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Kate E Waimey, Francesca E Duncan,
H Irene Su,
Kristin Smith,
Harlan Wallach,
Kemi Jona,
Christos Coutifaris,
Clarisa R Gracia,
Lonnie D Shea,
Robert E Brannigan,
R Jeffrey Chang,
Mary B Zelinski,
Richard L Stouffer,
Robert L Taylor,
Teresa K Woodruff
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ABSTRACT: Fertility impairment and loss due to cancer or its treatment is a significant survivorship consideration for many pediatric, adolescent, and young adult cancer survivors. Chemotherapeutics, radiation, and surgery can impact the future fertility of men, women, and children with cancer. The field of oncofertility, founded to ensure the reproductive future of cancer survivors, gained momentum with 5 years of funding through a 2007 National Institutes of Health Roadmap Grant for Biomedical Research. This report from working group meetings at the fifth annual Oncofertility Consortium Conference speaks to the present state of oncofertility research and clinical care, existing gaps, and future directions for the field. This summary from conference participants and leaders in the field addresses the science, clinical specialties, and academic scholarship that can guide the field as the Roadmap Grant funding comes to a close.
Journal of adolescent and young adult oncology. 03/2013; 2(1):25-30.
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ABSTRACT: In vitro follicle growth in alginate hydrogels is a unique and versatile method for studying ovarian and follicle biology that may also have implications for fertility preservation. Current culture systems support the development of isolated mouse follicles from the secondary stage onward. However, it has been a challenge to grow smaller follicles in vitro due to the dissociation of the oocyte from companion somatic cells. Recent work has demonstrated that co-culturing primary follicles with mouse embryonic fibroblasts or ovarian stromal cells supports follicle survival and growth. In this study, we demonstrate that follicles themselves can exert a beneficial co-culture effect. When primary follicles were cultured in groups of 5 or 10 (multiple follicle culture), there was increased growth and survival. The multiple follicle culture approach maintained follicle integrity and resulted in the formation of antral stage follicles containing meiotically-competent gametes. The growth and survival of primary follicles was highly number dependent, with the most significant enhancement observed when the largest number of follicles were grown together. Our data suggest that the follicle unit is necessary to produce the secreted factors responsible for the supportive effects of multiple follicle culture, as neither denuded oocytes, oocyte-secreted factors nor granulosa cells alone were sufficient to support early follicle growth in vitro. Therefore, there may be signaling from both the oocyte and the follicle that enhances growth but requires both components in a feedback mechanism. This work is consistent with current in vivo models for follicle growth and thus advances the movement to recapitulate the ovarian environment in vitro.
Reproduction 10/2012; · 2.58 Impact Factor
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ABSTRACT: Aneuploidy in human eggs increases with maternal age and can result in infertility, miscarriages, and birth defects. The molecular mechanisms leading to aneuploidy, however, are largely unknown especially in the human where eggs are exceedingly rare and precious. We obtained human eggs from subjects ranging from 16.4 to 49.7 years old following in vitro maturation of oocyte-cumulus complexes isolated directly from surgically removed ovarian tissue. A subset of these eggs was used to investigate how age-associated aneuploidy occurs in the human. The inter-kinetochore distance between sister chromatids increased significantly with maternal age, indicating weakened cohesion. Moreover, we observed unpaired sister chromatids from females of advanced age. We conclude that loss of cohesion with increasing maternal age likely contributes to the well-documented increased incidence of aneuploidy.
Aging cell 07/2012; · 7.55 Impact Factor
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ABSTRACT: The bipolar spindle is an integral part of the cell division machinery required for faithful chromosome segregation. During meiosis in the mammalian females, this machinery must function sequentially during a reductive (meiosis I) and equational (meiosis II) cell division to ultimately produce a haploid egg that can be fertilized and give rise to the next generation. Errors in this process can result in aneuploidy (incorrect chromosome number), which can have adverse reproductive outcomes such as infertility, miscarriages, and birth defects. Mol. Reprod. Dev. © 2012 Wiley Periodicals, Inc.
Molecular Reproduction and Development 07/2012; 79(9):587. · 2.53 Impact Factor
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ABSTRACT: Facing a cancer diagnosis at any age is devastating. However, young cancer patients have the added burden that life-preserving cancer treatments, including surgery, chemotherapy, and radiotherapy, may compromise their future fertility. The possibility of reproductive dysfunction as a consequence of cancer treatment has a negative impact on the quality of life of cancer survivors. The field of oncofertility, which merges the clinical specialties of oncology and reproductive endocrinology, was developed to explore and expand fertility preservation options and to better manage the reproductive status of cancer patients. Fertility preservation for females has proved to be a particular challenge because mature female gametes are rare and difficult to acquire. The purpose of this article is to provide the gynecologist with a comprehensive overview of how cancer treatments affect the female reproductive axis, delineate the diverse fertility preservation options that are currently available or being developed for young women, and describe current measures of ovarian reserve that can be used pre- and post-cancer treatment. As a primary care provider, the gynecologist will likely interact with patients throughout the cancer care continuum. Thus, the gynecologist is in a unique position to join the oncofertility team in providing young cancer patients with up-to-date fertility preservation information and referrals to specialists.
US obstetrics & gynaecology. 01/2011; 6(1):24-34.
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ABSTRACT: Aneuploidy arising early in development is the leading genetic cause of birth defects and developmental disabilities in humans. Most errors in chromosome number originate from the egg, and maternal age is well established as the key risk factor. Although the importance of this problem for reproductive health is widely recognized, the underlying molecular basis for age-related aneuploidy in female meiosis is unknown. Here we show that weakened chromosome cohesion is a leading cause of aneuploidy in oocytes in a natural aging mouse model. We find that sister kinetochores are farther apart at both metaphase I and II, indicating reduced centromere cohesion. Moreover, levels of the meiotic cohesin protein REC8 are severely reduced on chromosomes in oocytes from old mice. To test whether cohesion defects lead to the observed aneuploidies, we monitored chromosome segregation dynamics at anaphase I in live oocytes and counted chromosomes in the resulting metaphase II eggs. About 90% of age-related aneuploidies are best explained by weakened centromere cohesion. Together, these results demonstrate that the maternal age-associated increase in aneuploidy is often due to a failure to effectively replace cohesin proteins that are lost from chromosomes during aging.
Current biology: CB 09/2010; 20(17):1522-8. · 10.99 Impact Factor
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ABSTRACT: Gene expression profiling using microarray technology is a robust, efficient, and cost-effective approach to assay a cell or tissue's transcriptome at a particular time or under a specific condition. Application of this technology to oocytes and preimplantation embryos has been limited largely because this biological material is difficult to acquire in sufficient quantities. We describe here a protocol to isolate and amplify mRNA from oocytes and preimplantation embryos that is suitable for microarray experiments. This protocol is based on a linear two-step amplification protocol using T7 RNA polymerase-based in vitro transcription and has been used to isolate more than 80 microg of cRNA from only 20 oocytes or preimplantation embryos. Gene expression profiling has provided insight into the molecular mechanisms of meiotic maturation, fertilization, and preimplantation embryo development. It has also been used to characterize female gametes and embryos from animals harboring gene-specific knockouts or knockdowns. Finally, this technology has been useful in evaluating how various Assisted Reproductive Technologies impact global patterns of gene expression in resulting embryos.
Methods in enzymology 01/2010; 477:457-80. · 1.90 Impact Factor
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ABSTRACT: Fertilization triggers a rise in intracellular Ca(2+) concentration ([Ca(2+)](i)) in the egg that initiates a series of events known as egg activation. These events include cortical granule exocytosis that establishes a block to polyspermy, resumption of meiosis, and recruitment of maternal mRNAs into polysomes for translation. Several calcium-dependent proteins, including calcium/calmodulin-dependent protein kinase II (CaMKII), have been implicated in egg activation. However, the precise role of CaMKII in mediating specific events of egg activation and the identity of the isoform(s) present in mouse eggs have not been unequivocally established. Through targeted deletion of the gamma isoform of CaMKII, we find that CaMKIIgamma is the predominant CaMKII isoform in mouse eggs and that it is essential for egg activation. Although CaMKIIgamma(-/-) eggs exhibit a normal pattern of Ca(2+) oscillations after insemination and undergo cortical granule exocytosis, they fail to resume meiosis or to recruit maternal mRNAs. Surprisingly, we find that the recruitment of maternal mRNAs does not directly depend on CaMKII, but requires elevated [Ca(2+)](i) and metaphase II exit. We conclude that CaMKIIgamma specifically controls mouse egg activation by regulating cell cycle resumption.
Proceedings of the National Academy of Sciences 12/2009; 107(1):81-6. · 9.68 Impact Factor
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ABSTRACT: Advanced maternal age is unequivocally associated with increased aneuploidy in human eggs and infertility, but the molecular basis for this phenomenon is unknown. An age-dependent deterioration of the spindle assembly checkpoint (SAC) has been proposed as a probable cause of aneuploidy. Accurate chromosome segregation depends on correct chromosome attachment to spindle microtubules, and the SAC provides time for this process by delaying anaphase onset until all chromosomes are stably attached. If SAC function decreases with age, oocytes from reproductively old mice would enter anaphase of meiosis I (AI) prematurely, leading to chromosome segregation errors and aneuploid eggs. Although intuitively appealing, this hypothesis is largely untested. We used a natural reproductive aging mouse model to determine if a defective SAC is the primary cause of aneuploidy in eggs. We tracked the progress of individual oocytes from young and old mice through meiosis I by time-lapse microscopy and counted chromosomes in the resulting eggs. This data set allowed us to correlate the timing of AI onset with aneuploidy in individual oocytes. We found that oocytes from old mice do not enter AI prematurely compared to young counterparts despite a 4-fold increase in the incidence of aneuploidy. Moreover, we did not observe a correlation between the timing of AI onset and aneuploidy in individual oocytes. When SAC function was challenged with a low concentration of the spindle toxin nocodazole, oocytes from both young and old mice arrested at meiosis I, which is indicative of a functional checkpoint. These findings indicate that a defective SAC is unlikely the primary cause of aneuploidy associated with maternal age.
Biology of Reproduction 07/2009; 81(4):768-76. · 4.01 Impact Factor
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ABSTRACT: The blastomere biopsy procedure does not affect preimplantation embryo development or global patterns of gene expression in a mouse model of Preimplantation Genetic Testing (PGT). However, zona breaching, which is inherent to the blastomere biopsy procedure, causes significant premature and sometimes abnormal hatching.
Fertility and sterility 10/2008; 91(4 Suppl):1462-5. · 3.97 Impact Factor
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ABSTRACT: In mammalian oocytes, cyclic AMP-dependent protein kinase (PKA) is responsible for maintaining meiotic arrest. We examined the role of the predominant regulatory subunit, RIalpha in regulating PKA activity during mouse oocyte maturation by knocking down the protein levels using an RNA interference approach. In oocytes in which RIalpha protein was reduced to non-detectable levels, compensatory decreases were also observed in the RIIalpha and catalytic (Calpha) subunit levels. These oocytes resumed meiosis, despite culture under conditions that maintain elevated intracellular cAMP levels, suggesting that the remaining Calpha was not sufficient to maintain meiotic arrest. The resulting eggs, however, displayed meiotic spindle abnormalities and abnormal cleavage planes leading to extrusion of large polar bodies. These results demonstrate that RIalpha is required for regulating PKA activity in maturing oocytes and that compensatory upregulation of RII does not occur. Furthermore, we implicate PKA as a modulator of spindle morphology and function during meiosis.
Developmental Dynamics 12/2006; 235(11):2961-8. · 2.54 Impact Factor
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ABSTRACT: The evolutionarily conserved partitioning defective (PAR) protein PAR-3 is pivotal for establishing and maintaining cell polarity. During mammalian oocyte maturation, the radially symmetric oocyte is transformed into a highly polarized metaphase II (MII)-arrested egg. We therefore examined several aspects of PAR-3 expression during oocyte maturation. We cloned two novel PAR-3 transcripts from an oocyte library that likely encode proteins of Mr = 73 K and 133 K that are phosphorylated during maturation. PAR-3, which is found throughout the GV-intact oocyte, becomes asymmetrically localized during meiosis. Following germinal vesicle breakdown, PAR-3 surrounds the condensing chromosomes and associates with the meiotic spindles. Prior to emission of the first and second polar bodies, PAR-3 is located within a central subdomain of the polarized actin cap, which overlies the spindle. This cortical PAR-3 localization depends on intact microfilaments. These results suggest a role for PAR-3 in establishing asymmetry in the egg and in defining the future site of polar body emission.
Developmental Biology 05/2005; 280(1):38-47. · 4.07 Impact Factor
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ABSTRACT: Gene expression profiling using microarray technology is a robust, efficient, and cost-effective approach to assay a cell or tissue's transcriptome at a particular time or under a specific condition. Application of this technology to oocytes and preimplantation embryos has been limited largely because this biological material is difficult to acquire in sufficient quantities. We describe here a protocol to isolate and amplify mRNA from oocytes and preimplantation embryos that is suitable for microarray experiments. This protocol is based on a linear two-step amplification protocol using T7 RNA polymerase-based in vitro transcription and has been used to isolate more than 80 μg of cRNA from only 20 oocytes or preimplantation embryos. Gene expression profiling has provided insight into the molecular mechanisms of meiotic maturation, fertilization, and preimplantation embryo development. It has also been used to characterize female gametes and embryos from animals harboring gene-specific knockouts or knockdowns. Finally, this technology has been useful in evaluating how various Assisted Reproductive Technologies impact global patterns of gene expression in resulting embryos.
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