human cryopreservaton

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Genetic Engineering Sperm & Zygote banking

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I. HISTORY 1776 - First observations on the effects of freezing temperatures on human sperm 1866 - First banks for frozen human semen suggested 1949 - Glycerol first used as protective agent for bovine spermatozoa 1953 - "Dry Ice" preservation method developed by Bunge and Sherman - First successful human pregnancy using frozen sperm 1953 Bunge and Sherman, using dry ice for freezing and storing semen, reported the first successful human pregnancy resulting from insemination with frozen human semen. Since that time, new and improved methods of freezing and storing semen by immersion in liquid nitrogen at –I96.5°C (Behrman and Ackerman, I969) have improved the fertilizing capacity of frozen semen and led to the emergence of a number of commercial human sperm banks in the United States. 1960 - Sperm frozen and stored using liquid nitrogen 1972 - First commercial cryobanks founded 1973 - Normal child born from semen stored for over one year

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II. DEFINITION Sperm and Zygote banking are technically & medically termed as human semen/sperm cryobanking or cryopreservation. Cryopreservation is the process of freezing embryos, eggs or sperm for future use. Semen Cryopreservation (Sperm Banking) Sperm from two sources can be frozen: from ejaculates or from fluid extracted in the operating room during surgical procedures (vasal, epididymal and testicular sperm specimens). The sperm is usually frozen for a period of one year; at that time, future arrangements are discussed. Embryo Cryopreservation (Zygote Banking) Embryo cryopreservation or embryo freezing is a method used to preserve embryos by cooling and storing them at low temperatures. They can then be thawed at a future date and transferred to the uterus, providing additional opportunity for achieving conception.

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III. SYNOPSIS

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Both are initial procedures of Assisted Reproductive Techniques Insures paternity a baby has been conceived in the UK using sperm frozen for 21 years. Before freezing, sperm may be prepared so that it can be used for intra-cervical insemination (ICI), intrauterine insemination (IUI) or for IVF (or assisted reproduction) (ART).

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Zygote banking, embryo cryopreservation ZIFT Zygote Intrafallopian Transfer (ZIFT) The sperm and eggs are combined in the lab. Once fertilization takes place, they are placed in the woman's fallopian tubes, where they will hopefully travel to the uterus. ZIFT has the highest success rate of all of the ART procedures. It has a live birth rate of about 29% per cycle.

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Applications/ Uses: means of birth control for iatrogenic infertility seen as a supplemental income  to conceive a child for critically ill or deceased men Genetic banking of laboratory animal models of human health and diseases. Maintenance of genetic diversity in domestic & wild species population. for research purposes

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How Sperm Is Preserved You will be taken to a private room and asked to masturbate and ejaculate into a specimen jar. Sperm promptly taken to a sperm bank's laboratory. There, the sperm is analyzed for count and motility. If the specimen is adequate and the donor has passed all medical qualifications, then the sperm will be frozen and stored. Sperm is frozen with the use of cryopreservation. This is a special process of freezing designed specifically for cells or tissue. In order for sperm to remain vital for long-term storage, it must be kept in liquid nitrogen at approximately -300 degrees Fahrenheit (-169 Celsius or 77 Kelvin)

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When a specimen is processed for cryopreservation: A semen analysis is performed on each ejaculate. This includes a complete seminal fluid analysis quantitating sperm motility, forward progression, sperm density, and morphology. All specimens are stored in liquid nitrogen storage tanks (-196°C). There does not appear to be any increased risk of birth defects using frozen semen. There is no guarantee that any given specimen will necessarily produce a pregnancy; however, recent studies indicate that the overall success rate following the use of cryopreserved semen is from 40%-50%.

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Safety Precautions Potential sperm donors must cooperate with extensive background checks and medical examinations in order to qualify for donation. Sperm banks will ensure that the sperm is disease-free and that all donors are of healthy mind and body. Once a specimen is frozen, it will stay in quarantine for at least six months during this time period, the donor will be periodically checked to make sure that he is healthy and will not pass diseases to others if his sperm is used.

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IV. ETHICAL ISSUES

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Ethical implications: Promise of fertility 'insurance' by freezing and storing semen may mislead and persuade individuals to undergo vasectomy in a hasty manner without proper consideration of the consequences. Protect the rights and welfare of all parties using frozen semen, a consent agreement should be implemented. Instances in other fields of biomedical research where an overly ambitious investigator, in promoting his own scientific career, has failed to consider properly the best interests of his patients. Social and emotional impact: Possible psychological reactions false expectations the possible transmission of genetic diseases where the majority of genetic diseases cannot yet be detected by screening tests.

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Solutions: Be fully informed of the scientific knowledge regarding frozen semen banking, including a statement that there is at present no way of ensuring that their semen will maintain its fertilizing capacity following frozen storage. Consent to the donation of supernumerary embryos for hESC research should be sought. Provide patients and their partners with sufficient time and information before they make a final decision. Prospective embryo donors should also be given a choice about the uses to which hESCs derived from their donated embryos will be put in order to honor their ethical convictions and ensure that there are sufficient embryos for this research.

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V. CONCLUSION

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The history of mammalian sperm cryopreservation dates back several centuries to when the motility of sperm cooled by snow was measured (Sherman, 1964). There has been great progress in cryopreservation, as the sperm of many species have been successfully cryopreserved with resulting offspring. However, there are still many avenues that need to be explored as ART’s in different species become available & cryopreservation efficiencies improve. Furthermore, the possible applications of cryopreservation continue to increase as new GEM models are developed for the understanding of many human diseases. The future of cryopreservation continues to have a positive outlook.

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REFERENCE: Cryobanking of human sperm Mark S Frankell Program of Policy Studies in Science and Technology, George Washington University, Washington, DC, USA FAMILYHOPES.COM EN.WIKIPEDIA.ORG USSFIVF.ORG GOOGLE - CAMBRIDGE UNIVERSITY PRESS YAHOO EHOW.COM DISCOVERYCHANNEL.CO.UK Researchers: Elvin P. Arao,