The development of in vitro embryo production in the horse

Morris, L. H. A.

doi:10.1111/evj.12839

Cited by 31 publications

(27 citation statements)

References 110 publications

(271 reference statements)

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“…In vitro embryo production (IVEP) by intracytoplasmic sperm injection (ICSI) of in vitro matured oocytes has become an increasingly popular technology in the equine breeding industry because it offers a solution for subfertility of mares and stallions, and allows scarce or expensive frozen semen to be used efficiently . The success of IVEP, in terms of ‘number of embryos produced per mare’ often exceeds the availability of recipient mares and this, in combination with out of breeding season production of in vitro produced (IVP) embryos, has made it desirable to cryopreserve these IVP embryos.…”

Section: Introductionmentioning

confidence: 99%

Monozygotic multiple pregnancies after transfer of single in vitro produced equine embryos

Dijkstra

Cuervo‐Arango

Stout

et al. 2019

Equine Veterinary Journal

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Summary Background Monozygotic multiple pregnancy is rare in horses, but may be more common after transfer of an in vitro produced (IVP) embryo. Objectives To determine the occurrence, incidence, characteristics and outcome of monozygotic siblings arising from in vivo and IVP equine embryos. Study design Retrospective case series. Methods A total of 496 fresh in vivo and 410 frozen‐thawed IVP blastocysts, produced by intracytoplasmic sperm injection (ICSI) of in vitro matured oocytes from Warmblood mares, were transferred into recipient mares. The likelihoods of pregnancy and multiple pregnancy were calculated, and the clinical features and outcome of any multiple pregnancy were recorded. Results The likelihood of pregnancy after transfer of a single IVP or in vivo embryo was 62% (254/410) and 83% (413/496) respectively. The incidence of multiple pregnancy was 1.6% (4/254) and 0% (0/413) for IVP and in vivo blastocysts, respectively. More specifically, three IVP blastocysts yielded twin embryo propers/fetuses, and one IVP conceptus developed three distinct embryonic bodies. Interestingly, only one embryonic vesicle was detected at all ultrasonographic examinations prior to embryo proper development. Multiple embryonic bodies only became apparent at later scans to check for an embryo proper and heartbeat, or when the recipient mare aborted. Two twin pregnancies aborted spontaneously at 3 and 9 months, respectively, while the heartbeat was lost from all three embryos in the triplet pregnancy before day 35 of gestation. Twin reduction by per rectum compression of one fetal thorax was attempted at day 50 of gestation in the fourth case; however, both fetuses were lost. Main limitations Small number of cases. Conclusions In vitro embryo production resulted in a higher incidence of multiple monozygotic pregnancy, which could only be diagnosed after development of the embryo proper and is likely to result in pregnancy loss later in gestation if left untreated.

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Section: Introductionmentioning

confidence: 99%

Monozygotic multiple pregnancies after transfer of single in vitro produced equine embryos

Dijkstra

Cuervo‐Arango

Stout

et al. 2019

Equine Veterinary Journal

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“…In the horse, in vitro embryo production (IVEP) has become a commercial reality in the past decade and equine reproduction centres now increasingly offer ovum pick-up (OPU) followed by intracytoplasmic sperm injection (ICSI) to overcome fertility problems in mares and stallions, to increase the offspring of a single frozen sperm straw and to plan and increase the propagation of valuable female genetics (Claes et al 2016;Maserati and Mutto 2016;Morris 2018). An important complement to clinical ICSI would be the ability to cryopreserve oocytes, which would improve overall flexibility.…”

Section: Introductionmentioning

confidence: 99%

Cryopreservation of equine oocytes: looking into the crystal ball

Coster

Angel‐Velez

Soom

et al. 2020

Reprod. Fertil. Dev.

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In vitro embryo production has evolved rapidly in the horse over the past decade, but blastocyst rates from vitrified equine oocytes remain quite poor and further research is needed to warrant application. Oocyte vitrification is affected by several technical and biological factors. In the horse, short exposure of immature oocytes to the combination of permeating and non-permeating cryoprotective agents has been associated with the best results so far. High cooling and warming rates are also crucial and can be obtained by using minimal volumes and open cryodevices. Vitrification of in vivo-matured oocytes has yielded better results, but is less practical. The presence of the corona radiata seems to partially protect those factors that are necessary for the construction of the normal spindle and for chromosome alignment, but multiple layers of cumulus cells may impair permeation of cryoprotective agents. In addition to the spindle, the oolemma and mitochondria are also particularly sensitive to vitrification damage, which should be minimised in future vitrification procedures. This review presents promising protocols and novel strategies in equine oocyte vitrification, with a focus on blastocyst development and foal production as most reliable outcome parameters.

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“…For these reasons, cloning is postulated as a promising technique to generate gene edited animals as the cell line with the desired edition can be selected before the somatic cell nuclear transfer (SCNT) procedure. This technique becomes even more relevant in species such as the horse, in which embryo generation by intracytoplasmic sperm injection (ICSI) is inefficient 28,29 , and the successful of embryo generation by in vitro fertilization (IVF) is not reliable 30,31 .In this work we aimed to generate edited horse embryos by knocking out MSTN using CRISPR/Cas9 and SCNT ( Fig. 1).…”

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confidence: 99%

Generation of myostatin edited horse embryos using CRISPR/Cas9 technology and somatic cell nuclear transfer

Moro

Viale

Bastón

et al. 2020

Sci Rep

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The application of new technologies for gene editing in horses may allow the generation of improved sportive individuals. Here, we aimed to knock out the myostatin gene (MSTN), a negative regulator of muscle mass development, using CRISPR/Cas9 and to generate edited embryos for the first time in horses. We nucleofected horse fetal fibroblasts with 1, 2 or 5 µg of 2 different gRNA/Cas9 plasmids targeting the first exon of MSTN. We observed that increasing plasmid concentrations improved mutation efficiency. The average efficiency was 63.6% for gRNA1 (14/22 edited clonal cell lines) and 96.2% for gRNA2 (25/26 edited clonal cell lines). Three clonal cell lines were chosen for embryo generation by somatic cell nuclear transfer: one with a monoallelic edition, one with biallelic heterozygous editions and one with a biallelic homozygous edition, which rendered edited blastocysts in each case. Both MSTN editions and off-targets were analyzed in the embryos. In conclusion, CRISPR/Cas9 proved an efficient method to edit the horse genome in a dose dependent manner with high specificity. Adapting this technology sport advantageous alleles could be generated, and a precision breeding program could be developed.

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The development of in vitro embryo production in the horse

Cited by 31 publications

References 110 publications

Monozygotic multiple pregnancies after transfer of single in vitro produced equine embryos

Monozygotic multiple pregnancies after transfer of single in vitro produced equine embryos

Cryopreservation of equine oocytes: looking into the crystal ball

Generation of myostatin edited horse embryos using CRISPR/Cas9 technology and somatic cell nuclear transfer

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