Perspectives in Gamete and Embryo Cryopreservation

Abstract

Cryopreserved gametes and embryos are a major feature of human-assisted reproduction and patient care services, accounting for an increasing number of births worldwide. Since the first success obtained using frozen human spermatozoa, cryopreservation technology has been successfully extended to include oocytes and embryos, in a variety of both medical and nonmedical indications. Over the years, the available procedures have become widely implemented and the increasing evidence of its efficacy has contributed to acceptance of the technology. Nevertheless, a gold standard protocol that would be universally shared by clinics has yet to be definitively established and, therefore, research into cryopreservation of gametes and embryos cannot be considered concluded. Moreover, much effort should be committed to the definition and resolution of safety issues, the establishment of automation, and investigations about the potentiality of immature germ cells or stem cells.

WITHDRAWN: Intra-Ovarian Injection of Bone Marrow c-Kit+ Cells Induced Ovarian Rejuvenation in Menopausal Rats

“…Various strategies have been proposed for treating POF; suggestions include clinical interventions such as hormonal replacement or immunomodulation therapy and several clinical or experimental assisted reproduction modalities [8][9][10][11]. Advances in the cryopreservation of oocytes, embryos, and ovarian tissue are promising in the preservation of the reproductive potential, especially when combined with restoration of endocrine function [12-14, 6, 15].…”

Cryopreservation in Assisted Reproduction and Fertility Preservation

“…Additionally, this technique allows the postponement of embryo transfer during a treatment cycle to prevent ovarian hyperstimulation syndrome. Single embryo transfer and cryopreservation of surplus embryos is also an effective policy that diminishes the multiple pregnancy rates and enhances the cumulative pregnancy rates (2,4). Cryopreservation has facilitated the introduction of elective deferred embryo transfers in cases which necessitate pre-implantation genetic diagnosis or screening (5).…”

“…Cryopreservation has facilitated the introduction of elective deferred embryo transfers in cases which necessitate pre-implantation genetic diagnosis or screening (5). By cooling Mechanical damage by ice crystal formation, osmotic stress, membrane permeability and cytoskeletal structural changes due to the cold shock are the major problems that may cause damage to the cells (4,6). Biological systems involved lack of efficient internal defense mechanisms against chilling and ice formation, but intracellular structures and membranes could be protected from cryoinjuries and could be stabilized by cryoprotectants (CPAs).…”

“…Although these agents are used in order to is to prevent damage during freezing, their incorrect use (time of exposure, concentration, temperature of exposure) may result in cytotoxicity (4,7). As an example, exposure of bovine blastocysts to ethylene glycol concentrations greater than 5.4 mol/l for 10 minutes was shown to be detrimental to continued development.…”

Novel Low-Voltage Electro-Ejaculation Approach for Sperm Collection from Zoo Captive Lanyu Miniature Pigs (Sus barbatus sumatranus)

“…Preservation of gametes requires collection of sperm cells and/or oocytes using optimized protocols to minimize potential damages on gametes [ 2 , 3 ]. However, due to species-specific and individual variations, the collection, preservation, and retrieval of gametes are always challenging for veterinarians [ 1 , 4 , 5 , 6 , 7 , 8 , 9 , 10 ]. Semen collection in animals can be achieved by either electro-ejaculation (EEJ) or by penile hand massage.…”