Developmental consequences of supplementing with matrix metallopeptidase-9 during <i>in vitro</i> maturation of heat-stressed bovine oocytes

Abstract

Because latent form of matrix metallopeptidase-9 (proMMP9) levels are positively related to blastocyst development, it was hypothesized that addition during maturation may improve development of heat-stressed oocytes. To test hypothesis, 0, 30 or 300 ng/ml human proMMP9 (hMMP9) was added at 18 h of in vitro maturation (hIVM) to cumulus-oocyte complexes matured at 38.5 or 41.0ºC (first 12 h only). Heat stress decreased 24 hIVM proMMP9 levels only in 0 and 30 ng/ml groups and increased progesterone in 0 and 300 ng/ml hMMP9 groups. Heat stress decreased cleavage and blastocyst development. Independent of maturation temperature, hMMP9 at 18 hIVM decreased blastocyst development. In a second study, cumulus-oocyte complexes were matured for 24 h at 38.5 or 41.0ºC (HS first 12 h only) with 0 or 300 ng/ml hMMP9 added at 12 hIVM. Without hMMP9, heat stress decreased 24 hIVM proMMP9 levels and increased progesterone production. Addition of 300 ng/ml of hMMP9 produced equivalent levels of proMMP9 at 24 hIVM (271 vs. 279 ± 77 for 38.5ºC and 41.0ºC treated oocytes, respectively). Heat stress did not affect ability of oocytes to cleave but reduced blastocyst development. Independent of temperature, hMMP9 decreased cleavage and blastocyst development. In summary, hMMP9 supplementation during IVM did not improve development of heat-stressed oocytes even when it was added for the entire maturation period. At doses tested, hMMP9 appeared detrimental to development when supplemented during the last 12 or 6 h of oocyte maturation.

Heat stress impairs gap junction communication and cumulus function of bovine oocytes

“…Heat-induced increases in progesterone production during maturation have been described previously by our laboratory [ 38 , 39 ]. Efforts of study three extend these findings and document an effect of heat stress exposure to increase progesterone production during the early period of maturation.…”

“…Effort to include earlier maturation times in this study allowed for assessing when levels in the conditioned medium become detectable. Priority for examining consequences of 41°C was based on previous efforts reporting heat-induced increases in progesterone during the latter part of maturation [ 38 , 39 ]. Effort to examine consequences of a more severe heat stress (42°C) was prioritized over examining consequences of 40.0°C to increase the likelihood of detecting heat-induced differences during times when progesterone production by the cumulus is low.…”

Heat-induced hyperthermia impacts the follicular fluid proteome of the periovulatory follicle in lactating dairy cows

“…Direct exposure of cumulus-oocyte complexes to a physiologically-relevant elevated temperature during the first half of in vitro maturation reduces embryo development [9–12] in a manner consistent with what has been observed after heat-induced hyperthermia occurring in vivo near the time of estrus [8, 13, 14]. Heat stress exposure during the first half of in vitro maturation heightens progesterone production and alters the transcriptome and interconnectedness of the cumulus [15–17] surrounding the maturing oocyte. Heat-induced differences in cumulus function persist despite efforts to mature cumulus-oocyte complexes under thermoneutral conditions for the remainder of maturation [16].…”

Oocyte in vitro maturation: A sytematic review

“…In an experimental study, the oocytes in the ovaries of mice were destroyed chemically and the oocytes removed and later injected with bone marrow cells and the chemically-depleted ovary resumed small antral follicle formations ( 79 ) . Adding matrix metallopeptidase to heat-stressed bovine oocytes during IVM has not been shown to improve the in vitro oocyte growth and even resulted in a detrimental effect ( 80 ) . The development of culture systems for animals provides valuable information to develop culture media for human oocyte IVM.…”