Data di Pubblicazione:
2022
Citazione:
Microenvironment factors promoting the quality of vitrified cat oocytes / M. Colombo, I.M. Alkali, G.C.R. Luvoni. ((Intervento presentato al convegno The 9th International Symposium on Canine and Feline Reproduction in a joint meeting with the 24th European Veterinary Society for Small Animal Reproduction Congress - ISCFR-EVSSAR 2020+2 tenutosi a Milano nel 2022.
Abstract:
In oocyte cryopreservation programs, vitrification has overthrown conventional slow freezing both
in veterinary and human medicine. In animals, its feasibility in field conditions makes it the preferred
technique for the safeguard of genetic resources from zoo or wild animals, including threatened felids,
for which the domestic cat is an outstanding model.
The avoidance of ice formation saves oocytes from a certain extent of damage, but other cellular
injuries, such as cytoskeleton, mitochondria and meiotic spindle alterations, DNA damage, zona
pellucida hardening and cumulus cell loss, might occur as a consequence of vitrification. After
warming, although the exact mechanisms are still unclear, degeneration is a frequent outcome for cat
vitrified oocytes. For immature (germinal vesicle) gametes, in vitro maturation after warming is a
challenge, and cleavage after fertilization barely reaches 15-30%, while for mature (metaphase II)
cryopreserved gametes it can get to 30-50%. Anyway, the progression to late embryos stages is often
impaired, and improvements are needed.
Despite being necessary to achieve the vitrification state, the exposure to high concentrations of
cryoprotectants and the sharp decrease of temperature are far from physiological conditions, and after
warming the conventional in vitro culture may not be enough for vitrified oocytes to recover and
demonstrate their full developmental potential. Physical or chemical enrichments to the culture
microenvironment could create more favorable conditions and promote vitrified oocyte survival and
embryo development.
To better preserve intracellular architecture, our recent studies employed three-dimensional (3D)
culture systems for the in vitro maturation of vitrified oocytes. The 3D system, together with
companion cells, was able to support meiotic progression, but the physicochemical-enriched
environment was not enough to obtain a significant change in vitrified oocyte developmental abilities
[1]. The use of a different physical modification of the culture environment (i.e., 3D liquid marble
microbioreactor), also led to similar results. Following a different approach, some studies focused
their attention on specific intracellular pathways. For instance, the chemical inhibition of apoptosissignaling
molecules to prevent cell death [2,3] gave encouraging results for what concerns in vitro
maturation and embryo development.
Although continuous progresses are being made, there is still a strong need to enhance feline vitrified
oocytes outcomes. When specific genetic pools have to be preserved or when there is no male
counterpart for fertilization, oocyte cryopreservation is the only possibility, and the development of
new vitrification and culture strategies will be crucial.
Supported by Polish National Agency for Academic Exchange, Grant
PPI/APM/2019/1/00044/U/00001 and by Università degli Studi di Milano "Piano di Sostegno alla
Ricerca 2020 (Linea 2 Azione A).
[1] Colombo M, Morselli MG, Tavares MR, et al. Developmental competence of domestic cat
vitrified oocytes in 3D enriched culture conditions. Animals 2019;9:329.
[2] Arayatham S, Tiptanavattana N, Tharasanit T. Effects of vitrification and a Rho-associated coiledcoil
containing protein kinase 1 inhibitor on the meiotic and developmental competence of feline
oocytes. J Reprod Dev 2017;63:511-7.
[3] Colombo M, Zahmel J, Jänsch S, et al. Inhibition of apoptotic pathways improves DNA integrity
but not developmental competence of domestic cat immature vitrified oocytes. Frontiers in Veterinary
Science 2020;7:766.
Tipologia IRIS:
14 - Intervento a convegno non pubblicato
Elenco autori:
M. Colombo, I.M. Alkali, G.C.R. Luvoni
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