Background
There are various topics concern in ART programs all over the world that greatly influence patients and significantly influence scientists and clinicians in the same way: female and male gamete cryopreservation and minimizing multiple pregnancies. Independently, every topic leads to the need for research and continuous discussions;
- Storage of the male gamete is now an accepted clinical method. Many questions still are unanswered and need more attention which includes the variation in male to male freezability of the sperm.
- The scientific public including the communities have a concern about the increased multiple births, and the only remedy closer to preventing multiple births is by way transferring a single embryo which should lead in cryopreservation of more embryos. Although, international and national registers show that the outcome achieved with embryos cryopreserved are significantly lower as compared to those with fresh ones.
- It is evident that the storage of female gametes may have a significant influence on the reproductive drug. Despite a number of clinical trials that have been a success, there are a lot of difficulties accompanied by the procedure of female gamete cryopreservation.
In optimizing the cryopreservation of gamete and human embryos, clinical embryologists all over the world have empirically modified the most critical methods. In most cases, the modifications were without any excuse introduced, and this has also caused the results to improve significantly. Hence, understanding the vital principles of cryopreservation and cryobiology helps clinicians and scientists to optimize procedures for producing multiple choices for the patients. The SIG embryology gives a chance for a two-day course specifically for clinical staff, clinical embryologists and other interested individuals in the understanding of gamete cryopreservation and human embryo and fundamental cryobiology.
Pregnancies from the frozen oocytes that were a success were first attained in the 1980s by use of rapid-thaw cryopreservation and slow freeze procedures. (Gupta, Lodha, Karthick, & Tandulwadkar, 2018) Although there was no improvement in the field hence low rates of success and technical concerns (Starmer, Baird, & Lucky, 2018). It is challenging to cryopreserve oocyte cells because of their high vulnerability to the intracellular formation of ice and low surface area to volume ratio (Del Vento, et al., 2018)The previous article outlined challenges in predicting the characteristics of the permeable membrane of human oocytes together with other biophysical parameters.
Studies have shown that the negative impact of cryopreservation on the stability of microfilaments and microtubules in oocytes of mammals. The Human Fertilization and Embryology Authority has embraced the frozen oocytes to be used in the treatment of infertility in the United Kingdom in. The regulations enhance for the gametes to be stored for a standard period of 10 years which may be extended under given instances (Gowda, Thippeswamy, & Chaturvedi, 2018). The American Society for Reproductive Medicine, lifted the label experiment used to freeze oocytes due to the four randomized trials that were conducted under control (Saumet, et al., 2018). Suggestions were that using warmed or vitrified oocytes of in-vitro fertilization could result in same pregnancy and fertilization of in-vitro fertilization by fresh oocytes (Dupesh, Rasappan, Shila, & Gunasekaran, 2018). This has led to the use of oocyte cryopreservation in the number of in-vitro fertilization clinics coming up in the world.
Slow freezing
Literature Review of Methods of Gamete and Embryo Storage
(Munsie & Gyngell, 2018) Achieved the first births as a result of mice morulae transfer obtained from mature oocytes and freezing in dimethyl sulfoxide in following the slow freeze-slow thaw method and preserving at 1960 C The similar procedure resulted to the first pregnancy reported in humans, produced by freezing eight-cell embryo (Strong, 2018) the births of twins in the Netherlands followed. Dimethyl sulfoxide is currently less applied in the multicellular freezing of embryo. It elongates the procedure as it engages a slow thaw and slows free of up to – 800 C or a fast one crushed on ice with no proof of effectiveness.
(Martinez, Martinez, & Gil, 2018) There was an introduction of propanediol in embryo freezing in rabbit and mice and linked sucrose with aiding the cell to dehydrate through the effect of osmosis. The procedure of using sucrose (0.1 mol/I) and propanediol(1.5 mol/I) were recorded to be a success where embryos were slow cooled to – 300 C and rapidly thawed after storing in liquid nitrogen. Using this procedure and by lowering the method of freeze-thaw to around two and a half hours, was at first used in 1985 to humans whereby it showed efficiency for one, two or three days old embryos. Numerous application of cryopreservation of embryo was hence started in in-vitro fertilization clinics through this method.
In cattle, cryotechnology was used industrially where a relatively higher than 100,000 transfers of embryo annually across the world was experienced in 1980. The blastocyst was the preferred stage and glycerol, cryoprotectant, turned out to be the most preferred according to the blastomere membranes permeability at this period. The first human blastocyst was recorded by (Moghbelinejad, Mozdarania, Ghoraeian, & Asadi, 2018), using (10%) glycerol alone adding in a stepwise method. Although the survival rate of the blastocysts was 53%, the rate of implantation concerning transferred blastocysts on a small scale hit 35% (n=23). Blastocyst cryopreservation was however abandoned for a period. Only 25% zygotes managed to reach the blastocyst period in vitro regular culture medium, and the outcome of various groups was far closer to success (Goedeke, Daniels, Thorpe, & du Preez, 2018).
Research on mice by (Genoff, Rubin, Lobel, Stelling, & Pastore, 2018) on the long-term impact of embryo freezing with standard procedures indicated that cryopreservation did not cause main anomalies instead would be lead to minor differences. For example, the number of responses to the neurosensorial and behavior tests, features in the morphology of the mandibles and the body weight of males increases by 11% during senescence. Depending on age or sex, genotype, these characteristics arise from changes in the epigenetic caused by embryo freezing.
Equally, cryopreservation has an effect on the gene’s regular pattern expression in the development stage of human pre-implantation (Vij, Sabanegh Jr, & Agarwal, 2018). Embryos that are intact thawed are hence not equal to the non-frozen ones. In future, it will be important that before initiating any cryopreservation technology, to depend on extensive studies on human and animal embryos as well as epigenetic and genetic screening.
Vitrification
Research in the previous years has recommended vitrification superiority than slow freeze procedures. A meta-analysis on cryopreservation of oocyte meant that rates of pregnancy with oocytes cryopreservation could be developed using vitrification even though at this stage low pregnancies were reported. Alternatively, comparing in-vitro fertilization results with vitrified or slow-frozen oocytes have shown that vitrification causes better fertilization, survival and pregnancy rates (Aliabadi, Jahanshahi, Talaei?Khozani, & Banaei, 2018). Increasing attestation of in-vitro fertilization effectiveness using vitrified oocytes has recommended that same results would be attained as using in-vitro fertilization with fresh oocytes, the oocytes having survival possibilities of relatively higher than 84% (Khatun, Rahman, & Pang, 2018).
The controlled random tests underpinning the same success rates between warmed or vitrified oocytes in-vitro fertilization and fresh oocytes in-vitro fertilization, all have applied open systems of vitrification. Besides their apparent effectiveness, questions have been raised about the infertility of open systems because of the ability to cross-contamination in comparison to the liquid nitrogen and sample vitrification. Correspondingly, research has outlined the prospective of liquefied nitrogen sterilization by use of ultra-violet lights or storing the oocytes in vapor phase liquefied nitrogen containing less density of airborne environmental contaminants (Herta, Lolicato, & Smitz, 2018).
After subjection to contaminated liquefied nitrogen, (Gilman, 2018), discovered that enclosed devices were free from bacteria while there was the presence of bacteria in 45% of the tools that were open. Although, using the closed systems raises contemporary questions on the effectiveness of oocyte vitrification, because of their lower rates of cooling. A study recommended that using closed vitrification may not maintain the oocyte ultrastructure and even in open systems. Another research in comparison of the closed and open vitrification systems discovered reduced clinical pregnancy, cleavage and fertilization rates in the latter (Pomatto, Gai, Deregibus, Tetta, & Camussi, 2018).
Contrary research recommends that the use of closed vitrification may influence great result while also creating an aseptic surrounding. A cross of clinics in the United Kingdom urged the use of closed containers for vitrification at 75% as compared to open containers. Either of the protocols of vitrification preferred it is essential to examine the warming rate. Studies have shown that the warming rate is indeed very vital as compared to the cooling rate for the survival of the oocytes in vitrification protocols. Notably, the optimal results are by higher chances attained if warming and vitrification are conducted in the same clinic and by similar protocols (Walters, et al., 2018).
Back then in 2000 over about 100 cryopreserved oocytes were required for a single pregnancy to be achieved unlike now around 20 vitrified oocytes are needed. However, it highly relies on the oocytes age. Randomized controlled tests have resulted in clinical pregnancy rates for every transfer at a range of about 35.5% and 65.2%. A new meta-analysis of 5 research found that the high-quality embryo, embryo cleavage, ongoing pregnancy and fertilization rates were not different from the vitrification and fresh oocytes grouping (Rosenbusch, 2018).
Effects of Gamete and Embryo Storage
Cryopreservation leads to a big reduction in chromatin stability, motility, membrane integrity viability as well as leads to serious morphological interferences. The loss in quality of sperm in most cases is highly experienced in patients that have a poor sperm parameter (Genoff et al., 2018). The profoundly affected setting is motility, (Dupesh et al., 2018) suggested that the decline in sperm motility is caused by physical changes to the sperm tail and damage of the mitochondria. Harm to mitochondria membrane interferes with the energy production process causing declined availability of adenosine triphosphate in the spermatozoa. Cryopreservation may trigger irreparable coiling of the flagellum, hampering the propelling motion of the tail.
Cryopreservation may also cause damage to the DNA. The DNA packaging in a sperm nucleus requires a lengthy procedure that starts in spermiogenesis whereby the protamines replaces the histones (Strong, 2018). The spermatozoa integrity appears to be the factor determining successful fertilization in both the assisted and natural methods of reproduction. Similarly, it has been observed that the decline in the quality of post-thaw is high as the result of fragmentation of the DNA that happens after cryopreservation. Such damage to the DNA may affect the viability and quality of the embryo. Equally an observation has been made that different samples of sperm produce different extent of DNA harm. The outlined studies show the need to evaluate DNA integrity as a segment of the routine sterility work up (Genoff et al., 2018).
It is equally necessary to record that frozen samples obtained from men who are healthy appear to be of a greater post-thaw quality as compared to samples acquired from men who are sterile. Numerous research is associated with the difference in the morphology of frozen samples of sperm, even though it doesn’t seem accurate as maintained by studies conducted by (Saumet, et al., 2018). (Aliabadi et al., 2018) Established that the usage of slow freezing that is programmable was superior to rapid programmable freezing and vapor freezing for high standard samples of semen. Moreover, all the protocols of freezing led to remarkable changes in parameters and sperm cell motility.
In contrary, various reports have indicated that the standard fast freezing method is preferable for preserving the motility of the sperm as compared to the slow manual procedure. The unsteady difference in the motility outcome attained can be described by differences in glycolipid, sperm membrane phospholipid and sterol content (Gowda et al., 2018).
Pros
Improvement in the technology
As discussed earlier on, egg freezing is currently an accomplished technique with improved results. The process of freezing previously used the slow-freeze method whereby crystals of ice in most cases were present in the eggs to the greater extent causing the decline in their quality. Fast freeze of vitrification is being used now hence lowering the risks of damaging egg crystals from forming (Genoff et al., 2018).
One need not be concerned about the quality of eggs declining after 30 years of age.
Usually, the egg quality diminishes after the age of 30 and significantly decline after the age of 35 leading to an increased risk of miscarriages and chromosomal abnormalities. However, there are many things a lot of women accomplish at 35 years of age before bearing children or bearing even more children. Preservation of young eggs gives women the opportunity to get their desired jobs, eat a lot of lunch meat and cold cheese, and explore the world as well as anything a woman wishes to do before motherhood (Dupesh et al., 2018).
Less stigma in sterility treatment because every person is doing it.
Making use of the current medical technologies to bear children, is not anymore as viewed as an abomination way to parenthood, however, may be discussed in shameful whispers. It is currently understood and valued and celebrated women like Mariah Carey, Chrissy Teigen, Jamie King and Nicole Kidman have taken it to social media platforms to tell their unique journey to motherhood (Gowda et al., 2018).
Cons
No guaranteed pregnancy
Preserving an egg in the bank is not surety of an eventual removal producing a baby. As time goes by, there are higher risks of health complications developing that may impact a healthy pregnancy which include; diabetes, endometriosis, high blood pressure and fibroids. It is neither a surety that sperms of the partner will swim into the ovum membrane. Therefore, it is required of the parties to maintain a lifestyle that is healthy and ensure consistent medical checkups (Gupta et al., 2018).
Subjection to anesthetics
The process of egg freezing involves ovary stimulation with hormones through injection which triggers the production of multiple eggs. Getting back the eggs via a rapid method which needs one to be subjected to mild anesthesia thereby the egg transferred to the laboratory for freezing (Herta et al., 2018).
It is expensive
The process of harvesting eggs including drugs are quite costly. The IVF may not be successful during the first attempt. Therefore, it is not sure how many rounds one may need to undergo (Aliabadi et al., 2018).
Conclusion
The method of vitrification has experienced increasing concerns for the past few years. There is not enough justification to determine if vitrified embryos are the most viable as compared to embryos frozen by slow-freezing technique. Comparative research from a few numbers of clinics recommends that the clinical results by vitrification produce similar or the best outcome as compared to slow-frozen procedures at different stages of development of the human embryo. Even though a lot of vitrification protocols are in place, the pregnancy rates and survival of embryos have been correspondent than with slow-freezing procedures. Recently, cryobiology field has advanced by using vitrification protocols which are very useful and very short. Therefore it is predictable that in future vitrification will be used widely and commonly in the storing of all types of the human embryo.
References
Aliabadi, E., Jahanshahi, S., Talaei?Khozani, T., & Banaei, M. (2018). Comparison and evaluation of capacitation and acrosomal reaction in freeze?thawed human ejaculated spermatozoa treated with L?carnitine and pentoxifylline. Andrologia, 12845.
Del Vento, F., Vermeulen, M., de Michele, F., Giudice, M. G., Poels, J., des Rieux, A., & Wyns, C. (2018). Tissue engineering to improve immature testicular tissue and cell transplantation outcomes: one step closer to fertility restoration for prepubertal boys exposed to gonadotoxic treatments. International journal of molecular sciences, 286.
Dupesh, S., Rasappan, P., Shila, S., & Gunasekaran, K. (2018). Human Sperm Freezing: Mini Update. Advances in Reproductive Sciences, 59.
Genoff, M. C., Rubin, L. R., Lobel, M., Stelling, J., & Pastore, L. M. (2018). Review of patient decision?making factors and attitudes regarding preimplantation genetic diagnosis. Clinical Genetics, 22-42.
Gilman, L. (2018). Toxic money or paid altruism: The meaning of payments for identity?release gamete donors. Sociology of health & illness, 702-717.
Goedeke, S., Daniels, K., Thorpe, M., & du Preez, E. (2018). The Fate of Unused Embryos: Discourses, Action Possibilities, and Subject Positions. Qualitative health research, 1529-1540.
Gowda, S. M., Thippeswamy, H., & Chaturvedi, S. K. (2018). Psychosocial needs of cancer survivors in fertility preservation: A systematic review. The Onco Fertility Journal, 24.
Gupta, S., Lodha, P., Karthick, M. S., & Tandulwadkar, S. R. (2018). Role of autologous bone marrow-derived stem cell therapy for follicular recruitment in premature ovarian insufficiency: Review of literature and a case report of world’s first baby with ovarian autologous stem cell therapy in a perimenopausal woman of age. Journal of Human Reproductive Sciences, 125.
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Khatun, A., Rahman, M. S., & Pang, M. G. (2018). Clinical assessment of the male fertility. Obstetrics & gynecology science, 179-191.
Martinez, C. A., Martinez, E. A., & Gil, M. A. (2018). Importance of oil overlay for production of porcine embryos in vitro. Reproduction in Domestic Animals, 281-286.
Moghbelinejad, S., Mozdarania, H., Ghoraeian, P., & Asadi, R. (2018). Basic and clinical genetic studies on male infertility in Iran during 2000-2016: A review. International Journal of Reproductive Biomedicine, 131.
Munsie, M., & Gyngell, C. (2018). Ethical issues in genetic modification and why application matters. Current opinion in genetics & development, 7-12.
Pomatto, M. A., Gai, C., Deregibus, M. C., Tetta, C., & Camussi, G. (2018). Noncoding RNAs Carried by Extracellular Vesicles in Endocrine Diseases. International journal of endocrinology, 2018.
Rosenbusch, B. (2018). To What Extent Are Cryopreserved Sperm and Testicular Biopsy Samples Used in Assisted Reproduction? Journal of Reproduction & Infertility, 115-118.
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Starmer, B. Z., Baird, A., & Lucky, M. A. (2018). Considerations in fertility preservation in cases of testicular trauma. BJU international, 466-471.
Strong, D. M. (2018). Tissue banking, biovigilance and the notify library. Cell and tissue banking, 187-195.
Vij, S. C., Sabanegh Jr, E., & Agarwal, A. (2018). Biological therapy for non-obstructive azoospermia. Expert opinion on biological therapy, 19-23.
Walters, J. L., De Iuliis, G. N., Dun, M. D., Aitken, R. J., McLaughlin, E. A., Nixon, B., & Bromfield, E. G. (2018). Pharmacological inhibition of arachidonate 15-lipoxygenase protects human spermatozoa against oxidative stress. Biology of reproduction, 784-794.
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