Curative treatments for hematologic conditions can sometimes affect reproductive health. In certain cases, steps can be taken to preserve fertility. The Fertility Preservation Program at Children’s Hospital of Philadelphia (CHOP) is the most comprehensive service of its kind in the nation. Our team works closely with the Sickle Cell and Red Cell Disorders Curative Therapy Center (CuRED) to counsel patients about the risk for impaired fertility related to their diagnosis and treatment and to plan for fertility preservation procedures, if needed. We offer options to boys and girls who have reached puberty, as well as to younger children.

Keeping an eye of on the future

The chemotherapy that is used to prepare a patient for a curative therapy like bone marrow transplant or gene therapy can affect the sperm making cells of the testicles and the eggs in the ovaries. This can cause infertility.

Not all males and females will be infertile after a curative therapy like transplant or gene therapy, but there is risk. It is important to consider whether fertility is likely to be impacted before pursuing curative therapies, when a window of opportunity may exist to preserve the patient’s future reproductive potential.

What can be done?

For pubertal boys: sperm banking

For males who have reached puberty, freezing sperm is the gold standard for fertility preservation, and it has a well-demonstrated success rate. We recommend that sperm banking be offered to all males who have reached puberty and are seeking curative treatments for hematologic conditions. Males as young as 12 years of age can sperm bank.

Our team facilitates the process by discussing sperm banking with families and by helping families to make appointments at a local reproductive endocrinology practice. A doctor, nurse practitioner or nurse will discuss this option and guide the family through the process. This conversation is often unexpected and can sometimes be embarrassing, but patients and parents tell us it helps them to feel hopeful for the future.

For prepubertal males: testicular tissue cryopreservation

Prepubertal males pose a challenge for fertility preservation, since they do not yet have mature sperm in the testicles. The prepubertal testicle does, however, contain a small amount of the stem cells that, with the right signals, will eventually become mature sperm.

Promising research with animals in the lab has shown that testicular tissue can be removed and frozen. At a later time, the tissue can be reimplanted and sperm-making can be restored. It may also be possible to expand the stem cells that become sperm outside the body and then use those cells to achieve pregnancy with assisted reproductive techniques. The laboratory science needed to make this process successful in humans is still being investigated. At this time, clinical applications of this science in humans are purely experimental. There have been no human births using frozen testicular tissue.

However, research is currently underway at CHOP that allows prepubertal boys at the highest risk for treatment-related infertility to have a testicular biopsy at diagnosis and freeze the tissue for their potential future use. A small piece of the tissue is also being studied in the laboratory to help scientists determine how the germ cells in the testicular tissue should be handled so that the maximum number of sperm can be obtained. Parents have indicated that they welcome an opportunity to potentially preserve their son’s fertility through testicular-tissue freezing, even if the science does not currently exist to use the tissue for this purpose.

For pubertal girls: egg or embryo freezing

While not an option for all females, both egg and embryo freezing can be pursued when the patient’s circumstances will allow. Egg or embryo freezing can only be considered in females who have gone through puberty and are physically mature. Hormone injections are used to stimulate the formation of multiple egg follicles. This process can take several weeks or more to complete and can be done only if the patient’s care team agrees that it is safe to do so. After stimulation, eggs are then removed and are frozen for the patient’s potential future use. If the patient has an intimate partner, embryo freezing may be considered.

Egg freezing is becoming more widely accepted, and there have been many live births from frozen eggs.

For prepubertal girls: ovarian tissue cryopreservation

Embryo freezing and oocyte freezing require ovarian stimulation at diagnosis and are not appropriate for prepubertal girls. An alternative approach is the cryopreservation (freezing) of ovarian tissue. This tissue can then be thawed and reimplanted at a later date, thereby restoring ovarian function, or eggs in the tissue can be matured outside of the body and used with reproductive technologies to achieve pregnancy. Ovarian tissue cryopreservation is beginning to show promise as a viable clinical option for fertility preservation.

Successful live births have been achieved in humans using frozen ovarian tissue. The number of live births is still small but is growing as the science is improved. As part of a research protocol at CHOP, we can offer ovarian tissue cryopreservation to girls as young as 1 year old who are at highest risk for infertility. As part of this study, a small portion of the ovary is surgically removed. Eighty percent of the tissue is frozen and stored for the participant’s own use in the future. Any mature eggs in this tissue can also be extracted and frozen. The remainder of the ovarian tissue is used by researchers in the laboratory to explore the best ways to mature the eggs found in this tissue.

Next steps

A visit to CHOP’s CuRED Clinic will include consultation with a healthcare provider from the Fertility Preservation Team. They will provide an overview of the fertility options that are available and will help to facilitate fertility preservation procedures as needed.

For any questions and more information, contact Claire Carlson, RN, BSN at 215-590-0432.