Establishing refined inclusion criteria for immature testicular tissue banking based on patient followup and assessing the (need for and) efficiency of fertility restoration by autologous grafting

Since the first reports of immature testicular tissue banking (TTB) in the early 2000s, an increasing
number of fertility centers offer fertility preservation to boys at significant risk of lifelong sterility. But
are we offering immature TTB to the right patient population? Impaired testicular development and
function after childhood gonadotoxic treatment has been reported in small studies. This highlights
the need for larger, longer (inter)national patient follow-up to refine the selection criteria for
immature TTB. Immature TTB remains experimental until autologous grafting of immature testicular
tissue is shown to be successful in restoring sperm production in infertile men. Proof-of-concept in
non-human primates has encouraged the UZ Brussel to perform the first autologous grafting of
frozen-thawed immature testicular tissue in men. If successful, this would be beneficial for the
patients and immature TTB could be considered as an established fertility preservation option for
boys. The proposed project aims to refine the selection criteria for immature TTB by (1) following the
patients after treatment and biopsy on a regular basis, and (2) assessing the need for and efficiency
of fertility restoration by autologous grafting of testicular tissue. We are the best positioned because
we were the first hospital to implement immature TTB in 2002 and pioneered research on fertility
restoration techniques. Our patients are now reaching the age of wanting to start a family