<p>Role of stem cells in fertility preservation: current insights</p>

Abstract

While improvements made in the field of cancer therapy allow high survival rates, gonadotoxicity of chemo- and radiotherapy can lead to infertility in male and female pre- and postpubertal patients. Clinical options to preserve fertility before starting gonadotoxic therapies by cryopreserving sperm or oocytes for future use with assisted reproductive technology (ART) are now applied worldwide. Cryopreservation of pre- and postpubertal ovarian tissue containing primordial follicles, though still considered experimental, has already led to the birth of healthy babies after autotransplantation and is performed in an increasing number of centers. For prepubertal boys who do not produce gametes ready for fertilization, cryopreservation of immature testicular tissue (ITT) containing spermatogonial stem cells may be proposed as an experimental strategy with the aim of restoring fertility. Based on achievements in nonhuman primates, autotransplantation of ITT or testicular cell suspensions appears promising to restore fertility of young cancer survivors. So far, whether in two- or three-dimensional culture systems, in vitro maturation of immature male and female gonadal cells or tissue has not demonstrated a capacity to produce safe gametes for ART. Recently, primordial germ cells have been generated from embryonic and induced pluripotent stem cells, but further investigations regarding efficiency and safety are needed. Transplantation of mesenchymal stem cells to improve the vascularization of gonadal tissue grafts, increase the colonization of transplanted cells, and restore the damaged somatic compartment could overcome the current limitations encountered with transplantation.

Fertility preservation in BRCA mutation carriers—efficacy and safety issues: a review

“…Despite the discovery of female germline stem cells (FGSCs) in the ovary, experiments of FGSCs haven't been done on human in vitro and the debate on using FGSCs to treat ovarian reproductive is not over yet. Several types of SCs have been used to improve ovarian tissue transplantation by improving graft oxygenation and follicle survival [79,80]. OTC has a low usage [64] and is currently considered experimental, but pioneers consider it promising [81,82].…”

Ovarian follicular cells - living in the shadow of stemness cellular competence

“…GCs have many functions in their lifetime such as ovarian follicular development; secretion of sex hormones and synthesising growth factors to induce oocyte growth [17]. Nutrients are also provided by GCs to developing oocytes via gap junctions [18].…”

“…Follicles are located inside the ovary cortex, below the OSE [22,23]. Gonadotropins and growth factors stimulate GCs to change their gene expression and morphology [16,17], so flat-shaped GCs will become cuboidal, and express the Follicle Stimulating Hormone Receptor (FSHR) [2].…”

“…Understanding follicular fluid cells such as GCs, has allowed the effects of aging on oocyte quality and overall fertility to be shown, which has prompted studies to overcome the natural loss of fertility, as well as restore fertility for patients with prema-ture ovarian failure (POF) [12,17,27,44,[46][47][48]. POF is a condition that describes the loss of function of female fertility before the age of 40.…”

Human Pluripotent Stem Cells in Reproductive Science—A Comparison of Protocols Used to Generate and Define Male Germ Cells from Pluripotent Stem Cells

“…The lack of treatment options for men suffering germ-cell loss-related infertility as well as the still inadequate level of knowledge of human embryonic germ-cell development, mainly limited as a result of inaccessibility of experimental material, results in a big interest in in vitro derivation of germ cells from hPSCs [9][10][11]. Differentiation of hPSCs towards germ cells in vitro was first observed as spontaneous differentiation into embryoid bodies (EBs), where the expression of DEAD-box helicase 4 (DDX4) indicated the presence of germ-cell-like cells [12].…”