Endometrial co-culture is a laboratory method that utilizes the mother's own uterine lining cells to enhance embryo quality. Simply stated, in a separate menstrual cycle one to two months before undergoing an IVF procedure, the woman undergoes a biopsy of her endometrial lining seven to ten days after ovulation. The cells are separated, grown in the laboratory, and frozen, later to be thawed during the subsequent IVF cycle. After her eggs are fertilized through IVF techniques, the embryos are grown on top of the mother's extracted cells. This provides a better environment for the embryos, especially for couples who have exhibited poor embryo quality in previous IVF cycles.
Co-culture is usually reserved for use in "poor prognosis" patients, particularly when other cycles have failed because of slow growth of the embryo. This method is not a "cure" for age-related IVF failures, but in properly selected couples, it has significantly improved embryo quality.
Preimplantation Genetic Diagnosis
IVF technology allows us to analyze the genetic makeup of embryos that are developing outside the body. We can now remove a single cell from the developing embryo without harm and analyze that embryo for specific genetic disorders (or flaws) that may exist in either or both parents. By removing one or two cells from the embryo, we can successfully screen for genetic diseases such as cystic fibrosis, sickle cell disease, and Tay-Sachs disease, among many other conditions. More than two hundred genetic diseases have been successfully analyzed in preimplantation embryos. Embryos can also be sorted to avoid X-linked (sex-linked) disorders such as hemophilia, muscular dystrophy, and many others. We can also detect chromosomal abnormalities in couples who suffer from recurrent pregnancy losses as well as in women who have miscarriages due to too many or too few chromosomes. If you have a sex-linked disorder, we can identify the gender of the embryos to avoid transmission of these diseases. New methods of genetic screening allow us to screen for multiple disorders at the same time. Future developments in this area will allow us not only to diagnose genetic problems better but to treat genetically related disorders.
For more detailed information on donor eggs, see Chapter 13, and for more on embryo co-culture and PGD, see Chapter 12.
In the Future Egg Maturation in the Laboratory
During an IVF cycle, eggs are recovered from a woman's ovaries after a seven-to-twelve-day treatment with hormones to stimulate her ovaries. In this process we override the woman's natural tendency to produce a single egg. On average, we aim to harvest between five and fifteen eggs. These eggs are then fertilized with the male partner's sperm, and the ensuing embryos are then transferred into the woman's uterus.
Unfortunately, not all women respond to the stimulating hormones in a predictable fashion. Some respond excessively and others not at all. One potential approach to circumvent stimulation problems is to collect immature eggs and mature them in the laboratory. While this approach is not quite as effective as conventional IVF, it is being optimized in several laboratories throughout the world. This could be the treatment of choice for women when ovarian stimulation is not recommended for medical reasons.