In vitro spermatogenesis: a myth or reality?

Abstract

Spermatogenesis is a complex, unique and tightly coordinated process takes place in the seminiferous tubules. It is divided broadly into three distinct phases; proliferation of spermatogonial stem cells (mitosis), reduction of chromosome number (meiosis) and transformation of spermatids into sperm (spermiogenesis). Recapitulation of this orchestrated process in vitro is significant in understanding germ cell biology, onset of some inherited disorders, treatment of infertility, and deciding methods of genetic manipulations and fertility preservation. Different attempts have been made using embryonic stem cells, somatic stem cells, induced pluripotent stem cells and spermatogonial stem cells to achieve this goal. Studies have shown the potential capacity of stem cells to differentiate into germ cells under appropriate culture conditions. However, producing a functionally normal sperm is still a greater challenge for scientists. Results of our recent study indicated that umbilical cord blood derived mesenchymal stem cells can differentiate in to male germ cells lineage when induction with retinoic acid and co-culture with Sertoli cells. However, we could reach only up to post meiotic spermatid level as shown by majority of studies. Lack of epididymal support and correct endocrine profile may be the reason behind this failure. We have planned to elucidate this hypothesis in a future research.