Q1. What is cytoplasmic transfer?

A1. Cytoplasmic transfer, also known as cytoplasmic donation or transplantation, is an assisted reproduction procedure that involves the injection of a small amount of cytoplasm — the portion of the egg surrounding the nucleus — from a donor egg directly into the patient’s egg. The injected cytoplasm replaces missing or abnormally functioning components of the recipient egg, while the genetic blueprints of the parents are retained.

Q2. What were the steps involved in the cytoplasmic transfer case reported in The Lancet?

A2. Initially, both the patient and the donor were simultaneously stimulated in order to produce (oocytes) eggs that would mature at approximately the same time. The patient’s eggs were then divided into two groups: a control group of six untreated eggs for comparison and a group of 14 that would eventually be injected with the donor cytoplasm. The 14 patient eggs were then fertilized with sperm from the father and the donor cytoplasm was transplanted. When cultured, the treated eggs developed considerably better than the untreated eggs. Four of these embryos were transferred to the patient’s uterus and a clinical pregnancy was subsequently confirmed. Any leftover donor eggs were inseminated with the husband’s spermatozoa (just like conventional egg donation) and resulting embryos were frozen, in case the patient had not become pregnant.

Q3. Were the pregnancy and birth normal or were there complications?

A3. Both the pregnancy and delivery were uneventful, resulting in the birth of Emma, a 9 lb. 7 oz., 21" long baby girl. The baby had jaundice at birth, but this is common. It disappeared after a few days.

Q4. What is the goal of cytoplasmic transfer?

A4. The goal of cytoplasmic transfer is to overcome any problems that may exist in the cytoplasm of the egg. Every cell in the body consists of two components:

a nucleus, which provides the genetic material and cytoplasm, which is best described as the fuel that enables development. By transferring cytoplasm from a healthy donor egg, some of the problems that exist in the patient’s cytoplasm may be alleviated, while allowing the mother’s own genetic material to remain intact.

Q5. Is cytoplasmic transfer considered a significant advance in reproductive medicine?

A5. Until now, women with recurrent poor embryo development and failed implantation had no options for having their own genetic children. This process enables embryologists and physicians to selectively correct problems in the eggs, which then allows for the conception of children with the genes of both parents.

Q6. What type of patient may benefit from cytoplasmic transfer?

A6. The patient that will benefit most from this procedure is one who makes an adequate number of eggs during stimulation for in vitro fertilization, but whose eggs perform poorly during embryonic development. Typically, this patient will be in her 30’s.

Q7. Will this technique be helpful to all women who produce poor quality eggs?

A7. When there is a fertility problem, sperm and eggs are evaluated to see if the problem may be genetic or non-genetically based. This type of research focused on the non-genetic problems in the egg. However, there also may be future potential for this procedure to help genetically based problems, such as aneuploidy, a condition involving the presence of an extra chromosome or the absence of a chromosome. This occurs in a large group of eggs and may cause diseases such as Down’s syndrome in offspring.

Q8. What happens to the egg when the cytoplasm is impaired?

A8. Approximately 70 percent of eggs are anatomically impaired. Other eggs do not produce sufficient energy or lack crucial proteins. For some women, cytoplasmic transfer may correct or repair some of these abnormalities. If done early enough, before egg maturation, some of the genetic abnormalities also may be corrected.

Q9. What was the hypothesis for developing this procedure?

A9. Work on farm and laboratory animals has shown the importance of the interaction between the cytoplasm and the nucleus. A cell can have a normal nucleus and still not develop normally because of a simple defect in the cytoplasm. Observations such as these and observations of human eggs and embryos have led the researchers to believe there is a place for these new techniques in human infertility treatment.

Q10. In the case reported in The Lancet, the baby (Emma) was found to have the genetic make-up of both parents. Can you guarantee that all eggs fertilized with this procedure will carry the genetic material of the parents and not the donor?

A10. Each donor egg is carefully tested after cytoplasm is extracted from it to ensure that none of the genetic material was removed accidentally. Eggs are only allowed to develop with donor cytoplasm, once results of the test are negative. DNA fingerprinting performed on fetal cells retrieved through amniocentesis at 16 weeks of pregnancy and again at birth confirmed that baby Emma had the genetic make-up of her parents.

Q11. Is this new technique considered gene manipulation?

A11. No. The primary purpose of this technique is to correct the problems within the egg without changing the genetic blueprint in the nucleus. The fuel, or cytoplasm, is altered to allow it to further the development of the nucleus. This procedure is not gene therapy or any form of genetic engineering.

Q12 Is there any DNA in cytoplasm?

A12 Yes, but cytoplasmic DNA does not determine the individual’s genetic code. It is part of small structures called mitochondria, which provide energy to metabolic and other cellular processes. Altering the mitochondria of the egg with a donor’s mitochondria may be advantageous for women who suffer from so-called mitochondrial disease.

Q13 The cytoplasm injected only constitutes 5 percent of the volume of the egg. Is this enough to affect the egg’s future development?

A13 The egg is a very large cell, larger than any other cells. Most of the cytoplasm is not needed and sometimes the egg or its daughter cells split into two or three as is the case with identical twins or triplets. Although it is not known precisely how much donor cytoplasm should be added or indeed whether all the cytoplasm should be removed first and replaced with that from a donor, the amount of cytoplasm which was injected in these patients was considerably more than the volume of regular body cells.

Q14. Has this procedure been successful with any other patients?

A14. The Institute has recently completed a cytoplasmic transfer in a patient who had seven previous in vitro fertilizations with poor quality embryonic development. The patient has conceived and currently has a healthy ongoing clinical pregnancy.

Q15. What are the various techniques that the Institute has utilized for cytoplasmic transfer?

A15. In the technique which was used in the case reported in The Lancet, the donor egg is penetrated and the cytoplasm withdrawn. The aspirated cytoplasm is then deposited into the recipient egg. A second type of technique that is used to transfer larger amounts of cytoplasm involves electrofusion. Using a micromanipulator (a specialized microscope that can manipulate tiny cells), the cytoplasm is withdrawn and a small amount is then placed underneath the recipient’s egg, which is surrounded by the zona pellucida ¾ a thick, transparent, non-cellular membrane. The two substances then receive an electrical impulse that causes the membranes to fuse. The donor cytoplasm is then incorporated into the recipient’s cytoplasm.

Q16. How long does this process take?

A16. It depends on the method used. Changing the cytoplasm entirely by removal of the donor nucleus and electrofusion will take about 20 minutes per egg or longer. The technique of cytoplasmic injection is faster and takes about 10 minutes per egg.

Q17. What were the results of the other women who received this treatment?

A17. Two women whose eggs were treated with "electrofusion" did not become pregnant. They returned for frozen egg donor embryos and became pregnant. One other patient who was treated with the injection method became pregnant, however, she miscarried very early on. One patient’s eggs and donor egg embryos were very poor after fertilization, indicating that the sperm cell caused a problem in the embryo and not the egg.

Q18. What are the future plans for research and application of cytoplasmic transfer?

A18. Research at the Institute is focusing on three basic issues that need further clarification:

1.Identification of the best candidates for the procedure. 2.Deciding at what phase of cellular development the procedure should be done. 3.Determining the best method for cytoplasmic transfer.

There are numerous applications for this technique because there are many patients that have structural problems in the cytoplasm of their eggs. There are potential future variations of the procedure which may even allow researchers to help patients with eggs that have genetic abnormalities. At present, cytoplasmic transfer is available as a research protocol to a small number of patients who receive care at The Institute for Reproductive Medicine and Science of Saint Barnabas Medical Center.

Q19. How much does this procedure cost? Will it be covered by health insurance?

A19. The procedure is costly, since it essentially includes all the initial treatments of both the patient as well as the donor. It is only covered in part by health insurance. The procedure will become more affordable once its efficiacy is statistically proven in a large number of patients . Donor eggs or only the cytoplasm can then be frozen and possibly used for multiple cytoplasmic transfer procedures.

Q20. How does this new technique fit into the development of assisted reproduction techniques?

A20. Initially, the treatment of infertility patients focused on the anatomy of the parents. Over the years, the focus shifted to analyzing the eggs and sperm in an attempt to successfully join the two. This involved in vitro fertilization and embryo transfer. Cytoplasmic transfer takes science a step further in order to evaluate and correct certain disorders that are present in the individual egg. This may be the next leap forward in the evolution of assisted reproduction.

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