Orthotopic and heterotopic ovarian tissue transplantation

Abstract

BACKGROUNDTransplantation of ovarian tissue is, at present, the only clinical option available to restore fertility using cryopreserved ovarian tissue. More than 30 transplantations of cryopreserved tissue have been reported, and six babies have been born, worldwide, following this procedure. Despite these encouraging results, it is essential to optimize the procedure by improving the follicular survival, confirming safety and developing alternatives. Here, we review the different factors affecting follicular survival and growth after grafting.METHODSRelevant studies were identified by searching Pubmed up to January 2009 with English language limitation. The following key words were used: (ovarian tissue or whole ovary) AND (transplantation) AND (cryopreservation or pregnancy). Using the literature and personal experience, we examined relevant data on the different exogenous and clinical factors affecting follicular development after grafting.RESULTSClinical factors such as the patient's age and the transplantation sites influenced the lifespan of the graft. A heterotopic transplantation site is not optimal but offers some advantages and it may also promote the hormonal environment after a combined heterotopic and orthotopic transplantation. Exogenous factors such as antioxidants, growth factors or hormones were tested to improve follicular survival; however, their efficiency regarding further follicular development and fertility potential remains to be established.CONCLUSIONAdditional evidence is required to define optimal conditions for ovarian tissue transplantation. Alternatives such as whole ovary or isolated follicles transplantations require further investigation but are likely to be successful in humans in the future.

Efficacy of ovarian tissue cryopreservation in a major European center

“…The observed percentages of tissue viability impairment as a result of cryopreservation and thawing are roughly consistent with the 70-80 % follicle survival reported earlier for various slowfreezing protocols. [8,27,29,30,35,38,39] In addition, we observed a 24-27 % reduction in overall tissue viability using the glucose uptake assay. This decreased glucose uptake indicates a reduced metabolism of the tissue during culture as a result of cryodamage.…”

“…[27][28][29][30][31][32][33][34][35][36][37][38] Moreover, most of these studies did not take the viability of the stromal cell compartment into account. [27][28][29][30][31][32][33][34][35][36][37][38] This compartment, however, is essential for post-autotransplantation neovascularization, follicle survival, and life span of the ovarian graft [39] and is considered to be more sensitive to ischemic and cryoinjury than primordial follicles [8,40].…”

VEGF and bFGF increase survival of xenografted human ovarian tissue in an experimental rabbit model

“…Revascularization process is completed associated with massive follicle loss and limits the longevity and success of ovarian transplants [10]. Ischemic injury during autograft processes induces the depletion of 60-95 % of the follicular reserve, including the loss of virtually the entire population of growing follicles [11]. It has proved that more follicles die from ischaemia during transplantation than from freeze-thaw injury during cryopreservation [12].…”

In-vitro maturation of human oocytes: before or after vitrification?

“…Moreover, for cancer patients, transplantation of cryopreserved ovarian tissue is not always conceivable because of the risk of retransmission of the disease due to the presence of neoplasic cells in the tissue. In these cases, combining IVM and vitrifcation offers a novel approach for fertility preservation, especially when the risk and the delay due to classical gonadotrophin stimulation before collecting mature oocytes is not indicated, as in advanced breast cancer patients [6].…”