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Colombo M, Alkali IM, Luvoni GC. Microenvironment factors promoting the quality of vitrified cat oocytes. Theriogenology 2023; 196:275-283. [PMID: 36442286 DOI: 10.1016/j.theriogenology.2022.11.027] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2022] [Revised: 11/17/2022] [Accepted: 11/19/2022] [Indexed: 11/23/2022]
Abstract
In oocyte cryopreservation programs, vitrification has overthrown conventional slow freezing both in veterinary and human medicine. In animals, its feasibility in field conditions makes it the preferred technique for the safeguard of genetic resources from zoo or wild animals, including threatened felids, for which the domestic cat is an excellent model. However, many cellular injuries, such as cytoskeleton, mitochondria and meiotic spindle alterations, DNA damage, zona pellucida hardening and cumulus cell loss, might occur following vitrification. After warming, although the exact mechanisms are still unclear, degeneration is a frequent outcome for cat vitrified oocytes. For immature (germinal vesicle) gametes, in vitro maturation after warming is a challenge, and cleavage after fertilization barely reaches 15-30%, while for mature (metaphase II) cryopreserved gametes it can get to 30-50%. Anyway, the progression to late embryos stages is often impaired, and improvements are needed. Standard cryopreservation protocol and the use of conventional in vitro culture systems after warming may not be enough for vitrified oocytes to recover and demonstrate their full developmental potential. Physical or chemical factors applied to oocytes undergoing vitrification, as an enrichment to the vitrification step, or to the culture microenvironment, could create more favorable conditions and promote vitrified oocyte survival and development. From the use of three-dimensional culture systems to the regulation of metabolic activities and cellular pathways, this review aims to explore all the possibilities employed so far, including the studies performed by our own lab, and the future perspectives, to present the most effective strategies for cat oocyte vitrification and the best time for their application (i.e., before, during, or after vitrification-warming).
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Affiliation(s)
- Martina Colombo
- Dipartimento di Medicina Veterinaria e Scienze Animali (DIVAS), Università degli Studi di Milano, 26900, Lodi, Italy.
| | - Isa Mohammed Alkali
- Dipartimento di Medicina Veterinaria e Scienze Animali (DIVAS), Università degli Studi di Milano, 26900, Lodi, Italy.
| | - Gaia Cecilia Luvoni
- Dipartimento di Medicina Veterinaria e Scienze Animali (DIVAS), Università degli Studi di Milano, 26900, Lodi, Italy.
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2
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Gardela J, Ruiz-Conca M, García-Sanmartín J, Martínez A, Mogas T, López-Béjar M, Álvarez-Rodríguez M. Mild hypothermia and vitrification increase the mRNA expression of cold-inducible proteins in bovine oocytes and cumulus cells. Theriogenology 2022; 185:16-23. [DOI: 10.1016/j.theriogenology.2022.03.010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2021] [Revised: 03/09/2022] [Accepted: 03/11/2022] [Indexed: 12/01/2022]
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Whynott RM, Summers KM, Ball GD, Van Voorhis BJ, Sparks A. Fresh embryo transfer after in vitro insemination of fresh vs. cryopreserved anonymous donor oocytes: which has a better live birth rate? A Society for Assisted Reproductive Technology Clinic Outcome Reporting System analysis. Fertil Steril 2022; 117:803-810. [PMID: 35216830 DOI: 10.1016/j.fertnstert.2022.01.008] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2021] [Revised: 01/01/2022] [Accepted: 01/04/2022] [Indexed: 01/15/2023]
Abstract
OBJECTIVE To determine if transfer of fresh embryos derived from fresh or cryopreserved donor oocytes yields a higher live birth rate. DESIGN Historical cohort study. SETTING Society for Assisted Reproductive Technology Clinic Outcome Reporting System database. PATIENT(S) A total of 24,663 fresh embryo transfer cycles of donor oocytes. INTERVENTION(S) None. MAIN OUTCOME MEASURE(S) The primary outcome was live births per number of embryos transferred on day 5. The secondary outcomes included number of infants per embryo transfer, surplus embryos cryopreserved, and characterization of US oocyte recipients. RESULT(S) A total of 16,073 embryo transfers were from fresh oocytes and 8,590 were from cryopreserved oocytes. Recipient age, body mass index (BMI), gravidity, and parity were similar between the groups. Most recipients were of White non-Hispanic race (66.9%), followed by Asian (13.7%), Black non-Hispanic (9.3%), and Hispanic (7.2%). Fresh oocyte cycles were more likely to use elective single embryo transfer (42.5% vs. 37.8%) or double embryo transfer (53.2% vs. 50.4%) and resulted in more surplus embryos for cryopreservation (4.6 vs. 1.2). The live birth rate from fresh oocytes was 57.5% vs. 49.7% from cryopreserved oocytes. Negative predictors of live birth included the use of cryopreserved oocytes (odds ratio [OR] 0.731, 95% confidence interval [CI] 0.665-0.804), Black non-Hispanic race (OR 0.603, 95% CI 0.517-0.703), Asian race (OR 0.756, 95% CI 0.660-0.867), and increasing recipient BMI (OR 0.982, 95% CI 0.977-0.994) after controlling for recipient age, number of embryos transferred on day 5, and unexplained infertility diagnosis. The proportion of multifetal deliveries was greater in cycles utilizing fresh (26.4%) vs. cryopreserved (20.6%) oocytes. CONCLUSION(S) The live birth rate is higher with use of fresh oocytes vs. cryopreserved oocytes in fresh embryo transfer cycles. Negative live birth predictors include recipient Black non-Hispanic or Asian race and increasing BMI.
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Affiliation(s)
| | - Karen M Summers
- Department of Obstetrics and Gynecology, Division of Reproductive Endocrinology and Infertility, University of Iowa Carver College of Medicine, Iowa City, Iowa
| | - G David Ball
- Seattle Reproductive Medicine, Seattle, Washington
| | - Bradley J Van Voorhis
- Department of Obstetrics and Gynecology, Division of Reproductive Endocrinology and Infertility, University of Iowa Carver College of Medicine, Iowa City, Iowa
| | - Amy Sparks
- Department of Obstetrics and Gynecology, Division of Reproductive Endocrinology and Infertility, University of Iowa Carver College of Medicine, Iowa City, Iowa
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Peinado I, Moya I, Sáez-Espinosa P, Barrera M, García-Valverde L, Francés R, Torres P, Gómez-Torres MJ. Impact of Maturation and Vitrification Time of Human GV Oocytes on the Metaphase Plate Configuration. Int J Mol Sci 2021; 22:ijms22031125. [PMID: 33498768 PMCID: PMC7865957 DOI: 10.3390/ijms22031125] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2020] [Revised: 01/20/2021] [Accepted: 01/21/2021] [Indexed: 12/28/2022] Open
Abstract
The combination of in vitro maturation (IVM) techniques and oocyte vitrification (OV) could increase the number of useful oocytes in different types of patients. IVM and subsequent OV is the most widely used clinical strategy. Would the results improve if we reverse the order of the techniques? Here, we evaluated survival, in vitro maturation, time to extrude the first polar body (PB), and the metaphase plate configuration of human prophase I (GV) oocytes before or after their vitrification. Specific, 195 GV oocytes from 104 patients subjected to controlled ovarian stimulation cycles were included. We stablished three experimental groups: GV oocytes vitrified and IVM (Group GV-Vit), GV oocytes IVM and vitrified at MII stage (Group MII-Vit), and GV oocytes IVM (Group not-Vit). All of them were in vitro matured for a maximum of 48 h and fixed to study the metaphase plate by confocal microscopy. According to our results, the vitrification of immature oocytes and their subsequent maturation presented similar survival, maturation, and metaphase plate conformation rates, but a significantly higher percentage of normal spindle than the standard strategy. Additionally, the extension of IVM time to 48 h did not seem to negatively affect the oocyte metaphase plate configuration.
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Affiliation(s)
- Irene Peinado
- Assisted Human Reproduction Unit, La Fe University and Polytechnic Hospital, 46026 Valencia, Spain; (I.P.); (I.M.); (M.B.); (L.G.-V.); (R.F.); (P.T.)
| | - Isabel Moya
- Assisted Human Reproduction Unit, La Fe University and Polytechnic Hospital, 46026 Valencia, Spain; (I.P.); (I.M.); (M.B.); (L.G.-V.); (R.F.); (P.T.)
| | | | - Macarena Barrera
- Assisted Human Reproduction Unit, La Fe University and Polytechnic Hospital, 46026 Valencia, Spain; (I.P.); (I.M.); (M.B.); (L.G.-V.); (R.F.); (P.T.)
- Biotechnology Department, Alicante University, 03690 Alicante, Spain;
| | - Laura García-Valverde
- Assisted Human Reproduction Unit, La Fe University and Polytechnic Hospital, 46026 Valencia, Spain; (I.P.); (I.M.); (M.B.); (L.G.-V.); (R.F.); (P.T.)
- Biotechnology Department, Alicante University, 03690 Alicante, Spain;
| | - Raquel Francés
- Assisted Human Reproduction Unit, La Fe University and Polytechnic Hospital, 46026 Valencia, Spain; (I.P.); (I.M.); (M.B.); (L.G.-V.); (R.F.); (P.T.)
- Energy and Memory, Brain Plasticity Unit, CNRS, ESPCI Paris, PSL Research University, 75005 Paris, France
| | - Patricia Torres
- Assisted Human Reproduction Unit, La Fe University and Polytechnic Hospital, 46026 Valencia, Spain; (I.P.); (I.M.); (M.B.); (L.G.-V.); (R.F.); (P.T.)
| | - María José Gómez-Torres
- Biotechnology Department, Alicante University, 03690 Alicante, Spain;
- Cátedra Human Fertility, Universidad de Alicante, 03690 Alicante, Spain
- Correspondence:
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Lei C, Sui Y, Ye J, Lu Y, Xi J, Sun Y, Jin L, Sun X. Comparison of PGS2.0 versus conventional embryo morphology evaluation for patients with recurrent pregnancy loss: a study protocol for a multicentre randomised trial. BMJ Open 2020; 10:e036252. [PMID: 33033011 PMCID: PMC7542939 DOI: 10.1136/bmjopen-2019-036252] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
INTRODUCTION Pregnancy loss (PL) is an adverse life event, and there is no proven effective treatment for recurrent PL (RPL). Preimplantation genetic screening (PGS) can be performed to reduce the risks of PL; however, there is still no solid scientific evidence that PGS improves outcomes for couples experiencing RPL. Comprehensive chromosome screening (PGS2.0) has become a routine practice in in vitro fertilisation (IVF) clinics. Previous studies based on PGS1.0 with a focus on RPL couples where the female is of advanced maternal age have reported contradictory results. Hence, a multicentre randomised trial is needed to provide evidence for the clinical benefits of PGS2.0 treatment for RPL couples. METHODS AND ANALYSIS Overall, 268 RPL couples undergoing IVF cycles will be enrolled. Couples will be randomised according to a unique grouping number generated by a random digital software into (1) PGS2.0 group and (2) non-PGS (conventional embryo morphology evaluation) group. This study aims to investigate whether the live birth rate (LBR) per initiated cycle after PGS2.0 is superior to the LBR per initiated cycle after conventional embryo evaluation (non-PGS group). Live birth will be defined as a live baby born after a gestation period of >28 weeks, with a birth weight of more than 1000 g. A multivariate logistic regression model will be used to adjust for confounding factors. ETHICS AND DISSEMINATION Ethical approval has been granted by the Ethics Committee of Obstetrics and Gynecology Hospital, Fudan University and the participating hospitals. Written informed consent will be obtained from each couple before any study procedure is performed. Data from this study will be stored in the Research Electronic Data Capture. The results of this trial will be presented and published via peer-reviewed publications and presentations at international conferences. TRIAL REGISTRATION NUMBER NCT03214185; Pre-results.
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Affiliation(s)
- Caixia Lei
- Prenatal Diagnosis Center, Obstetrics and Gynecology Hospital of Fudan University, Shanghai, China
- Department of Genetics, Shanghai JiAi Genetics & IVF Institute, Shanghai, China
| | - Yilun Sui
- Department of Genetics, Shanghai JiAi Genetics & IVF Institute, Shanghai, China
| | - Jiangfeng Ye
- Clinical Epidemiology, Obstetrics and Gynecology Hospital of Fudan University, Shanghai, China
| | - Yao Lu
- Reproductive Medical Center, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
| | - Ji Xi
- Reproductive Medical Center, International Peace Maternity and Child Health Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
| | - Yun Sun
- Reproductive Medical Center, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
| | - Li Jin
- Reproductive Medical Center, International Peace Maternity and Child Health Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
| | - Xiaoxi Sun
- Department of Genetics, Shanghai JiAi Genetics & IVF Institute, Shanghai, China
- Key Laboratory of Female Reproductive Endocrine Related Diseases, Obstetrics and Gynecology Hospital of Fudan University, Shanghai, China
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Gardela J, Ruiz-Conca M, Álvarez-Rodríguez M, Mogas T, López-Béjar M. Induction of CIRBP expression by cold shock on bovine cumulus-oocyte complexes. Reprod Domest Anim 2020; 54 Suppl 4:82-85. [PMID: 31625234 DOI: 10.1111/rda.13518] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2019] [Revised: 07/11/2019] [Accepted: 07/12/2019] [Indexed: 11/30/2022]
Abstract
The aim of this study was to induce the cold-inducible RNA-binding protein (CIRBP) expression on cumulus-oocyte complexes (COCs) through exposure to a sub-lethal cold shock and determine the effects of hypothermic temperatures during the in vitro maturation of bovine oocytes. Nuclear maturation, cortical granule redistribution and identification of cold-inducible RNA-binding protein (CIRBP) were assessed after 24 hr of in vitro maturation of control (38.5°C) and cold-stressed oocytes (33.5°C). The presence of CIRBP was assessed by Western blot in COCs or denuded oocytes and their respective cumulus cells. Based on the odds ratio, cold-stressed oocytes presented higher abnormal cytoplasmic distribution of cortical granules and nuclear maturation than the control group. Although CIRBP was detected in both control and cold-stressed groups, cold-stressed COCs had 2.17 times more expression of CIRBP than control COCs. However, when denuded oocytes and cumulus cells were assessed separately, CIRBP only was detected in cumulus cells in both groups. In conclusion, cold shock induced CIRBP expression, but it negatively affected nuclear maturation and cortical granule distribution of bovine oocytes. Moreover, the expression of CIRBP was only identified in cumulus cells but not in oocytes.
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Affiliation(s)
- Jaume Gardela
- Department of Animal Health and Anatomy, Veterinary Faculty, ERPAW (Endocrinology, Reproductive Physiology and Animal Welfare) Research Group, Universitat Autònoma de Barcelona, Bellaterra, Barcelona, Spain
| | - Mateo Ruiz-Conca
- Department of Animal Health and Anatomy, Veterinary Faculty, ERPAW (Endocrinology, Reproductive Physiology and Animal Welfare) Research Group, Universitat Autònoma de Barcelona, Bellaterra, Barcelona, Spain
| | - Manuel Álvarez-Rodríguez
- Department of Animal Health and Anatomy, Veterinary Faculty, ERPAW (Endocrinology, Reproductive Physiology and Animal Welfare) Research Group, Universitat Autònoma de Barcelona, Bellaterra, Barcelona, Spain.,Department of Clinical and Experimental Medicine (IKE), Linköping University, Linköping, Sweden
| | - Teresa Mogas
- Department of Animal Medicine and Surgery, Veterinary Faculty, Universitat Autònoma de Barcelona, Bellaterra, Barcelona, Spain
| | - Manel López-Béjar
- Department of Animal Health and Anatomy, Veterinary Faculty, ERPAW (Endocrinology, Reproductive Physiology and Animal Welfare) Research Group, Universitat Autònoma de Barcelona, Bellaterra, Barcelona, Spain
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Giolo E, Martinelli M, Luppi S, Romano F, Ricci G, Lazzarino M, Andolfi L. Study of the mechanical properties of fresh and cryopreserved individual human oocytes. EUROPEAN BIOPHYSICS JOURNAL: EBJ 2019; 48:585-592. [PMID: 31230258 DOI: 10.1007/s00249-019-01379-y] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/14/2018] [Revised: 03/05/2019] [Accepted: 06/17/2019] [Indexed: 01/02/2023]
Abstract
In assisted reproduction technologies, the cryopreservation of oocytes is a common procedure used to circumvent female infertility. However, some morphological and functional alterations of oocytes have been observed depending on the protocol applied. In this work, the mechanical response of individual human oocytes before and after a freeze-thawing procedure was characterised. Oocytes, immediately after retrieval, were morphologically evaluated by bright-field optical microscopy and their elasticity measured by indentation measurements using atomic force microscopy. Oocytes were then frozen according to the open-vitrification protocol and stored in liquid nitrogen. Afterwards, the same oocytes were thawed and the indentation measurements repeated. Using this approach, we can follow the elasticity of a set of single oocytes from retrieval up to the freeze-thawing procedure. The analysis of the resulting data shows that the retrieved healthy oocytes, which preserve their healthy morphological features after cryopreservation, maintain unchanged also in stiffness values. In contrast, oocytes having dysmorphic characteristics, before and/or after freeze-thawing, show significant variations in their mechanical response. In addition, the dysmorphic oocytes are generally observed to be softer than the healthy oocytes. Our results indicate that stiffness of healthy oocytes is not considerably affected by the open-vitrification-thawing procedure, and that distinct elasticity ranges can be identified for healthy and dysmorphic oocytes. These findings indicate that the mechanical characterization of oocytes represents an opportunity to detect cellular defects, and assess the quality and bio-viability of processes such as cryopreservation.
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Affiliation(s)
- Elena Giolo
- Institute for Maternal and Child Health, IRCCS Burlo Garofolo, Trieste, Italy
| | - Monica Martinelli
- Institute for Maternal and Child Health, IRCCS Burlo Garofolo, Trieste, Italy
| | - Stefania Luppi
- Institute for Maternal and Child Health, IRCCS Burlo Garofolo, Trieste, Italy
| | - Federico Romano
- Institute for Maternal and Child Health, IRCCS Burlo Garofolo, Trieste, Italy
| | - Giuseppe Ricci
- Institute for Maternal and Child Health, IRCCS Burlo Garofolo, Trieste, Italy. .,Department of Medicine, Surgery and Health Sciences, University of Trieste, Trieste, Italy.
| | - Marco Lazzarino
- Istituto Officina dei Materiali, Consiglio Nazionale delle Ricerche, Basovizza, 34149, Trieste, Italy
| | - Laura Andolfi
- Istituto Officina dei Materiali, Consiglio Nazionale delle Ricerche, Basovizza, 34149, Trieste, Italy.
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Snoeck F, Szymanska KJ, Sarrazin S, Ortiz-Escribano N, Leybaert L, Van Soom A. Blocking connexin channels during vitrification of immature cat oocytes improves maturation capacity after warming. Theriogenology 2018; 122:144-149. [PMID: 30268031 DOI: 10.1016/j.theriogenology.2018.09.011] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2018] [Revised: 09/05/2018] [Accepted: 09/12/2018] [Indexed: 11/28/2022]
Abstract
In the domestic cat, nuclear maturation and embryo development after vitrification of immature oocytes have been obtained but developmental competence after warming remains low. It has been reported that during folliculogenesis, the association and communication between the oocyte and the surrounding cumulus cells through connexin-based gap junctions is essential for normal oocyte and follicular development. Gap junctions result from the head-to-head interaction of two hemichannels; however, there is always a population of hemichannels not incorporated into gap junctions. These unopposed hemichannels are normally closed but may open under certain stress conditions, potentially also during vitrification and warming, turning them into toxic pores inducing cell injury and cell death. The aim of our study was to test whether inhibiting connexin 37 (Cx37) and connexin 43 (Cx43) channels with the connexin-targeting peptide Gap26 during vitrification and warming of cat immature cumulus-oocyte-complexes (COCs) could improve oocyte maturation and competence of resultant blastocysts derived by parthenogenetic activation. In the first experiment, our immunostainings confirmed the presence of Cx43 protein in the cytoplasm of immature cat oocytes and in the plasma membranes of cumulus cells. In the second experiment, COCs were randomly divided in three different groups: a control group (control), a group vitrified without Gap26 (vitrified) and a group vitrified with Gap26 (vitrified-peptide). The maturation rate was checked and oocytes from all three different experimental groups were parthenogenetically activated and cultured in vitro until day 8. After vitrification and warming, 49% of the oocytes in the control group matured, while this was 8% and 19% in the vitrified and vitrified-peptide groups, respectively. Compared to the vitrified group, oocytes in the vitrified-peptide group had significantly larger maturation rates. No blastocysts were detected at day 8 in the vitrified group, while 2% and 13% of the oocytes further developed to blastocyst at day 8 in the vitrified-peptide and control non-vitrified group, respectively. We conclude that the use of Gap26 in vitrification and warming media to vitrify immature cat oocytes improves maturation success and allows such oocytes to reach the blastocyst stage (2%) at day 8 after parthenogenetic activation.
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Affiliation(s)
- Féline Snoeck
- Faculty of Veterinary Medicine, Department of Reproduction, Obstetrics and Herd Health, Ghent University, Merelbeke, Belgium.
| | - Katarzyna Joanna Szymanska
- Faculty of Medicine and Health Sciences, Department of Basic Medical Sciences - Physiology Group, Ghent University, Ghent, Belgium
| | - Steven Sarrazin
- Faculty of Veterinary Medicine, Department of Reproduction, Obstetrics and Herd Health, Ghent University, Merelbeke, Belgium
| | - Nerea Ortiz-Escribano
- Faculty of Veterinary Medicine, Department of Reproduction, Obstetrics and Herd Health, Ghent University, Merelbeke, Belgium
| | - Luc Leybaert
- Faculty of Medicine and Health Sciences, Department of Basic Medical Sciences - Physiology Group, Ghent University, Ghent, Belgium
| | - Ann Van Soom
- Faculty of Veterinary Medicine, Department of Reproduction, Obstetrics and Herd Health, Ghent University, Merelbeke, Belgium
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Calcium ion regulation by BAPTA-AM and ruthenium red improved the fertilisation capacity and developmental ability of vitrified bovine oocytes. Sci Rep 2017; 7:10652. [PMID: 28878377 PMCID: PMC5587528 DOI: 10.1038/s41598-017-10907-9] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2017] [Accepted: 08/16/2017] [Indexed: 01/25/2023] Open
Abstract
Vitrification reduces the fertilisation capacity and developmental ability of mammalian oocytes; this effect is closely associated with an abnormal increase of cytoplasmic free calcium ions ([Ca2+]i). However, little information about the mechanism by which vitrification increases [Ca2+]i levels or a procedure to regulate [Ca2+]i levels in these oocytes is available. Vitrified bovine oocytes were used to analyse the effect of vitrification on [Ca2+]i, endoplasmic reticulum Ca2+ (ER Ca2+), and mitochondrial Ca2+ (mCa2+) levels. Our results showed that vitrification, especially with dimethyl sulfoxide (DMSO), can induce ER Ca2+ release into the cytoplasm, consequently increasing the [Ca2+]i and mCa2+ levels. Supplementing the cells with 10 μM 1,2-bis (o-aminophenoxy)ethane-N,N,N′,N′-tetraacetic acid (BAPTA-AM or BAPTA) significantly decreased the [Ca2+]i level and maintained the normal distribution of cortical granules in the vitrified bovine oocytes, increasing their fertilisation ability and cleavage rate after in vitro fertilisation (IVF). Treating vitrified bovine oocytes with 1 μM ruthenium red (RR) significantly inhibited the Ca2+ flux from the cytoplasm into mitochondria; maintained normal mCa2+ levels, mitochondrial membrane potential, and ATP content; and inhibited apoptosis. Treating vitrified oocytes with a combination of BAPTA and RR significantly improved embryo development and quality after IVF.
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