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Technical challenges in freeze–thawing of human ovary

2005; Elsevier BV; Volume: 83; Issue: 4 Linguagem: Inglês

10.1016/j.fertnstert.2005.01.005

1556-5653

Mohamed A. Bedaiwy, Tommaso Falcone,

Tissue Engineering and Regenerative Medicine

We have read with great interest the recent article on freeze–thawing of intact human ovary with its vascular pedicle by Martinez-Madrid et al. (1Martinez-Madrid B. Dolmans M.M. Van Langendonckt A. Defrere S. Donnez J. Freeze-thawing intact human ovary with its vascular pedicle with a passive cooling device.Fertil Steril. 2004; 82: 1390-1394Abstract Full Text Full Text PDF PubMed Scopus (163) Google Scholar). There are some details that are not discussed in the article that are important for understanding their work. We agree that cryopreservation of the entire organ with its vascular pedicle is technically feasible, as we showed in our earlier work (2Bedaiwy M.A. Jeremias E. Gurunluoglu R. Hussein M.R. Siemianow M. Biscotti C. et al.Restoration of ovarian function after autotransplantation of intact frozen-thawed sheep ovaries with microvascular anastomosis.Fertil Steril. 2003; 79: 594-602Abstract Full Text Full Text PDF PubMed Scopus (124) Google Scholar, 3Bedaiwy M.A. Jeremias E. Gurunluoglu R. Miller K. Harasaki H. Falcone T. Cryoperfusion protocol for the long-term preservation of an entire ovary.Fertil Steril. 2001; 3(suppl 1): S79Abstract Full Text Full Text PDF Google Scholar); however the authors need to address the following points. First, they said the ovary was placed in a cryovial where it was pre-equilibrated, without stating exactly what size cryovial was used. To our knowledge, the available cryovials that can fit in the Nalgene® 5100 Cryo 1°C Freezing Container (Nalge Nunc International, Rochester, NY) is 1 cm in diameter, which is approximately one third the caliber of the human ovary. Consequently, detailed clarification of the procedure that allowed fitting the ovary into this cryovial is necessary. Second, we are not sure that using a 1° gradient to −80°C is enough to prevent intracellular ice formation, despite the favorable in vitro results presented. Only transplantation of a cryopreserved–thawed intact ovary can show exactly how much damage was inflicted by freeze–thaw trauma. In our experience, intact ovaries do well after thawing, but upon re-implantation, considerable damage to their vascular endothelium occurred. Did the authors evaluate the vascular endothelium? The restoration of fertility after successful transplantation in rats of ovaries, fallopian tubes, and the upper segment of the uterus en bloc after storage in liquid nitrogen (4Wang X. Chen H. Yin H. Kim S.S. Lin Tan S. Gosden R.G. Fertility after intact ovary transplantation.Nature. 2002; 415: 385Crossref PubMed Scopus (233) Google Scholar) cited by the authors was achieved after controlled-rate freezing with a more complicated freezing protocol compared with the one they used. Moreover, the partial restoration of hormonal function in merino sheep after autotransplantation of intact cryopreserved–thawed ovary with vascular anastomosis reported by our group with a similar cryopreservation protocol was achieved in approximately 30% of the transplants with variable degrees of vascular damage (2Bedaiwy M.A. Jeremias E. Gurunluoglu R. Hussein M.R. Siemianow M. Biscotti C. et al.Restoration of ovarian function after autotransplantation of intact frozen-thawed sheep ovaries with microvascular anastomosis.Fertil Steril. 2003; 79: 594-602Abstract Full Text Full Text PDF PubMed Scopus (124) Google Scholar). Although we believe that whole organ transplantation is the most viable option for long-term preservation of the graft, further research is required to evaluate these critical parameters before proceeding to a human trial.