Clinical insights: Assisted reproductive techniques: More than a solution to subfertility?

Stout, T.A.E.; Griffiths, Huw

doi:10.1111/evj.13510

Cited by 5 publications

(1 citation statement)

References 20 publications

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“…Failure of in vitro capacitation of stallion sperm has been cited as a major limiting factor in the development of conventional IVF in the horse ( Tremoleda et al, 2003 ). This means that equine IVF in practice is currently achieved via intracytoplasmic sperm injection (ICSI), a time-consuming process that requires highly-trained individuals and expensive equipment ( Stout and Griffiths, 2021 ). Although previous studies have reported successful induction of sperm-zona pellucida interaction between equine gametes ( Macías-García et al, 2015 ), media developed to support gamete interaction have not yielded repeatable IVF success ( Choi et al, 1994 ; Dell’Aquila et al, 1997a ; Dell’Aquila et al, 1997b ; Alm et al, 2001 ; Hinrichs et al, 2002 ; Mugnier et al, 2009 ).…”

Section: Discussionmentioning

confidence: 99%

Bicarbonate-Stimulated Membrane Reorganization in Stallion Spermatozoa

Maitan

Bromfield

Hoogendijk

et al. 2021

Front. Cell Dev. Biol.

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Classical in vitro fertilization (IVF) is still poorly successful in horses. This lack of success is thought to be due primarily to inadequate capacitation of stallion spermatozoa under in vitro conditions. In species in which IVF is successful, bicarbonate, calcium, and albumin are considered the key components that enable a gradual reorganization of the sperm plasma membrane that allows the spermatozoa to undergo an acrosome reaction and fertilize the oocyte. The aim of this work was to comprehensively examine contributors to stallion sperm capacitation by investigating bicarbonate-induced membrane remodelling steps, and elucidating the contribution of cAMP signalling to these events. In the presence of capacitating media containing bicarbonate, a significant increase in plasma membrane fluidity was readily detected using merocyanine 540 staining in the majority of viable spermatozoa within 15 min of bicarbonate exposure. Specific inhibition of soluble adenylyl cyclase (sAC) in the presence of bicarbonate by LRE1 significantly reduced the number of viable sperm with high membrane fluidity. This suggests a vital role for sAC-mediated cAMP production in the regulation of membrane fluidity. Cryo-electron tomography of viable cells with high membrane fluidity revealed a range of membrane remodelling intermediates, including destabilized membranes and zones with close apposition of the plasma membrane and the outer acrosomal membrane. However, lipidomic analysis of equivalent viable spermatozoa with high membrane fluidity demonstrated that this phenomenon was neither accompanied by a gross change in the phospholipid composition of stallion sperm membranes nor detectable sterol efflux (p > 0.05). After an early increase in membrane fluidity, a significant and cAMP-dependent increase in viable sperm with phosphatidylserine (PS), but not phosphatidylethanolamine (PE) exposure was noted. While the events observed partly resemble findings from the in vitro capacitation of sperm from other mammalian species, the lack of cholesterol removal appears to be an equine-specific phenomenon. This research will assist in the development of a defined medium for the capacitation of stallion sperm and will facilitate progress toward a functional IVF protocol for horse gametes.

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Section: Discussionmentioning

confidence: 99%

Bicarbonate-Stimulated Membrane Reorganization in Stallion Spermatozoa

Maitan

Bromfield

Hoogendijk

et al. 2021

Front. Cell Dev. Biol.

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Effect of cloprostenol on luteolysis and comparison of different estrus synchronization protocols in jennies

Yang

et al. 2023

Animal Reproduction Science

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Equine ICSI: an update on semen perspective

Oliveira,

Alonso,

Fonte

et al. 2024

Anim. Reprod.

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Intracytoplasmic Sperm Injection (ICSI) has increased usage in cases of stallion fertility issues, particularly for older stallions, those with reduced sperm numbers or quality, or stallions that have passed away, and only a limited amount of frozen semen is available. By manipulating the frozen semen through thawing, diluting, and refreezing or by cutting the straw under liquid nitrogen, the supply of semen for ICSI can be extended. While ICSI requires a minimal number of spermatozoa per procedure, it is important to consider sperm quality as a crucial factor affecting fertilization and embryo development. Although it is possible to produce healthy embryos and offspring from low quality sperm samples, it is preferable to process and select morphologically and functionally superior sperm to maximize the chances of successful fertilization and embryo development. Several techniques are available for selecting the spermatozoa for ICSI, such as swim-up, washing, density gradient centrifugation, microfluidic sorting, and some combinations. In this review, we will focus on semen type, handling, recent breakthroughs, stallion effects on ICSI efficiency and the prospects of this technology within the equine industry.

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Clinical insights: Assisted reproductive techniques: More than a solution to subfertility?

Cited by 5 publications

References 20 publications

Bicarbonate-Stimulated Membrane Reorganization in Stallion Spermatozoa

Bicarbonate-Stimulated Membrane Reorganization in Stallion Spermatozoa

Effect of cloprostenol on luteolysis and comparison of different estrus synchronization protocols in jennies

Equine ICSI: an update on semen perspective

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