Stem Cells Helping Reproductive Medicine

Carlos Simón, MD, PhD

The stem cell field, with its ups and downs, owes much to the work by clinicians, embryologists, and researchers working in reproductive medicine. It seems that the time is fast approaching when all of our careful investment in this field will finally come to fruition. This issue of Seminars in Reproductive Medicine presents both real and potential breakthroughs in reproductive medicine based on translational stem cell research. Its special value is derived from the inclusion of outstanding work from the most relevant internationally recognized experts working in this hybrid field today.

The opening article sets the stage by presenting the concept and the current status of stem cell research, and by reviewing the different types of stem cells including pluripotent embryonic stem cells and induced pluripotent cells, somatic stem cells, and cancer stem cells.

The following section presents four exceptional articles dealing with the production of gametes from pluripotent and somatic stem cells. The meiotic progression of germ cells, derived in vitro from human pluripotent cells using different genetic approaches, is presented by my group. The controversial issue of the existence of germline stem cells in human adult ovaries, set in the context of recent major publications, is presented in a review by Dori Woods and Jonathan Tilly. Karim Nayernia's group presents their approach for the in vitro differentiation of male gametes, and Ellen Goossens and Herman Tournaye provide an outstanding update of the adult stem cell population in the human testis, and the derivation of stem cell lines without the destruction of the human embryo is updated by Irina Klimanskaya.

The second part of this issue focuses on the trophectoderm and its derivatives. The existence of human trophoblast stem cells is uncovered by the pioneering work of Susan Fisher's group, and Anthony Atala's laboratory unveils unexpected sources of pluripotent cells such as amniotic fluid and the placental membranes.

The identification and characterization of adult stem cells and their niches in the human endometrium and myometrium occupies the third section, presented by my group and Tetsuo Maruyama's group, respectively.

The final section of this issue explores several amazing achievements that have changed not only our vision but also the future of pluripotent stem cell clinical applications; cutting-edge technologies such as dedifferentiation, transdifferentiation, and reprogramming is presented by Izpizua Belmonte's group.

I would like to thank my international colleagues who have generously contributed to this publication. I am sincerely grateful for their time and effort. I also thank Dr. Bruce Carr for inviting me to guest edit this issue. I do hope that you will find this issue useful as both a reference and as a valuable tool for the continued improvement of research in reproductive medicine.