Using Cumulus Cell Biopsy as a Non-Invasive Tool to Access the Quality of Bovine Oocytes: How Informative Are They?

Abstract

The present study aimed to determine whether cumulus cells (CC) biopsy, acquired before or after in vitro maturation (IVM), presents similar gene expression pattern and if would compromises oocyte quality. First, immature cumulus oocyte complexes (COCs) were distributed: (1) maturated in groups (control); (2) individually maturated, but not biopsied; (3) subjected to CC biopsy before maturation and individually matured; (4) individually matured and submitted to CC biopsy after maturation; (5) individually matured and CC biopsied before and after maturation. Secondly, candidate genes, described as potential markers of COCs quality, were quantified by RT-qPCR in CCs before and after IVM. After in vitro fertilization (IVF), zygotes were tracked and sorted regarding their developmental potential: fully developed to embryo, cleaved and arrested, and not-cleaved. The COC’s biopsy negatively affects embryo development (p < 0.05), blastocyst cell number (p < 0.05), and apoptotic cell ratio (p < 0.05), both before and after IVM. The PTGS2, LUM, ALCAM, FSHR, PGR, SERPINE2, HAS2, and PDRX3 genes were differentially expressed (p < 0.05) on matured CCs. Only PGR gene (p = 0.04) was under-expressed on matured CCs on Not-Cleaved group. The SERPINE2 gene was overexpressed (p = 0.01) in the Cleaved group on immature CCs. In summary, none of the selected gene studies can accurately predict COC’s fate after fertilization.

Effects of Heat Stress on Bovine Oocytes and Early Embryonic Development—An Update

“…Such a situation leads to disturbances in the energy metabolism in oocytes and embryos, which fundamentally impacts their developmental competence. Finally, precisely recognizing the biological factors responsible for the heat stress-mediated induction of impairments in reproductive physiology and endocrinology in cattle and other mammalian species might enable the multifaceted estimation of genomic, epigenomic, transcriptomic and proteomic profiles in the embryos, fetuses and offspring created and multiplied by such novel assisted reproductive technologies and in vitro embryo production strategies as the ex vivo fertilization of oocytes, with the aid of either classic penetration by capacitated spermatozoa [ 91 , 92 ] or intra-cytoplasmic sperm injection [ 93 , 94 ] and somatic cell cloning [ 95 , 96 ]. The harmful effects of heat stress on cow reproduction are of key importance to the economic status of the farm, producing financial losses every year.…”

Biochemical profiling of the follicular environment to predict oocyte competence in cattle

“…The transcript levels of eight genes that have been investigated by our group for some years, and correlated in the literature with oocyte competence and quality: CASP3 (caspase 3) [ 31 ], SERPINE2 (serpina belonging to the E family, member 2) [ 32 , 33 ], VCAN (versican) [ 11 , 22 , 34 ], LUM (lumican) [ 25 ], FSHR (follicle-stimulating hormone receptor) [ 20 , 23 ], EGFR (epidermal growth factor receptor) [ 20 , 32 ], PGR (progesterone receptor) [ 35 ], and GHR (growth hormone receptor) [ 20 , 22 , 23 , 36 ], were quantified by qPCR. PCR was performed using the 7500 Fast Real-Time PCR System (Applied Biosystems, Foster City, CA, USA).…”

Superovulation and aging perturb oocyte-granulosa cell communication

“…28 Indeed, during IVF granulosa cells that could be used for noninvasive screening are routinely collected yet discarded. Identifying a reliable transcriptomic signature connecting granulosa cells to clinical outcome has remained elusive, 29 due to variation in IVF procedures and retrospective study designs, 30 small sample numbers, 27 non-sensitive detection methods, 31,32 and pooling of COCs. 33 Current models that explain the lower quality of superovulated eggs as reflecting developmental immaturity were based on morphological and biochemical characterization, [34][35][36][37] fertilization and implantation rates, [38][39][40] and oocyte epigenetics.…”

“…28 Indeed, during IVF granulosa cells that could be used for non-invasive screening are routinely collected yet discarded. Identifying a reliable transcriptomic signature connecting granulosa cells to clinical outcome has remained elusive, 29 due to variation in IVF procedures and retrospective study designs, 30 small sample numbers, 27 non-sensitive detection methods, 31,32 and pooling of COCs. 33…”