In vitro production (IVP) of embryos has been broadly employed in cattle seeking to maximize female reproductive efficiency and germplasm dissemination, among other aims [1]. Indeed, IVP has proved to be a powerful tool in current livestock systems, especially when combined with sexed semen and genomic selection [2]. However, there are still some unresolved aspects of IVP that hinder its efficiency and wider application [3]. Chromosomal abnormalities, decreased number of cells, aberrant gene expression, and dysregulated metabolism are common phenotypes of IVP-derived embryos, altogether leading to lower pregnancy rates and calves of poorer viability [4].

During the past decades, embryonic abnormalities resulting from IVP systems have been tackled by the development of improved culture systems [5]. This has been made possible by studies mimicking the in vivo reproductive environment where oocytes are generated, fertilized, and develop to the blastocyst stage [6]. Accordingly, there is a growing debate regarding the static conditions under which oocytes and embryos are maintained during IVP [7]. Mainly after ovulation, oocytes and embryos are exposed to fluid flows and mechanical forces resulting from the movement of ciliated cells and muscle contraction in the oviduct and the uterus [8,9]. These stimuli are thought to activate intracellular pathways regulating pre-implantation development, beside contributing to the diffusion of substances (e.g., gases, nutrients, reactive oxygen species, and waste materials) in the reproductive tract. In agreement with these, studies with humans, mice, cows, and pigs indicate a positive effect of dynamic IVP systems, ultimately boosting embryonic quality, developmental rates, and cryotolerance [5,7].

Dynamic IVP systems may encompass the use of microchannels [10,11], microfunnels [12] and tilting embryo culture systems [13,14]. Also, in keeping with in vivo embryos being exposed to micro-vibrations ranging from 5 to 20 Hz, Isachenko et al. [7,15] found that a similar mechanical stimulus during in vitro culture (IVC) of human embryos led to increased developmental rates. Likewise, Mizobe et al. [16] reported a beneficial effect of micro-vibration when applied during in vitro maturation (IVM) of pig oocytes. Later on, these findings were confirmed by a few other studies in humans, mice, and cows [[17], [18], [19], [20], [21]], but it remains largely unclear to what extension micro-vibration affects the embryo.

Cells can sense mechanical cues and respond accordingly through adaptative pathways that determine genome integrity and regulate cell survival, proliferation, and differentiation. Mechanosensitive transmembrane junctions, the actomyosin cytoskeleton, the linker of nucleoskeleton and cytoskeleton (LINC) and the nuclear lamina are responsible for propagating mechanical forces to the nucleus, shaping chromatin structure and gene expression [22]. Alternatively, mechanical stimuli are transduced through signaling molecules such as YAP1 and WWTR1 that translocate to the nucleus and interact with SMAD2/3 to promote the Hippo pathway. YAP1/WWTR1-SMAD2/3 complex also binds to POU5F1 to activate pluripotency-related genes [23]. Changes in chromatin structure induced by mechanical forces are linked to histone post-translation modifications such as acetylation and methylation, profoundly changing gene expression and determining cell fate [[24], [25], [26]].

Here, we tested the hypothesis that micro-vibration can improve developmental rates of IVP-derived bovine embryos, an effect that we expected to be paralleled by changes in the chromatin structure and gene expression. As a result, the employment of micro-vibration during both IVM and IVC led to cryoresistant blastocysts as indicated by the lower incidence of apoptosis following vitrification-thawing, although pre-implantation developmental rates were not boosted. Furthermore, the treatment led to several epigenetic and transcriptional changes, highlighting the profound impact of micro-vibration on the embryo.