regular estrous cycle after exposure of rat OT graft to various
glycerol concentrations and duration and various cooling rates
[2, 3]. Robertson [4] and Krohn [5] were able to produce live
offspring after orthotopic transplantation of freshly collected
mouse ovaries. This achievement was followed by the delivery of
live offspring after orthotopic transplantation (ovarian bursa) of
slowly frozen mouse and hamster ovaries in 15% glycerol
[6, 7]. Although these achievements were considered as major
breakthroughs, interest in OT cryopreservation and transplantation
technologies had not received much attention for another three
decades, perhaps due in part to poor rates of cryo-survival and lack
of assisted reproductive technologies (ARTs) that are crucial to
complement utilization of OT. In the 1990s, dimethyl sulfoxide
(DMSO), ethylene glycol (EG), and propylene glycol (PG) were
found to have cryoprotective properties. Among these, DMSO and
EG and sometimes in combination with sucrose have been the most
commonly used CPAs to cryopreserve OT due to their higher
permeation rates as compared to glycerol. Furthermore, slow cooling procedure has been generally favored to rapid or ultra-rapid
cooling during the cryopreservation of OT from a wide range of
mammalian species.
In addition to cryobanking of rodent sperm and embryos,
ovary is an additional tissue for preserving the scientifically important rodent strains in circumstances such as sudden death, diseases,
accidents, poor breeding, or reproductive performance
[8, 9]. Orthotopic transplantations of frozen-thawed OT were
successfully used to rescue genetically modified mouse and rat
strains by using syngenic or athymic mice or rats [10–20]. Recent
cancer treatment modalities are increasingly effective, leading to
successful remission and cure. Unfortunately, aggressive chemo- or
radiotherapy during cancer treatment can have gonadotoxic effects,
causing many young women to live the rest of their lives in
menopause-like state, without the chance to become pregnant.
Furthermore, these women suffer from other health problems
such as osteoporosis, obesity, and heart diseases. OT cryopreservation from the appropriate group of oncology patients before cancer
treatment, and subsequent auto-transplantation after treatment,
may provide future fertility options and prevention of conditions
caused by menopause including osteoporosis [21]. In this context,
rodent models are critical for the studies involving general and
reproductive health since such experiments in humans have ethical
concerns associated with experimenting on human eggs and
embryos and time constraints [22–26]. The achievements made
in rodent models have already led to successful autologous orthotopic (pelvic cavity) transplantation of frozen-thawed OT and lead
to pregnancies and live births in human via natural conception [27–
29]. Similarly, there are other ARTs by which laboratory rodents
could serve as model to restore endocrine and reproductive
470
Yuksel Agca and Cansu Agca
glycerol concentrations and duration and various cooling rates
[2, 3]. Robertson [4] and Krohn [5] were able to produce live
offspring after orthotopic transplantation of freshly collected
mouse ovaries. This achievement was followed by the delivery of
live offspring after orthotopic transplantation (ovarian bursa) of
slowly frozen mouse and hamster ovaries in 15% glycerol
[6, 7]. Although these achievements were considered as major
breakthroughs, interest in OT cryopreservation and transplantation
technologies had not received much attention for another three
decades, perhaps due in part to poor rates of cryo-survival and lack
of assisted reproductive technologies (ARTs) that are crucial to
complement utilization of OT. In the 1990s, dimethyl sulfoxide
(DMSO), ethylene glycol (EG), and propylene glycol (PG) were
found to have cryoprotective properties. Among these, DMSO and
EG and sometimes in combination with sucrose have been the most
commonly used CPAs to cryopreserve OT due to their higher
permeation rates as compared to glycerol. Furthermore, slow cooling procedure has been generally favored to rapid or ultra-rapid
cooling during the cryopreservation of OT from a wide range of
mammalian species.
In addition to cryobanking of rodent sperm and embryos,
ovary is an additional tissue for preserving the scientifically important rodent strains in circumstances such as sudden death, diseases,
accidents, poor breeding, or reproductive performance
[8, 9]. Orthotopic transplantations of frozen-thawed OT were
successfully used to rescue genetically modified mouse and rat
strains by using syngenic or athymic mice or rats [10–20]. Recent
cancer treatment modalities are increasingly effective, leading to
successful remission and cure. Unfortunately, aggressive chemo- or
radiotherapy during cancer treatment can have gonadotoxic effects,
causing many young women to live the rest of their lives in
menopause-like state, without the chance to become pregnant.
Furthermore, these women suffer from other health problems
such as osteoporosis, obesity, and heart diseases. OT cryopreservation from the appropriate group of oncology patients before cancer
treatment, and subsequent auto-transplantation after treatment,
may provide future fertility options and prevention of conditions
caused by menopause including osteoporosis [21]. In this context,
rodent models are critical for the studies involving general and
reproductive health since such experiments in humans have ethical
concerns associated with experimenting on human eggs and
embryos and time constraints [22–26]. The achievements made
in rodent models have already led to successful autologous orthotopic (pelvic cavity) transplantation of frozen-thawed OT and lead
to pregnancies and live births in human via natural conception [27–
29]. Similarly, there are other ARTs by which laboratory rodents
could serve as model to restore endocrine and reproductive
470
Yuksel Agca and Cansu Agca