Experimental study on the vitrification and xenotransplantation of human ovarian tissue

Background:Cryopreservation of ovarian tissue is a promising method for preserving fertility.Transmission electron microscopy(TEM)is an evaluation system for cryo-injury during the cooling and warming process which is very laborious and needs to be optimized.Objective:In this study,we evaluated that serum 17β-oestradiol(E2)may be used as an indicator of vitrified ovarian tissue.Methods:Immunodeficient nude mice were used as hosts for xenografting of vitrified-warmed human ovarian tissues.A total of 54 mice were divided into two group:vitrified ovarian xenotransplant(VOX)group(n?45)and non-transplant control group(n?9).The transplanted mice were grouped into vitrified/warmed grafted-4 weeks(VOX-4w,n?15),vitrified/warmed grafted-6weeks(VOX-6w n?15)and vitrified/warmed grafted-12 weeks(VOX-12w n?15)according to the time after transplantation.The viable and functional recovery of grafted ovarian tissue was assessed by light microscopy,transmission electron microscopy,and hormone(E2)assays.Results:Serum E2 concentration was significantly higher in VOX-6w(group(21.07 pg/ml)than that of VOX-12w group(15.59 pg/ml).VOX-12w group showed a lower value(12.61 pg/ml)for E2 concentration.The trend for E2 concentration was consistent with the morphological identification of the grafts.Conclusion:In vivo serum hormone E2 released by cortical biopsies can be used as a functional marker for xenotransplanted vitrified-warmed human ovarian tissue reserve.