School of Medicine

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  • Shin Yajima

    Shin Yajima

    Postdoctoral Scholar, Cardiothoracic Surgery

    BioI am a board-certified cardiothoracic surgeon in Japan. Throughout my clinical experience and research, I realized that insufficient myocardial blood flow had little impact on myocardial functional recovery because percutaneous coronary intervention or coronary artery bypass grafting (CABG) could approach and supply blood flow to the superficial large coronary arteries, but not to intramyocardial microvascular arteries, especially where microvasculature was scarce or absent. Moreover, myocardial ischemia-reperfusion (I/R) impaired cardiac functional recovery in ischemic hearts, including transplanted hearts. As a result, my research interests include myocardial microvascular dysfunction and myocardial I/R injury.
    During my Ph.D. studies in cardiovascular surgery, I focused on a prostacyclin analog that inhibits thromboxane A2 synthase and promotes angiogenesis and restores myocardial blood flow via proangiogenic and vasodilatory effects. Direct epicardial placement of a microform of this compound in a porcine ischemia cardiomyopathy model resulted in enhanced myocardial angiogenesis and recovery of myocardial function. Then, I developed nanoparticles (NPs) that contained this compound, which I applied to a rat ischemia myocardial reperfusion model with intravenous injection to demonstrate attenuated myocardial I/R injury with selective accumulation in the ischemic myocardium, better-preserved capillary networks, better-preserved myocardial blood flow, and a smaller infarct size. Using induced pluripotent stem cells (iPSCs) and adipose-derived mesenchymal stem cells, I have also worked on tissue engineering for myocardial regeneration. With direct implantation of cardiomyocyte sheets derived from human iPSCs onto ischemic myocardial tissue, we elucidated myocardial regeneration through thickened myocardial tissue, proangiogenic effects, improved cardiac performance, and reduced left ventricular remodeling in both small and large animals. These works have already been published (representative examples are provided below), and I have received a number of academic honors and research grants (ongoing research support; Japan Heart Foundation/Bayer Research Grant Abroad, 01/01/2022 - 12/31/2022).
    My career goal is to attain leadership in academic cardiovascular surgery. During my postdoctoral fellowship, I intend to create novel therapeutic methods to improve the outcomes of ischemic heart disease through engineering analysis and the development of innovative solutions. My mentor, Dr. Woo, is a distinguished mentor with a stellar reputation for training academic surgeons, and Stanford University provides extraordinary research resources. I feel extremely fortunate to have such an ideal environment in which to carry out this project and continue bioengineering's advancement of cardiothoracic surgery.