|Embryology - 13 Dec 2019 Expand to Translate|
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2. Guest Lecturer - Prof Robert Gilchrist
|The Reproductive Technology Revolution
Riepsamen AH, Chan K, Lien S, Sweeten P, Donoghoe MW, Walker G, Fraison EHJ, Stocker WA, Walton KL, Harrison CA, Ledger WL, Robertson DM & Gilchrist RB. (2019). Serum concentrations of oocyte-secreted factors BMP15 and GDF9 during IVF and in women with reproductive pathologies. Endocrinology , , . PMID: 31211369 DOI.
- "Oocyte-secreted factors, bone morphogenetic protein-15 (BMP15) and growth differentiation factor-9 (GDF9) are critical for folliculogenesis and fertility. This study developed ELISAs for the measurement of BMP15 and GDF9 in serum and investigated their usefulness as biomarkers of female reproductive function. Serum samples were obtained from women undergoing infertility treatments (n=154), and from peri- and post-menopausal women (n=28). Serum concentrations of BMP15 and GDF9 in women relative to age, AMH, number of oocytes retrieved, and polycystic ovaries/syndrome (PCO(S)) after superovulation for IVF. BMP15 and GDF9 immunoassays were validated for specificity, sensitivity (24 and 26 pg/ml, respectively) and reproducibility. BMP15 and GDF9 were detectable in 61% and 29% of women, respectively. BMP15 and GDF9 varied 64- and 15-fold respectively between women, but did not change within subjects following ovarian stimulation with gonadotropins. Serum GDF9 concentration, but not BMP15, was associated with oocyte number retrieved in non-PCO(S) patients (p=0.018). GDF9 and BMP15 associations with oocyte number differed significantly (p<0.05) with PCO(S) status. GDF9 concentrations were lower in poor responders (women with <4 oocytes retrieved or cancelled cycles; p=0.020). Serum BMP15, but not GDF9, was lower in women over 55 years, compared to women of reproductive age (p<0.01). This study develops and validates immunoassays to quantitate BMP15 and GDF9 in human serum, and to correlate concentrations with female reproductive potential. Although assay sensitivities require improvement, this study demonstrates the diagnostic potential of oocyte-secreted BMP15 and GDF9 as serum biomarkers in reproductive medicine."
Sugimura S, Yamanouchi T, Palmerini MG, Hashiyada Y, Imai K & Gilchrist RB. (2018). Effect of pre-in vitro maturation with cAMP modulators on the acquisition of oocyte developmental competence in cattle. J. Reprod. Dev. , 64, 233-241. PMID: 29503399 DOI.
- "The administration of follicle-stimulating hormone (FSH) prior to oocyte retrieval improves oocyte developmental competence. During bovine embryo production in vitro, however, oocytes are typically derived from FSH-unprimed animals. In the current study, we examined the effect of pre-in vitro maturation (IVM) with cAMP modulators, also known as the second messengers of FSH, on the developmental competence of oocytes derived from small antral follicles (2-4 mm) of FSH-unprimed animals. Pre-IVM with N6,2'-O-dibutyryladenosine 3',5'-cyclicmonophosphate (dbcAMP) and 3-isobutyl-1-methylxanthine (IBMX) for 2 h improved the blastocyst formation in oocytes stimulated by FSH or amphiregulin (AREG). Furthermore, pre-IVM enhanced the expression of the FSH- or AREG-stimulated extracellular matrix-related genes HAS2, TNFAIP6, and PTGS2, and epidermal growth factor (EGF)-like peptide-related genes AREG and EREG. Additionally, pre-IVM with dbcAMP and IBMX enhanced the expression of EGFR, and also increased and prolonged cumulus cell-oocyte gap junctional communication. The improved oocyte development observed using the pre-IVM protocol was ablated by an EGF receptor phosphorylation inhibitor. These results indicate that pre-IVM with cAMP modulators could contribute to the acquisition of developmental competence by bovine oocytes from small antral follicles through the modulation of EGF receptor signaling and oocyte-cumulus/cumulus-cumulus gap junctional communication."
Brown HM, Dunning KR, Sutton-McDowall M, Gilchrist RB, Thompson JG & Russell DL. (2017). Failure to launch: aberrant cumulus gene expression during oocyte in vitro maturation. Reproduction , 153, R109-R120. PMID: 27879344 DOI.
- "In vitro maturation (IVM) offers significant benefits for human infertility treatment and animal breeding, but this potential is yet to be fully realised due to reduced oocyte developmental competence in comparison with in vivo matured oocytes. Cumulus cells occupy an essential position in determining oocyte developmental competence. Here we have examined the areas of deficient gene expression, as determined within microarrays primarily from cumulus cells of mouse COCs, but also other species, between in vivo matured and in vitro matured oocytes. By retrospectively analysing the literature, directed by focussing on downregulated genes, we provide an insight as to why the in vitro cumulus cells fail to support full oocyte potential and dissect molecular pathways that have important roles in oocyte competence. We conclude that the roles of epidermal growth factor signalling, the expanded extracellular matrix, cumulus cell metabolism and the immune system are critical deficiencies in cumulus cells of IVM COCs."
Gilchrist RB, Luciano AM, Richani D, Zeng HT, Wang X, Vos MD, Sugimura S, Smitz J, Richard FJ & Thompson JG. (2016). Oocyte maturation and quality: role of cyclic nucleotides. Reproduction , 152, R143-57. PMID: 27422885 DOI.
- "The cyclic nucleotides, cAMP and cGMP, are the key molecules controlling mammalian oocyte meiosis. Their roles in oocyte biology have been at the forefront of oocyte research for decades and many of the long standing controversies in relation to the regulation of oocyte meiotic maturation are now resolved. It is now clear that the follicle prevents meiotic resumption through the actions of natriuretic peptides and cGMP inhibiting the hydrolysis of intra-oocyte cAMP and that the preovulatory gonadotrophin surge reverses these processes. The gonadotrophin surge also leads to a transient spike in cAMP in the somatic compartment of the follicle; research over the past 2 decades has conclusively demonstrated that this surge in cAMP is important for the subsequent developmental capacity of the oocyte. This is important, as oocyte in vitro maturation (IVM) systems practiced clinically do not recapitulate this cAMP surge in vitro, possibly accounting for the lower efficiency of IVM compared to clinical IVF. This review focuses in particular on this latter aspect - the role of cAMP/cGMP in the regulation of oocyte quality. We conclude that clinical practice of IVM should reflect this new understanding of the role of cyclic nucleotides, thereby creating a new generation of ART and fertility treatment options."
Robertson DM, Gilchrist RB, Ledger WL & Baerwald A. (2016). Random start or emergency IVF/in vitro maturation: a new rapid approach to fertility preservation. Womens Health (Lond) , 12, 339-49. PMID: 27248769 DOI.