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Kovacsy S, Ismer A, Funes J, Hoogewijs M, Wilsher S. Successful vitrification of equine embryos >300 microns without puncture or aspiration. Equine Vet J 2024; 56:815-822. [PMID: 38450769 DOI: 10.1111/evj.14081] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2023] [Accepted: 02/19/2024] [Indexed: 03/08/2024]
Abstract
BACKGROUND Equine embryos >300 μm require puncture before vitrification. Protocols that do not require pre-puncture would make vitrification easier and allow for its widespread use. OBJECTIVES To design a successful vitrification protocol for embryos >300 μm without puncture as a pre-treatment. STUDY DESIGN Experimental in vivo study. METHODS Thirty-eight embryos were divided into 3 groups (G1: ≤300 μm, n = 11; G2: >300-500 μm, n = 20; G3: >500 μm, n = 7). Embryos were vitrified using a human vitrification kit. Following a 15 min exposure to equilibration solution (ES; 7.5% DMSO +7.5% ethylene glycol [EG] in a base medium [BM] of M199 HEPES-buffered medium [H199] + hydroxypropyl cellulose + gentamycin), embryos were exposed for ≤90 s to a vitrification solution (15% DMSO +15% EG + 0.5 M trelahose in BM), loaded onto a Cryolock and plunged into LN2. Warming was undertaken by plunging the Cryolock tip into 1 mL of H199 + 20% FBS + pen/strep +1 M sucrose at 42°C for 1 min. The embryos were then moved to a 0.5 M sucrose solution for 4 min, then placed in Vigro Hold for 4 min prior to transfer to a recipient. RESULTS Pregnancy rates were 81.8% (9/11) for G1, 80% (16/20) for G2, and 0% (0/7) for G3. The largest embryo to survive was 480 μm. MAIN LIMITATIONS Limited numbers and only one pregnancy was followed to term. CONCLUSIONS Equine embryos ≤480 μm can be successfully vitrified using a protocol with a longer exposure time to the ES. This does not appear to have a negative effect on early embryonic development.
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Affiliation(s)
| | - Ann Ismer
- Sharjah Equine Hospital, Sharjah, UAE
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Piñeiro-Silva C, Gadea J. Optimizing oocyte electroporation for genetic modification of porcine embryos: Evaluation of the parthenogenetic activation. Theriogenology 2024; 218:126-136. [PMID: 38325149 DOI: 10.1016/j.theriogenology.2024.01.041] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2023] [Revised: 01/31/2024] [Accepted: 01/31/2024] [Indexed: 02/09/2024]
Abstract
In reproductive biology, understanding the effects of novel techniques on early embryo development is of paramount importance. To date, the effects of electrical activation on oocytes prior to in vitro fertilization (IVF) are not well understood. The aim of this study was to investigate the effects of oocyte electroporation prior to IVF on embryo development and to differentiate between true embryos and parthenotes by using a TPCN2 knock-out (KO) male to evaluate the presence of the KO allele in the resulting blastocysts. The study consisted of three experiments. The first one examined oocyte electroporation with and without subsequent IVF and found that electroporated oocytes had higher activation rates, increased occurrence of a single pronucleus, and no effect on sperm penetration. Cleavage rates improved in electroporated oocytes, but blastocyst rates remained constant. Genotype analysis revealed a significant increase in the proportion of parthenotes in the electroporated groups compared to the IVF control (30.2 % vs. 6.8 %). The second experiment compared two electroporation media, Opti-MEM and Nuclease-Free Duplex Buffer (DB). DB induced higher oocyte degeneration rates, and lower cleavage and blastocyst rates than Opti-MEM, while parthenogenetic formation remained consistent (60.0 and 48.5 %). In the third experiment, the timing of electroporation relative to IVF was evaluated (1 h before IVF, immediately before IVF and 7 h after IVF). Electroporation immediately before IVF resulted in higher activation rates and different pronuclear proportions compared to the other timing groups. The penetration rate was higher in the immediate electroporation group, and cleavage rate improved in all electroporated groups compared to the control. Blastocyst rates remained constant. Genotyping revealed no significant differences in parthenote proportions among the timing groups, but these were higher than the control (56.25 %, 63.89 %, 51.61 %, 2.44 %, respectively), and showed higher mutation rates when electroporation was performed 7 h after IVF. Overall, this comprehensive study sheds light on the potential of electroporation for creating genetically modified embryos and the importance of media selection and timing in the process, the best media being the Opti-MEM and the more efficient timing regarding mutation rate, 7 h post-IVF, even when the parthenote formation did not differ among electroporated groups. Further studies are needed to reduce the parthenogenetic activation while maintaining high mutation rates to optimize the use of this procedure for the generation of gene-edited pig embryos by oocyte/zygote electroporation.
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Affiliation(s)
- Celia Piñeiro-Silva
- Department of Physiology, University of Murcia, International Excellence Campus for Higher Education and Research "Campus Mare Nostrum" and Institute for Biomedical Research of Murcia (IMIB-Arrixaca), 30100, Murcia, Spain
| | - Joaquín Gadea
- Department of Physiology, University of Murcia, International Excellence Campus for Higher Education and Research "Campus Mare Nostrum" and Institute for Biomedical Research of Murcia (IMIB-Arrixaca), 30100, Murcia, Spain.
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3
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Todrin AF, Kovalenko IF, Smolyaninova YI, Timofeyeva OV, Popivnenko LI, Gordiyenko OI. Determination of cell membrane permeability coefficients: Comparison of models in the case of oocytes. Cryobiology 2023; 113:104789. [PMID: 37924929 DOI: 10.1016/j.cryobiol.2023.104789] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2023] [Revised: 09/29/2023] [Accepted: 11/01/2023] [Indexed: 11/06/2023]
Abstract
Values of cell membranes permeability coefficients for water and molecules of cryoprotective agents (CPAs) are the necessary characteristics for developing physical-mathematical models describing mass transfer processes through cell membranes in order to predict optimal cell cooling rates. We carried out a comparative analysis of the permeability coefficients of mouse oocyte membranes for molecules of water, ethylene glycol (EG), propane-1,2-diol (1,2-PD) and dimethyl sulfoxide (Me2SO), determined by applying the classical Kedem-Katchalsky model, which considers only the penetration of non-electrolyte molecules (water and CPA) through the membrane, and the model developed by us, which takes into account the transmembrane transfer of ions and the associated changes in the transmembrane electric potential. We shown that calculations based on the developed modified model provide lower values of the permeability coefficients of the oocyte membrane for water and CPA molecules. What is important that the obtained by our modified model permeability coefficients for water molecules do not depend on the type of cryoprotectant, while the application of the classical model both in our studies and works of other authors always gave different values of these coefficients in solutions with different cryoprotectants. Our modified model also makes it possible to determine the dynamics of the transmembrane electric potential of the cell under the conditions of transmembrane mass transfer and the duration of the membrane being influenced by the changes in electric potential, that is a parameter that can directly affect the viability of cells.
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Affiliation(s)
- A F Todrin
- Institute for Problems of Cryobiology and Cryomedicine, National Academy of Sciences of Ukraine, 23, Pereyaslavskaya str., 61016, Kharkiv, Ukraine.
| | - I F Kovalenko
- Institute for Problems of Cryobiology and Cryomedicine, National Academy of Sciences of Ukraine, 23, Pereyaslavskaya str., 61016, Kharkiv, Ukraine.
| | - Ye I Smolyaninova
- Institute for Problems of Cryobiology and Cryomedicine, National Academy of Sciences of Ukraine, 23, Pereyaslavskaya str., 61016, Kharkiv, Ukraine.
| | - O V Timofeyeva
- Institute for Problems of Cryobiology and Cryomedicine, National Academy of Sciences of Ukraine, 23, Pereyaslavskaya str., 61016, Kharkiv, Ukraine
| | - L I Popivnenko
- Institute for Problems of Cryobiology and Cryomedicine, National Academy of Sciences of Ukraine, 23, Pereyaslavskaya str., 61016, Kharkiv, Ukraine.
| | - O I Gordiyenko
- Institute for Problems of Cryobiology and Cryomedicine, National Academy of Sciences of Ukraine, 23, Pereyaslavskaya str., 61016, Kharkiv, Ukraine.
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Yan G, Yao Y, Yang W, Lu L, Wang L, Zhao D, Zhao S. An all-37 °C thawing method improves the clinical outcomes of vitrified frozen-thawed embryo transfer: a retrospective study using a case-control matching analysis. Arch Gynecol Obstet 2023; 307:1991-1999. [PMID: 37041370 DOI: 10.1007/s00404-023-07029-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2022] [Accepted: 03/27/2023] [Indexed: 04/13/2023]
Abstract
PURPOSE The purpose of this study is to assess the impact of different temperatures and incubation times on the clinical outcomes of FET cycles during the thawing procedure and to select a better thawing method to improve clinical outcomes. METHODS This retrospective study included 1734 FET cycles from January 1, 2020, to January 30, 2022. Embryos vitrified using a KITAZATO Vitrification Kit were thawed at 37 °C in all steps (the case group, denoted the "all-37 °C" group) or at 37 °C and then at room temperature (RT; the control group, denoted the "37 °C-RT" group), according to the kit instructions. The groups were matched 1:1 to avoid confounding. RESULTS After case-control matching, 366 all-37 °C cycles and 366 37 °C-RT cycles were included. The baseline characteristics were similar (all P > 0.05) between the two groups after matching. FET of the all-37 °C group yielded a higher clinical pregnancy rate (CPR; P = 0.009) and implantation rate (IR; P = 0.019) than FET of the 37 °C-RT group. For blastocyst transfers, the CPR (P = 0.019) and IR (P = 0.025) were significantly higher in the all-37 °C group than in the 37 °C-RT group. For D3-embryo transfers, the CPR and IR were non-significantly higher in the all-37 °C group than in the 37 °C-RT group (P > 0.05). CONCLUSIONS Thawing vitrified embryos at 37 °C in all steps with shortening wash time can enhance CPR and IR in FET cycles. Well-designed prospective studies are warranted to further evaluate the efficacy and safety of the all-37 °C thawing method.
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Affiliation(s)
- Gaofeng Yan
- Department of Reproduction and Genetics, First Affiliated Hospital of Kunming Medical University, Kunming, 650032, Yunnan, China
| | - Youlin Yao
- Department of Reproduction and Genetics, First Affiliated Hospital of Kunming Medical University, Kunming, 650032, Yunnan, China
| | - Wenjuan Yang
- Department of Reproduction and Genetics, First Affiliated Hospital of Kunming Medical University, Kunming, 650032, Yunnan, China
| | - Ling Lu
- Department of Reproduction and Genetics, First Affiliated Hospital of Kunming Medical University, Kunming, 650032, Yunnan, China
| | - Longda Wang
- Department of Reproduction and Genetics, First Affiliated Hospital of Kunming Medical University, Kunming, 650032, Yunnan, China
| | - Di Zhao
- Department of Reproduction and Genetics, First Affiliated Hospital of Kunming Medical University, Kunming, 650032, Yunnan, China
| | - Shuhua Zhao
- Department of Reproduction and Genetics, First Affiliated Hospital of Kunming Medical University, Kunming, 650032, Yunnan, China.
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Gonzalez‐Plaza A, Brullo C, Cambra JM, Garcia M, Iacono E, Parrilla I, Gil MA, Martinez EA, Martinez CA, Cuello C. Equilibration time with cryoprotectants, but not melatonin supplementation during in vitro maturation, affects viability and metaphase plate morphology of vitrified porcine mature oocytes. Reprod Domest Anim 2022; 57 Suppl 5:58-63. [PMID: 35567517 PMCID: PMC9790282 DOI: 10.1111/rda.14158] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2022] [Accepted: 05/12/2022] [Indexed: 12/30/2022]
Abstract
The aims of this study were to investigate the effects of different equilibration times with cryoprotectants on viability and metaphase plate morphology of vitrified-warmed porcine mature oocytes (Experiment 1) and to evaluate the effects of supplementation with 10-9 M melatonin during in vitro maturation on these parameters (Experiment 2). In Experiment 1, 2,392 mature oocytes were vitrified using different equilibration times of oocytes with cryoprotectants (3, 10, 15, 20, 30, 40, 60 and 80 min). Fresh oocytes matured in vitro for 44 hr (n = 509) were used as controls. In Experiment 2, a total of 573 COCs were used. COCs were matured with 10-9 M melatonin supplementation or without melatonin (control). Some oocytes from each group were vitrified with a 60-min equilibration time with cryoprotectants according to the results of Experiment 1. The remaining oocytes from each maturation group were used as fresh control groups. In both experiments, oocytes were stained with 2',7'-dichlorodihydrofuorescein diacetate and Hoechst 33342 to assess viability and metaphase plate morphology, respectively. Vitrification and warming affected (p < .01) oocyte viability compared with controls, which were all viable after 44 hr of IVM. In Experiment 1, the longer the equilibration time with cryoprotectants, the higher the viability. Oocytes equilibrated for 60 and 80 min had the highest (p < .05) viability and similar metaphase plate characteristics to the fresh control oocytes. In Experiment 2, supplementation with melatonin during in vitro maturation had no effect on oocyte viability or metaphase plate morphology of vitrified-warmed oocytes. In conclusion, under our experimental conditions, vitrified porcine mature oocytes equilibrated with cryoprotectants for 60 or 80 min exhibited the highest viability and similar metaphase plate characteristics to fresh controls. Furthermore, supplementation with 10-9 M melatonin during in vitro maturation had no effect on these parameters.
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Affiliation(s)
- Alejandro Gonzalez‐Plaza
- Department of Medicine and Animal Surgery, Faculty of Veterinary Medicine, International Excellence Campus for Higher Education and Research (CMN)University of MurciaMurciaSpain,Institute for Biomedical Research of Murcia (IMIB‐Arrixaca)MurciaSpain
| | - Cristiano Brullo
- Department of Veterinary Medical Sciences and CIRI‐SDVUniversity of BolognaBolognaItaly
| | - Josep M. Cambra
- Department of Medicine and Animal Surgery, Faculty of Veterinary Medicine, International Excellence Campus for Higher Education and Research (CMN)University of MurciaMurciaSpain,Institute for Biomedical Research of Murcia (IMIB‐Arrixaca)MurciaSpain
| | - Manuela Garcia
- Department of Medicine and Animal Surgery, Faculty of Veterinary Medicine, International Excellence Campus for Higher Education and Research (CMN)University of MurciaMurciaSpain,Institute for Biomedical Research of Murcia (IMIB‐Arrixaca)MurciaSpain
| | - Eleonora Iacono
- Department of Veterinary Medical Sciences and CIRI‐SDVUniversity of BolognaBolognaItaly
| | - Inmaculada Parrilla
- Department of Medicine and Animal Surgery, Faculty of Veterinary Medicine, International Excellence Campus for Higher Education and Research (CMN)University of MurciaMurciaSpain,Institute for Biomedical Research of Murcia (IMIB‐Arrixaca)MurciaSpain
| | - Maria Antonia Gil
- Department of Medicine and Animal Surgery, Faculty of Veterinary Medicine, International Excellence Campus for Higher Education and Research (CMN)University of MurciaMurciaSpain,Institute for Biomedical Research of Murcia (IMIB‐Arrixaca)MurciaSpain
| | - Emilio A. Martinez
- Department of Medicine and Animal Surgery, Faculty of Veterinary Medicine, International Excellence Campus for Higher Education and Research (CMN)University of MurciaMurciaSpain,Institute for Biomedical Research of Murcia (IMIB‐Arrixaca)MurciaSpain
| | - Cristina A. Martinez
- Department of Biomedical & Clinical Sciences (BKV), BKH/Obstetrics & Gynaecology, Faculty of Medicine and Health SciencesLinköping UniversityLinköpingSweden
| | - Cristina Cuello
- Department of Medicine and Animal Surgery, Faculty of Veterinary Medicine, International Excellence Campus for Higher Education and Research (CMN)University of MurciaMurciaSpain,Institute for Biomedical Research of Murcia (IMIB‐Arrixaca)MurciaSpain
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6
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García-Martínez T, Martínez-Rodero I, Roncero-Carol J, Vendrell-Flotats M, Gardela J, Gutiérrez-Adán A, Ramos-Ibeas P, Higgins AZ, Mogas T. The Role of Aquaporin 7 in the Movement of Water and Cryoprotectants in Bovine In Vitro Matured Oocytes. Animals (Basel) 2022; 12:ani12040530. [PMID: 35203238 PMCID: PMC8868131 DOI: 10.3390/ani12040530] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2022] [Revised: 02/16/2022] [Accepted: 02/18/2022] [Indexed: 02/01/2023] Open
Abstract
Simple Summary The permeability of the plasma membrane to water and cryoprotectants is a critical factor in the effective vitrification of oocytes. The goal of this study is to better understand the pathways used to transport water and other cryoprotectants through the plasma membrane of bovine in vitro matured oocytes, with a focus on the role of aquaporin 7 (AQP7). We demonstrated that cryoprotectants stimulated AQP3 and AQP7 but not AQP9 expression in mature bovine oocytes. Dimethyl sulfoxide upregulates AQP3 expression, while ethylene glycol upregulates AQP7 expression in oocytes in a CPA-dependent fashion. We also demonstrated that exogenous expression of aquaglyceroporins such as AQP7 is possible in in vitro matured oocytes. When permeability values for membrane transport of dimethyl sulfoxide, ethylene glycol and sucrose were assessed, we observed that AQP7 overexpressed oocytes are more permeable to water in the presence of dimethyl sulfoxide solution. These biophysical characteristics, together with the use of membrane transport modeling, will allow re-evaluation and possibly improvement of previously described protocols for bovine oocyte cryopreservation. Abstract Aquaglyceroporins are known as channel proteins, and are able to transport water and small neutral solutes. In this study, we evaluate the effect of exposure of in vitro matured bovine oocytes to hyperosmotic solutions containing ethylene glycol (EG), dimethyl sulfoxide (Me2SO) or sucrose on the expression levels of AQP3, AQP7 and AQP9. Moreover, we studied whether artificial protein expression of AQP7 in bovine oocytes increases their permeability to water and cryoprotectants. Exposure to hyperosmotic solutions stimulated AQP3 and AQP7 but not AQP9 expression. Oocytes exposed to hyperosmotic Me2SO solution exhibited upregulated AQP3 expression, while AQP7 expression was upregulated by EG hyperosmotic exposure. Microinjection of oocytes at the germinal vesicle stage with enhanced green fluorescent protein (EGFP) or EGFP+AQP7 cRNAs resulted in the expression of the corresponding proteins in ≈86% of the metaphase-II stage oocytes. AQP7 facilitated water diffusion when bovine MII oocytes were in presence of Me2SO solution but not EG or sucrose solution. However, the overexpression of this aquaporin did not increase membrane permeability to Me2SO or EG. In summary, cryoprotectant-induced increase of AQP3 and AQP7 expression could be one of the mechanisms underlying oocyte tolerance to hyperosmotic stress. Water diffusion appears to be improved when AQP7 overexpressed oocytes are exposed to Me2SO, shortening the time required for oocytes to achieve osmotic balance with cryoprotectant solutions.
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Affiliation(s)
- Tania García-Martínez
- Department of Animal Medicine and Surgery, Autonomous University of Barcelona, ES-08193 Cerdanyola del Vallès, Spain; (T.G.-M.); (I.M.-R.); (J.R.-C.); (M.V.-F.)
| | - Iris Martínez-Rodero
- Department of Animal Medicine and Surgery, Autonomous University of Barcelona, ES-08193 Cerdanyola del Vallès, Spain; (T.G.-M.); (I.M.-R.); (J.R.-C.); (M.V.-F.)
| | - Joan Roncero-Carol
- Department of Animal Medicine and Surgery, Autonomous University of Barcelona, ES-08193 Cerdanyola del Vallès, Spain; (T.G.-M.); (I.M.-R.); (J.R.-C.); (M.V.-F.)
| | - Meritxell Vendrell-Flotats
- Department of Animal Medicine and Surgery, Autonomous University of Barcelona, ES-08193 Cerdanyola del Vallès, Spain; (T.G.-M.); (I.M.-R.); (J.R.-C.); (M.V.-F.)
- Department of Animal Health and Anatomy, Autonomous University of Barcelona, ES-08193 Cerdanyola del Vallès, Spain;
| | - Jaume Gardela
- Department of Animal Health and Anatomy, Autonomous University of Barcelona, ES-08193 Cerdanyola del Vallès, Spain;
| | - Alfonso Gutiérrez-Adán
- Department of Animal Reproduction, National Institute for Agriculture and Food Research and Technology (INIA), Avda. Puerta de Hierro 12, Local 10, 28040 Madrid, Spain; (A.G.-A.); (P.R.-I.)
| | - Priscila Ramos-Ibeas
- Department of Animal Reproduction, National Institute for Agriculture and Food Research and Technology (INIA), Avda. Puerta de Hierro 12, Local 10, 28040 Madrid, Spain; (A.G.-A.); (P.R.-I.)
| | - Adam Z. Higgins
- School of Chemical, Biological and Environmental Engineering, Oregon State University, Corvallis, OR 97331-2702, USA;
| | - Teresa Mogas
- Department of Animal Medicine and Surgery, Autonomous University of Barcelona, ES-08193 Cerdanyola del Vallès, Spain; (T.G.-M.); (I.M.-R.); (J.R.-C.); (M.V.-F.)
- Correspondence: ; Tel.: +34-696-64-51-27
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7
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Aquaporins and Animal Gamete Cryopreservation: Advances and Future Challenges. Animals (Basel) 2022; 12:ani12030359. [PMID: 35158682 PMCID: PMC8833750 DOI: 10.3390/ani12030359] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2021] [Revised: 01/27/2022] [Accepted: 01/31/2022] [Indexed: 02/01/2023] Open
Abstract
Simple Summary Cryopreservation is the method for the long-term preservation of gametes and embryos. In recent years, intensive research has focused on improving cryopreservation protocols for the determination of optimal freezing conditions and cryoprotective agents’ concentration for each cell type. The optimal cryopreservation protocol comprises the adequate balance between the freezing rate and the correct concentration of cryoprotective agents to achieve controlled cellular dehydration and minimal intracellular ice formation. Osmoregulation is, therefore, central in cryobiology. Water and some solutes can cross the plasma membrane, whereas facilitating transport takes a great part in intracellular/extracellular fluid homeostasis. Cells express water channels known as aquaporins that facilitate the transport of water and small uncharged solutes on their plasma membrane, including some cryoprotective agents. This review explores the expression and the function of aquaporins in gametes and embryos. In addition, the putative role of aquaporins for cryopreservation procedures is discussed. Abstract Cryopreservation is globally used as a method for long-term preservation, although freeze-thawing procedures may strongly impair the gamete function. The correct cryopreservation procedure is characterized by the balance between freezing rate and cryoprotective agents (CPAs), which minimizes cellular dehydration and intracellular ice formation. For this purpose, osmoregulation is a central process in cryopreservation. During cryopreservation, water and small solutes, including penetrating cryoprotective agents, cross the plasma membrane. Aquaporins (AQPs) constitute a family of channel proteins responsible for the transport of water, small solutes, and certain gases across biological membranes. Thirteen homologs of AQPs (AQP0-12) have been described. AQPs are widely distributed throughout the male and female reproductive systems, including the sperm and oocyte membrane. The composition of the male and female gamete membrane is of special interest for assisted reproductive techniques (ART), including cryopreservation. In this review, we detail the mechanisms involved in gamete cryopreservation, including the most used techniques and CPAs. In addition, the expression and function of AQPs in the male and female gametes are explored, highlighting the potential protective role of AQPs against damage induced during cryopreservation.
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Hochi S. Cryodevices developed for minimum volume cooling vitrification of bovine oocytes. Anim Sci J 2022; 93:e13683. [PMID: 35075717 PMCID: PMC9286375 DOI: 10.1111/asj.13683] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2021] [Revised: 12/22/2021] [Accepted: 01/06/2022] [Indexed: 11/28/2022]
Abstract
Unfertilized bovine oocytes can be efficiently cryopreserved only when an extremely rapid cooling rate (>20,000°C/min) is applied to oocytes with a very limited amount of surrounding vitrification solution. This protocol is defined as minimum volume cooling (MVC) vitrification. Various types of cryodevices, such as open pulled straw, Cryoloop, and Cryotop, have been developed to accelerate the cooling efficacy. Furthermore, hollow fibers with nano-scale pores, triangle nylon mesh sheets, and multilayer silk fibroin sheets have been optimized for the loading of large quantities of oocytes and/or the subsequent removal of excess vitrification solution, without requiring skillful operation to transfer individual oocytes using fine capillaries. This article provides an up-to-date review of cryodevices suitable for the MVC vitrification of bovine oocytes at the immature (germinal vesicle-) and mature (metaphase II-) stages.
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Affiliation(s)
- Shinichi Hochi
- Faculty of Textile Science and TechnologyShinshu UniversityUedaNaganoJapan
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9
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Effect of cryoprotectant concentration on bovine oocyte permeability and comparison of two membrane permeability modelling approaches. Sci Rep 2021; 11:15387. [PMID: 34321576 PMCID: PMC8319298 DOI: 10.1038/s41598-021-94884-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2021] [Accepted: 07/12/2021] [Indexed: 11/24/2022] Open
Abstract
The plasma membrane permeability to water and cryoprotectant (CPA) significantly impacts vitrification efficiency of bovine oocytes. Our study was designed to determine the concentration-dependent permeability characteristics for immature (GV) and mature (MII) bovine oocytes in the presence of ethylene glycol (EG) and dimethyl sulphoxide (Me2SO), and to compare two different modeling approaches: the two parameter (2P) model and a nondilute transport model. Membrane permeability parameters were determined by consecutively exposing oocytes to increasing concentrations of Me2SO or EG. Higher water permeability was observed for MII oocytes than GV oocytes in the presence of both Me2SO and EG, and in all cases the water permeability was observed to decrease as CPA concentration increased. At high CPA concentrations, the CPA permeability was similar for Me2SO and EG, for both MII and GV oocytes, but at low concentrations the EG permeability of GV oocytes was substantially higher. Predictions of cell volume changes during CPA addition and removal indicate that accounting for the concentration dependence of permeability only has a modest effect, but there were substantial differences between the 2P model and the nondilute model during CPA removal, which may have implications for design of improved methods for bovine oocyte vitrification.
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10
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Elad D, Jaffa AJ, Grisaru D. Biomechanics of Early Life in the Female Reproductive Tract. Physiology (Bethesda) 2021; 35:134-143. [PMID: 32027564 DOI: 10.1152/physiol.00028.2019] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Early human life that starts at the onset of fertilization and ends with implantation of the embryo in the uterine wall is the foundation for a successful pregnancy. The different stages during this period require biomechanical mechanisms, which are mostly unknown due to difficulties to conduct in vivo studies in humans.
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Affiliation(s)
- David Elad
- Department of Biomedical Engineering, Faculty of Engineering, Tel-Aviv University, Tel-Aviv, Israel
| | - Ariel J Jaffa
- Department of Obstetrics and Gynecology, Lis Maternity Hospital, Tel-Aviv Medical Center, Tel-Aviv, Israel.,Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Dan Grisaru
- Gynecological Oncology Unit, Lis Maternity Hospital, Tel-Aviv Medical Center, Tel-Aviv, Israel.,Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
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11
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Enhancing transient protein expression in HEK-293 cells by briefly exposing the culture to DMSO. J Neurosci Methods 2020; 350:109058. [PMID: 33359979 DOI: 10.1016/j.jneumeth.2020.109058] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2020] [Revised: 12/17/2020] [Accepted: 12/20/2020] [Indexed: 12/11/2022]
Abstract
BACKGROUND Transient expression of proteins in mammalian cells is a key technique for many functional and structural studies of human and higher eukaryotic genes as well as for the production of recombinant protein therapeutics. Maximizing the expression efficiency to achieve a higher expression yield is desirable and may be even critical when, for instance, an expressed protein must be characterized at the single-cell level. NEW METHODS Our goal was to develop a simple method by which protein expression yield in human embryonic kidney (HEK)-293 cells could be enhanced with a brief treatment of dimethyl sulfoxide (DMSO) solution. RESULTS By expressing green fluorescent protein (GFP) as a reporter protein using the calcium phosphate transfection method and imaging a large population of cells, we found that a 5-min exposure of 10 % DMSO to HEK-293 cells, 4 h after transfection of the protein of interest, leads to ∼1.6-fold increase in the expression yield without causing any appreciable cytotoxicity. By expressing an α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) and separately a kainate receptor in HEK-293 cells and measuring glutamate-induced whole-cell current response, we also found that such a brief DMSO treatment did not affect channel activity. CONCLUSION This method is simple, efficient and inexpensive to use for enhancing transient transfection yield in HEK-293 cells.
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Qiu J, Hasegawa A, Mochida K, Ogura A, Koshimoto C, Matsukawa K, Edashige K. Equilibrium vitrification of mouse embryos using low concentrations of cryoprotectants. Cryobiology 2020; 98:127-133. [PMID: 33285110 DOI: 10.1016/j.cryobiol.2020.11.015] [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: 09/07/2020] [Revised: 11/02/2020] [Accepted: 11/16/2020] [Indexed: 11/15/2022]
Abstract
Previously, we developed a method for vitrification of mouse embryos in a near-equilibrium state using EFS35c, PB1 medium containing 35% (v/v) ethylene glycol, and 0.98 M sucrose. This method has advantages in both slow freezing and vitrification. However, since the vitrification solution in this method contains high concentrations of cryoprotectants and thus has high osmolality, the solution would injure oocytes and embryos with high sensitivity to chemical toxicity and high osmolality. In this study, we examined whether embryos could be vitrified in a near-equilibrium state using a solution containing low concentrations of cryoprotectants and thus with low osmolality. To investigate whether embryos were vitrified in a near-equilibrium state, 2-cell mouse embryos were vitrified with EDFS10/10a, PB1 medium containing 10% (v/v) ethylene glycol, 10% (v/v) DMSO, and 0.4 M sucrose, in liquid nitrogen, stored at -80 °C for 4-28 days, and warmed in water at 25 °C. The viability of the embryos was evaluated by the appearance of embryos after warming and developmental ability. When embryos were vitrified in liquid nitrogen using EDFS10/10a, the survival and developmental ability into blastocysts after storage at -80 °C for 7 days were high, indicating that embryos were vitrified in a near-equilibrium state. A high proportion of embryos vitrified with EDFS10/10a developed to term after transportation with dry ice, re-cooling in liquid nitrogen, and transfer to recipients. Therefore, new equilibrium vitrification developed in this study may be useful for oocytes and embryos that are highly sensitive to the toxicity of cryoprotectants and high osmolality.
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Affiliation(s)
- Juan Qiu
- Laboratory of Animal Science, College of Agriculture, Kochi University, Nankoku, Kochi, Japan
| | - Ayumi Hasegawa
- RIKEN BioResource Center, Tsukuba, Ibaraki, 305-0074, Japan
| | - Keiji Mochida
- RIKEN BioResource Center, Tsukuba, Ibaraki, 305-0074, Japan
| | - Atsuo Ogura
- RIKEN BioResource Center, Tsukuba, Ibaraki, 305-0074, Japan
| | - Chihiro Koshimoto
- Frontier Science Research Center, University of Miyazaki, Miyazaki, 889-1692, Japan
| | - Kazutsugu Matsukawa
- Laboratory of Animal Science, College of Agriculture, Kochi University, Nankoku, Kochi, Japan
| | - Keisuke Edashige
- Laboratory of Animal Science, College of Agriculture, Kochi University, Nankoku, Kochi, Japan.
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Raju R, Bryant SJ, Wilkinson BL, Bryant G. The need for novel cryoprotectants and cryopreservation protocols: Insights into the importance of biophysical investigation and cell permeability. Biochim Biophys Acta Gen Subj 2020; 1865:129749. [PMID: 32980500 DOI: 10.1016/j.bbagen.2020.129749] [Citation(s) in RCA: 45] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2020] [Revised: 09/16/2020] [Accepted: 09/22/2020] [Indexed: 12/31/2022]
Abstract
BACKGROUND Cryopreservation is a key method of preservation of biological material for both medical treatments and conservation of endangered species. In order to avoid cellular damage, cryopreservation relies on the addition of a suitable cryoprotective agent (CPA). However, the toxicity of CPAs is a serious concern and often requires rapid removal on thawing which is time consuming and expensive. SCOPE OF REVIEW The principles of Cryopreservation are reviewed and recent advances in cryopreservation methods and new CPAs are described. The importance of understanding key biophysical properties to assess the cryoprotective potential of new non-toxic compounds is discussed. MAJOR CONCLUSIONS Knowing the biophysical properties of a particular cell type is crucial for developing new cryopreservation protocols. Similarly, understanding how potential CPAs interact with cells is key for optimising protocols. For example, cells with a large osmotically inactive volume may require slower addition of CPAs. Similarly, a cell with low permeability may require a longer incubation time with the CPA to allow adequate penetration. Measuring these properties allows efficient optimisation of cryopreservation protocols. GENERAL SIGNIFICANCE Understanding the interplay between cells and biophysical properties is important not just for developing new, and better optimised, cryopreservation protocols, but also for broader research into topics such as dehydration and desiccation tolerance, chilling and heat stress, as well as membrane structure and function.
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Affiliation(s)
- Rekha Raju
- School of Science, RMIT University, Melbourne, Victoria 3001, Australia
| | - Saffron J Bryant
- School of Science, RMIT University, Melbourne, Victoria 3001, Australia.
| | - Brendan L Wilkinson
- School of Science and Technology, University of New England, Armidale, NSW 2351, Australia
| | - Gary Bryant
- School of Science, RMIT University, Melbourne, Victoria 3001, Australia.
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de Almeida Monteiro Melo Ferraz M, Fujihara M, Nagashima JB, Noonan MJ, Inoue-Murayama M, Songsasen N. Follicular extracellular vesicles enhance meiotic resumption of domestic cat vitrified oocytes. Sci Rep 2020; 10:8619. [PMID: 32451384 PMCID: PMC7248092 DOI: 10.1038/s41598-020-65497-w] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2020] [Accepted: 05/05/2020] [Indexed: 12/16/2022] Open
Abstract
Extracellular vesicles (EVs) contain multiple factors that regulate cell and tissue function. However, understanding of their influence on gametes, including communication with the oocyte, remains limited. In the present study, we characterized the proteome of domestic cat (Felis catus) follicular fluid EVs (ffEV). To determine the influence of follicular fluid EVs on gamete cryosurvival and the ability to undergo in vitro maturation, cat oocytes were vitrified using the Cryotop method in the presence or absence of ffEV. Vitrified oocytes were thawed with or without ffEVs, assessed for survival, in vitro cultured for 26 hours and then evaluated for viability and meiotic status. Cat ffEVs had an average size of 129.3 ± 61.7 nm (mean ± SD) and characteristic doughnut shaped circular vesicles in transmission electron microscopy. Proteomic analyses of the ffEVs identified a total of 674 protein groups out of 1,974 proteins, which were classified as being involved in regulation of oxidative phosphorylation, extracellular matrix formation, oocyte meiosis, cholesterol metabolism, glycolysis/gluconeogenesis, and MAPK, PI3K-AKT, HIPPO and calcium signaling pathways. Furthermore, several chaperone proteins associated with the responses to osmotic and thermal stresses were also identified. There were no differences in the oocyte survival among fresh and vitrified oocyte; however, the addition of ffEVs to vitrification and/or thawing media enhanced the ability of frozen-thawed oocytes to resume meiosis. In summary, this study is the first to characterize protein content of cat ffEVs and their potential roles in sustaining meiotic competence of cryopreserved oocytes.
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Affiliation(s)
| | - Mayako Fujihara
- Wildlife Research Center, Kyoto University, 2-24 Tanaka-Sekiden-cho, Sakyo, Kyoto, 606-8203, Japan
| | - Jennifer Beth Nagashima
- Smithsonian National Zoo and Conservation Biology Institute, 1500 Remount Road, Front Royal, Virginia, 22630, USA
| | - Michael James Noonan
- Smithsonian National Zoo and Conservation Biology Institute, 1500 Remount Road, Front Royal, Virginia, 22630, USA
| | - Miho Inoue-Murayama
- Wildlife Research Center, Kyoto University, 2-24 Tanaka-Sekiden-cho, Sakyo, Kyoto, 606-8203, Japan
- Wildlife Genome Collaborative Research Group, National Institute for Environmental Studies, 16-2 Onogawa, Tsukuba, Ibaraki, 305-8506, Japan
| | - Nucharin Songsasen
- Smithsonian National Zoo and Conservation Biology Institute, 1500 Remount Road, Front Royal, Virginia, 22630, USA
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Awan M, Buriak I, Fleck R, Fuller B, Goltsev A, Kerby J, Lowdell M, Mericka P, Petrenko A, Petrenko Y, Rogulska O, Stolzing A, Stacey GN. Dimethyl sulfoxide: a central player since the dawn of cryobiology, is efficacy balanced by toxicity? Regen Med 2020; 15:1463-1491. [PMID: 32342730 DOI: 10.2217/rme-2019-0145] [Citation(s) in RCA: 85] [Impact Index Per Article: 21.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Dimethyl sulfoxide (DMSO) is the cryoprotectant of choice for most animal cell systems since the early history of cryopreservation. It has been used for decades in many thousands of cell transplants. These treatments would not have taken place without suitable sources of DMSO that enabled stable and safe storage of bone marrow and blood cells until needed for transfusion. Nevertheless, its effects on cell biology and apparent toxicity in patients have been an ongoing topic of debate, driving the search for less cytotoxic cryoprotectants. This review seeks to place the toxicity of DMSO in context of its effectiveness. It will also consider means of reducing its toxic effects, the alternatives to its use and their readiness for active use in clinical settings.
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Affiliation(s)
- Maooz Awan
- Institute for Liver & Digestive Health, UCL Division of Medicine, Royal Free Hospital, UCL, London, NW3 2PF, UK
| | - Iryna Buriak
- Institute for Problems of Cryobiology & Cryomedicine, National Academy of Sciences of Ukraine, Pereyaslavska 23, 61016, Kharkiv
| | - Roland Fleck
- Centre for Ultrastructural Imaging, Kings College London, London, SE1 1UL, UK
| | - Barry Fuller
- Department of Surgical Biotechnology, UCL Division of Surgery, Royal Free Hospital, UCL, London, NW3 2QG, UK
| | - Anatoliy Goltsev
- Institute for Problems of Cryobiology & Cryomedicine, National Academy of Sciences of Ukraine, Pereyaslavska 23, 61016, Kharkiv
| | - Julie Kerby
- Cell & Gene Therapy Catapult, 12th Floor Tower Wing, Guy's Hospital, Great Maze Pond, London, SE1 9RT, UK
| | - Mark Lowdell
- Centre for Cell, Gene & Tissue Therapy, Royal Free London NHS FT & UCL, London, NW3 2PF, UK
| | - Pavel Mericka
- Tissue Bank, University Hospital Hradec Kralové, Czech Republic
| | - Alexander Petrenko
- Institute for Problems of Cryobiology & Cryomedicine, National Academy of Sciences of Ukraine, Pereyaslavska 23, 61016, Kharkiv
| | - Yuri Petrenko
- Department of Biomaterials & Biophysical Methods, Institute of Experimental Medicine of the Czech Academy of Sciences, Prague, Czech Republic
| | - Olena Rogulska
- Institute for Problems of Cryobiology & Cryomedicine, National Academy of Sciences of Ukraine, Pereyaslavska 23, 61016, Kharkiv
| | - Alexandra Stolzing
- University of Loughborough, Centre for Biological Engineering, Loughborough University, Holywell Park, Loughborough, UK
| | - Glyn N Stacey
- International Stem Cell Banking Initiative, 2 High Street, Barley, Hertfordshire, SG8 8HZ
- Beijing Stem Cell Bank, Institute of Zoology, Chinese Academy of Sciences, 25–2 Beishuan West, Haidan District, 100190 Beijing, China
- Institute of Stem Cells & Regeneration, Chinese Academy of Sciences, Beijing 100101, China
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Nakayama K, Yamanaka T, Tamada Y, Hirabayashi M, Hochi S. Supplementary cryoprotective effect of carboxylated ε-poly-l-lysine during vitrification of rat pancreatic islets. Cryobiology 2019; 88:70-74. [PMID: 30922739 DOI: 10.1016/j.cryobiol.2019.03.009] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/25/2018] [Revised: 02/17/2019] [Accepted: 03/20/2019] [Indexed: 11/18/2022]
Abstract
This study was designed to investigate whether cryosurvival of rat pancreatic islets can be improved by carboxylated ε-poly-l-lysine (CPLL). Islets isolated from Wistar × Brown-Norway F1 rats (101-200 μm in diameter) were cryopreserved in three vitrification solutions containing ethylene glycol (EG; 30%, v/v) and CPLL (0%, 10%, or 20%, v/v) by Cryotop® protocol (10 islets per device). The post-warm survival rate of the islets vitrified in the presence of 20% CPLL (74%), assessed by FDA/PI double staining, was higher than those in 0% and 10% CPLL (65% and 66%, respectively). Decreased EG concentrations (10% and 20%) in the presence of 20% CPLL resulted in impaired post-warm islet survival rates (50% and 64%, respectively). Value of stimulus index (SI) for 20 mM/3 mM glucose-stimulated insulin secretion was 4.1 in islets vitrified-warmed in the presence of 30% EG and 20% CPLL, which was comparable with those in fresh control islets and vitrified islets in 30% EG alone (4.1 and 4.4, respectively). A large number of islets (50 islets per device) could be cryopreserved in the presence of 30% EG and 20% CPLL by using nylon mesh as the device, without considerable loss of post-warm survival (68%) and SI value (3.7). In conclusion, supplementation of antifreeze 20% CPLL was effective in improving the post-warm survival of isolated rat pancreatic islets when vitrification solution containing 30% EG was used.
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Affiliation(s)
- Kenyu Nakayama
- Graduate School of Science and Technology, Shinshu University, Ueda, Nagano, 386-8567, Japan
| | - Takahiro Yamanaka
- Graduate School of Medicine, Science and Technology, Shinshu University, Ueda, Nagano, 386-8567, Japan
| | - Yasushi Tamada
- Graduate School of Science and Technology, Shinshu University, Ueda, Nagano, 386-8567, Japan; Graduate School of Medicine, Science and Technology, Shinshu University, Ueda, Nagano, 386-8567, Japan; Faculty of Textile Science and Technology, Shinshu University, Nagano, 386-8567, Japan
| | - Masumi Hirabayashi
- National Institute for Physiological Sciences, Okazaki, Aichi, 444-8787, Japan; School of Life Science, The Graduate University for Advanced Studies, Okazaki, Aichi, 444-8787, Japan
| | - Shinichi Hochi
- Graduate School of Science and Technology, Shinshu University, Ueda, Nagano, 386-8567, Japan; Graduate School of Medicine, Science and Technology, Shinshu University, Ueda, Nagano, 386-8567, Japan; Faculty of Textile Science and Technology, Shinshu University, Nagano, 386-8567, Japan.
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Successful cryopreservation of coral larvae using vitrification and laser warming. Sci Rep 2018; 8:15714. [PMID: 30356142 PMCID: PMC6200823 DOI: 10.1038/s41598-018-34035-0] [Citation(s) in RCA: 44] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2018] [Accepted: 10/07/2018] [Indexed: 01/21/2023] Open
Abstract
Climate change has increased the incidence of coral bleaching events, resulting in the loss of ecosystem function and biodiversity on reefs around the world. As reef degradation accelerates, the need for innovative restoration tools has become acute. Despite past successes with ultra-low temperature storage of coral sperm to conserve genetic diversity, cryopreservation of larvae has remained elusive due to their large volume, membrane complexity, and sensitivity to chilling injury. Here we show for the first time that coral larvae can survive cryopreservation and resume swimming after warming. Vitrification in a 3.5 M cryoprotectant solution (10% v/v propylene glycol, 5% v/v dimethyl sulfoxide, and 1 M trehalose in phosphate buffered saline) followed by warming at a rate of approximately 4,500,000 °C/min with an infrared laser resulted in up to 43% survival of Fungia scutaria larvae on day 2 post-fertilization. Surviving larvae swam and continued to develop for at least 12 hours after laser-warming. This technology will enable biobanking of coral larvae to secure biodiversity, and, if managed in a high-throughput manner where millions of larvae in a species are frozen at one time, could become an invaluable research and conservation tool to help restore and diversify wild reef habitats.
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Edashige K. Permeability of the plasma membrane to water and cryoprotectants in mammalian oocytes and embryos: Its relevance to vitrification. Reprod Med Biol 2016; 16:36-39. [PMID: 29259448 PMCID: PMC5715871 DOI: 10.1002/rmb2.12007] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2016] [Accepted: 05/25/2016] [Indexed: 11/28/2022] Open
Abstract
The permeability of the plasma membrane to water and cryoprotectants is one of the important factors for determining the suitable condition for the vitrification of mammalian oocytes and embryos. Water and cryoprotectants move slowly through oocytes and early embryos, principally by simple diffusion, in the mouse, bovine, pig, and human. In contrast, water, glycerol, and ethylene glycerol move rapidly through morulae and blastocysts, principally by facilitated diffusion via aquaporin 3, in the mouse and bovine; whereas, in the pig, the permeability to water and these cryoprotectants increases not at the morula stage but at the blastocyst stage and further increases at the expanded blastocyst stage. Dimethyl sulfoxide also moves rapidly via channels other than aquaporin 3 in the mouse. In contrast, propylene glycol moves through morulae and blastocysts principally by simple diffusion in the mouse, bovine, and pig, as through oocytes. Therefore, the permeability of mammalian oocytes and embryos at early stages to water and cryoprotectants is low, but that of embryos at later stages to water and some cryoprotectants is markedly high by channel processes, although species specificity exists in some cases.
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