Options for fertility preservation in prepubertal boys.
BACKGROUND
Fertility in adult life may be severely impaired by gonadotoxic therapies. For young boys who do not yet produce spermatozoa, cryopreservation of immature testicular tissue (ITT) is an option to preserve their fertility, albeit still experimental. This paper covers current options for ITT cryopreservation and fertility restoration.


METHODS
Relevant studies were identified by an extensive Medline search of English and French language articles. Search terms were: gonadotoxicity, cytoprotection, cryopreservation, ITT, spermatogonia, testicular transplantation, testicular grafting and in vitro maturation (IVM).


RESULTS
Although no effective gonadoprotective drug is yet available for in vivo spermatogonial stem cell protection in humans, current evidence supports the feasibility of ITT cryopreservation before gonadotoxic treatment with a view to fertility preservation. Controlled slow freezing with dimethyl sulfoxide allows survival and proliferation of human spermatogonia after xenotransplantation, but only partial differentiation. Animal data look promising, since healthy offspring have been obtained after transplantation of frozen testicular cell suspensions or tissue pieces. However, none of the fertility restoration options from frozen tissue, i.e. cell suspension transplantation, tissue grafting and IVM have proved efficient and safe in humans as yet.


CONCLUSIONS
While additional evidence is required to define optimal conditions for ITT cryopreservation with a view to transplantation or IVM, the putative indications for such techniques, as well as their limitations according to disease, are outlined.
Wyns
Christine
C
Department of Gynecology, Université Catholique de Louvain, Cliniques Universitaires St Luc, Avenue Hippocrate 10, Brussels, Belgium.
Curaba
Mara
M
Vanabelle
Bernard
B
Van Langendonckt
Anne
A
Donnez
Jacques
J
D000818:Animals; D000970:Antineoplastic Agents / Q000009:adverse effects; D002648:Child; D002675:Child, Preschool; D015925:Cryopreservation / Q000379:methods / Q000639:trends; D019610:Cytoprotection; D005298:Fertility / Q000187:drug effects* / Q000528:radiation effects*; D005854:Germ Cells / Q000637:transplantation; D006801:Humans; D007248:Infertility, Male / Q000175:diagnosis / Q000517:prevention & control*; D008297:Male; D011379:Prognosis; D011878:Radiotherapy / Q000009:adverse effects; D013737:Testis / Q000187:drug effects* / Q000528:radiation effects* / Q000637:transplantation; D035703:Therapies, Investigational / Q000009:adverse effects / Q000379:methods / Q000639:trends; D014015:Tissue Banks
D000970:Antineoplastic Agents