Criopreserved ovarian tissue transplantation and bone restoration metabolism in castrated rats / Transplante de tecido ovariano criopreservado e restauração do metabolismo ósseo em ratas castradas

ABSTRACT Objectives: to evaluate estradiol levels and autotransplantation heated ovarian tissue effects, after vitrification, on rats bone metabolism previously oophorectomized bilaterally. Methods: experimental study with 27 rats aged 11 to 12 weeks and weighing 200g to 300g, submitted to bilateral oophorectomy and ovarian tissue cryopreservation for subsequent reimplantation. Animals were divided into two groups, A and B, with 8 and 19 rats, respectively. Autotransplantation occurred in two periods according to castration time: after one week, in group A, and after one month in group B. Serum estradiol measurements and ovary and tibia histological analysis were performed before and after oophorectomy period (early or late) and one month after reimplantation. Results: in groups A and B, tibia median cortical thickness was 0.463±0.14mm (mean±SD) at the baseline, 0.360±0.14mm after oophorectomy and 0.445±0.17mm one month after reimplantation p<0.005). Trabecular means were 0.050±0.08mm (mean±SD) at baseline, 0.022±0.08mm after oophorectomy and 0.049±0.032mm one month after replantation (p<0.005). There was no statistical difference in estradiol variation between the two study groups (p=0.819). Conclusion: cryopreserved ovarian tissue transplantation restored bone parameters, and these results suggest that ovarian reimplantation in women may have the same beneficial effects on bone metabolism.

RESUMO Objetivos: avaliar os níveis de estradiol e os efeitos do autotransplante de tecido ovariano aquecido, após vitrificação, no metabolismo ósseo de ratas previamente ooforectomizadas bilateralmente. Métodos: trabalho experimental com 27 ratas com idades entre 11 e 12 semanas e pesando 200g a 300g, submetidas à ooforectomia bilateral e criopreservação de tecido ovariano para posterior reimplante. Os animais foram divididos em dois grupos, A e B, com oito e 19 ratas, respectivamente. O autotransplante ocorreu em dois períodos de acordo com o tempo de castração: após uma semana, no grupo A, e após um mês no grupo B. Mensurações de estradiol sérico e análise histológica de ovário e tíbia foram feitos antes e após o período de ooforectomia (precoce ou tardio) e um mês após o reimplante. Resultados: nos grupos A e B, as espessuras corticais médias da tíbia foram 0,463±0,14mm (média±DP) na linha de base, 0,360±0,14mm após ooforectomia e 0,445±0,17mm em um mês após o reimplante (p<0,005). As médias trabeculares foram 0,050±0,08mm (média±DP) na linha de base, 0,022±0,08mm após ooforectomia e 0,049±0,032mm em um mês após o reimplante (p<0,005). Não houve diferença estatística entre a variação do estradiol entre os dois grupos de estudo (p=0,819). Conclusão: o transplante de tecido ovariano criopreservado restabeleceu os parâmetros ósseos, e estes resultados sugerem que a reimplantação ovariana em mulheres pode apresentar os mesmos efeitos benéficos sobre o metabolismo ósseo.

Histological study of rat ovaries cryopreserved by vitrification or slow freezing and reimplanted in the early or late postmenopausal stage

PURPOSE: To compare two rat ovary cryopreservation techniques (vitrification vs. slow freezing) and two postmenopausal stages (early vs. late) with regard to graft take. METHODS: Thirty-three Wistar rats were submitted to bilateral oophorectomy. One ovary was submitted to histological analysis while the other was cryopreserved by slow freezing or vitrification. The cryopreserved ovary was thawed and reimplanted in the greater omentum one week (early menopause) or one month (late menopause) after oophorectomy. One month after ovary reimplantation, the graft take was evaluated macroscopically and histologically. RESULTS: Six of the animals were used ascontrols and seven died. The histological findings of 20 animals included atretic follicles (n=4), primordial follicles (n=2), and corpus luteum with primordial follicles (n=3). No ovarian tissue was found in 11 animals. Vitrification resulted in a higher graft take rate than slow freezing (50% vs. 38.5%), but the difference was not statistically significant. However, the graft take rate was 9.3 times higher in the early than in the late postmenopausal stage (61.5% vs. 14.3%) (p=0.043). CONCLUSION: Vitrification was superior to slow freezing as ovarian cryopreservation technique, and grafting was significantly more successful when the ovary was reimplanted in the late postmenopausal stage. .