An interventional study of Autologous testicular tissue transplantation of prepubertal frozen testicular tissue in Cancer, Sickle Cell Thalassemia and Hematologic Diseases, sponsored by Universitair Ziekenhuis Brussel. Recruiting at 1 site in Belgium. Open to male participants aged 18 Years to 50 Years. Per ClinicalTrials.gov, last updated 2026-04-23.
Sponsored by Universitair Ziekenhuis Brussel · Not applicable, Interventional, and Treatment
Freezing testicular tissue of prepubertal boys is a method for preserving spermatogonial stem cells in case of imminent gonadotoxic treatment during childhood. In case of total azoospermia or absence of spermatozoa that can be used for intra-cytoplasmic injection (ICSI) in adulthood, the investigators intend to perform the first in men autologous testicular tissue transplantation to restore fertility.
Freezing testicular tissue of prepubertal boys is a method for preserving spermatogonial stem cells. In 2002, the University hospital in Brussels (UZB) was the first hospital worldwide to offer testicular tissue cryobanking for fertility preservation in boys and ado-lescents. Since then, several other centers in Europe and USA have implemented similar fertility preservation programs. However, up till now, autologous transplantations of cryopreserved testicular tissue have not been performed yet.
As soon as a patient returns to the Centre for Reproductive Medicine at UZB with the request to transplant the preserved testicular tissue, the investigators will first analyse semen and blood. If spermatozoa are found in their semen, men can immediately enroll in standard care for natural conception, intra-uterine insemination (IUI), in-vitro fertilization (IVF) or intra-cytoplasmic injection (ICSI). However, if no spermatozoa suitable for ICSI are detected in the ejaculate, the investigators intend to propose and eventually perform autologous testicular tissue transplantation with the primary objective being to restore spermatogenesis and fertility.
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The eligible patients opted as a prepubertal boy to enroll in the fertility preservation program and on the moment of cancer diagnosis or hematological disorder, their parents have agreed to cryopreserve testicular tissue for later transplantation.
Inclusion Criteria:
Exclusion criteria:
Underlined terms in the criteria open these too. Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Stem cell (bone marrow) transplants. Allogeneic uses cells from a donor; autologous uses your own cells, collected earlier and given back.
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
A reason a treatment, test or procedure should not be given to a particular person, such as an allergy, another illness or a medicine they take.
Weight in kilograms divided by height in metres squared. Example: 70 kg and 1.75 m gives 70 ÷ (1.75 × 1.75) ≈ 22.9.
What counts as overweight or obesity differs between countries (some use lower cut-offs), so go by the range the study states.
Allogeneic and autologous transplant
Stem cell (bone marrow) transplants. Allogeneic uses cells from a donor; autologous uses your own cells, collected earlier and given back.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Informed consent
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Contraindication
A reason a treatment, test or procedure should not be given to a particular person, such as an allergy, another illness or a medicine they take.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
BMI (body mass index)
Weight in kilograms divided by height in metres squared. Example: 70 kg and 1.75 m gives 70 ÷ (1.75 × 1.75) ≈ 22.9.
What counts as overweight or obesity differs between countries (some use lower cut-offs), so go by the range the study states.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Procedure: Autologous testicular tissue transplantation of prepubertal frozen testicular tissue
Freezing testicular tissue of prepubertal boys is a method for preserving spermatogonial stem cells. If no spermatozoa suitable for ICSI are detected in the ejaculate, the investigators will perform autologous testicular tissue transplantation with the primary objective being to restore spermatogenesis and fertility.
Restoration of spermatogenesis and fertility by performing an autologous testicular tissue transplantation. Primary endpoint is the presence of spermatozoa in the graft.
Freezing testicular tissue of prepubertal boys is a method for preserving spermatogonial stem cells. If the patient has no spermatozoa suitable for ICSI in the ejaculate in adulthood, the investigators will perform autologous testicular tissue transplantation with the primary objective being to restore spermatogenesis and fertility. Grafting will be performed intra-testicular and intrascrotal for each patient. Grafts will be removed 12 months after grafting. Primary endpoint is the presence of spermatozoa in the grafted tissue. In the IVF laboratory mechanical mincing and enzymatic digestion will be performed on the tissue to find spermatozoa. If spermatozoa are present concentration and motility will be available.
Time frame: Graft-removal of intratesticular and intrascrotal grafts is planned 12 months after grafting.
Histological study to define the optimal transplantation site
The presence of sperm-generating stem cells, as well as their possible maturation to sperm cells will be evaluated through available and validated microscopic staining techniques applied to the testicular tissue. The maturity of other, non-sperm-generating testicular cells (Sertoli cells and Leydig cells) will also be evaluated. The results from tissue fragments transplanted to the testicle will be compared to the results from the tissue fragments transplanted to the scrotum. During the removal procedure of the transplanted fragments, a control biopsy (TESE) will be performed on the contra-lateral testicle (the one on which no transplantation was performed).
Time frame: Graft-removal of intratesticular grafts and intrascrotal grafts are planned 12 months after initial grafting. Histological study will be performed 12 months after initial grafting
Imaging study
The investigators will study the possibility of analyzing the growth of the transplanted fragments and the development of sperm cell production in these fragments by using ultrasound and Doppler techniques in a non-invasive way. Ultrasound will be performed 3, 6, 9 and 12 months after grafting. These findings will be compared to the findings of the semen and blood analysis and the clinical examination.
Time frame: Each patient in the study will be followed-up after screening during a period of 12 months post-grafting on 3, 6, 9 and 12 months after initial grafting.
Endocrinological (hormonal) study
The investigators plan a follow-up of the functionality of the transplanted tissue by performing blood analyses with LH (IU/L), FSH (IU/L), testosterone (ng/L), Inhibine B (ng/L) and Insulin-like factor 3 (INSL3, ng/ml). Blood analyses will be repeated 3, 6, 9 and 12 months after the transplantation procedure.
Time frame: Each patient in the study will be followed-up after screening during a period of 12 months post-grafting on 3, 6, 9 and 12 months after initial grafting.
Biomarker Study
As an exploratory part of this study, the investigators will study the possibility to predict the presence of testicular spermatogenesis in a non-invasive way (by semen and/or urine samples). If different biomarkers could be identified specificaly for the different stages of spermatogenesis, the development of the transplanted biopsies could be monitored this way. For this study, a urine and semen sample will be needed 3, 6, 9 and 12 months after the transplantation procedure.
Time frame: Each patient in the study will be followed-up after screening during a period of 12 months post-grafting on 3, 6, 9 and 12 months after initial grafting.
Complications
Each patient in the study will be followed-up during a period of 15 months after initial grafting or 3 months after graft-removal to report any complication(s) of the procedures.
Time frame: Each patient in the study will be follow-up after screening during a period of 15 months post-grafting.
Plan to share: No
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