Chick embryo chorioallantoic membrane (CAM) model: a useful tool to study short-term transplantation of cryopreserved human ovarian tissue

Abstract

To investigate the chorioallantoic membrane (CAM) model for the study of short-term transplantation of frozen human ovarian tissue. Prospective study. Academic research unit. Ovarian tissue was obtained from three women. Frozen-thawed human cortical fragments were grafted onto traumatized CAM or beneath the CAM of 10-day-old chick embryos. Grafts were retrieved after 1, 2, 3, 4, and 5 days in ovo. Viability was assessed by calcein-AM and ethidium homodimer I. Tissue integrity, ischemic injury, and neovascularization were evaluated by histology. Cell proliferation was analyzed by Ki-67 immunohistochemistry. All the grafts showed adhesion when placed onto CAM, compared with only 30.4% beneath the CAM. Follicles were healthy, apart from a few degenerated follicles in necrotic and fibrotic areas. After 5 days, the majority of follicles were intermediate (32%) or primary (45.7%). Ki-67 immunohistochemistry revealed 12.5% proliferative follicles on day 2, reaching 20.7% on day 5. Fibrosis appeared on day 1; necrosis, follicular degeneration and follicular proliferation on day 2; and neovascularization and stromal cell proliferation on day 3. The present study showed that the CAM model provides a new approach to study human ovarian tissue transplantation in its first ischemic stages, yielding information on the timing of tissue changes before the establishment of neovascularization.