Expression of angiogenic factors in cryopreserved mouse ovaries after heterotopic autotransplantation

OBJECTIVE: Revascularization is critical for successful ovarian tissue transplantation. Vascular endothelial growth factor (VEGF) and angiopoietin-2 (angpt-2) are the principal mediators of neovascularization. This study was designed to assess VEGF and angpt-2 levels in cryopreserved ovarian tissue after heterotopic autotransplantation. METHODS: Ovarian tissues harvested from ICR mice at 5 to 6 weeks of age were stratified as follows: no cryopreservation (controls, group I); vitrification in VFS-40 (vitrification, group II); and gradual freezing in dimethyl sulfoxide (slow-freezing, group III). Frozen specimens were thawed at room temperature, assaying VEGF and angpt-2 levels 1 week after cryopreservation and 2 weeks after autotransplantation. RESULTS: VEGF and angpt-2 protein levels were significantly lower in cryopreserved ovaries of groups II and III than in controls (group I, P<0.05), whereas groups II and III did not differ significantly in this regard. After autotransplantation of cryopreserved ovarian tissue, VEGF and angpt-2 protein levels did not differ significantly by technique but tended to be lower than corresponding levels in controls. CONCLUSION: Expression of angiogenic factors in ovarian tissue is thought to vary by method of cryopreservation. Our findings indicate that levels of angiogenic factors expressed in cryopreserved ovarian tissue after autotransplantation do not differ appreciably from control levels, regardless of cryopreservation technique.