Intramuscular Autotransplantation of Vitrified Rat Ovary Encapsulated with Hyaluronic Acid Hydrogel

Acceleration of revival of ovarian function and maintaining of follicular reserve is mandatory after transplantation of cryopreserved ovarian tissue. In this study, hyaluronic acid hydrogel was used as a scaffold to improve restoration of ovarian estrous cycle and follicular preservation. Mature (∼ 8 weeks old) female Wistar rats with normal estrous cycles were divided in two groups: A: autotransplanted vitrified ovarian tissue without hyaluronic acid (HA), and B: autotransplanted vitrified ovarian tissue encapsulated with HA. Bilateral ovariectomy was performed in the diestrus stage; then ovaries were vitrified, warmed, and autotransplanted intramuscularly. Daily vaginal monitoring was performed until re-initiation of first full estrous cycle. Thereafter, follicular preservation, fibrosis, and apoptosis incidence were assessed histologically and immunohistochemically. The serum follicle stimulating hormone (FSH) levels were also accessed and compared for normal and ovariectomized rats. Re-initiation of first full cycle, atretic follicles, apoptotic index, and area of fibrosis in group A were approximately similar to group B. However, the total numbers of intact follicles were significantly lower in group B than group A. Moreover, the level of FSH in both experimental groups and normal rats was similar and in group B reduced significantly compared to the ovariectomized rats. Hyaluronic acid hydrogel did not show any negative effect on restoration of estrous cycle, but could not support follicular preservation after autotransplantation.