Sperm Selection for ICSI: Do We Have a Winner?

In assisted reproductive technology (ART), the aim of sperm cells’ preparation is to select competent spermatozoa with the highest fertilization potential and in this context, the intracytoplasmic sperm injection (ICSI) represents the most applied technique for fertilization. This makes the process of identifying the perfect spermatozoa extremely important. A number of methods have now been developed to mimic some of the natural selection processes that exist in the female reproductive tract. Although many studies have been conducted to identify the election technique, many doubts and disagreements still remain. In this review, we will discuss all the sperm cell selection techniques currently available for ICSI, starting from the most basic methodologies and continuing with those techniques suitable for sperm cells with reduced motility. Furthermore, different techniques that exploit some sperm membrane characteristics and the most advanced strategy for sperm selection based on microfluidics, will be examined. Finally, a new sperm selection method based on a micro swim-up directly on the ICSI dish will be analyzed. Eventually, advantages and disadvantages of each technique will be debated, trying to draw reasonable conclusions on their efficacy in order to establish the gold standard method.

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Sperm selection methods in the 21st century

Biology of Reproduction ◽

10.1093/biolre/ioz032 ◽

2019 ◽

Vol 101 (6) ◽

pp. 1076-1082 ◽

Cited By ~ 4

Author(s):

Denis A Vaughan ◽

Denny Sakkas

Keyword(s):

Reproductive Tract ◽

Assisted Reproductive Technologies ◽

Semen Analysis ◽

Mammalian Species ◽

Annexin V ◽

Reproductive Technologies ◽

Female Reproductive Tract ◽

Sperm Selection ◽

Selection Processes ◽

Sperm Membrane

Abstract Natural sperm selection in humans is a rigorous process resulting in the highest quality sperm reaching, and having an opportunity to fertilize, the oocyte. Relative to other mammalian species, the human ejaculate consists of a heterogeneous pool of sperm, varying in characteristics such as shape, size, and motility. Semen preparation in assisted reproductive technologies (ART) has long been performed using either a simple swim-up method or density gradients. Both methodologies provide highly motile sperm populations; however neither replicates the complex selection processes seen in nature. A number of methods have now been developed to mimic some of the natural selection processes that exist in the female reproductive tract. These methods attempt to select a better individual, or population of, spermatozoa when compared to classical methods of preparation. Of the approaches already tested, platforms based upon sperm membrane markers, such as hyaluronan or annexin V, have been used to either select or deselect sperm with varied success. One technology that utilizes the size, motility, and other characteristics of sperm to improve both semen analysis and sperm selection is microfluidics. Here, we sought to review the efficacy of both available and emerging techniques that aim to improve the quality of the sperm pool available for use in ART.

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Practical Applications of Sperm Selection Techniques as a Tool for Improving Reproductive Efficiency

Veterinary Medicine International ◽

10.4061/2011/894767 ◽

2011 ◽

Vol 2011 ◽

pp. 1-9 ◽

Cited By ~ 24

Author(s):

J. M. Morrell ◽

H. Rodriguez-Martinez

Keyword(s):

Hyaluronic Acid ◽

Reproductive Tract ◽

Sex Selection ◽

Female Reproductive Tract ◽

Sperm Selection ◽

Domestic Species ◽

Practical Applications ◽

Selection For ◽

Hyaluronic Acid Binding

Modern biotechnologies are used extensively in the animal breeding industry today. Therefore, it is essential that sperm handling procedures do not modulate the normal physiological mechanisms occurring in the female reproductive tract. In this paper, the different selection mechanisms occurringin vivoare described briefly, together with their relevance to artificial insemination, followed by a detailed description of the different selection processes used in reproductive biotechnologies. These selection methods included fractionated semen collection, cryopreservation, biomimetic sperm selection, selection based on hyaluronic acid binding, and last, but not least, sperm sex selection. Biomimetic sperm selection for AI or for cryopreservation could improve pregnancy rates and help to reverse the decline in fertility seen in several domestic species over the recent decades. Similarly, selection for hyaluronic acid binding sites may enable the most mature spermatozoa to be selected for IVF or ICSI.

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3D in situ imaging of the female reproductive tract reveals molecular signatures of fertilizing spermatozoa in mice

eLife ◽

10.7554/elife.62043 ◽

2020 ◽

Vol 9 ◽

Cited By ~ 1

Author(s):

Lukas Ded ◽

Jae Yeon Hwang ◽

Kiyoshi Miki ◽

Huanan F Shi ◽

Jean-Ju Chung

Keyword(s):

Reproductive Tract ◽

Female Reproductive Tract ◽

Sperm Selection ◽

Pharmacological Studies ◽

Sperm Migration ◽

Selection For ◽

Insight Into

Out of millions of ejaculated sperm, a few reach the fertilization site in mammals. Flagellar Ca2+ signaling nanodomains, organized by multi-subunit CatSper calcium channel complexes, are pivotal for sperm migration in the female tract, implicating CatSper-dependent mechanisms in sperm selection. Here using biochemical and pharmacological studies, we demonstrate that CatSper1 is an O-linked glycosylated protein, undergoing capacitation-induced processing dependent on Ca2+ and phosphorylation cascades. CatSper1 processing correlates with protein tyrosine phosphorylation (pY) development in sperm cells capacitated in vitro and in vivo. Using 3D in situ molecular imaging and ANN-based automatic detection of sperm distributed along the cleared female tract, we demonstrate that spermatozoa past the utero-tubal junction possess the intact CatSper1 signals. Together, we reveal that fertilizing mouse spermatozoa in situ are characterized by intact CatSper channel, lack of pY, and reacted acrosomes. These findings provide molecular insight into sperm selection for successful fertilization in the female reproductive tract.

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3D in situ imaging of female reproductive tract reveals molecular signatures of fertilizing spermatozoa in mice

10.1101/2020.08.14.251736 ◽

2020 ◽

Author(s):

Lukas Ded ◽

Jae Yeon Hwang ◽

Kiyoshi Miki ◽

Huanan F. Shi ◽

Jean-Ju Chung

Keyword(s):

Reproductive Tract ◽

Female Reproductive Tract ◽

Sperm Selection ◽

Pharmacological Studies ◽

Sperm Migration ◽

Selection For ◽

Insight Into

AbstractOut of millions of ejaculated sperm, only a few reach the fertilization site in mammals. Flagellar Ca2+ signaling nanodomains, organized by multi-subunit CatSper calcium channel complexes, are pivotal for sperm migration in the female tract, implicating CatSper-dependent mechanisms in sperm selection. Here, using biochemical and pharmacological studies, we demonstrate that CatSper1 is an O-linked glycosylated protein, undergoing capacitation-induced processing dependent on Ca2+ and phosphorylation cascades. CatSper1 processing correlates with protein tyrosine phosphorylation (pY) development in sperm cells capacitated in vitro and in vivo. Using 3D in situ molecular imaging and ANN-based automatic detection of sperm distributed along the cleared female tract, we demonstrate that all spermatozoa past the UTJ possess intact CatSper1 signals. Together, we reveal that fertilizing mouse spermatozoa in situ are characterized by intact CatSper channel, lack of pY, and reacted acrosomes. These findings provide molecular insight into sperm selection for successful fertilization in the female reproductive tract.

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Seminal vesicle proteins SVS3 and SVS4 facilitate SVS2 effect on sperm capacitation

Reproduction ◽

10.1530/rep-15-0551 ◽

2016 ◽

Vol 152 (4) ◽

pp. 313-321 ◽

Cited By ~ 8

Author(s):

Naoya Araki ◽

Natsuko Kawano ◽

Woojin Kang ◽

Kenji Miyado ◽

Kaoru Yoshida ◽

...

Keyword(s):

Seminal Vesicle ◽

Reproductive Tract ◽

Female Reproductive Tract ◽

The Other ◽

Sperm Capacitation ◽

Other Hand ◽

Sperm Membrane ◽

Vesicle Secretion ◽

Mammalian Spermatozoa

Mammalian spermatozoa acquire their fertilizing ability in the female reproductive tract (sperm capacitation). On the other hand, seminal vesicle secretion, which is a major component of seminal plasma, inhibits the initiation of sperm capacitation (capacitation inhibition) and reduces the fertility of the capacitated spermatozoa (decapacitation). There are seven major proteins involved in murine seminal vesicle secretion (SVS1-7), and we have previously shown that SVS2 acts as both a capacitation inhibitor and a decapacitation factor, and is indispensable forin vivofertilization. However, the effects of SVSs other than SVS2 on the sperm have not been elucidated. Since mouseSvs2–Svs6genes evolved by gene duplication belong to the same gene family, it is possible that SVSs other than SVS2 also have some effects on sperm capacitation. In this study, we examined the effects of SVS3 and SVS4 on sperm capacitation. Our results showed that both SVS3 and SVS4 are able to bind to spermatozoa, but SVS3 alone showed no effects on sperm capacitation. On the other hand, SVS4 acted as a capacitation inhibitor, although it did not show decapacitation abilities. Interestingly, SVS3 showed an affinity for SVS2 and it facilitated the effects of SVS2. Interaction of SVS2 and spermatozoa is mediated by the ganglioside GM1 in the sperm membrane; however, both SVS3 and SVS4 had weaker affinities for GM1 than SVS2. Therefore, we suggest that separate processes may cause capacitation inhibition and decapacitation, and SVS3 and SVS4 act on sperm capacitation cooperatively with SVS2.

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Spermatozoa Obtained From Alpaca vas deferens. Effects of Seminal Plasma Added at Post-thawing

Frontiers in Veterinary Science ◽

10.3389/fvets.2021.611301 ◽

2021 ◽

Vol 8 ◽

Author(s):

Eduardo G. Aisen ◽

Wilfredo Huanca López ◽

Manuel G. Pérez Durand ◽

Edita Torres Mamani ◽

Juan C. Villanueva Mori ◽

...

Keyword(s):

Seminal Plasma ◽

Artificial Insemination ◽

Reproductive Tract ◽

Vas Deferens ◽

Female Reproductive Tract ◽

Low Fertility ◽

Sperm Cells ◽

South American Camelids ◽

Thawing Process

The viscous seminal plasma (SP) is currently a major impediment to the handling of ejaculate and the development of some biotechnologies in South American camelids. The vas deferens-collected spermatozoa of alpacas is a useful technique to avoid this problem. On the other hand, SP contains a large protein component that has been implicated in the function of spermatozoa within the female reproductive tract. In this sense, the low fertility achieved using transcervical insemination with frozen-thawed spermatozoa in alpacas could be improved by adding SP. This study aimed to evaluate the effect of the whole SP on some in vitro parameters of alpaca spermatozoa after the freezing-thawing-process and the fertility after artificial insemination. It would contribute to a better understanding of the interaction between thawed sperm cells and SP. Spermatozoa were obtained by surgically diverted vas deferens. The samples were diluted with a Tris-based extender, packaged in straws, and frozen. At thawing, each straw was divided into two post-thawing conditions: with the addition of 10% of PBS (control) or with 10% SP (treatment). The sperm cells were evaluated using dynamic parameters, sperm cell morphology, and morphometry. Fertility was assessed by an artificial insemination trial. All in vitro parameters were analyzed by ANOVA. A heterogeneity test was scheduled for the fertility trial. After the freezing-thawing process, motility and plasma membrane functionality was improved when SP was added. No differences were found for post-thaw viability between the control and treatment samples. The percentage of normal cells was higher with SP at post-thawing, and a decrease of the presence of bent tailed spermatozoa with a droplet in the SP group was observed. The length of the head spermatozoa was 3.4% higher in the samples with PBS compared to those in which SP was added. Females pregnant at day 25 post-insemination were 0/12 (with SP inside the straw) and 1/10 (without SP inside the straw). In conclusion, the presence of 10% SP at post-thawing improves sperm cells' motility, functionality, and morphology, indicating that it would be beneficial to improve the frozen-thawed alpaca's physiology spermatozoa. More fertility trials must be developed to increase this knowledge.

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KSper, a pH-sensitive K+ current that controls sperm membrane potential

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.0702018104 ◽

2007 ◽

Vol 104 (18) ◽

pp. 7688-7692 ◽

Cited By ~ 137

Author(s):

Betsy Navarro ◽

Yuriy Kirichok ◽

David E. Clapham

Keyword(s):

Membrane Potential ◽

Acrosome Reaction ◽

Reproductive Tract ◽

Female Reproductive Tract ◽

Male Reproductive Tract ◽

Sperm Flagellum ◽

K Current ◽

Sperm Membrane ◽

Principal Piece ◽

Mammalian Spermatozoa

Mature mammalian spermatozoa are quiescent in the male reproductive tract. Upon ejaculation and during their transit through the female reproductive tract, they undergo changes that enable them to fertilize the egg. During this process of capacitation, they acquire progressive motility, develop hyperactivated motility, and are readied for the acrosome reaction. All of these processes are regulated by intracellular pH. In the female reproductive tract, the spermatozoan cytoplasm alkalinizes, which in turn activates a Ca2+-selective current (ICatSper) required for hyperactivated motility. Here, we show that alkalinization also has a dramatic effect on membrane potential, producing a rapid hyperpolarization. This hyperpolarization is primarily mediated by a weakly outwardly rectifying K+ current (IKSper) originating from the principal piece of the sperm flagellum. Alkalinization activates the pHi-sensitive IKSper, setting the membrane potential to negative potentials where Ca2+ entry via ICatSper is maximized. IKSper is one of two dominant ion currents of capacitated sperm cells.

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Oocyte-sperm interactions in the fertilization of birds

Medycyna Weterynaryjna ◽

10.21521/mw.6181 ◽

2019 ◽

Vol 75 (01) ◽

pp. 6181-2019

Author(s):

ALEKSANDRA KRAWCZYK ◽

JADWIGA JAWORSKA-ADAMU

Keyword(s):

Reproductive Tract ◽

Abdominal Cavity ◽

Bird Species ◽

Transgenic Animals ◽

Female Reproductive Tract ◽

Sperm Cells ◽

Single Male ◽

Male Pronucleus ◽

Male Gametes ◽

Female Pronucleus

A thorough understanding of the mechanisms leading to the interaction between the sperm and the ovum in the process of fertilization in birds can facilitate more effective programming and control of the reproduction of these animals in breeding farms. In addition, it may allow the introduction of extracorporeal fertilization techniques, which may be important in the creation of transgenic animals and the reproduction of endangered species. In birds, the process of fertilization is not well known. It is conditioned by a series of interactions between mature reproductive cells. Oocytes are formed in the ovarian follicles of the left ovary. After ovulation, an ovum in the metaphase of the second meiotic division enters the oviduct along with the inner perivitelline layer (IPVL). It gets fertilized in this infundibulum. Male gametes are formed in paired testes located in the abdominal cavity. Sperm cells in the female reproductive tract do not require capacitation and are already fully capable of fertilization. As a result of internal insemination, male reproductive cells enter the oviduct. In this organ, they are selected and stored in the primary and secondary sperm storage tubules of the mucous membrane. They are released in batches shortly before ovulation. After reaching the oocyte, the sperm binds to the IPVL. This induces an acrosomal reaction that allows the male reproductive cells to penetrate to the surface of the oocyte, especially at the germinal pole. Next, as a result of physiological polyspermy, many sperm cells reach the ooplasm where they form haploid male pronucleus. This phenomenon is necessary to activate an polylecithal egg and produce a haploid female pronucleus. In the final stage, the female pronucleus merges with the single male pronucleus, which leads to the formation of a diploid zygote. The excess male pronuclei present in ooplasm are broken down by endonucleases (DNases). Understanding the mechanisms leading to the interaction between sperm and oocyte in birds may allow for more accurate programming and breeding of these animals in poultry farms and the introduction of extracorporeal fertilization techniques. In addition, it could be useful for the reproduction of endangered bird species

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Effect of flagellar beating pattern on sperm rheotaxis and boundary-dependent navigation

10.1101/2020.01.20.913145 ◽

2020 ◽

Author(s):

Meisam Zaferani ◽

Farhad Javi ◽

Amir Mokhtare ◽

Alireza Abbaspourrad

Keyword(s):

Reproductive Tract ◽

Complex Structure ◽

Clinical Importance ◽

Microfluidic System ◽

Female Reproductive Tract ◽

Circular Motion ◽

Sperm Cells ◽

Progressive Motility ◽

Mammalian Sperm ◽

Correct Path

AbstractThe study of navigational mechanisms used by mammalian sperm inside a microenvironment yields better understanding of sperm locomotion during the insemination process, which aids in the design of tools for overcoming infertility. Near- and far-field hydrodynamic interactions with nearby boundaries and rheotaxis are known to be some of the steering strategies that keep sperm on the correct path toward the egg. However, it is not known how the beating patterns of sperm may influence these navigational strategies. In this study, we investigate the effect of flagellar beating pattern on navigation of sperm cells both theoretically and experimentally using a two-step approach. We first isolate bovine sperm based on their rheotactic behavior in a zone with quiescent medium using a microfluidic system. This step ensures that the swimmers are able to navigate upstream and have motilities higher than a selected value, even though they feature various flagellar beating patterns. We then explore the flagellar beating pattern of these isolated sperm and their subsequent influence on boundary-dependent navigation. Our findings indicate that rheotaxis enables sperm to navigate upstream even in the presence of circular motion in their motility, whereas boundary-dependent navigation is more sensitive to the circular motion and selects for progressive motility. This finding may explain the clinical importance of progressive motility in semen samples for fertility, as the flow of mucus may not be sufficiently strong to orient the sperm cells throughout the process of insemination.SignificanceFinding the egg and moving toward it while traversing the complex structure of the female reproductive tract is necessary for mammalian sperm. Previous studies have shown how sperm use navigational steering mechanisms that are based on swimming upstream (i.e. rheotaxis) and along the boundaries of the female reproductive tract. We demonstrate that the performance of theses navigational mechanisms is associated with the primary characteristics of sperm motility. In fact, sperm rheotaxis is more sensitive to the motility and thus average velocity of sperm while navigation via rigid boundaries is more sensitive to the flagellar beating pattern and selects for symmetric beating. Our results can be expanded to other autonomous microswimmers and their subsequent navigation mechanisms.

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Structure and Function of Caltrin (Calcium Transport Inhibitor) Proteins

Biochemistry Insights ◽

10.1177/1178626417745822 ◽

2017 ◽

Vol 10 ◽

pp. 117862641774582

Author(s):

Ernesto Javier Grasso ◽

Carlos Enrique Coronel

Keyword(s):

Intracellular Signaling ◽

Calcium Transport ◽

Molecular Mechanisms ◽

Reproductive Tract ◽

Structural Features ◽

Female Reproductive Tract ◽

Sperm Cells ◽

Transport Inhibitor ◽

Acrosomal Exocytosis ◽

And Function

Caltrin (calcium transport inhibitor) is a family of small and basic proteins of the mammalian seminal plasma which bind to sperm cells during ejaculation and inhibit the extracellular Ca2+ uptake, preventing the premature acrosomal exocytosis and hyperactivation when sperm cells ascend through the female reproductive tract. The binding of caltrin proteins to specific areas of the sperm surface suggests the existence of caltrin receptors, or precise protein-phospholipid arrangements in the sperm membrane, distributed in the regions where Ca2+ influx may take place. However, the molecular mechanisms of recognition and interaction between caltrin and spermatozoa have not been elucidated. Therefore, the aim of this article is to describe in depth the known structural features and functional properties of caltrin proteins, to find out how they may possibly interact with the sperm membranes to control the intracellular signaling that trigger physiological events required for fertilization.

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