The Safe Use of a PTEN Inhibitor for the Activation of Dormant Mouse Primordial Follicles and Generation of Fertilizable Eggs

Abstract

BackgroundPrimordial ovarian follicles, which are often present in the ovaries of premature ovarian failure (POF) patients or are cryopreserved from the ovaries of young cancer patients who are undergoing gonadotoxic anticancer therapies, cannot be used to generate mature oocytes for in vitro fertilization (IVF). There has been very little success in triggering growth of primordial follicles to obtain fertilizable oocytes due to the poor understanding of the biology of primordial follicle activation.Methodology/Principal FindingsWe have recently reported that PTEN (phosphatase and tensin homolog deleted on chromosome ten) prevents primordial follicle activation in mice, and deletion of Pten from the oocytes of primordial follicles leads to follicular activation. Consequently, the PTEN inhibitor has been successfully used in vitro to activate primordial follicles in both mouse and human ovaries. These results suggest that PTEN inhibitors could be used in ovarian culture medium to trigger the activation of primordial follicle. To study the safety and efficacy of the use of such inhibitors, we activated primordial follicles from neonatal mouse ovaries by transient treatment with a PTEN inhibitor bpV(HOpic). These ovaries were then transplanted under the kidney capsules of recipient mice to generate mature oocytes. The mature oocytes were fertilized in vitro and progeny mice were obtained after embryo transfer.Results and ConclusionsLong-term monitoring up to the second generation of progeny mice showed that the mice were reproductively active and were free from any overt signs or symptoms of chronic illnesses. Our results indicate that the use of PTEN inhibitors could be a safe and effective way of generating mature human oocytes for use in novel IVF techniques.

Inhibition of Phosphatase and Tensin Homologue (PTEN) in Human Ovary In Vitro Results in Increased Activation of Primordial Follicles But Compromises Development of Growing Follicles

“…Pharmacological promotion of follicle growth in vitro followed by a xeno-transplantation model has resulted in embryo development and live litters being achieved in mice (Li et al, 2010;Adhikari et al, 2012). The initial results presented here are in agreement with previous work demonstrating that pharmacological inhibition of PTEN stimulates follicle activation in the human ovarian cortex (Li et al, 2010).…”

“…Disruption of the PI3K pathway using knockout models (Fan et al, 2008;Reddy et al, 2008) and pharmacological stimulators and/or inhibitors (Li et al, 2010;Adhikari et al, 2012) promotes activation of follicle growth in mice and xeno-transplanted human ovarian tissue and enhances murine ovulation. In this study we investigated the ability of bpV(HOpic) a pharmacological inhibitor of PTEN, a major negative regulator of the PI3K pathway, to affect human ovarian follicle activation and development in both tissue fragments and isolated follicles in vitro.…”

“…It is unclear whether the morphological normality of human follicles activated by higher doses of bpV(HOpic) was assessed prior to xeno-transplantation (Li et al, 2010). It is however noteworthy that Adhikari et al (2012) exposed mouse ovaries to 1 mM bpV(HOpic) to produce fertilizable IVG oocytes (Adhikari et al, 2012). bpV(HOpic) activated follicles were intact after 6 days incubation and not different in diameter from controls.…”

“…Moreover using a xenotransplantation model human ovarian follicles treated with bpV(HOpic) developed into pre-ovulatory follicles with oocytes that appeared to be capable of undergoing in vitro maturation (Li et al, 2010). It has been suggested that PTEN inhibitors could be used to generate mature oocytes in women whose oocyte reserve is impaired due to illness or treatment and to provide oocytes for derivation of embryonic stem cells (Li et al, 2010;Adhikari et al, 2012). Investigation of the human follicle response to bpV(HOpic) has so far required a xeno-transplantation model to complete follicle development.…”

Hippo signaling disruption and Akt stimulation of ovarian follicles for infertility treatment

“…After monitoring of follicle growth and obtaining four four-cell embryos developed from six oocytes, two embryos were transferred and a successful singleton pregnancy was established. Consistent with reported safety of short-term treatment with Akt stimulators to activate primordial follicles in mice (20), a healthy baby (male; birth weight, 3,254 g; and Apgar score, 9 at 1 min/10 at 5 min) was delivered at 37 wk and 2 d of pregnancy. Physical features of the baby are normal, together with normal placenta and umbilical cord.…”