Accurately selecting oocytes and embryos with high developmental potential is essential for improving the success rate of in vitro fertilization (IVF). KAIST researchers have developed a foundational technology that combines time-lapse imaging, which continuously tracks changes over time, with quantitative three-dimensional analysis to predict developmental potential at an early stage without damaging live oocytes and embryos.
KAIST (President Choongsik Bae) announced on July 21 that Dr. Chungha Lee, a postdoctoral researcher in Professor YongKeun Park's research group in the Department of Physics, received the Basic Science Award for poster presentation at the 2026 Annual Meeting of the European Society of Human Reproduction and Embryology (ESHRE), the world's largest reproductive medicine conference, held in London, United Kingdom, in July.
The Basic Science Award for poster presentation recognizes the most outstanding poster in the basic science category at the ESHRE Annual Meeting, which attracts more than 10,000 participants each year. After reviewing submitted abstracts, the society selects five candidate studies and determines the final winner based on a comprehensive evaluation of the on-site poster presentation and question-and-answer session.
The award recognizes the originality and academic significance of applying holotomography—a technology that uses information about the refraction of light to image the internal structures of live cells in three dimensions without damaging them—to the field of reproductive medicine.
The research demonstrates the potential to develop a next-generation assessment technology that can non-invasively monitor changes in live oocytes and embryos over time, quantitatively analyze them in three dimensions, and predict their developmental potential at an early stage. It also presents a pathway for advancing conventional two-dimensional oocyte and embryo assessment, which has relied heavily on expert experience, toward a more objective and quantitative three-dimensional approach.
In IVF procedures, the selection of oocytes and embryos is a critical factor determining the likelihood of pregnancy. However, because oocytes and embryos are cells that may ultimately be transferred to patients, analytical methods involving stains or fluorescent markers that could affect the cells are difficult to apply.
Clinical practice currently relies primarily on Hoffman modulation contrast microscopy and phase-contrast microscopy, which visualize cellular morphology using differences in light intensity and phase without staining the cells. Embryologists—specialized medical professionals who culture and assess oocytes and embryos during IVF procedures—select embryos for transfer by examining characteristics such as their shape, size, cell-division status, and developmental timing using these microscopes.
However, current assessment methods have limitations because they depend mainly on two-dimensional images and the experience of embryologists, making them largely qualitative. There has therefore been a continuing demand for more objective and quantitative assessment methods.
To overcome these limitations, the research team applied holotomography. This label-free technique requires neither cellular staining nor fluorescent markers. Instead, it measures how light is refracted as it passes through a cell, enabling the internal structure of a live cell to be imaged in three dimensions without causing damage.
The technology can also quantitatively measure the refractive index, which varies according to the density and composition of intracellular materials, allowing researchers to analyze even subtle changes in cellular structure.
Using holotomography, the researchers analyzed the internal structures of oocytes and embryos in three dimensions while keeping them alive and intact. Through experiments using mouse models, they also demonstrated that various biophysical features obtained from early-stage embryos could be used to predict their subsequent development.
Furthermore, the study demonstrated that combining quantitative measurements with artificial intelligence (AI) analysis could enable more advanced assessment of oocytes and embryos beyond conventional morphological assessment, which primarily evaluates features such as cell shape and size.
The related studies have been submitted to international academic journals and are currently under review.
※ Papers:
Title: Label-free 3D subcellular phenotyping of mouse embryos by holotomography enables early prediction of blastocyst formation
DOI: https://doi.org/10.1101/2024.05.07.592317
Title: Holotomography reveals biophysical remodeling of mouse oocytes during post-ovulatory aging
DOI: https://doi.org/10.64898/2026.06.18.733271
The research was conducted through an industry–academia–clinical collaboration involving the KAIST Department of Physics, the Fertility Center at CHA Bundang Medical Center led by Professor Ji Hyang Kim, Avenues, and Tomocube.
It represents a notable example of interdisciplinary research in which an advanced optical platform developed through fundamental physics research was applied to the field of reproductive medicine.
"This award is particularly meaningful because it demonstrates that a new approach for quantitatively analyzing live oocytes and embryos in three dimensions without damaging them has been recognized for its academic value in reproductive medicine," said Professor Park.
"We are currently conducting validation studies using human oocytes. We will continue our research to develop this approach into an objective and accurate technology for assessing oocytes and embryos and ultimately contribute to improving the success rate of fertility treatment."
The research was supported by the Global Leader Research Program of the National Research Foundation of Korea and the Research-Centered Hospital R&D Program of the Korea Health Industry Development Institute.
