Yorino Sato

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

Significance Human ovaries hold follicles containing oocytes. When follicles mature, they release eggs for fertilization. Patients with primary ovarian insufficiency develop menopausal symptoms at less than 40 y of age. They have few remaining follicles and their only chance for bearing a baby is through egg donation. Kawamura et al. demonstrated that Hippo and Akt signaling pathways regulate follicle growth. Using an in vitro activation approach, they first removed ovaries from infertile patients, followed by fragmentation to disrupt Hippo signaling and drug treatment to stimulate Akt signaling. After grafting ovarian tissues back to patients, they found rapid follicle growth in some patients and successfully retrieved mature eggs. After in vitro fertilization and embryo transfer, a live birth is now reported. Primary ovarian insufficiency (POI) and polycystic ovarian syndrome are ovarian diseases causing infertility. Although there is no effective treatment for POI, therapies for polycystic ovarian syndrome include ovarian wedge resection or laser drilling to induce follicle growth. Underlying mechanisms for these disruptive procedures are unclear. Here, we explored the role of the conserved Hippo signaling pathway that serves to maintain optimal size across organs and species. We found that fragmentation of murine ovaries promoted actin polymerization and disrupted ovarian Hippo signaling, leading to increased expression of downstream growth factors, promotion of follicle growth, and the generation of mature oocytes. In addition to elucidating mechanisms underlying follicle growth elicited by ovarian damage, we further demonstrated additive follicle growth when ovarian fragmentation was combined with Akt stimulator treatments. We then extended results to treatment of infertility in POI patients via disruption of Hippo signaling by fragmenting ovaries followed by Akt stimulator treatment and autografting. We successfully promoted follicle growth, retrieved mature oocytes, and performed in vitro fertilization. Following embryo transfer, a healthy baby was delivered. The ovarian fragmentation–in vitro activation approach is not only valuable for treating infertility of POI patients but could also be useful for middle-aged infertile women, cancer patients undergoing sterilizing treatments, and other conditions of diminished ovarian reserve.

C-Type Natriuretic Peptide Stimulates Ovarian Follicle Development

C-type natriuretic peptide (CNP) encoded by the NPPC (Natriuretic Peptide Precursor C) gene expressed in ovarian granulosa cells inhibits oocyte maturation by activating the natriuretic peptide receptor (NPR)B (NPRB) in cumulus cells. RT-PCR analyses indicated increased NPPC and NPRB expression during ovarian development and follicle growth, associated with increases in ovarian CNP peptides in mice. In cultured somatic cells from infantile ovaries and granulosa cells from prepubertal animals, treatment with CNP stimulated cGMP production. Also, treatment of cultured preantral follicles with CNP stimulated follicle growth whereas treatment of cultured ovarian explants from infantile mice with CNP, similar to FSH, increased ovarian weight gain that was associated with the development of primary and early secondary follicles to the late secondary stage. Of interest, treatment with FSH increased levels of NPPC, but not NPRB, transcripts in ovarian explants. In vivo studies further indicated that daily injections of infantile mice with CNP for 4 d promoted ovarian growth, allowing successful ovulation induction by gonadotropins. In prepubertal mice, CNP treatment alone also promoted early antral follicle growth to the preovulatory stage, leading to efficient ovulation induction by LH/human chorionic gonadotropin. Mature oocytes retrieved after CNP treatment could be fertilized in vitro and developed into blastocysts, allowing the delivery of viable offspring. Thus, CNP secreted by growing follicles is capable of stimulating preantral and antral follicle growth. In place of FSH, CNP treatment could provide an alternative therapy for female infertility.

Successful differentiation to T cells, but unsuccessful B-cell generation, from B-cell-derived induced pluripotent stem cells

Forced expression of certain transcription factors in somatic cells results in generation of induced pluripotent stem (iPS) cells, which differentiate into various cell types. We investigated T-cell and B-cell lineage differentiation from iPS cells in vitro. To evaluate the impact of iPS cell source, murine splenic B-cell-derived iPS (B-iPS) cells were generated after retroviral transduction of four transcription factors (Oct4, Sox2, Klf4 and c-Myc). B-iPS cells were identical to embryonic stem (ES) cells and mouse embryonic fibroblast (MEF)-derived iPS cells in morphology, ES cell marker expression as well as teratoma and chimera mouse formation. Both B-iPS and MEF-derived iPS cells differentiated into lymphocytes in OP9 co-culture systems. Both efficiently differentiated into T-cell lineage that produced IFN-γ on T-cell receptor stimulation. However, iPS cells including B-iPS cells were relatively resistant to B-cell lineage differentiation. One of the reasons of the failure of B-cell lineage differentiation seemed due to a defect of Pax5 expression in the differentiated cells. Therefore, current in vitro differentiation systems using iPS cells are sufficient for inducing T-cell but not B-cell lineage.

Actin polymerization-enhancing drugs promote ovarian follicle growth mediated by the Hippo signaling effector YAP

Hippo signaling pathway consists of conserved serine/threonine kinases to maintain optimal organ sizes. Studies have demonstrated that fragmentation of murine ovaries increases actin polymerization and disrupts Hippo signaling, leading to nuclear translocation of Hippo signaling effector Yes‐associated protein (YAP) in ovarian follicles and follicle growth. For patients with polycystic ovarian syndrome showing follicle arrest, ovarian wedge resection and laser drilling promote follicle growth. Because these damaging procedures likely involve actin polymerization, we tested whether actin polymerization‐promoting drugs could promote YAP translocation and stimulate follicle growth. Treatment of murine ovaries with μM Jasplakinolide (JASP), an actin polymerization‐promoting cyclic peptide, or sphingosine‐1‐phosphate (S1P), a follicular fluid constituent known to promote actin polymerization, increased the conversion of globular actin to the filamentous form, followed by increased nuclear YAP and expression of downstream connective tissue growth factor (CCN2). After short‐term treatments with JASP or S1P, in vitro cultured and in vivo grafted ovaries showed follicle growth. Furthermore, induction of constitutively active YAP in ovarian grafts of transgenic mice enhanced follicle development, whereas treatment of human ovarian cortices with JASP or S1P increased CCN2 expression. Thus, JASP and S1P stimulate follicle growth and are potential therapeutic agents for treating polycystic ovarian syndrome and other ovarian disorders.—Cheng, Y., Feng, Y., Jansson, L., Sato, Y., Deguchi, M., Kawamura, K., Hsueh, A. J. Actin polymerization‐enhancing drugs promote ovarian follicle growth mediated by the Hippo signaling effector YAP. FASEB J. 29, 2423‐2430 (2015). www.fasebj.org

Analysis of Late-Onset Ovarian Insufficiency after Ovarian Surgery: Retrospective Study with 75 Patients of Post-Surgical Ovarian Insufficiency

The primary objectives of the present study are to determine the period of onset of ovarian insufficiency after surgery and to confirm potential risk factors for ovarian insufficiency after surgery for the removal of benign ovarian cysts. Data were obtained from 75 patients who underwent surgery for benign ovarian cysts prior to the onset of ovarian insufficiency. Our analysis included 835 ovarian insufficiency patients who were referred to our institution from July 2003 to July 2013. Several epidemiological parameters of ovarian insufficiency after surgery (age at operation, period of onset of ovarian insufficiency, operation procedure, and pathological diagnosis) were investigated. Of the 835 patients who had ovarian insufficiency, 75 patients (9.0%) underwent ovarian surgery before the onset of ovarian insufficiency. Of those 75 patients, 66 patients (88.0%) underwent cystectomy. For the majority of the 75 patients the surgical indication was the presence of endometriotic cysts (57 patients; 76.0%). Twelve patients (16.0%) underwent multiple surgeries (all bilateral cystectomies). The mean age of the patients at the time of surgery was 27.8±5.5 years-old, and the mean period of onset of ovarian insufficiency was 5.8±3.8 years. In patients with cystectomy, the patients age at the time of surgery and period of onset of ovarian insufficiency was well-correlated (coefficient of correlation; hemilateral endometriotic cystectomy: −0.64, bilateral endometriotic cystectomy: −0.61, and multiple endimetriotic cystectomy: −0.40). We found that cystectomy of endometriotic cysts is the potential risk factor for ovarian insufficiency after surgery, at times, the onset of ovarian insufficiency long after cystectomy. Therefore, it is important to monitor ovarian reserve for an extended period of time after ovarian surgery. It is particularly important to monitor ovarian reserve long-term for patients who wish to conceive in the future and to suggest a variety of infertility treatments appropriate for their ovarian reserve.

The role of menstrual cycle phase and AMH levels in breast cancer patients whose ovarian tissue was cryopreserved for oncofertility treatment.

PurposeTo determine the factors that affect oocyte extraction efficiency when using the “combined procedure”. In the present “combined procedure” ovarian tissue cryopreservation and oocyte extraction from an isolated ovary, later used in In Vitro Maturation (IVM), are performed concurrently.MethodsData were analyzed retrospectively and obtained from the clinical records of 27 young breast cancer patients referred for fertility preservation.ResultsThe patients’ mean age was 33.7 (±3.8) years, mean serum anti-Müllerian hormone (AMH) concentration was 3.5 (±2.1) ng/ml, and mean number of extracted oocytes was 8.3 (±6.1). The phase of menstruation (follicular or luteal) did not affect either the number of oocytes extracted (P = 0.99) nor oocyte survival or maturation rates. Likewise, the number of oocytes that could be extracted was not affected by the type of laparoscopic procedure (multiple-port or single-incision laparoscopy; P = 0.94) or the molecular subtype of breast cancer (either Luminal A or B; P = 0.52). Analysis revealed that the number of extracted oocytes was well-correlated with the patient’s AMH serum level and age (coefficient of correlation: 0.60 and −0.48, respectively).ConclusionWe conclude that the outcome of the “combined procedure” primarily depends upon the patient’s serum AMH level and age. Importantly, the “combined procedure” may be used during any phase of the menstrual cycle to preserve the fertility of breast cancer patients.

Accuracy and safety verification of ovarian reserve assessment technique for ovarian tissue transplantation using optical coherence tomography in mice ovary

Except for histological study, there are currently no suitable techniques available for the detection and identification of primordial follicles in ovary of primary ovarian insufficiency patients who have undetectable AMH levels. Also, the ability to locate and quantify follicles on ovarian cortex strips, without fixation, is valuable for patients who could undergo subsequent successful ovarian tissue transplantation. Although optical coherence tomography (OCT) is a well-established high resolution imaging technique without fixation commonly applied in biomedicine, few reports are available on ovarian tissue imaging. In present study, we established standard OCT follicle images at each developmental stage, including the primordial follicle, and demonstrated the efficacy of OCT to estimate IVF outcome in transplanted mice ovary like ovarian reserve tests. Unfortunately, the current commercial OCT could not be used to accurate follicle count the number of follicles for whole ovary, because the maximum depth of examination was 100 μm. And we demonstrated the safety of OCT examination, it did not affect IVF outcome and birth defect rate, and reproductive ability. Although there is room for improvement, these findings will be first step to bring OCT examination a step closer to clinical application for measuring true ovarian reserve and localizing follicles.

Preliminary human application of optical coherence tomography for quantification and localization of primordial follicles aimed at effective ovarian tissue transplantation

PurposeThe purpose of this study was to evaluate the possible clinical application of optical coherence tomography for assessing ovarian reserve in individual specimens of human ovarian tissue for fertility preservation.MethodsOvarian tissue examination by optical coherence tomography was performed before ovarian tissue cryopreservation. Three of the four subjects had hematological disease or cancer, and they faced a threat to their fertility due to impending chemotherapy. One patient underwent ovarian tissue extraction for in vitro activation of dormant follicles as fertility treatment.ResultsThe current full-field optical coherence tomography technique can detect primordial follicles in non-fixed and non-embedded human ovarian tissue. These images are well correlated with histological evaluation and the ovarian reserve test, including follicle counts.ConclusionIt was demonstrated that optical coherence tomography could assess localization of primordial follicles and ovarian reserve in specimens of non-fixed human ovarian cortex, although optimization for examination of human ovarian tissue is needed for clinical application. Additionally, this technique holds the possibility of assessing the ovarian reserve of patients with unevaluable ovarian reserve.Trial registration numberUMIN000023141

Regulation of Preimplantation Embryo Development in Mice by FMS-like Tyrosine Kinase 3 Ligand

Abstract: Successful development of preimplantation embryos is essential for reproduction. Growth factors secreted by reproductive tracts are important for the development of preimplantation embryos. FMS-like tyrosine kinase 3 (FLT3) is a tyrosine kinase receptor related to colony-stimulating factor-1 receptor and c-KIT, promoting preimplantation embryo development following their ligand binding. We found expression of FLT3 ligand transcripts in the oviducts and uteri of pregnant mice. The transcripts for its receptor, FLT3, were detectable throughout the early embryonic stages with an increase after the eight-cell stage. In contrast, the expression of FLT3 ligand was negligible after the morula stage, suggesting potential paracrine actions of FLT3 ligand produced by the reproductive tracts. Treatment with FLT3 ligand promoted the development of two-cell embryos to the morula and blastocyst stages in a dose-dependent manner with increases in cell proliferation, but not inhibition of cell survival. The effects of FLT3 ligand were blocked by a FLT3 receptor inhibitor, TCS359. Studies using specific inhibitors demonstrated the potential involvement of the PI3K pathway in mediating FLT3 ligand actions. Our findings suggest that the FLT3 ligand/FLT3 signaling system plays important paracrine roles during the development of preimplantation embryos.