Real-time multiparametric monitoring of oxidative stress status during embryo development by implementing high-performances electrochemical microdevices – EmbryoElecSense

In western developed countries, about 3% of births proceed from assisted reproductive technologies, most of them involving in vitro culture of the embryos. It was recently shown that oxidative stress, related to reactive oxygen (ROS) and reactive nitrogen (RNS) species in the culture medium, are major factors influencing the success rate of such embryo biotechnologies. This will affect the future health of the humans born from these biotechnologies.
In this context, the project EmbryoElecSense will develop innovative multiparametric microdevices to monitor in real time, in situ and in label-free manner, the oxidative stress during in vitro embryo development in the pre-implantation period (4 days), at the level of embryo population and then at the scale of a single embryo. Rabbit embryos will be used as the model. The challenges in terms of sensing performance are related to (i) the expected low levels of ROS and RNS due to their relative short-life time and (ii) to the success of performing simultaneous detections. To this end, specific microdevices will be designed, with the incorporation of several microelectrodes in the bottom of culture wells, for monitoring the release of ROS and RNS from embryos. Such non-invasive approach based on electrochemical techniques will bring high selectivity, high temporal and spatial resolutions. The monitoring will be undertaken in situ during the period corresponding to the embryo development within incubator.
According to the objectives, this project comprises four main tasks. The first task will assess the level of intracellular oxidative stress thanks to fluorescence measurements and gene expressions at each stage of embryo development. The second task will be related to the design and optimization of innovative microdevices for the in-situ monitoring of ROS and RNS , from embryo populations to the scale of single embryo. The devices will be characterized for their analytical performance under experimental conditions used for embryo development in incubator. Then, in the third task, these microdevices will used for monitoring extracellular releases of ROS and RNS by embryos. Results will be compared with subsequent measurements by fluorescence. Finally, the last task will be devoted to the investigation of oxidative stress at the level of single embryos, to assess the inter individual variability as a function of the culture conditions .
Thus, this project is aiming at establishing any correlations between intra and extracellular productions of ROS and RNS during early stages of embryo development. Such investigation will allow a deep analysis of the kinetics involved in intra/extra oxidative stress. In addition, it will also provide quantitative determinations of ROS and RNS levels implied during the different stages of embryo development. Finally, correlations between intra and extra production of reactive species will be indicative of the redox status of embryos. The development of this methodology for real time and label-free extracellular detections of ROS and RNS should thus provide an innovative tool for monitoring embryo development during in vitro culture, optimizing culture media, and preventing damages and long term effects on embryos.
The proposed scientific consortium of EmbryoElecSense is composed of three complementary research groups specialized and actively working on embryo development, engineering of microelectrodes in confined space, and in vivo and vitro micro-electroanalysis.
The proposed new technological tools will undoubtly pave the way for understanding interindividual variabiliy in the embryo resistance to culture inducing oxidative stress.