embryo transfer
Assisted reproductive technology has made it possible for many couples who otherwise would not be able to conceive to conceive. However, the low pregnancy rate after embryo transfer remains a serious problem. Causes of pregnancy failure after embryo transfer include poor embryo quality, low uterine receptivity, and ineffective embryo transfer [1]. Currently, the solutions for each problem are as follows:
The first problem is the poor quality of the embryos. Embryos with abnormal karyotypes or morphological problems are considered to be of poor embryo quality. To solve this problem, embryo culture and screening technologies have been developed [2,3].
The second problem is that the uterus is less receptive. If the uterus has anatomical or immunological problems, it is less receptive for embryo implantation. Surgery and drug therapy are considered effective for this problem.
The third problem is that ET is not valid. Even if the embryo is injected, if it does not reach a suitable site for implantation, ET is ineffective. However, there are no measures to solve this third problem.
Therefore, we propose a new in vitro fertilization system consisting of a microrobot, catheter, and guiding magnet. Microrobots transport the embryo and control its implantation position [4].
1.W. B. Schoolcraft, “Importance of embryo transfer technique in maximizing assisted reproductive outcomes” Fertility and Sterility, Vol.105, No.4, 2016.
2.P. R. Brezina, R. Anchan, W. G. Kearns, “Preimpantation genetic testing for aneuploidy: what technology should you use and what are differences?” J. Assit. Reprod. Genet., 33, 823-832, 2016.
3.A. Simon, N. Laufer, “Assessment and treatment of repeated implantation failure (RIF)” Assisted Reproduction Technologies, 29, 1227-1239, 2012.
4.S. Koseki, K. Kawamura, F. Inoue, K. Ikuta and M. Ikeuchi, "Magnetically Controlled Microrobot for Embryo Transfer in Assisted Reproductive Technology," 2019 20th International Conference on Solid-State Sensors, Actuators and Microsystems & Eurosensors XXXIII (TRANSDUCERS & EUROSENSORS XXXIII), 2019, pp. 2217-2220, doi: 10.1109/TRANSDUCERS.2019.8808545.
Light-activated cell sorting array
Cell sorters are widely used in biological research using cells, and are expected to be applied to new medical fields, such as collecting large amounts of cell clusters for regenerative medicine and collecting rare cells for infertility treatment. However, FACS, which is currently a commonly used cell sorter, is not suitable for these applications because there are concerns that high-speed flow and fluorescent staining may have an adverse effect on cells, and it is not possible to sort cells based on temporal observation. is considered unsuitable.
Therefore, in our laboratory, we created a light-responsive microwell array, cultured and observed cells in the wells, and addressed and manipulated the wells with a light-responsive microvalve array. We are conducting research with the aim of developing a new cell sorter that enables cell sorting.
We fabricated a photoresponsive microwell array, drove a photoresponsive microvalve using a more efficient photothermal conversion material, and conducted experiments to collect microbeads into wells using liquid. As a result, we created a photoresponsive microwell array with microvalves up to 0.15 mm in diameter and succeeded in driving the photoresponsive microvalves with high observability and reproducibility [1].
1.A. Mifune, Y. Ezaki, D. Saito, K. Uto and M. Ikeuchi, "Image-Based Cell Sorting System Using Light-Actuated Microvalve Array," 2022 IEEE 35th International Conference on Micro Electro Mechanical Systems Conference (MEMS), 2022, pp. 309-312, doi: 10.1109/MEMS51670.2022.9699838.
Development of technologies for the viability assessment and
developmental competence prediction of oocytes and early-stage embryos
Most oocytes in the ovaries perish without the chance to be fertilized, and only a limited number of fertilized oocytes reach the blastocyst stage. This research aims to answer the questions “What determines the developmental competence (cell fate) of an oocyte?” and “What characteristics should oocytes and early embryos possess for proper development?” We are currently investigating these complex phenomena at the molecular level. Our efforts include elucidating the biological characteristics of healthy oocytes and early embryos with high developmental competence, identifying effective markers for cell evaluation, and developing technologies employing these markers. In addition, we plan to explore methods to activate or rescue cells with insufficient developmental competence. Through cellular evaluation, we hope to contribute to the field of reproductive medicine and the aquatic and livestock industry.