Reproductive Medicine

Assisted Reproductive Technology have enabled many couples who would otherwise be unable to conceive. However, the low pregnancy rate after embryo transfer (ET) remains as a serious problem. Failure of pregnancy after ET is caused by poor embryo quality, low uterine receptivity, or ineffective ET [1]. The solution for each problem at present is as follows. The first problem is about poor embryo quality. The quality of an embryo is bad if the embryo has abnormal karyotypes or morphologic problems. Embryo culturing and screening techniques have been developed to solve this first problem [2,3]. The second problem is about low uterine receptivity. If the patient’s uterus has anatomic or immunologic difficulty, the receptivity for embryo implantation is low. Surgery or drug therapy have been considered effective for this second problem. The third problem is about ineffective ET. If an embryo is injected, but cannot be delivered to an area suitable for implantation, the ET is ineffective. However, there is no countermeasure to resolve this third problem. To keep an embryo at the right position after ET, we propose a novel ET system composed of a microrobot, a catheter, and a guiding magnet. The microrobot delivers an embryo and control the place of the embryo implantation [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.

Cell sorters are widely used in cell-based biology research and are expected to be applied to new medical fields such as the mass collection of cell clumps in regenerative medicine and the collection of rare cells in fertility treatment. However, FACS, which is a cell sorter commonly used today, is not suitable for these applications due to concerns about the adverse effects of high-speed flow and fluorescent staining on cells, and the inability to perform cell sorting based on temporal observation. In this study, we develop a new cell sorter that is minimally invasive and can be used for cell sorting based on temporal observation by creating a photoresponsive microwell array in which cells can be cultured and observed in wells and wells can be manipulated by addressing them with photoresponsive microvalve array. To achieve this goal, we created a photoresponsive microwell array, drove a photoresponsive microvalve using a photothermal conversion material with better efficiency, and conducted experiments to collect microbeads in wells using liquid. As a result, we succeeded in fabricating photoresponsive microwell arrays with microvalves up to 0.15mm in diameter, driving 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.