Cryopreservation of prepubertal testicular tissue for future autologous transplantation of spermatogonial stem cells: preserving fertility in young boys with cancer

Modern cancer treatment allows the majority of prepubertal boys to survive
their malignancy. Unfortunately, many of these boys treated with high dose
chemotherapy will become infertile (Brougham & Wallace, 2005;van den Berg et
al, 2004). Currently, in prepubertal boys diagnosed with cancer there are no
means to preserve their reproductive potential, which contrasts with
adolescents and adults, for whom cryopreservation of semen prior to the start
of chemotherapy is available and widely used.
We have pioneered cryopreservation of testicular tissue and subsequent
autotransplantation of spermatogonial stem cells (SSCs) in animal
models(Izadyar et al, 2003) and have recently succeeded in cryopreserving and
propagating human SSCs from adult men (Sadri Ardekani et al., submitted). We
estimate that we will be ready for clinically applying SSC autotransplantation
within the next decade. Given the long time interval between cryopreserving
testicular tissue in prepubertal boys and possibly using this tissue for
autotransplantation when these boys have become adults and have been diagnosed
with infertility (most likely at least 15 years), we feel it is now time to
start with cryopreservation of testicular tissue of young boys with cancer.

To preserve testicular tissue of young boys with cancer for possible autologous
transplantation in the future if infertility has become apparent.

Prospective cohort study in prepubertal boys.

Under general anaesthesia a testicular biopsy will be taken; provided that a
signed informed consent is obtained from both parents and, if 12 years of age
or older, the prepubertal boy. Scheduling the testicular biopsy at the moment
of performing pre-treatment procedures minimizes the burden for the patient and
will not postpone start of therapy. To minimize the risk of the biopsy, the
procedure will only be done on one testis under the condition that there is no
history of testicular torsion or cryptorchidism. The biopsy will be
approximately 0.6-0.8 ml in size and will never exceed 50% of one testis. The
microsurgical techniques will ensure that substantial loss of testicular tissue
does not occur. Since anti-cancer treatment has not yet started at the moment
of biopsy, the patient*s immune system will not be compromised and the risk of
infection is minimal. In solid tumours bleeding is unlikely to be a major
problem since thrombocyte numbers and function are generally normal in these
patients. In leukaemia patients thrombocytopenia does occur at the moment of
diagnosis, but haemostasis is routinely secured by thrombocyte transfusion in
view of the other procedure performed during the same session. As a result no
additional thrombocyte transfusions are expected to be necessary. Follow-up
will be done at the moment of follow-up for the malignancy. No additional
hospital visits are foreseen in conjunction with this proposal.