Ovarian tissue cryopreservation and transplantation in cancer patients.

Advances in the diagnosis and treatment of childhood, adolescent and adult cancer have greatly increased the life expectancy of premenopausal women with cancer. The ovaries are very sensitive to cytotoxic treatment, especially to alkylating agents. The only established method of fertility preservation is embryo cryopreservation according to the Ethics Committee of the American Society for Reproductive Medicine (2005), but this option requires the patient to be of pubertal age, have a partner or use donor sperm and be able to undergo a cycle of ovarian stimulation, which is not possible when the chemotherapy has to be initiated immediately or when stimulation is contraindicated, according to the type of cancer. For patients who need immediate chemotherapy, cryopreservation of ovarian tissue is the only possible alternative. This article reports the techniques and results of orthotopic transplantation of cryopreserved ovarian tissue. Among almost 30 cases reported in the literature, six live births have been achieved to date.

Both host and graft vessels contribute to revascularization of xenografted human ovarian tissue in a murine model.

OBJECTIVE: To characterize the human ovarian xenograft revascularization process. DESIGN: Prospective experimental study. SETTING: Gynecology research unit in a university hospital. PATIENT(S): Ovarian biopsies were obtained from 12 women aged 22-35 years. INTERVENTION(S): Frozen-thawed human ovarian fragments were intraperitoneally grafted into nude mice. MAIN OUTCOME MEASURE(S): Graft perfusion was evaluated by Hoechst 33342 uptake. Murine and human vascularization was analyzed by CD31 and von Willebrand factor double immunostaining. RESULT(S): On day 3, some murine neovessels and perfused areas were located at the periphery of the fragments. Nonperfused native human vessels were present in the fragments. From day 5, perfused areas and murine endothelial areas progressively increased. Host angiogenesis initiated ovarian graft reperfusion: murine neovessels penetrated from the periphery and were colocalized with perfused areas. By day 10, the increase in perfusion and murine vascularization was significant. The center of the fragments was perfused and a significant increase was observed in human vasculature. CONCLUSION(S): Host and graft vessels contributed sequentially to graft revascularization: murine angiogenesis initiated reperfusion from day 5 and, by day 10, human angiogenesis was shown to participate in graft revascularization. Host and graft angiogenesis are potential targets to reduce the avascular period after grafting.

Chick embryo chorioallantoic membrane (CAM) model: a useful tool to study short-term transplantation of cryopreserved human ovarian tissue.

OBJECTIVE: To investigate the chorioallantoic membrane (CAM) model for the study of short-term transplantation of frozen human ovarian tissue. DESIGN: Prospective study. SETTING: Academic research unit. PATIENT(S): Ovarian tissue was obtained from three women. INTERVENTION(S): Frozen-thawed human cortical fragments were grafted onto traumatized CAM or beneath the CAM of 10-day-old chick embryos. Grafts were retrieved after 1, 2, 3, 4, and 5 days in ovo. MAIN OUTCOMES MEASURE(S): Viability was assessed by calcein-AM and ethidium homodimer I. Tissue integrity, ischemic injury, and neovascularization were evaluated by histology. Cell proliferation was analyzed by Ki-67 immunohistochemistry. RESULT(S): All the grafts showed adhesion when placed onto CAM, compared with only 30.4% beneath the CAM. Follicles were healthy, apart from a few degenerated follicles in necrotic and fibrotic areas. After 5 days, the majority of follicles were intermediate (32%) or primary (45.7%). Ki-67 immunohistochemistry revealed 12.5% proliferative follicles on day 2, reaching 20.7% on day 5. Fibrosis appeared on day 1; necrosis, follicular degeneration and follicular proliferation on day 2; and neovascularization and stromal cell proliferation on day 3. CONCLUSION(S): The present study showed that the CAM model provides a new approach to study human ovarian tissue transplantation in its first ischemic stages, yielding information on the timing of tissue changes before the establishment of neovascularization.

Electron paramagnetic resonance as a tool to evaluate human ovarian tissue reoxygenation after xenografting.

OBJECTIVE: To develop electron paramagnetic resonance (EPR) oximetry as a tool to characterize the oxygen environment in human ovarian xenografts in the early postgrafting period. DESIGN: Prospective experimental study. SETTING: Gynecology research unit in a university hospital. PATIENT(S): Biopsies were obtained from 6 women aged 22-35 years. INTERVENTION(S): Frozen-thawed human ovarian tissue fragments were grafted to an intraperitoneal site in nude mice. Before grafting, lithium phthalocyanine, an oxygen reporter, was implanted inside the fragments. MAIN OUTCOME MEASURE(S): To monitor partial pressure of oxygen (pO(2)) by EPR on postgrafting days 3, 5, 7, 10, 14, 17, and 21 and validate the technique by histologic assessment. RESULT(S): A period of hypoxia was identified before day 5, followed by gradual but significant oxygenation over the next 5 days, suggesting an active process of graft revascularization. Reoxygenation kinetics in human ovarian xenotransplants were quantified. CONCLUSION(S): Our data validated the EPR oximetry technique as a tool to monitor pO(2) in ovarian grafting. The critical early period of hypoxia was identified, and the first steps of reoxygenation were characterized. In the future, our model may be used to evaluate new freezing and grafting protocols with the aim of reducing potential cryoinjury and initial ischemia-reperfusion damage.

Restoration of ovarian function in orthotopically transplanted cryopreserved ovarian tissue: a pilot experience.

Cryopreservation of ovarian tissue is currently proposed to young cancer patients before chemo- or radiotherapy to preserve their fertility. In this study, ovarian cortex was removed by laparoscopy from five women and cryopreserved before chemotherapy. After chemotherapy, they all experienced amenorrhoea due to premature ovarian failure and requested reimplantation of their cryopreserved ovarian tissue several years later. Thawed fragments were then grafted to an orthotopic site in all five women. Two of them underwent a second reimplantation. Ovarian function recovery was evaluated by hormone concentration measurement, follicular development on ultrasound and menstruation recovery. The first signs of ovarian function restoration (oestradiol peak, decrease in FSH, ultrasound showing follicular development) occurred between 16 and 26 weeks after reimplantation. Elevated FSH concentrations were sometimes observed between series of consecutive ovulatory cycles, demonstrating the presence of a relatively low ovarian reserve. There were no signs of disease recurrence in any patients with malignant disease. In conclusion, restoration of ovarian function was observed in all cases. Grafts remained functional in all the women. Transplantation of cryopreserved ovarian tissue to an orthotopic site appears to restore ovarian endocrine function, without any signs of disease recurrence.

Ficoll density gradient method for recovery of isolated human ovarian primordial follicles.

OBJECTIVE: To develop a simple and efficient technique to allow rapid recovery of a maximum number of good quality isolated follicles. DESIGN: Prospective experimental study. SETTING: Academic research unit of the department of gynecology in a university hospital. PATIENT(S): Biopsies were obtained from five women (between 26 and 31 years of age). INTERVENTION(S): Biopsies were cut with a tissue sectioner. Enzymatic digestion was performed in a collagenase solution for 90 min at 37 degrees C. The follicles were recovered using a discontinuous Ficoll density gradient method. MAIN OUTCOME MEASURE(S): The number of follicles present in the interface layers of Ficoll gradient was quantified. Follicular viability of these recovered follicles was assessed with live-dead stains, using calcein-AM and ethidium homodimer-I. RESULT(S): Out of a total of 6,811 recovered follicles, we found 63% (n = 4,201) at the medium-1.06 Ficoll interface and 36.9% (n = 2,590) at the 1.06-1.09 Ficoll interface, which represents 99.9% of total recovered follicles. Analysis by vital fluorescent staining showed that 95.8% of the follicles treated with Ficoll were totally viable. CONCLUSION(S): The Ficoll density gradient method allows us to maximize the recovery of isolated human ovarian follicles and minimize the manipulation time while maintaining high follicular viability.