary of what might be considered a sentinel of what reproductive medicine may look like in the coming years is provided below. Progress in the area of germline stem cells continues to dominate a research landscape aiming to define the embryonic origins of primordial germ cells (PGCs) in molecular terms while at the same time nudging this line of research into the domain of treating infertility in men and women. That the horizon indeed holds the promise of making germline stem cells in vivo and in vitro is evidenced by the latest contributions from the laboratory of Surani and colleagues who have now mapped a molecular signature for the production of PGCs in humans (Tang et al., A Unique Gene Regulatory Network Resets the Human Germline Epigenome for Development. Cell. 2015 Jun 4;161(6):1453–67. doi: 10. 1016/j.cell.2015.04.053. http://www.ncbi.nlm.nih.gov/ pubmed/26046444). And the continuing quest for ways to obtain the best quality stem cells, which the field of regenerative medicine has been waiting for (as human ARTs sets the gold standards for quality embryo production), has taken an interesting twist of fate with a recent publication from the laboratory of Susan Fisher and her colleagues at UCSF (Zdavkovic et al., Human stem cells from single blastomeres reveal pathways of embryonic or trophoblast fate specification. http://dev.biologists.org/lookup/ doi/10.1242/dev.122846). Taking single blastomeres from four 8-cell and one 12-cell embryos from a single individual lead to the derivation of ten ES cell lines, each of which displayed unique transcriptomic and protein heterogeneities, providing new insights into the allocation of cell lineages in the human embryo. Gene editing in human embryos captured the attention of many this past year. The power of CRISPR/Cas9 entered the arena of reproductive medicine with much fanfare as a result of the publication by Liang and colleagues proof-of-principle case using ART generated three PN zygotes (Liang et al., CRISPR/Cas9-mediated gene editing in human tripronuclear zygotes. Protein Cell. 2015 May;6(5):363–72. doi: 10.1007/ s13238-015-0153-5. Epub 2015 Apr 18. http://www.ncbi. nlm.nih.gov/pubmed/25894090). This work sparked renewed interest in prospects for genetic engineering but in tandem has brought the level of discourse to new heights in light of ethical and societal implications that are only now being subject to the degree of scrutiny they deserve. That RNAs of the many varieties now understood to have important physiological functions have been catching their fair share of attention at both the basic and clinical levels has come as no surprise. From the Kravetz and Diamond groups, this year came the exciting finding that certain spermassociated RNAs detected by next gen sequencing could be Capsule 2015 was a year of unprecedented discovery in the fields of reproductive biology and medicine. Here, we take note of ten publications that have drawn upon technological advances of the past decade to bring new ways of thinking about old problems into the realm of human ARTs and reproductive genetics.